The American Pleistocene Expansion Page

A Companion to 11,000 Years Lost

A Note to Researchers

Populating the Western Hemisphere Megafaunal Extinction
The Ice-Free Corridor Overkill
Boat People Climate
The Solutrean Hypothesis Disease
Who Came? Replacement
Bibliography and Netguide Bibliography and Netguide

Oral Prehistory
Parsimony and the Magic Bullet

A Note to Researchers

If you have a true and passionate interest in the Ice Age and the mysteries it holds, you may like this site anyway; but be warned. I'm not a professional archeologist, anthropologist, geologist, botanist, zoologist, or geneticist; or even an experienced amateur in any of those fields. I'm a children's writer who wrote a book set in Clovis-era Texas and found that I couldn't leave it behind when I was, theoretically, finished. For the story, I had to ignore certain questions and pick a version of Clovis life that suited my public's needs; alternate versions of Clovis, opinions on the Pre-Clovis paradigm, the process of populating the western hemisphere, and the many other fascinating topics that fit under the heading of "Pleistocene" continue to bop around in my head, and I continue to pay attention to the field. Occasionally, to maintain my sanity, I write some of it down. Possibly, you will find some topic here that intrigues you enough to look into further, or an idea that you can revise into a useful idea of your own, or a topic on which to hang a research paper.

For the benefit of such people, I will endeavor to provide links and references sufficient to launch your own research. If you came here looking for an authority on the Ice Age, however, keep looking. Research is a process of finding out what work has been done in a field and/or uncovering new facts for yourself, then synthesizing that work in the way most relevant to your purposes. Different people with different goals synthesize data in different ways. In my case, I have done massive infodumps into my own head in order to generate a story; as a side-effect of which, I also have opinions on topics outside the range of that story.

Because I am oriented toward creating stories, I interpret evidence so that it makes narrative sense; and I'm not afraid to fill in the gaps where evidence doesn't exist, because if I don't do that, I can't tell the story. Occasionally this may enable me to have an insight that a scientist, bound by the data, cannot; and this insight may or may not prove to be close to the truth as more data emerge. The scientist's job is to uncover the truth, however long that may take and however often that may have to be revised. My job is to make things up that sound real. Don't believe anything I tell you - unless you examine the scientific data for yourself and still think my idea makes sense.

Also - it has been brought to my attention that students exist out there who, when their research paper comes due, go out into the internet and download somebody else's work instead of doing their own. You will so get busted if you try that with this site! For one thing, I am deliberately keeping hard facts to a minimum, though I provide enough references that anyone interested should be able to look them up for themselves. It's poor role-modeling, but I didn't have the energy to footnote, sorry. Copying this wholesale will net you a failing grade on that score even if your plagiarism is not detected, which isn't very likely.

Whoever assigned you this research paper may have wanted a compendium of facts or he may have wanted your synthesis of the facts, but one thing I can guarantee you - he did not want my synthesis of the facts! And don't fool yourself - he'll know it's not you. He's been hearing your voice all semester and you don't sound like me. All he has to do is put some distinctive turn of phrase into a search engine and voila, big fat failing grade for you and serve you right. Plagiarism isn't just against school policy; it's a crime punishable by law; and it's not just a crime, it's a massive stupidity; and it's not just stupid, it's boring. Doing the work is more fun than not doing the work. Cheating is like junk food - maybe it feels better at first, but as time goes on, you find all it gets you is a combination of malnutrition and obesity. We have enough fat heads with starved imaginations in the world without adding you to the number, sweetie.

Oh, and about those dates
Numbers confuse me. I have a hard time remembering them. Archeological dating methods similarly confuse me. There's three ways to refer to dates in this context: Calendar Years Before Present, Radiocarbon Years Before Present, and B.C./A.D. The reason there's a difference between CYPB and RCYBP (I'm not making up those acronyms! They're both used in the literature!) is that, after we'd been using radiocarbon dates for awhile, a discrepancy between radiocarbon dates and confirmable calendar dates was discovered. Since you can't dig back through every paper ever published and change them, somebody came up with conversion formulae and everybody kept going. Archeologists deal in geologic time, anyway, in which the difference between "100 years" and "instantly" is negligible. It doesn't help that "present" as defined in the "before present" years above, is 1950. I'm always moderately confused about what dates I'm using and I make no attempt to be consistent, mostly talking about "the late Pleistocene" when I have to. (See, you really don't want me as your chief reference source!) I used 11,000 Years Lost, referencing Radiocarbon Years Before Present, as my title instead of the equivalent 13,000 Years Lost, referencing Calendar Years Before Present, because my protagonist was eleven years old. That's also kind-of-sort-of 9,000 years B.C., but I never use that system and only the oldest archeological work on this material does. Anyway, let's get on to the good stuff.

Populating the Western Hemisphere

It's the 40,000--or-more-year question: How did we get to the Americas, when did we get to the Americas, and who were "we" when we did it? It's a difficult question not only because the evidence is scanty, difficult to find, and equally difficult to interpret, all of which is bad enough, but because of social questions it also gets touchy as people try to claim some vague credit for being first or most innovative or whatever for certain regions or population groups.

So, let's talk about population movements. In The Real Eve, Stephen Oppenheimer discusses the spread of modern humanity out of Africa into the remainder of the globe. According to his genetic data, which I freely admit I didn't understand in detail, homo sapiens came out of Africa in a single migration event - which may, however, have taken a long time in human terms - and proceeded to advance into territories previously occupied by archaic homo species such as erectus, neanderthalensis, and heidelbergensis. All modern human beings are descended from these original Africans, some of whom stayed in Africa. This model or a version of it is accepted by most modern scientists as far as I know, so I'm comfortable using Oppenheimer's popular book on the subject as a basis for this discussion.

Oppenheimer's theory for how the population dispersed is that we were, by choice, beachcombers. We followed the beaches, which had a constant supply of shellfish, safe sandy/gravelly places to build fires, and far less cover for dire wolves and tigers than the interior. Since water levels rose at the end of the Pleistocene, and archeology along the continental shelves is difficult and has only recently begun to be undertaken on any kind of scale, the evidence for this theory is absent, and it's a little hard to falsify. However, it makes so much sense to me that I'm willing to take it as a working hypothesis until several sites which, under this hypothesis, ought to produce artifacts, don't.

Under this hypothesis, the subset of Beachcombers in whom we are interested gradually make their way around the south and east coasts of Asia. At some point prior to 60,000 years ago, they start to use boats in some capacity. We know this, because they could not have gotten to the Australia/New Zealand mega-island without them, and they did so. Recent discoveries on the island of Flores indicate that homo erectus had some sort of boat as long as 800,000 years ago - a revolutionary notion that I've noticed has not bent minds as much as it deserves to. We must stop thinking of boats as a high-tech concept - they are part of our evolutionary history that should not be ignored. (There's a tangent here about the importance of boats to humanity that I'm not boat-savvy enough to go off on. Suffice to say that I think it's really strange that culture has created so many people like me to whom boats are not a part of daily life that American archeology didn't take their use into account at all when discussing this question until forced to within the last 20 years.)

Following beaches could permit coastal occupation throughout Asia and Europe, and as close to the Americas as Beringia, the famous "land-bridge." I dislike that term, as it implies that Beringia was only important as a means to get from one continent to another. In fact, it was a geographic entity in its own right, as Central America is today. During large chunks of the available time, the beaches of Western Beringia would have been covered by glaciers, so the presumed Beachcomber lifeway would have had to undergo significant change to get any further.

This is all expressed in geologic time, and we today are all too likely to look on these population movements as a mass migration, with reaching Australia and America as goals. But everything happened in human time. The world was populated for human reasons and at a human rate of speed, not in response to some global directive to go forth and colonize, but in response to ordinary daily human desires and necessities.

American history, in particular, is so full of individuals with "itchy feet" who long perpetually to see over the next hill that we cannot rule out curiosity and wanderlust as an agent of discovery; but to ordinary, responsible men and women with children to feed, simple restlessness is an inadequate reason to move. Going into unexplored territory involves leaving behind known sources of food, clothing, shelter, fresh water, and tool materials. This is one reason to stick to the beach as long as you can get enough fresh water - despite variations in beaches, the range of food resources is likely to be similarly located and call on a similar range of skills along any ocean in the world. Since all rivers eventually find their way to the sea, following the beach in unfamiliar territory is a sensible way to locate fresh water, and rivers - especially for a population with boats - provide access to the interior with less chance of getting lost than walking across forest or coastal plain. Even for beachcombers, the interior would provide important resources, such as wood and hide for boats, fruit, and stone for tools.

So what I envision is small groups of people traveling in response to specific stimuli. They would have a particular territory with which they were familiar, and would expand into new territory a mile or so at a time, as they began to strain an area's resources - which might be because they consumed too much food and fuel for the territory to replace; or because a disaster such as drought, disease, or a hurricane changed the available resources; or because Individual A couldn't get along with Individual B any more and there "wasn't room on the beach for both of them." This movement would not have been linear and certainly would not have been directed toward specific geographical goals, but would follow the beach, explore the interior, and go east, west, north, and south in an unsystematic way depending on need. Over the course of millennia, the descendants of a group that had left an area might return to it, carrying various genetic and morphological changes that had occurred in that population as they adapted (for example) to cold or heat, a high-protein or high-carb diet, a shortage of some nutrient, or the unexpected reproductive success of some individual with an otherwise irrelevant trait like blue eyes or shovel-shaped incisors.

Possibly the Beachcombing cultures would have some class of people who were designated as explorers or traders - young men who weren't considered ready to marry, old women past their reproductive years, gay people of either gender - who gained status by taking the risks of entering new territory. That's probably the tack I'd take if I were writing a story about this stage of human prehistory.

The Ice-Free Corridor

When I first began research, the Clovis-first paradigm reigned supreme, and I was willing to accept it as a working hypothesis. Certainly any pre-Clovis cultures in North America must have been very clean livers indeed, for their traces are few and ambiguous. I chose Clovis as the culture to exhibit in 11,000 Years Lost because they were the earliest culture we could make any reasonable deductions about, because they cohabited with mammoths (and the importance of mammoths, charismatic creatures that they are, in my desire to write this book is not easily overstated), because they definitely lived in Texas, and because their points are so pretty. (See the Fenn Cache in all its glory)

Bear in mind that I was reading publications available to me in university libraries, which necessarily lag behind the actual work, though they run ahead of general public knowledge. The first cracks had begun to appear in this construction already, but the conservative and deliberate progress of archeological publication had not yet made this clear to a lay reader such as myself; and the handful of professional archaeologists with whom I communicated had no interest in feeding me fringe theories. This, then, is the vision of the peopling of the Americas offered to me as a synthesis in the mid-90s:

The existence of Beringia and the existence of the joined Cordilleran and Laurentide ice sheets were mutually dependent. So long as Beringia existed, no way south of the ice existed as the glaciers blocked it. When the glaciers began to melt, however, and the sea level began to rise, a way opened up at the meeting of the two large ice sheets at the same time that the big game hunting grounds of Beringia began to sink beneath the cold waters of the northern Pacific. With retreat to Asia cut off behind them, the human inhabitants, in company with Asian megafauna such as elk (wapiti) and grizzly bears (which are genetically identical to the large brown bears of Eurasia) traveled down the Ice Free Corridor and exploded into a lower continent that had never seen man before. The Clovis culture developed rapidly and, in the manner of people everywhere faced with easy abundance, overdid a good thing. Pursuing easy game, they made an Incredible Journey from south central Canada to the tip of Tierra del Fuego in a mere 500 years. At that point, the extinction of the megafauna - helped along if not actually caused by exuberantly wasteful human hunting practices - forced people to scale back their big game hunting activities and adapt to local conditions.

This remarkable story had a number of strengths, not least of which was, that it is falsifiable. This means that it's possible to think of ways to prove it wrong. That sounds backwards, I know - but if nothing you could possibly learn could prove something wrong, it's pointless to investigate it. A theory that is not falsifiable (for instance: "I'm God and I created the world last Tuesday, planting all kinds of false memories and artificially aging everything I created so it would look billions of years old") is scientifically irrelevant. "Reindeer can fly" is not a falsifiable statement, because any reindeer that doesn't fly might have a reason not to want to. Someone who seriously believes that reindeer can fly can come up with endless excuses for any particular reindeer not to do so. "No reindeer can fly," however, is falsifiable, because we can easily imagine a circumstance to prove it wrong - a single instance of reindeer flying disproves it. We can never prove that no reindeer can fly, because we can't test every reindeer; but, until we get a good, solid demonstration of reindeer flight, we can comfortably accept "no reindeer can fly" as a working hypothesis.

Similarly, any human artifacts from south of the ice sheets which can be securely dated to a time when the ice had not yet melted enough to permit human passage would prove that the first humans in America did not come down the ice-free corridor. In the absence of such artifacts, the Ice Free Corridor/Clovis First theory explained the poverty of the archeological record - for Clovis sites are notoriously scant in their production of recognizable artifacts, and pre-Clovis sites have for the most part been few, widely-scattered, insecurely dated, and scanty even when you find them. A highly-mobile population of big game hunters that burned through resources like wildfire would seldom stay long enough in one place to create a good site and would use lightweight, perishable materials in preference to heavy, permanent ones that they'd have to carry around. Like any good hypothesis, it provided a starting point for choosing sites to explore. The entire surface area of the Western Hemisphere being rather a large area to investigate properly, and discovery of artifacts without looking for them being random and uncontrollable, some criteria must be adopted for locating the most potentially interesting places to stick one's trowel into the ground.

This "Blitzkrieg" model of human expansion also served as a framework for an elegant theory of megafaunal extinction, known as "Overkill." Postulated by Paul Martin, the Overkill theory essentially stated that Ice Age humans, like Atomic Age ones, are bad for the environment. Looking over the globe, and comparing the best estimates for arrival of modern humans with best estimates for the worldwide extinction of megafauna, Martin found that the one followed the other as the night the day. Given that the climactic changes were already putting large animals under stress, and that human beings grow wasteful when faced with abundance and are capable of such behavior as killing for sport, we all found it easy to accept that then, as now, human beings were directly responsible for many extinctions. Overkill became the dominant hypothesis for megafaunal extinction.

It's all very tidy, but I never liked it much. There are scientific reasons for this now, but at the time, my problem was that the Ice-Free Corridor and Overkill didn't make story sense to me; and since they didn't, discontinuities in the evidence bothered me more than they did professional archeologists. Both seemed to me at best to be convenient interim theories that could serve as place-holders for the truth. I'll discuss Overkill later in the context of the megafaunal extinction. Let's deal with the Ice Free Corridor first.

In order for the dates to work, people would have to have started down through the Ice Free Corridor as soon as it opened; and I couldn't imagine why anyone would want to go there. Situated between two large glaciers, the Ice Free Corridor would be every bit as cold as the ice on either side of it; it would stretch for miles without a bite to eat in it for man or beast; and all beyond it would be a mystery. For all the first Americans would know, it could extend forever into the land of the spirits or another ice field. No one who could avoid such a place would enter it. The more I found out about the process of deglaciation, the less plausible the Corridor seemed. When a glacier first melts, it forms a lake; when the lake drains away in a catastrophic flood after the ice dam breaks, it leaves behind a wasteland of rocks, mud, and debris. Nothing will grow there until the wind carries in spores and seeds and these spores and seeds get enough warmth to germinate and enough soil to root in.

Imaginatively, I couldn't make it work, and this made me peculiarly sensitive to the lack of data to support it. No artifacts from the Corridor itself; a tendency for the oldest artifacts to be found well south of the area where the Corridor would have emptied into the unglaciated continent; little (though not no!) direct evidence of human predation on any large game other than mammoth (which died out) and bison (which speciated). I was glad to have set my story thousands of miles and 500 years away from this theoretical drama, absolving me from the need to incorporate it.

Boat People

Back in the mid-90s, I would wonder grumpily why no one was considering any hypothesis involving the use of boats. I didn't know about the Isle of Flores and the 800,000-year old watercraft in those days, but I knew about the Australians, and looking at the map, I saw a perfectly good coastal boat route into the Americas. Although it would be too optimistic to envision a population of Beringians with an Arctic adaptation as sophisticated as historic peoples such as the Inuit, projecting modern conditions backwards indicated that, for much of the year, the water would be as good as or better than the land as a food provider. Fish and sea plants thrive in cold conditions, and the cold-adapted mammals who exploit this have water resistant fur and lovely thick layers of fat. Blubber is wonderful stuff for a subsistence hunter - food, fuel, and lubricant in one. Why should not boat-savvy humans hunt around the edges of glaciers, perhaps following seals out of sight of land occasionally in the certainty that they'd fetch up on land someday? Why should not adventurous parties of hunters, separating themselves from the main group and steering by the stars, roam south of the ice to see where the whales or the otters go in the winter, long before Beringia began to sink beneath the waves or the Ice Free Corridor to melt? Such people might visit for a short time only, or only in certain seasons, and would presumably stay near their boats when they came to land, leaving low-impact campsites on drowned land where no one had yet looked for evidence of them.

I am proud to say that I thought this (though at that time, my thought consisted mostly of wondering crossly: "But what if they had boats? Why should they have to walk?") independently before I started running across archeologists who wondered the same thing. To my vague storyside objections, the professionals added the specialist knowledge that the coast of Canada would not have been entirely icebound. There would have been "glacial refugia," places where upwellings of warm water and other meteorological phenomena left the coast ice-free and accessible, at least as attractive as the Ice-Free Corridor would have been. The chief weakness of the Boat People theory was absence of evidence - but in the absence of funding for coastal archaeology, this was hardly a compelling weakness. At the time I started this research, the search for data had begun - in southeastern Alaska, western Canada, the northwestern U.S., and the islands off the coast all along the continent - but it did not begin to be accessible to me until my second round of research, in the late 90s and the first couple of years of the 21st century.

American archeology is a contentious, conservative discipline. Sites with evidence of Pre-Clovis occupation existed during my first round of research, but they were all nitpicked to death in peer review, to the point that the people championing these sites refer to the "Clovis police." One of the heroes of modern archaeology is James Adovasio, whose excavation at Meadowcroft Rockshelter has withstood more intense scrutiny than any other North American site I ever heard of. The lowest level with possible human occupation dates to 21,000 Years Before Present; the lowest level with undisputable traces of humans dates to 16,000 YBP - 3,000 Years Before Clovis. Is that cool or what? The Clovis Police have taken his dates apart and put them together again ad nauseum, but in the end the objections boiled down to "It's too weird and isolated; we can't believe it till we see more similar sites."

What finally prompted the active funding of the search for the Boat People at last was the "death" (so declared a little prematurely) of the Clovis First paradigm, not at Meadowcroft (which would have been satisfying) but in the field at Monte Verde, Chile (which in some ways is even better). This important site deserves to be studied for its own sake and I recommend you take a look at Tom Dillehay's books on the topic. It falsifies Clovis First at last by demonstrating conclusively that people had been living in Chile at the very time that the corridor would have been opening for the first time. Despite a few prominent holdouts (including many innovative workers who are not to be lightly dismissed), the sophisticated adaptations and solid dating of the Monte Verde site effectively falsify the notion that the first humans in the Americas came between the ice sheets. It doesn't mean that no one ever came that way at all, or explain what relationship the First Americans had with Clovis or later populations, and it doesn't tell us how or when they got here. An underlying layer dated by Dillehay, to 30,000 YBP is much less widely accepted, but the well-dated layer above it and the tantalizing older sites elsewhere in South and North America, open up a dizzying range of possibilities.

Another glorious finding is Dr. Silvia Gonzalez's 2005 announcement of fossilized human footprints in a volcanic layer dated to 40,000 YBP. This is so amazingly cool and a story to be followed with great interest. Although 40,000 years is farther than I ever would have pushed it back - that's contemporary with Neanderthal in Europe, wow! - the giddy rush of excitement I felt at the news was right up there with how I felt about Homo Floresienses and the return of the ivory billed woodpecker. The Clovis Police immediately doubted that the finds were footprints, and not without reason. "Human footprints" have turned up in absurd strata before now - most noticeably, in Glen Rose, Texas, in the same strata as dinosaur prints. (They are dinosaur prints.) Having read quite a bit about Bigfoot in my time and the ways in which the tracks of one critter can appear to be the tracks of another, I'm sure that debate can go on for ages before a consensus is reached, at which point a new anomalous fact might throw a monkey wrench into the consensus. This is one reason why archeology is so endlessly fascinating.

Whether America was first populated 14,000 or 40,000 years ago, Asian Boat People now seem the most parsimonious explanation for the existing data, and the search is on for the sites that will date, identify, and describe them. Unfortunately, so far we haven't even got a trace of a boat that old, but - how else could Luzia have gotten where she was? Suddenly ideas that were fringy the first time I heard the word "Paleoindian" can be discussed openly without ridicule. Canadian archaeologist Knut Fladmark has calculated that people equipped with skin boats could get from the Aleutians to Chile in four and a half years. I personally would still like to see an incentive for them to want to do so - a major animal migration to follow, for instance - but given these human time frames, geological time, which when people were assumed to be traveling on foot had been so tight, is now relaxed and expansive, ample for any need.

It makes me happy. This is my favorite theory - because I came up with it on my own, and now the scientists are supporting it. Because it's elegant, and human-time based, and contains so many stories. Boat-based exploration is fast, and subject to all sorts of human-time mishaps. Perhaps the first boatload of people to explore south of Puget Sound was caught in a raging storm and blown off course; or perhaps they were a group of young bucks in desperate pursuit of the Big One; or perhaps there was a shipwreck involved, or an intertribal quarrel, or - you get the picture. Stories out the wazoo. If I lived on the west coast, I doubt I'd ever write another book that wasn't set at the end of the Ice Age.

The primary problem with the Asian Boat People theory, as I see it, is that it's not nearly as easy to falsify as the Ice Free Corridor was. There's no absolute cut-off date for it, as there was the Corridor. Boats are made of biodegradable materials and it wouldn't prove a thing if we never found one. How many empty sites would it take to convince me, or even someone without my emotional attachment to them, that Boat People never existed? If the theory is wrong, it could hang around for a long, long time being picked to death, rather than being shot down in a satisfying ball of flame. But nothing's perfect.

The Solutrean Hypothesis

One hypothesis that has crawled out of the woodwork since Monte Verde, however, hacks me off a bit, even though it necessarily involves boats. You must judge for yourself how fair this is.

I refer to the Solutrean Hypothesis, proposed by Dennis Stanford and Bruce Bradley, and featured prominently in TV documentaries and in newspaper coverage - featured more prominently, it seems to me, than the far more plausible Asian boat route. You must read their arguments for yourself, of course, before you decide, but I resent the attention they're getting.

The high concept is as follows: No obvious Asian ancestors for the beautiful and sophisticated Clovis toolkit have been found, but the points resemble the points manufactured by the Solutrean culture of southwestern Europe, and the toolkits of the two cultures bear many similarities. Most notably, Clovis and Solutrean technologies rely on "overshot flaking," a distinctive way of removing flakes from cores by striking one side of the core in such a way that it removes material from the opposite side. Not many lithic technologies use this technique. Therefore, Clovis may be the descendants of western Europeans who took boats around the ice sheets covering England, Ireland, and Greenland to wind up in the mid-Atlantic and southern portions of the United States. This is supported, very slightly, by the existence of a genetic marker in some modern American Indians which exists today only in North American and Western European populations.

Okay - but the Solutrean industry predates Clovis by a little matter of 5,000 years!

In order for this to work, the Solutreans would have had to make a major maritime adaptation (of which there is so far no archeological record, but that's a pecadillo - we haven't looked for it) in order to exploit Northern Atlantic resources, colonize North America, and then resurrect their old (several thousand years old!) big game hunting technology.

Nope, sorry, uh-uh, don't buy it. Not when the Asian Boat People are so handy and independent invention can readily account for similar tools being created for similar uses thousands of miles and hundreds of generations apart. It smells ethnocentric - if not when Stanford proposes it, at least when the European-American media covers it. As for that genetic marker - there's no particular reason it can't have arisen in Central Asia somewhere, dispersed to Western Europe and North America, and died out in Central Asia. I feel very much about this as the Clovis Police did about Pre-Clovis sites in the pre-Monte Verde days.

Still, Stanford believes that investigation of sites on the East Coast of North America will close the time gap and is actively promoting excavation at Cactus Hill, North Carolina, and elsewhere on that basis. This is bound to turn up something interesting, whether in support of the hypothesis, in opposition to it, or about something else entirely. Nothing that creates financing for digs in new places can be all that bad. And "my" archeologists over at the Gault Site accept the Solutrean hypothesis as one possibility, and I certainly respect their opinions.

I cannot in honesty avoid mentioning that my reasoned rejection of the hypothesis follows a visceral emotional rejection. I don't want the Solutrean Hypothesis to be true, because it detracts credit from "my" Asian boat people and also because the SH is so ripe for racist exploitation - in both directions! If Stanford is correct, then Europeans may or may not have reached the continent before Asians, but they certainly invented the Clovis point, an elegant, effective, and beautiful piece of technology. This feels like having respect for the Asians jerked rudely out from under their feet. Also, if the descendants of Solutreans included Kennewick Man and other ancient Americans whose morphology looks "non-Asian," someone is bound to suggest (and Jim Chatters, the tactless archaeologist at the heart of the Kennewick controversy, has already hinted) that the "European" and "Asian" groups came into conflict, which the European groups - despite the technological expertise represented by the Clovis point - violently lost. No rational system of morality would see in this theoretical genocide a justification for the documented, actual attempted genocide of American tribal peoples by post-1492 European immigrants - but rational systems of morality have nothing to do with racist arguments.

In the other direction, even if no such Eurocentrist argument is ever overtly made, the reaction to Kennewick demonstrates how easily it can be read into the record. Modern tribal peoples have enough real disadvantages to deal with, without tackling semi-imaginary ones. Meanwhile, racism is not a European monopoly, and interpreting the Solutrean story into a saga of peace-loving ecologist Asians triumphing over the savage invading Europeans whose Clovis points killed off the megafauna would be child's play. Staring down these twin vistas of ugly mythmaking makes my stomach hurt, and I'd rather skip the whole thing and limit Ice Age immigration to the Boat People. It's not science, but it's there. We all have our limitations, and that's one of mine.

A Solutrean Saga
All that said - I have come up with a story for getting the Solutreans here if the evidence gets strong enough that we need one. It hinges on the map of the world at maximum glaciation. Please follow the link and check out the way the ice sheets extend into the midAtlantic and the coastlines extend into the ocean about 18,000 Years Before Present. You have a lot more France back then, at about the latitude of the Solutrean technology, and the ice sheet fills the North Atlantic as far as New England. So, picture this (and count the hypothetical statements based on hypothetical statements! This is a story, not a theory!):

The interior of France is occupied by tribes that hunt and gather using the Solutrean technology. Tribes along the coast, however, have a maritime adaptation, using sophisticated boat technology to harvest thick-furred, blubbery marine mammals, fish, and birds. These groups may or may not consider themselves to be separate tribes, but they trade, intermarry, and share skills. Perhaps coastal groups respond opportunistically to changing seasonal conditions by being primarily land-based during warm periods and primarily sea-based during cold ones. If that's so, then it could easily happen that some groups from southern Europe followed the ice sheets west either out of curiosity during prosperous times or in search of more resources in poor ones, and found the land on the other side. Once they knew about America, would it not make sense to winter westward along the ice sheet in one direction, summer in America, then winter eastward along the ice sheet, and summer in Europe in an endless loop?

I naturally imagine the Solutrean Sea Tribes meeting existing American people in the new land. It's possible for them to beat the descendents of the Asian Boat People to the east coast, but I'm much too jealous of the Boat People's prerogatives to allow it. Historically, when new peoples meet, three things happen: they trade, they fight, they have sexual congress. There's no reason to think these meetings would go any differently. Solutreans don't need to have gotten much past the beaches of New Jersey in order for their knapping techniques to spread throughout the population of North America and develop into the Clovis point, if one or two influential tribes adopted them. The technology I'm using right now, after all, owes a lot to the Japanese, with whom I share no significant genetic heritage.

I'd feel better about my scenario if I knew of any American genetic markers that showed up in southern France in the same way that the "European" marker shows up in American populations. After all, the sexual congress in this case would go both ways, as the Solutrean Sea Tribes would be traveling in family groups. There might, however, be social factors concentrating the mixed-heritage descendants on the western side of the ocean when the retreat of the ice sheets turned off the seasonal seesaw; or some devastating event might have wiped out the Asian-Boat-People descendants who ended up in Europe.

Well, it's a story. Given the expanse of Solutrean Europe that's been underwater since the ice sheets melted, I'd say we're due for as many surprises from that area as we are from the Americas, and that's saying a lot.

Who Came?

There's no point sugar-coating this - American anthropology historically has been dominated by European-American males and plagued with racist, elitist attitudes and unrecognized cultural biases. Any given anthropologist might not be a racist, but the framework within which he worked pushed him toward reacting to data in stereotyped ways. Modern Canadian and U.S. anthropologists are more aware of this than they used to be, but cultural inertia still operates on us all. Furthermore, North American culture still does not provide easy acceptance of our tribal peoples, or anyone else not middle-class and white, as "normal." (This is a particularly important point to me as an author for children, but I'll refer you to an expert rather than shooting off on that tangent now: Cynthia Leitich-Smith can speak far more authoritatively than I can.) Even when anthropologists behave well, it only takes one angry or politically-motivated tribal member to create divisive headlines - a deep well of legitimate grievance exists to be drawn on at will. When anthropologists and tribes work together cooperatively (as with the Haida and Tlingit tribes in Vancouver and the Pacific Northwest), on the other hand, good work is often done without anyone outside the field noticing. Such is life. The problem will go away eventually, when enough anthropologists (and writers and journalists and university administrators and presidents) are drawn from a diverse enough cultural pool.

We don't know what Oppenheimer's Beachcombers looked like. The San people of modern Africa, based on genetic evidence, are presumed to resemble them more than people in Norway do; but the San people have had exactly as much time to change in appearance and behavior as everyone else. If we assume - and it is a large assumption but not an unreasonable one - that modern homo sapiens was sufficiently genetically distinct that hybridization with existing European and Asian species didn't happen, then the original African emigrants contained the potential for all the genetic differences that have arisen since.

This is why I'm impatient with people who look at Luzia, the 12,500-year old South American skull, and say: "She's an Australian aborigine" or at Kennewick man and say "He's white; he must be European." Luzia's ancestors may have had nothing to do with Australia; but it would not be surprising if the parent population of the Australians also had descendants who paddled around Beringia. We have no evidence on Kennewick's skin color, and the morphological features of his skull don't look like any modern "race," though they resemble the Jomona (Ainu) people of Japan more than they resemble most people. The Jomona, as it happens, have lighter skin and more varied hair color than other Asian people, but there's no reason to presume an ancestral detour into Europe.

A theory that modern American Indians descend from approximately three waves of Asian migration has a lot going for it - genetically, morphologically, and linguistically, though genetics is an infant science and linguistics is a "soft" one. Certainly modern American tribes are ultimately descended from the same people modern Asians are descended from. There can be no doubt whatsoever about that.

This wasn't necessarily always so. Entire tribes of Americans were wiped out to the last man, even during the historical period, and other groups have been reduced in number or ceased to be distinct groups through the process of intermarriage - a natural process that occurs whenever two distinct human populations meet. Some Americans have appeared to be morphologically anomalous compared to the majority of Americans - the Tierra del Fuegans, for instance; the Olmecs, whom many (white) observers say display "negroid" traits in their portrait art; the Mandans of the Missouri and Ohio rivers, who early European travelers claimed had yellow hair. But a morphological trait does not have to come directly from the location with which that morphological trait is primarily associated today. We're far too early in this process to restrict our options in that way.

Possibly I feel more strongly about this than most people because I don't normally see the morphological traits in question when I look at them. Olmecs don't look "negroid" to me - they look Olmec. A family resemblance has to be very strong indeed for me to notice it, and I am continually not recognizing actors and people I haven't met very often. That being the case, theories that are based solely on the supposed resemblance of pictures, statues, or bones to some arbitrarily defined modern population seem absurd to me. Who is to say whether someone else's recognition of a resemblance is any more valid than my own failure of recognition? In the absence of intense scientific work performed under rigorous protocols to eliminate bias, recognition is a subjective action and I haven't much use for it, nor on theories based on it.

I believe (in the absence of other evidence) that Asia was the immediate source of every wave of immigration to the Americas during the late Pleistocene/early Holocene. I do not believe that this hypothesis is invalidated by morphological data which shows resemblances between ancient American populations and modern populations from non-Asian parts of the world. Applying modern labels to ancient populations does more harm than good, projecting modern racial conflicts backward in time inappropriately.

Enough of that.

Links to Clovis, Paleo-indian, and Population-Related Sites
Blackwater Draw - Go where it all began, the Clovis type site itself.
Discussion of Monte Verde from shortly after its spectacular peer review
Meadowcroft Rockshelter - I have so got to go here someday
The Mexican Footprints Homepage - So nice I linked it twice! Examine the 40,000-year-old footprints for yourself.
The Bradshaw Foundation: The Journey of Mankind - Population movements, and lots of rock art
Alibates Flint - Vacationing in the Panhandle? Take a personal look at one of the most desirable commodities of the Pleistocene - Alibates agate.
Lubbock Lake - While you're in the Panhandle, visit the Lubbock Lake site, representing every era of human occupation. Nice nature walk, too.
Center for the Study of the First Americans - Join and get all the latest research! I'm a Friendly Smilodon, myself.
Getting a little off the subject, The Lonely Islands: The Andamanese discusses theories of the process of populating Southeast Asia, which is by no means unrelated to the process of populating the Americas.
And while we're straying a bit, check out Homo Floresiensis - Surely the coolest archeological find of the past 200 years, even eclipsing my favorite Paleoindian sites, this small non-homo sapiens human survived well into the Pleistocene, after all other non-sapiens humans went extinct. At the risk of distracting you from my subject entirely, here's another site about "The Hobbit," with more linkage.
Relevant Books, Largely Biased Toward What I Own
Adovasio, J.M., with Jake Page. The First Americans: In Pursuit of Archaeology's Greatest Mystery. The Modern Library, 2003.
Boldurian, Anthony T. and John L. Cotter. Clovis Revisited: New Perspectives on Paleoindian Adaptations from Blackwater Draw, New Mexico. University Museum Monograph No. 103, 1999.
Bonnichsen, Robson and Karen L. Turnmire, editors. Ice Age Peoples of North America: Environments, Origins, and Adaptations of the First Americans. Center for the Study of the First Americans, Texas A&M University, 2005 (Second Edition; originally University of Oregon, 1999)
Bonnichsen, Robson, Bradley T. Lepper, Dennis Stanford, and Michael R. Waters, editors. Paleoamerican Origins: Beyond Clovis. Center for the Study of the First Americans, Texas A&M University, 2005
Chatters, James C. Ancient Encounters: Kennewick Man and the First Americans.Simon & Schuster 2001. Just so you know, the fact that I called him tactless earlier doesn't indicate any lack of respect for him as an archaeologist. Professional skill and personal skills are independent variables, and it's not as if I have any room to talk. Read him and decide for yourself.
Dillehay, Thomas D. The Settlement of the Americas: A New Prehistory. Basic Books, 2000.
Fagan, Brian M. The Great Journey: The Peopling of Ancient America, Thames and Hudson, Inc., New York, 1987. (I've heard there's been a revision and post-Monte Verde updating of this book, but I haven't seen it. I guess I should get on amazon...'cause y'know, I don't have enough books)
Haynes, Gary. The Early Settlement of North America: The Clovis Era. Cambridge University Press, 2002
Jablonski, Nina G., ed.The First Americans: The Pleistocene Colonization of the New World, The Edited Proceedings of the Paul L. and Phyllis Wattis Foundation Endowment Symposium, Memoirs of the California Academy of Sciences Number 27, San Francisco California April 2002
Johnson, Eileen, ed. Lubbock Lake: Late Quaternary Studies on the Southern High Plains. Texas A&M University Press, 1987.
Johnson, Eileen, ed. Ancient Peoples and Landscapes. Museum of Texas Tech University, 1995.
Koppel, Tom. Lost World: Rewriting the History of the First Americans. Atria Books. 2003.
Lauber, Patricia. Who Came First? New Clues to Prehistoric Americans. National Geographic, 2003.
Mithin, Steve. After the Ice: A Global Human History 20,000-5,000 BC. Harvard University Press, 2004.
Olsen, Steve. Mapping Human History: Discovering the Past Through Our Genes. Houghton Mifflin 2002.
Oppenheim, Stephen. The Real Eve. 2003
Silverberg, Robert. The Moundbuilders. Ohio University Press, 1970. Okay, so this isn't a book about the Pleistocene or anything else on this page, but pursuant to my remarks about the Solutreans above, this popular account of the history of Euroamerican speculation and scientific and psuedoscientific theories about the Mississippian culture specifically and the origins of the American Indians in general will give you a basis for understanding my gunshyness about racism in anthropology. Plus the Moundbuilders are almost as cool as the Paleo-indians.
Wells, Spencer. The Journey of Man: A Genetic Odyssey. Princeton University Press, 2003.
Wilson, Ian. Past Lives: Unlocking the Secrets of Our Ancestors. Cassell & Co., 2001. Facial reconstruction on skulls, notably including Luzia (9500 BC, Brazil) and the woman from the Wilson-Lenard site (central Texas, 8000 BC)

Megafaunal Extinction

My focus has always been on the Americas, and the south central portion of North America, at that; this is where my story was set, this is where I live, and in order to keep the mountain of research scalable I had to focus geographically as well as chronologically. Therefore, I must often remind myself that megafaunal extinction was not a local phenomenon. Africa is the only continent whose megafaunal assemblage is not impoverished compared to the beginning of the Pleistocene. Reflecting on this, and on the questions raised by the evidence of previous mass extinctions (known as the Devonian, K-T, Ordovician, and Permian, if you want to look them up), leads me to wonder whether our human perspective has hidden chronological bias, as well. A hundred million years from now, will the intelligent descendents of modern rats or pigs observe the fossil record, and subsume the event we call the megafaunal extinction into the mass extinction event going on today?

Unlike the racial undertones of the population debate, which at best are a nuisance distracting us from the science, the question of megafaunal extinction has tremendous relevance to our modern world. Global warming occurred at the end of the Pleistocene - and global warming is going on now. Many sudden extinctions occurred at the end of the Pleistocene - and mass extinction is going on now. Humans survived the end of the Pleistocene - will we survive the Age of Consumerism?

Extinction is a natural event - but what's the natural rate of extinction? We don't know. How fast does it happen, once the process is started? We don't know. This makes it hard to counter the complacency of those who assume that everything'll work out all right in the end and humanity has no responsibility to concern itself about those animals who can't adapt rapidly enough. Global warming has been occurring rapidly - but rapidly in geological time is still so gradual that people involved in their daily business cannot be forced to notice and acknowledge it. The weight of data demonstrating both global warming and human factors which contribute it is overwhelming - if you're looking at it, but many people do not, including many people whose job it is to look at it. The current ecological situation is full of bad news and if we face up to it, we have to change the way we do things drastically. No one wants to do that; and no one will do it, if they can help it.

That's the bad news. The good news is, humanity has been through these experiences before, and survived. The situation was a very different one; but it's all we've got. Human survival is not a given. Many human species - homo erectus, homo ergaster, homo heidelbergensis, homo floresiensis, homo neanderthalensis - have gone the way of the dinosaur far more thoroughly than did the dinosaur - one branch of which family survives as birds. Assuming the mythic quality of sasquatch, orang pendek, and other cryptozoological hominids, we are the last human species. This most recent mass extinction, for so much of which we must bear responsibility, could kill us just as dead as the dodo, the passenger pigeon, the short-faced bear, and the scimitar cat. It behooves us to understand what happened last time, if we wish to survive this time.

Overkill

As mentioned above, the Overkill hypothesis fits neatly with the Ice Free Corridor and Clovis First. Does the presumed death of this paradigm mean the death of Overkill?

Mmmmmmmaybe.

Overkill does have a number of things going for it, even now. If we abandon the big game hunters bursting out of the Ice Free Corridor and sweeping all the unwary animals before them into the sea, we can still construct a scenario in which the Boat People stick to their coasts, eating fish and marine mammals, so that when the Big Game/Clovis adaptation develops, the large animals of the interior are still unwary of humans and die like flies. The worldwide coincidence that where people go, other species go extinct, is too striking to ignore; the tendency of human beings to wreak destruction for destruction's sake is too visible all around us not to project backward in time. We have no call to fantasize about hypothetical ancestors who were too in-touch with their environments, too moral, and too noble to wipe out entire species. Past humans and present humans had precisely similar strengths and weaknesses. What one does, the other may well have done.

At the same time, the Overkill model would require us to do what we do now, on a scale as vast as we do it now, without the aid of oil and gas refineries, internal combustion engines, cheap plastic, mass production, subdivisions, overpopulation, agriculture, or industry. The only recorded instances of subsistence hunting leading to extinction occurred on islands, not continents. Extinction and eradication at the continent level, where genetic diversity and animal populations are both higher than on islands, occurs with the industrial-level hunting of animals for economic reasons other than personal use and with habitat change and destruction. Habitats certainly changed at the end of the Pleistocene, but we have no evidence to indicate that humans caused this on any large scale.

Moreover, although attention tends to be focused on a few high-profile animals (mostly mammals), the list of extinct animals, taken as a whole, is a curious one. The post-Pleistocene event is known as the megafaunal extinction because most of the native large animals died out - but not all of the extinct species were large, and when you look at the data in detail, you find several interesting anomalies.

Some species on the list are suitable candidates for Overkill. Mammoths, like modern elephants, reproduced slowly, so that any stresses on their population would be difficult to overcome. Computer modeling has shown that moderate hunting pressure could lead to a rapid decline. Examination of the growth rings in mammoth tusks, which I will not attempt to repeat here but which is accessibly explained in the The Call of Distant Mammoths, listed below, indicates that in the northern Midwest, at least, something was killing off juvenile mammoths faster than their mothers could replace them. We know that scimitar cats hunted juvenile mammoths in preference to other prey. (See the link to Friesenhahn Cave, below.) If Clovis people also hunted juvenile mammoths preferentially, or took females indiscriminately, or indulged in one of a dozen other unwise practices at a time when mammoths were also suffering other stresses due to climate change, a few generations would see the decline of the species past the point of return. This is not mysterious.

But - camels? Horses? Giant armadillos? They reproduce relatively rapidly, which provides a cushion against stresses, and their bones are uncommon to non-existent in conjunction with human traces. If we killed them off, how did we do so without leaving more evidence?

And what about bison? We didn't kill them off, though we hunted them in absurd numbers, leaving impressive bone beds scattered across the land. Bison were still here, and still hunted intensively, in historical times - not until the 19th century did we come close to killing them off with industrial level hunting, habitat degradation, and deliberate intent, and even so they have managed to hang on long enough to inspire our sympathy and get game-managed. More bison bones are found in conjunction with human artifacts than any other animal except turtles - and both bison and turtles did very well at the end of the Pleistocene.

One factor which, as far as I know, hasn't been studied effectively is the fact that, sometimes, animal species which are hunted by humans increase their populations. We see this in America today, when the most popular "big game" animal is the deer (whitetail or mule). Every year people head out to their hunting leases to hunt these animals - with bows and guns, from deer blinds or by stalking, for sport, for meat, for bragging rights, for the chance to hang out outside with their parents, children, siblings, cousins, friends. And every year deer increase their populations. Other animals, such as the ring-tailed pheasant, are deliberately introduced for the hunting pleasure of somebody or other, and they may take hold, or they may die out. In Kentucky and Tennessee, where rural sportsmen like to hunt squirrels and urban sportsmen like to hunt deer, squirrel habitat is being negatively impacted by attempts to make rural areas more deer-friendly - because deer hunters spend quite a bit of money (including licensing fees to the government, specialist clothing, and specialist equipment like blinds and mini-refrigerators) and squirrel hunters do not.

Pleistocene hunters didn't need licenses and had no government agencies or developers to introduce new species or commit wholesale habitat change; but a hunter-gatherer culture that collectively agreed (for instance) to burn off overgrowth in the fall, to selectively hunt young adult males and leave the cows, juveniles, and largest bulls alone; and kill off the young of certain predators whenever found, could have a powerful impact on its favored prey species and a deleterious one on competing species. Evidence of importations of wild animals to otherwise inaccessible habitats, such as islands, exists in some parts of the world. And then, as now, humans who altered the landscapes to suit themselves better, as by digging wells, damming streams, or cutting down trees, altered it for the species around them, too. We don't know enough about this process as it would have worked for hunter-gatherers to know how to factor it in; but Overkill could conceivably be a misnomer for an Underkill situation.

Now, consider the birds. Why did teratorns die out - the amazing thunderbird, essentially a gigantic vulture? Scavengers are excellently suited for survival, disease resistant, nasty tasting, unpleasant to hunt (they defend themselves with projectile vomiting), and poised to exploit rather than succumb to mass extinctions. No DDT was in the water supply to render their eggs unviable. No ranchers existed to fantasize that they would carry off their sheep and deliberately seek to eradicate them. Why did teratorns and Daggett's eagle - a long-legged bird of prey/possible scavenger - and a jay species die out when thousands of game birds, in company with other raptors and vultures and songbirds, throve? You'd expect hunting to affect ducks and geese, not the eminently unhuntable thunderbird in its inaccessible habitat.

And predators. Human beings, as far as we know, began systematically eradicating predators when sedentary agricultural and ranching operations made it economically important to do so. In a hunter/gatherer situation, adult predators are simply too dangerous to treat in that way without some pressing immediate motive. Some predators should die out with their overkilled prey. If scimitar cats overspecialized in hunting baby mammoths, dying out when the mammoths did is only to be expected. Fine. What about saber-toothed tigers, who seem to have eaten anything with enough fat to grip without breaking their teeth on the bones - why should they have any trouble switching to bison? What about the short-faced bear, that long-legged terror of the prairies, which should have been able to catch anything that ran away from it? What about cheetahs, ditto? Cheetahs appear to have specialized in American pronghorns (aka antelope) and those are still at home on the range!

Speaking of which - why didn't capromeryx, a much smaller species of pronghorn than the surviving one, make it through an extinction known as "megafaunal?" I know of no instances of human-altered capromeryx bones being uncovered. Maybe their little bones degraded too rapidly, maybe they were delicacies caught in hundreds in nets - but we see no evidence of it.

No, sorry, I can't buy it! Maybe human beings contributed to the mass extinction at the end of the Pleistocene, but I cannot make our conscious hunting behavior into more than a subsidiary cause; even before taking into account recent changes in interpretation of the dates of human incursions into new areas. Yet I have found a great deal of emotional attachment to this hypothesis in the literature.

The Overkill theory does not paint a flattering portrait of humanity - but it tells an epic story. Instead of modest beachcombers, one animal among many eking out a living in the world and under threat as often as we are threatened, the Overkill hypothesis places humanity at the center of the drama, striding like a conquering villain from sea to shining sea, leaving our mark where ever we go.

I think we need to get over ourselves.

Climate

The major alternative to Overkill, that the megafauna died out due to stresses caused by global warming, has the merit of attributing one thing we know happened to another thing we know happened, with no hypothetical new causes thrown in. Global warming necessarily adds new stresses onto adapted populations, requiring rapid behavioral and genetic changes which inevitably some species will not make. Factors include an increased seasonality - colder winters, hotter summers - changes in vegetative assemblages, population movements (notably the entry of Asian megafaunal species such as grizzly bears and wapiti/elk) adding new competitors to the mix, and increases in weather disasters such as tornadoes, hurricanes, and flooding. Animal behaviors which are neutral or adaptive in one set of circumstances may become liabilities in a new environment, so that (for instance) mammoths who graze by uprooting plants may denude their food supply at a time when conditions are not suitable for the growth of bunch grass, while bisons who graze by shearing off blades above the roots may protect rhizome-spreading grasses from the depradations of mammoths. No individual species can be considered safe during a time of major climactic change.

This is also the weakness of the scenario, however, because no visible major differences exist between the late Pleistocene and previous transition periods. All the species that died out had previously survived multiple cycles of glaciation and warming, and rates of extinction never approached the rate of this period. What was different this time?

One possibility, intuitively unattractive but in keeping with the evidence, is that nothing was. Although species such as horses and camels do not disappear from the fossil record until the Pleistocene/Holocene transition, species diversity had been in gradual decline for millennia. If every period of major climactic upheaval resulted in the extinction of a handful of species from each genus, and no new species arose, complete extinctions would be merely a matter of time. Some studies have shown long-term reduction of species diversity over time. The fewer species represent a genus, the more vulnerable the genus is. (A reality which should be sobering to members of the last hominid species on earth.)

An elegant possibility has been put forth by Dale Guthrie, that the megafauna were dependent on a particular terrain type which no longer exists today, the Mammoth Steppe. Under this theory, the Mammoth Steppe encircled the glaciated region, being a mixture of plants and animals with traits in common with both modern tundra (lichens and woody shrubs atop a layer of permafrost) and modern prairies (open grasslands dotted with mottes of trees). The particular floral mix in this hypothetical terrain type provided everything the megafauna needed in a handy location.

The evidence for the Mammoth Steppe, or something like it, exists all over North America, in fossilized floral and faunal assemblages that are anomalous by today's standards. Species that, today, we consider appropriate to cold areas existed cheek-by-jowl with modern "warm climate" species, in apparent harmony, along with extinct species that, perhaps, could only exist for extended periods in conjunction with all the others. The culprit here would be global warming, which - as we are learning today - not only means warmer summers, but colder winters; hence, shorter growing seasons, for plants and for large animals. Large animals have longer gestation periods than smaller ones, and need to consume large amounts of food in order to get big enough during the summer after birth to survive the first winter. If animals who required seven months of summer suddenly started getting only six, the toll on the new generation could be devastating.

The conditions necessary for the existence of Mammoth Steppe no longer exist, the glaciers having retreated to high latitudes (in the north and south) and high altitudes (in the Alps), and the floral assemblages having changed drastically in response to the new conditions. The final retreat of the glaciers was the death knell of the megafauna, for the mild winters and cool summers which created the Steppe were gone forever (or at least till the next major glaciation).

One aspect of the Mammoth Steppe that makes this theory particularly attractive is, the role of mammoths in maintaining it. Modern elephants have a huge effect on the areas where they live in Africa. They push down certain trees and spare others; they dig water holes with their tusks; they fertilize the earth with their droppings; and generally arrange things to suit themselves. If mammoth populations are especially vulnerable to hunting, and the Mammoth Steppe depends on mammoths, then any species which depends on Mammoth Steppe logically depends also on mammoths. It's wonderfully tidy - but is it true? And why should teratorns be dependent on Mammoth Steppe?

So climate change is a contender for Murderer of the Megafauna, but so far investigation of the environmental model hasn't answered very many specific questions. If environment is the major vehicle of extinction, we still have a lot to learn about it.

A synthesized Overkill/Climactic model is intuitively attractive and can be maintained even if humans have been in the Western Hemisphere since before the ice. So long as the human population during the most recent warming period lived and was located differently from the human population during previous warmings, they can reasonably be adduced as the "something different" that applied the last little bit of stress. They don't need to be mighty hunters - they just need to be the straw that broke the camelids.

In my book, insofar as I felt obliged to model the ongoing extinction, I modeled it on the environmental/overkill synthesis. One of the things I did was invent "mammoth reed," a plant resource that was essential during cold winters, which was dying out just as the winters got colder. No evidence for mammoth reed exists that I know of; and I do not know whether any plants died out during the mass extinction. Either I didn't look hard enough, or no list of extinct plants exists, although every site report worth its salt includes as much analysis of retrieved plant remains as possible. Alas, it's often true that very little is possible.

Plant remains are eminently biodegradable. This is good for the environment, as any gardener with a compost heap can tell you, but bad for archaeology. Even more so than with animal remains, we are dependent on the particular conditions of a site for preservation of plant remains, whether in the trace forms of pollen and charcoal, or in the recognizable forms of preserved parts. Possibly the most vivid example of the delicacy of interpretation of data is the pine forests of the Texas Panhandle. The first palynological analysis of this area turned up vast amounts of pine pollen in Ice Age levels of soil. The trouble was that the environment demonstrated by the condition of the soil and the other remains - zoological and botanical - did not seem compatible with large pine forests. The standard interpretation now is that the forests existed upwind in the New Mexican mountains; tough pine pollen blew in and fossilized, outlasting the more fragile native pollens of grasses, open woodlands, and marshes.

This highlights the inherent difficulties in interpreting plant remains. Under these circumstances, we cannot be sure that no plants flourished in the Ice Age that left no traces for us to interpret; so, any theory we advance has to have an out clause, an "Apparently" or "as far as we know today." In the absence of time travel technology, we will never be sure.

The interaction between plant and animal life is only beginning to be understood, though we see it around us today. Where modern prairies still exist, it is because large grazers still use them - but do not overuse them. If we understood the habits of the megafauna better, and could see their relationship to plant communities, we would be able to see better how one extinction leads to another. Nor should we be blinded by bulk - small species can be very influential. The forests of America evolved under the pervasive influence of the squirrel.

Thunderbolts and Lightning, Very Very Frightening
Okay, this is all on me, so laugh all you want.

In Adrienne Mayor's books about premodern interpretations of fossils, The First Fossil Hunters (about European traditions) and Fossil Legends of the First Americans, she mentions the common theme of prehistoric giants and monsters being killed by lightning hurled by gods or culture heroes. Is this independent invention, based on logic and the knowledge that lightning hits big things preferentially? After all, if a mammoth is standing next to a white-tailed deer in a field when a thunderstorm comes up, lightning's more likely to hit the mammoth than the deer! Or is there a source for it in the experience in the ancestors of the tellers of these stories? Modern global warming results in giant storms and freaky weather. Why shouldn't the end of the Ice Age have caused disastrous hurricanes and tornadoes? I don't mean that all the American horses got fried, but that a few castastrophic storms in key places could apply that little bit of extra pressure to some vulnerable populations. Also, if I saw a mammoth struck by lightning, I'd talk about it for the rest of my life, and my kids would tell the story to their kids with some embroidery, who would tell it to their kids with changes appropriate to the world they live in, and so on. It could happen.

Yeah, I know. I just thought I'd mention it.

Disease

The search for a plausible third factor leads us almost at once to the hypothesis: What about epidemic disease?

The theory that a virulent "hyperdisease" came in from Asia - in the guts of a mosquito or riding in a flea on a brown bear, perhaps - was posited in the wake of the migration of the Ebola virus from monkeys to humans. Since disease viruses mutate rapidly and can spread through the air, they are an attractive answer to most of the difficulties we encounter with the peculiarities of megafaunal extinction. Predators and scavengers can catch viruses from their prey, herd animals like camelids and horses can catch them from each other, disease can blow in like pollen or get into the water table or mutate to jump from one species to another - what is not to like in this hypothesis, other than the fact that it's nearly impossible to falsify?

Possibly, indirect ways to determine the presence of a hyperdisease may be invented by dedicated researchers; but the best way to prove it would be to find it. Leaving aside the inherent dangers of mucking about with frozen disease vectors, the difficulties involved in located traces of the hypothetical virus are enormous. First, you'd have to find an animal that was infected with the disease at the time it died; then you'd have to extract usable tissue; then you'd have to locate and identify the virus, establishing for the first time that you had the first requirement. Ross MacPhee, who first suggested the Hyperdisease Hypothesis, is in fact running around the formerly frozen north attempting to do just that. Depending on results (which probably won't come in until after he's dead - I'm not being pessimistic, I'm applying my knowledge of similar characters in the past), he will go down in history as either a crackpot or as a driven genius with the courage of his convictions.

Replacement

The notion that native species were displaced by newcomers from Asia on a large scale is one I'll give short shrift here because I find it hard to warm up to. Yes, imported species often wreak havoc on native species. The honeybee did for the Carolina parakeet by monopolizing the hollow trees; the starling and the English sparrow are ruthlessly crowding out the bluebird and the myriad species of American sparrows; zebra mussels, big-headed carp, and snakeheads devastate alien marine environments; and kudzu, Johnson grass, and Japanese honeysuckle strangle biodiversity wherever they go. Eradication and extinction via invasion of new species is a well-established occurrence; but did you notice something about all those cases?

Widespread invasion of species in modern times is most frequently a human-mediated event which goes hand-in-hand with degradation of habitat. Whether on purpose, or accidentally, humans have spread zebra mussels, rabbits, and kudzu across the earth. Natural invasions, such as the cattle egrets who colonized America from Africa, have occurred more slowly and had few or no deleterious effects.

The fact is, there are a lot of ecological niches left unfilled since the end of the Pleistocene. The bison herds could have supported far more predators than they did - the short-faced bears, the big prairie-running cats, and the dire wolves were gone. Grizzlies are not primarily prairie hunters, and gray wolves and coyotes were already here. The cats who compete directly with brown bears in their habitat, mountain lions, throve. Elk and caribou do not wholly replace mastodons and ground sloths. No new bird species invaded to out-compete teratorns and Daggett's eagle. If replacement was going on, it wasn't very thorough.

Besides, megafaunal extinction didn't just happen in America. It's a worldwide phenomenon. The only place it didn't happen is Africa. That's one of the things that made Overkill so persuasive when it was first proposed - at one time, the extinction of the megafauna coincided so closely with the supposed timing of the spread of humanity across the globe that it was easy to imagine a causal connection. If replacement was a causative factor of the extinction in the Americas, we arent any closer to understanding the Eurasian and Australian events.

Since, as we observe today, invasive species do not replace native species on a one-to-one basis, this difficulty does not disprove replacement - but in the absence of stronger evidence replacement, as a primary cause, is well down the list. As with Overkill and Clovis First, the more widely the invasion is separated from the extinction by time, the weaker the link between the two events appears to be. We recently learned that brown bears arrived in America before maximum glaciation, not after the melting. That's two species - humans and brown bears - originally implicated in the extinction due to the timing of their appearance, which now appear to have gotten here long before the extinction. This one isn't looking too hopeful at the moment.

Bibliography and Netguide

A Few Websites on Extinct Animals and the Extinction Debate
Friesenhahn Cave
Megafauna: A List of Remarkable Prehistoric Animals.
Hyperdisease
Prehistoric Times, the magazine for extinct animal art. They're mostly into dinosaurs, but I've got #66, with an article on the Short-faced Bear, and if you look through the back issues, you'll see mammals are occasionally featured.
Relevant Books, Largely Biased Toward What I Own
Barton, Miles and Nigel Bean, Stephen Dunleavy, Ian Gray, Adam White. Prehistoric America: A Journey Through the Ice Age and Beyond. BBC Worldwide, Ltd., 2002. Published to accompany a TV program. You can really see the inadequacy of CGI when it's superimposed on photographs like this; but at least they have some (really disappointing) pictures of Columbian mammoths. I want art!
Cohen, Claudine. The Fate of the Mammoth: Fossils, Myth, and History. Translated by William Rodamoar. University of Chicago Press, 2002. A European perspective.
Flannery, Tim. The Eternal Frontier: An Ecological History of North America and Its Peoples. Atlantic Monthly Press, 2001. As of this writing, Flannery was still a dedicated believer in Overkill.
Houle, Marcy. The Prairie Keepers: Secrets of the Grasslands. 1996. Just as knowledge of the Pleistocene can be reflected onto today's environment, today's environment can be used to understand the Pleistocene.
Knight, Charles R. Life Through the Ages, originally 1946, reprinted by University of Chicago Press 2001. Classic but oh-so-outdated and far too short - too many dinosaurs, not enough mammals!
Kurten, Bjorn. Before the Indians. Columbia University Press, New York, 1988. Art, art, art! This is the book that started it all for me. Some of the text has been superseded - we understand the behavioral implications of the anatomies of the short-faced bear and the saber-toothed cats better than we did back then and humans appear only at the very end, under a Clovis-first model - but the pictures don't date.
Lange, Ian M. and Dorothy S. Norton (illus.) Ice Age Mammals of North America: A Guide to the Big, the Hairy, and the Bizarre. Mountain Press Publishing Company, 2002.
Lister, Adrian & Paul Bahn. Mammoths. Time-Life Books, 1994/Marshall Books 2000. I understand this book's getting another update. Bring it!
Pielou, E.C. After the Ice Age: The Return of Life to Glaciated North America. The University of Chicago Press, 1991.
Raup, David M. Extinction: Bad Genes or Bad Luck? W.W. Norton & Co., 1991
Spinar, Zdenek V. Life Before Man: New Edition with 180 Colour Plates. Translated by Slavos Kadecka and Margot Schierlova. Thames & Hudson 1995, originally 1972. Begins with the birth of the solar system, so as so often happens the period I'm interested in is crowded into the end of the book. The art is outdated, but it's art. Check out the Columbian mammoth chasing off the smilodons.
Stone, Richard. Mammoth: The Resurrection of an Ice Age Giant. Perseus Publishing, 2002.
Wallace, David Rains. Beasts of Eden: Walking Whales, Dawn Horses, and Other Enigmas of Mammal Evolution, University of California Press, 2004.
Ward, P.D. The Call of Distant Mammoths

Oral Prehistory

One source of hints as to what happened millennia ago is the oral traditions of various surviving native peoples. Tales of ferocious giant beasts and the heroes who slew them may support the Overkill theory, recording the purposeful destruction of the megafauna on the grounds that they were too dangerous to have around. Or they may not. It's also possible that tales of monsters and the re-shaping of ferocious animals into ones that were easier to deal with were told as explanatory fables to explain the megafaunal extinction to those who lived through it. Traditions that Siberia was colonized from the Americas instead of the other way around should be of great interest to people studying population movements. Creation tales, which also often involve great floods (as in sea level rise and proglacial lakes) deserve to be studied and compared to the archaeological record.

The trouble is that the people who understand these stories best are underrepresented among those who understand the archaeological record best. Different traditions have different literary conventions. When a Euroamerican is reading a Grimm's fairy tale or a Norse myth or the Bible, he knows (usually) which parts to take literally, which parts to read as jokes, which parts to view symbolically, and which parts to read as pure entertainment. He can negotiate the complexities of jokes that have deep meanings and he knows what to expect of certain formulas. The same reader may soon be lost when he encounters stories from other cultures, treating the jokes deadly seriously while laughing out loud at the climax. Furthermore, a listener who is steeped in (say) the Seminole tradition may be stymied by the conventions of the Inuit. A synthesis of literary and scientific work is necessary to understand these stories in an historical context.

Certainly the uninitiated can't do much with most published records of "Indian folklore;" which is why I used it sparingly in the book (though I read a fair amount) and deliberately did not let Esther be with the group at a time suitable for hearing the most important tales. Many native traditions are hostile to the writing down or recording of stories, which may be "copyright" to a certain family, not for just any old body to come along and tell any way he likes. Others may only be suitable for telling at a particular time. Also, the context of a collecting event may distort the story. Why, for instance, would a member of a conquered people play it straight with a tenderfoot 19th century folklorist who, sponsored by the corrupt Indian agent, came onto the reservation looking for "sacred stories?" Fear of retaliation if they tell a story that doesn't meet expectations, or delight in putting one over on a representative of the arrogant conquering race, or delicacy about telling important things to outsiders who aren't equipped to understand them, or simple invention to suit the market and gain some benefit, like presents or an advocate with the agent, undoubtedly affected what interviewed storytellers decided to say to folklorists in the early days of collecting. These days, when tribal people decide to write down the stories for themselves, they do so for reasons which will be reflected in their selections, and must negotiate with the predominantly white, middle-class publishing industry if they don't want to go to the expense of self-publishing.

This is not to say that the work is hopeless. It's important, and it should be done, many times, by many people, in much the same way that the Bible and other Mediterranean traditions are used in conjunction with Old World archaeology - as interpretive guides rather than as literal blueprints. I would love to hear what modern tribal storytellers have to say about sites like Gault when they look at them in detail.

Claims that a given set of traditions - whether Inupiat, Tierra del Fuegan, or Hebrew - have been passed down "unchanged" carry no weight with me. Certainly it's possible that a strong memorization ethic in a culture could carry a story across a thousand, or three thousand, or maybe even 13,000, years with less change than my own experience would indicate. (The oral stories I pass on mutate over the course of an hour.) But no change? Not possible. If a story were literally unchanged from its initial codification after 13,000 years, it would be in a language no one spoke, and therefore would be useless.

Stories are vital to the way we human beings organize the world we live in. They contain practical, ethical, spiritual, and entertainment values; and as our needs mutate, so do our stories. To suggest that a story has not changed over time is to say that a culture has not changed - that it was static, not dynamic, as we know the diverse American cultures were. It is not possible for the same story to mean the same thing to a succession of listeners across 13,000 years; either the story or the meaning must change to meet changing needs. That's how the narrative process works. Older meanings lurk in the stories we have today, but it will take skill and cunning to tease them out of the tangle of history. This is as true of stories of kachinas as it is of the story of Noah.

This section is so embarrassingly short I'm not even going to call it a bibliography. If anyone knows of an Indian-edited collection organized with the questions discussed here in mind, please let me know!
Deloria, Vine, Jr. The World We Used to Live In: Remembering the Powers of the Medicene Men. Fulcrum Publishing, 2006.
Gaddis, Vincent H. American Indian Myths and Mysteries. Indian Head Books, 1977 and 1992.
Mayor, Adrienne. Fossil Legends of the First Americans. Princeton University Press, 2005. If you thought fossil hunting in America began with Europeans, think again.

Parsimony and the Magic Bullet

"Parsimony" is "Occam's Razor" is "The simplest solution that fits all the facts is the best solution" is "One should not increase, beyond what is necessary, the number of entities required to explain anything."

Parsimony is an important concept in science, but a consideration of the history of science demonstrates that, when you have all the facts, solutions often are not simple at all. The universe is a vast, complex system, functionally infinite, all its parts capable of interacting with all its other parts.

The strength of the principle lies, not in revealing the truth, but in revealing quickly when and where scientific reasoning is going wrong. This is the strength of science. It learns from experience, adapts itself to new facts, abandons old explanations when they cease to explain. Applying parsimony at every step of the process, keeping our explanations of facts as simple as possible, makes it easier to backtrack and to change paths. When scientists believed that the earth was the center of the solar system, they had a theory that accounted for the movements of the stars and planets; but as they observed the behavior of celestial bodies in more and more detail, this theory became more and more clunky and difficult to use. Adopting the radical explanation that the earth went around the sun suddenly made everything simple again, and paved the way toward the theory of gravity and Newtonian physics. Eventually, more sophisticated data became available, and Newtonian physics had to jump through more and more hoops to explain it all - until Einsteinian physics simplified it all again.

The extinction of the megafauna and the spread of humans across the globe were complex events. The ideal of parsimony has misled us, a little, into looking for a single model that will explain the evidence to hand. I don't believe there was a single cause for extinction; I don't believe that humans progressed around the world in a lineal, systematic fashion. Extinction is the sum total of many individual deaths and failures to reproduce. Population is the result of many individual births, weddings, hunts, explorations, quarrels, accidents, inventions, and ambitions.

Yet in order to discuss these matters, in order to study them, we must speak in generalities. The conversation otherwise rapidly becomes impossible. The ability to divide the world up into categories, to group and re-group its component parts into related entities, is essential. But the world is not obliged to limit itself to the categories we create. We define the humans who lived in North America at the end of the Ice Age as "the Clovis people," but we do no know how they defined themselves. When we learn more about them, we may be able to re-define them into many different sub-groups - the Connecticut Clovis, who painted their faces red and used skin boats, the Great Lakes Clovis who exploited the vast pro-glacial lakes and preferred dugout canoes, the High Plains Clovis who stalked bison and tattooed themselves, the Big Thicket Clovis who revered mastodons and created intricate porcupine-quill decorations. The Red Clovis, the Black Clovis, the White Clovis, the Long-nosed Clovis, the Bandy-legged Clovis. "Clovis" might encompass a thousand languages, a dozen "races," five hundred ways of making a living. We define Clovis by the point because it's their common feature. How will future archaeologists define the peoples of America today - as the Plastic-Using people? It's apt.

Similarly, mammoths may have died out under the stress of hunting added to the stress of environmental change, while the teratorns succumbed to an illness and the short-faced bear, unable to adapt to an omnivorous diet like the surviving American bears, was out-competed during a long drought and little capromeryx died out because the only plant that gave them certain essential nutrients died out first. The search for a "magic bullet" that killed them all may be a distraction - but if so, it is a temporary distraction, a necessary distraction, which allows us to phrase questions simple enough to answer.

Sometimes, discovery will be rapid and all the answers will seem to be within our grasp. Sometimes, we will go for decades without finding anything new and will wear ourselves out chewing over the same old evidence. Sometimes, when we think we know the answers, a Tom Dillehay will come along with a Monte Verde style bit of revolutionary data, and unsuspected fields of discovery will open up before us.

And all along, people like me will be poking along in the wake of science, looking at the sweeping epic and seeing the individual stories that shape it.

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