Tuesday, October 24, 2006

O Brother, Where Art Thou? A Paleolithic Drama in Three Acts

[AUTHOR'S NOTE: Following is a three-part series on a book I recently finished reading. I have divided it up because once I got started jotting things down the post sort of got away from me. I don't want to drive anyone away screaming, so I'm posting in bite-size pieces. The first piece is a short review and is fairly staid, but after that I start bringing in and elaborating on my own idle musings and it's Katie Bar the Door. The book is a serious, sober book on a serious, sober topic; I am frequently inclined to be neither. If books of science have to be serious matters for you, you may want to skip the whole thing and go elsewhere; I for one have been deadly serious for quite long enough and am determined to have fun with this, even if I make a complete fool of myself in the process. I claim no special expertise (other than a lively interest) in the subject matter of the book, but I do have a long history of dabbling in the Earth Mother business and thereby consider it no impertinence to weigh in in the places where the rigorous scholarly discipline of paleoanthropology brushes against the no less rigorous but scholarship-optional discipline of my own profession. If I can shine a little light somewhere it's needed, I will be pleased. If I'm completely offbase, pleasantly correct me or shrug me off for a fool; there's no lack of serious research out there to be read. This is my humble opinion, and nothing more. Crazier stuff than this has been posited as serious hypothesis before now, and probably will be again.]

Part the First: The Serious Stuff

I finally got to the end of James Shreeve's The Neandertal Enigma. It was published in 1995 so there have doubtless been some updates on the research since that I'm not up on; I'd be interested to see what's been published on this since. Our current public library is growing, but limited, and at the time this book came out we had little access to up-to-date books in English. Aside from what has run in National Geographic, I'm behind the curve on this topic.
Shreeve's book is excellent as an update of paleoanthropological research on Neandertals and 'modern' humans throughout the 1980's and early 90's, and not bad as a history mystery. Having gotten to the end, however, I was left pondering some questions. The funny thing is, they were less about the humans of the mid-to-late Paleolithic than about our own perspectives and how they affect our studies of them. [Warning: there is bound to be a spoiler somewhere in the folowing paragraphs, if you want to read this book without knowing how it comes out!]
The Big Questions about Neandertal Man for years were: What happened to him? Why did he fade away when we are still here? Both topics are rife with controversy and just about guaranteed to bring out the worst in us the survivors (more on this in the book. And they used to say you couldn't ask Leakey and Johanson to the same party.) Shreeve takes us through the ups and downs of the Eve hypothesis, the ancestor hypothesis, the shadowy hints of cannibalism, the indications of cooperation and language in both groups, and haul after haul of frustratingly similar tools throughout much of the two human groups' joint occupancy of Eurasia.

Eventually we come down to the possibilities that sift through when the collective archeological data is sorted:
Recent genetic evidence suggests that populations all over the Old World underwent dramatic "explosions" around the beginning of the Upper Paleolithic in Europe and the Late Stone Age in Africa. (Shreeve) That's an explosion for us, of course; not for the Neandertals (poor guys.) What made the difference? In Shreve's view it came pretty much entirely down to social factors. Our remote ancestors' advantages in brief:
Greater mobility (this was also a physical limitation for Neandertals. According to the fossil evidence they just weren't as well equipped for sustained long-distance travel as we were.) led to increased social contacts with other groups. This could be a good thing or a disastrous thing, but it led to:
The formation of social networks. The thought on this is influenced (a lot) by current studies of !Kung bushmen and their relationships within their ethnic group and views of other Bushman tribes. The idea is that our ancestors (H. sapiens) possessed a level of social awareness that H. neandertalensis lacked. This could have led to more complex strategies that enhanced the chances of survival:
Exogamy. Alliances between groups could be formed through intermarriage; these could then be beneficial to both. (Think Menelaus calling in his chips from all over the rest of Greece after Paris ran off to Troy with his wife. Though that sure didn't benefit Odysseus.) Extending incest taboos to all members of the extended family group or clan could have made this a matter of course.
Monogamy. A number of paleoanthropologists have explained the decline of Neandertals in terms of a simple matter of arrangement of the finds in many digs: the site is effectively split into two main areas, one associated with 'female' things and one with 'male' things. The conclusion? Neandertals din't have family life as we know it. Like elephants, the women and kids all hung together and foraged. The guys dropped in when they weren't otherwise occupied hunting, to mate or take shelter. They didn't bring food to their women and children; possibly they weren't even sure which children were theirs. Neandertal women, like the men and unlike modern women, were robust and could probably handle the tough life on their own. But remains of deceased juveniles indicate nutritional stress and Shreeve suggests that many of them didn't make it through adolescence (see, fathers matter!) Thus a slight advantage in offspring survivability provided by a few simple social innovations could have tipped the hand of fate in favor of Sapiens while Neandertalensis faded slowly away, a poster species for the Red Queen Hypothesis.*

Some final thoughts on the mobility issue: These are probably keen insights into the obvious, but I was surprised Shreeve didn't give them a little space while he was theorizing about the social aspects of mobility. They popped into my head at once while reading about the matter. The first is practically a truism, so I suppose he didn't feel like wasting the space: A population with limited mobility is going to be more at the mercy of outrageous fortune than is one of high mobility. They can't follow the herds or get out of town in a famine. The second is sanitation. If the Neandertals were basically sedentary, hygeine and disease avoidance would have been more of a problem for them than for mobile moderns; these could just pick up and move camp every few months, leaving the last site to self-clean until their return. Maybe it's the amount of time I spend cleaning things and snarling at people about leaving their junk all over the place, but for me this seems like a serious consideration.

*"It takes all the running you can to stay in the same place," said the Red Queen to Alice. "Now if you want to get somewhere else, you must go at least twice as fast as that!" Through the Looking-Glass In other words, adapt, or become extinct.

ADDENDUM: Another matter that had me perplexed was the attachment of the Eve Hypothesis (the folks who analyzed mitochondrial DNA and determined African ancestry of fairly recent origin for all living humans) proponents to what seemed to me a (shall we say?) fundamentalist attachment to Occam's Razor. Now, I'm not arguing that parsimony isn't a virtue, or that Occam didn't have a pretty good point. But Occam's point, if I'm not mistaken, was that the simplest answer is often the best; not that it's the only possible answer. Upholding parsimony as if it were sacred dogma doesn't make you scientific; it just makes you dogmatic. It gets a bit scary for us lay folk when we realize that by changing a few key terms we suddenly can't tell the difference between the assertions of certain scientists and those of certain preachers.

Furthermore, it seems to me that the rule is dependent on one's having all the facts in order. There's an awful lot about paleoanthropology we still don't know; lacking that information one oughtn't to be slashing around wildly with Occam's Razor as if we did. What looks like the simplest answer right now may with another decade of research be as tangled a mess as the worsted I've been undoing for my daughter while writing this. Here's a suggestion: if you're going to pursue parsimony for parsimony's sake, at least make sure all the data fit. There may have been things going on in those days of yore you haven't factored into the equation. If you have a valid reason for pursuing parsimony (other than that it's parsimonious,) please (as your fourth-grade teacher used to say) share it with the rest of us.

The Eve Hypothesis folks collected their DNA stats, which were in all probability reasonably good stats, made trees of all possible permutations of those stats, and chose the most parsimonious result--appparently merely because it was the most parsimonious. Had their fiercest detractors not come off as such obnoxious blowhards, I would have felt more sympathy: their timing doesn't jive with the fossil evidence and in order to accept it you have to assume that the entire paleolithic population of Europe and Asia was replaced (that's completely replaced; not one group absorbed the other,) by a small group of African neophytes fairly (geologically speaking) recently. Interesting idea, but it seems a bit presumptious to sweep away millenia of fossil record with a little DNA analysis. At the very least, you ought to have some better explanation than, "well, these are our data, and the most parsimonious arrangement is thus-and-such" prepared. I'm sorry, but if a large block of facts doesn't fit your thesis, you can't just ignore it.



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