Friday, July 24, 2009

Spear Chuckers
Tools and Bipedalism

That humans have an intimate connection with water is self-evident, beginning with where we live and the amount of water we consume on a daily basis. In this we are unique among surviving primates. Unquestionably, other primates make use of and enjoy water holes, but none has attached themselves to the water hole as have humans.

Humans are also the only current obligate bipedal apes on the planet, so it’s been hard not to assume a causal relationship between our water dependence and our bipedal behavior, though the exact mechanism and motivation has been foggy. What has seemed probable from the outset is that the shift from discretionary to obligate bipedality was dictated by increased access to either food quantity or quality or both. It makes a certain amount of sense to think that an ape finding food foraging particularly good in the marshes, lagoons, and shallow waters would eventually adopt as permanent behavior, bipedality, that which serves them so well in a foraging environment. The main problem with that scenario was imagining that almost all of our ancestral food foraging was done in the water, rather than a shared foraging between aquatic and terrestrial resources, which seems much more likely, and with, presumably, only occasional time spent in an aquatic environment, with the rest spent on land. It’s hard to see quite why such an ape would take up walking on two legs on land, simply because it was necessary while in the water. It’s one thing to imagine an ape harvesting aquatic resources, but it’s another to think that any, much less a whole species, would choose to essentially live in the water on a daily basis. Nonetheless, given no other options, it seemed that bipedality was likely connected to aquatic foraging. The Alice in Wonderlandish musings about other potential scenarios, such as bipedality reducing ones solar exposure or increasing ones ability to see ones enemies/food, have always been beyond the pale of refutation. They can’t be taken seriously. Furthermore, none of the mainline theories has had the courage to tackle the water dependency question, yet. And with good reason. It complicates things no end.

But. I should make that bigger: BUT!

But there have been some recent developments (or, probably more correctly said, “recently released to the public developments”) concerning the study of chimps and bonobos that throw into question what it means to be human; most specifically the discoveries surrounding chimps making and using wooden spears in the hunting of bushbabies, a small primate cousin which they favor for dinner. The chimps sharpen carefully chosen sticks by gnawing on them. Like the neanderthals, they don’t throw their spears but rather use them to poke around in bushbaby nests until they find one.

Now switch your attention to the British chimp at a zoo who developed a rapid-fire throwing technique for pelting gawkers at his cage. When the zookeepers removed his rocks, he began to tear off chunks of plaster from the walls of his cage and used them. Furthermore, this wasn’t a spontaneous display by the chimp; instead he would spend the morning readying his ammunition stash in anticipation of opening. His was premeditated warfare.

It’s my understanding that bonobos share hunting predilections with the chimps, if not to the same degree of intensity. Nonetheless, it’s now evident that tool using, and even tool making, is not uncommon among apes, and appears the norm, rather than the exception. Needless-to-say, we’ve never found evidence in the wild of discarded chimp weapons, we wouldn’t recognize them, if we saw them. A stone looks awfully much like a stone, unless it’s in someone’s, or something’s, hand. It simply disappears in the archaeological record. As does a wooden spear. We can probably assume, for example, that proto-people used stones and wooden spears as weapons for millions of years before they hit on sharpening the stones. Which, consequently, makes a pack of australopithecines armed with such spears and stones a much more formidable foe than I’d perviously considered. A big enough pack might make a pride of lions think twice about the food value of those skinny little twerps.

Which makes me wonder if being able to haul around spears and projectiles might be enough of a benefit for food gathering and safety that those apes who can do it all the time can out-feed and out-breed those who can’t. Are we bipedal because we learned to use and carry tools? Prior to these recent discoveries, it had been assumed that bipedality arose prior to tool use, but that’s clearly not the case with our cousins, and there’s no reason to assume that it happened thus with us. Certainly, there had to be eons of using stones as tools before someone hit upon shaping the tool by flaking, which is where the archaeological record begins. When we see a millions of years old, crude hand axe, what we’re seeing is an enormous technological advance on an age-old artifact: the stone. We are not seeing the beginning of a technology; we are seeing an increased sophistication. One could easily imagine a pre-shaped stone age that lasted considerably longer than the “neo-stone age.”

Which essentially turns the standard viewpoint on its head. In the history of archaeology it has always been assumed that bipedality predated tool use. It was felt a serendipitous development that bipedality freed our hands for tool use; whereas the truth appears to be that our tool use accelerated our bipedality. In retrospect, it’s fairly astounding that no one, myself included, came to the logical conclusion that when we were witnessing the first crudely flaked hand tools, we were, inevitably, not seeing a brand new technology, but rather a refinement on an extant, time-tested product. Surely people, or rather would-be people, used stone tools for millions of years before they thought of shaping them. It was one thing to sharpen wooden spears; it’s a whole other matter to sharpen stones and a lot less self-evidently possible. It takes an intimate knowledge of stone acquired, undoubtedly, through millennia of experience, to see the possibilities of shaping certain kinds of them. That I’ve never seen this self-evident part of the process of stone technology mentioned in any discussion of the beginnings of tool use, implies that is hadn’t occurred to anyone until now. (Which, I guess, makes me feel a little better; at least I wasn’t alone.) Now, of course, with the realization that many apes are tool users, it’s observable that tool use precedes manufacture of their permanent versions. It is, unquestionably, one of the great insights of modern evolutionary archaeology, ranking right up there with Alistair Hardy's cogent observation about human body fat.

If bipedalism is a byproduct of tool use, then it frees the development of bipedalism from environment. In other words, if bipedalism arose in response to tool use, it could have happened independent of the ape’s physical surroundings. It could and probably did arise in many different environmental niches, albeit probably all within the standard primate range. It means that it didn’t develop in response to aquatic foraging, nor to the disappearance of the forest, the two current standard models. Tool use, instead of defining humans, appears to be a common development among the apes; and if tool use is common, then the tendency towards bipedalism is probably common, as well; and given enough time and enough apes…

What this theory of bipedalism doesn’t do, though, is solve the problems of our aquatic connections. Even if tool use created our bipedality, it wouldn’t have changed our basic environmental niche, which is where our physiology was created. That humans are apes who inhabit the waterline is not a theory but an observation. Our water dependence may be unrelated to our bipedality, but it’s not unrelated to where we developed. And it’s still reasonable to think that the smartest ape would choose the best foraging/hunting ground for itself, which is always going to be at the water’s edge. There’s still no argument for our particular human development other than down at the waterside. We’ve undoubtedly been hunting whatever the neighborhood looked like for a long time, be it jungle, be it savanna, but we’ve always lived down by the water hole. There is simply no other call for how we came to be. Or if there is, it’s yet to show its head.

Gilligan’s Ideas

But I’m not done yet: a few remarks on Ian Gilligan’s theories.

Gilligan’s theories were recently expounded in Science Alert, an Australian-New Zealand online science news source. The main thrust of Gillian’s work, and you should read the piece, is that the development of clothing radically affected human development, which is almost tautological, but deserves close attention. He is absolutely right in noting that, without clothing we’d still be stuck in the jungle, more or less; something many people discount or undervalue.

But the middle of the article finds some words about the naked ape that are most interesting:

As Gilligan points out, Homo sapiens are thermally very vulnerable, having at some point lost the thick fur covering of other mammals. The idea that this might have occurred in response to heat doesn’t really hold up, as fur can also insulate animals in warmer environments. Gilligan’s guess is that human hair loss came about as a side-effect of a slowing of the expression of the genetic code in our species, meaning that we’re essentially juvenile mammals in physiological terms, if not in mental capacity.

“Slowing of the expression of the genetic code.” Now, what does that mean? How does that manifest itself? How is the code normally expressed, and how is its expression slowed down? This is important, because it’s essential for understanding the next thought: “meaning that we’re essentially juvenile mammals in physiological terms, if not in mental capacity.”

I don’t know how you read that, but I read it to say that early human development is retarded in some manner and that said retardation somehow affects hair growth. I’m not sure how “juvenile mammals” fit into the human equation, because it seems to me that juveniles of furry animals are every bit as furry as the adults; so I don’t know how this “slowing of the expression of the genetic code” is supposed to function, but at first glance it’s unexplained. Presumably there’s more to it.

But offhand, I’m not buying it. At least until further clarification, but the obfuscating terminology is not helping.

Other than that, he’s dead on about the clothes.

Except maybe the dates.

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