Standing upright made us human. At least it goes a long way to explaining humanity says Chip Walter in his book, Thumbs, Toes, and Tears: And other traits that make us human.
Here’s the basic plot: we started walking upright in order to move more efficiently across the African plains; that led to specialization of our foot, hips, and spine for balancing and moving on two legs; our hands were relieved of their locomotive labors and were thus free to become the most subtle grasping devices in nature; meanwhile our newly upright head was repositioned on the spine and our neck grew longer; as the neck lengthened, the pharynx began to slip down the throat:
When our ancestor hominids stood on their hind legs, their necks slowly began to straighten and elongate. Over time their shoulders and torsos centered under their heads, their brows grew less sloped, their jaws more square, and their skulls more rounded. All of these changes caused the roofs of their mouths to rise; their necks to stretch; and, most important of all, their tongues and larynx, or voice box, to drop farther down their throats. … With H. erectus, whose upright alignment was virtually identical to ours, the shape and length of our skulls and necks likely [NB that word!] forced our nasal passages and mouths to forsake their formerly separate routes and join one another, creating an intersection in the back of our throats. And therein lies the problem, because the formation of that intersection meant that the food and water coming from our mouths could cross paths with the air we were breathing and choking was born. [Oh, yes, and so was sustained speech born.] (pp. 90-91)
I don’t buy it, but maybe I would be forced to if Walter could have kept up this tour de force in which upright walking produces humanity from the top down. Regrettably, the quoted passage, coming not quite half way through the text, is the high point of the coherent thesis. Then we start getting chapters on consciousness, language, sociability, laughter, and tears, all those peculiar traits that just happen to “emerge” when things get complicated enough. They don’t seem to emerge inevitably from upright walking or even free hands, but are just out there as loose, amazing traits.
When coherence isn’t present, you fall back on good facts. There are plenty of them here in Walter’s book. One good one is about the hand. It isn’t controlled by muscles but by tendons, like a marionette being pulled on strings.
But too many facts are familiar and too much detail is glossed over for the book to be persuasive. For instance, there is a plenty of talk about African terrain, generally called savanna by Walter, but that is not precise enough when we are talking about evolution over a 5 million year span. The grasslands of the Serengeti and Masai Mara hold our imagination as the great savannas, but most African plain isn’t like that. Much more of it is the sort of terrain Hemingway called “a million miles of bloody Africa,” dry, uninviting, country peppered with thorn bushes and baobab trees. I once conversed with a resident of such a landscape who put it too me very succinctly, “When it rains, we do well. When it doesn’t rain, we are hungry.”
At the other end of the spectrum are beautiful parklands, woodlands with open patches and watering places that support a much greater variety. All this terrain is so uncertain that I think perhaps I shall look into the question myself. What did Africa look like 5 million years ago, 2 million years ago, 1 million years ago? Of course a book that makes much of the terrain should tell me rather than leave me wondering, but I do wonder.
Another disappointment is that this book is clearly on the far side of the attention revolution being covered on this blog. (See, for example, Attention! It’s a Revolution) Of course I did not expect to see this blog’s interest in joint attention reflected directly in the book, but reading Walter flounder as he tried to discuss the precursors of language drove home to me how different the inquiry on this blog has become by paying attention to attention.
… somehow we began to make noises that we came to attach to actions and things in the world around us, and then began to string them together into simple pidgins, or protolanguages. Proponents agree [presumably, opponents disagree] that these strings of sounds may not have worked very well, but they were more effective than body language and limited facial expressions. Whatever the case, from these protolanguages, the theories go, modern languages developed. (p. 64)
So there you have it. Human language is an amplification of body language and facial expression, “the nonverbal ways in which we communicated before true language emerged. These have primeval roots that find their way back to the most basic forms of animal communication.” (p. 65, italics Walter’s) Of course there is no evidence offered that language is simply animal communication writ syntactically; it is merely assumed.
Frankly, it beats me how people can take something as amazing as the capacity to speak and banalize it so. If speech were no more than an extension of existing animal communication systems, wouldn’t we see some examples of it in some crude form or other somewhere? That question led me long ago to tell myself speech must have evolved for completely different reasons than for the controlling and socially-interactive purposes we see in animal and machine communications. What was that reason? Something new. Only very recently have I turned toward the hypothesis that language is an extension of joint attention, an extension that became possible when a capacity for mutual listening replaced a dominance-based hierarchy. I did not expect Walter’s book to take that stand, but some acknowledgement that there is something fundamentally mysterious afoot would have been welcome.
Without any of that, here’s what I’m taking away from the book:
- 5 million years ago the human line of descent separated from the ape line.
- A variety of savanna-ape [grassland, woodland, border land, scrub land?] species evolved the capacity to walk upright because the distances that had to be covered were too great to be handled efficiently by knuckle walking.
- By 2.5 to 2 million years ago, upright walking was fully accomplished and the body fully adapted to its demands. The hand was making good progress too. Homo habilis had a “hand that was the anatomical equivalent of a jack-of-all-trades. It could hold, twist, turn, push, and pull unlike anything that had come down the evolutionary pike. … [Also] Africa’s savanna’s were growing even less forested than they had been previously … The clustered trees that remained, and the nuts and fruits they provided, were shrinking still further.” (p. 50)
In the book’s epilog we are told that our species’ days are numbered because a digital Cyber sapiens is on the way, but I’m not as sure about that part.