Learn to Speak: Toss a Spear
Human language evolved after our ancestors learned to throw a spear, according to William H. Calvin, in his new book A Brief History of the Mind: From Apes to Intellect and Beyond (Oxford, 2003). Robin Dunbar is not too sure about this, in a book review in the Feb. 26 issue of Nature.1 Although he respects Calvin, he is not convinced of his thesis for the origin of human language:
I found the themes of the book, broadly speaking, congenial, and the account well informed and authoritative, as one might expect from a neuroscientist and science popularist of Calvin’s stature. However, there are aspects of this particular book that I found less satisfying. Calvin’s insistence on the importance of a gesturally based phase to language evolution does not, I think, make sense. Language is a parsing skill, and, even though parsing is a hierarchical process, it seems to me to be a very different kind of skill from that used in coordinated throwing. Manipulating concepts is not the same kind of activity as manipulating muscle masses. Nor does the timing really work. The evidence, as Calvin himself notes, points to a period about 500,000 years ago as the likely timing for the origin of speech, if not full-blown language. But the archaeological record is very clear that real projectile-based hunting did not become widespread until the Upper Palaeolithic revolution, which kicked in around 50,000 years ago (perhaps a little earlier in Africa). The evolution of speech, then, pre-dates the fine muscle control of aimed throwing by a very wide margin.
He also found Calvin’s look into the future “unconvincing.” Nevertheless, Dunbar is glad that “After a century of neglect, the mind has suddenly become an issue of evolutionary interest once again.”
1Robin Dunbar, “Could throwing spears have laid the foundations for language acquisition?”, Nature 427, 783 (26 February 2004); doi:10.1038/427783a.
Dunbar is way too polite with his criticism. Why? Darwin Party members are loathe to call each other stupid. It might provide fodder for those darned creationists.
In support of evolution, all Calvin provides is a just-so story that spear throwing evolved our brains into speech machines. How can that be? It violates the principle learned by every child: “sticks and stones may break my bones, but words will never hurt me.” One would think that words, the later weapon, would be more effective in the struggle for survival.
What Calvin lacks in evidence for evolution he makes up for in evidence against it. Dunbar states:
Notwithstanding the enthusiasm in the 1970s and 1980s for the similarities between humans and our primate cousins, both in popular culture and among academics, the fact is that humans are very different from even our ape sister species. William Calvin’s latest book looks at how different we really are.
The essence of Calvin’s argument is that the difference between humans and other animals comes down to what he calls “structured stuff” (that is, coordinated, structured task processing). One of the most obvious examples is the way we deconstruct sentences to expose their meaning.
Apes, of course, have no such abilities, nor are there any transitional forms between us (see 01/20/2004 entry). From this clear statement declaring the gulf between apes and man, he launches into the JSS (just-so story):
We can do this, he argues, because we evolved the capacity to coordinate fine-tuned movements in the context of throwing. The great revolution in human evolutionary history stems from the shift from the older forms of heavy-duty hunting, mostly by dint of thrusting spears, to projectile hunting (throwing spears or using bows), which required careful aiming and much finer coordination.
Practice at these activities fine-tuned the neural machinery that allowed the delicate motor control required for speech and language. Much is made, in this respect, of the growing evidence for the brain’s ability to coopt neural circuits. For example, the neural substrates for reading have different location in the brain in different individuals, as one might expect of a skill that does not have a long evolutionary history. This ’softwiring’, as Calvin calls it, is clearly of major importance in human cognition.
Convinced? This is so lame. So Lamarckian. Even if practice stretched a hunter’s brain, it would not help his kids any more than a giraffe stretching its neck would promote the inheritance of that acquired characteristic. The trait has to get into the gametes.
No problem, we’ll just modify the JSS a little. Presumably, a chance mutation gave a hunter a more complex brain, granting him better aim at spear-throwing. He brought more meat back to the cave, which made him more attractive to the females. So he had more kids bearing the same mutation, who survived to reproductive age while all the others starved. Isn’t evolutionary storytelling fun? You never have to prove your JSS. As long as it keeps the Darwin Party in power, it is such a dreamy, endless pastime.