The Origin of Language

I did end up reading From Signal to Symbol: The Evolution of Language, by Ronald J. Planer and Kim Sterelny, but overall found it too academic to be enlightening. After over 200 pages, they conclude:

For us, then, the honesty and uniqueness questions become: Why did hominins evolve such cooperation-dependent lifeways? Why did only hominins develop such cooperation-dependent lifeways? Why (perhaps) did only sapiens develop the complex forms of cooperation that required the resources of full language? We have not answered these questions in this book, though we have said a little about the third. Rather, we have embedded our account of the evolution of language within the framework of a broader picture of the evolution of hominin cooperation. We have elaborated and defended that framework, but not here, as it requires book-length treatment in its own right (Sterelny 2012a; Sterelny 2021). If that account of the emergence and changing character of hominin cooperation is seriously wrong, this account of language falls with it. If, on the other hand, it is broadly correct, it answers the honesty and uniqueness questions.

Putting all this together then: we do not claim to have provided even a close approximation of a proper lineage explanation, taking us from an independently supported baseline identifying the communicative skills of the earliest hominins to language-equipped modern humans. But we do claim to have outlined, and in places done a little more than outline, an expandable lexicon, displaced reference, the core cognitive capacities on which syntax depends, the gesture-speech transition (assuming there was one), and the expanded functionality of language.

As you can see, these authors are not exactly bold in their assertions. I am primarily interested in the main process of language acquisition and how it led to what Ian Tattersall calls symbolic reasoning, i.e., intelligence. For this reason, I read another Tattersall essay, "Language Origins: An Evolutionary Framework." This contains the same ideas as "Brain Size and the Emergence of Modern Human Cognition," which I discussed earlier. Homo sapiens came into existence 200,000-300,000 years ago and began to move out of Africa 70,000-100,000 years ago. Tattersall relies on human-made items to judge cognitive ability, and he thinks that although humans may have been relatively modern in a neurological sense 200,000 years ago, modern human cognition did not develop until about 100,000 years ago:

In the period between around 100 and 70 thousand years ago we begin to find, at sites in the eastern Mediterranean and northern and southern Africa, evidence that hominids – almost certainly Homo sapiens – were piercing, stringing, and sometimes ochre-staining small gastropod shells, presumably for use in body ornamentation (Henshilwood et al. 2002, 2004; Vanhaeren et al. 2006; Bouzougger et al. 2010). In all documented modern human societies such ornamentation is redolent with implications of status, occupation, group membership, and so forth; and it is widely accepted as a robust proxy for self-identification and symbolic cognitive processes on the part of humans who decorated themselves....

Tattersall concludes:

Our cognitive and linguistic skills are, of course, built on a foundation of hundreds of millions of years of vertebrate brain evolution; and nothing would be the same today if even one of the innovations that accumulated over that long period had not been acquired. But there is something emergently different about us: something that was not fine-tuned by natural selection over a vast period of time, and that in consequence makes our behavioral repertoire infinitely flexible – just like language itself.

I am reminded of Improbable Destinies, by Jonathan B. Losos, which I discussed in 2018. In his experiments with lizards in the Bahamas, he found that evolutionary changes could occur in just one generation if long-legged ground lizards were pressured to live in the vegetation above due to the introduction of larger, predatory lizards at ground level. Because long legs were disadvantageous above ground level, the lizards immediately evolved shorter legs. Losos doesn't discuss the mechanism for the reduction in leg length – I would think that this would be too short a period for a genetic change. It seems more likely that the genotype allowed flexible outcomes in the phenotype for situations like this. A similar process may have occurred among humans. It seems plausible that Homo sapiens built up various cognitive skills through the use of language by living in cooperative groups for thousands of years. The advanced cognition of modern humans may have been precipitated by adverse environmental conditions during the late Pleistocene period. It seems unlikely that the extinction of all of the other Homo species alive at that time could have been a coincidence.

I should also add that the emergence of biological phenomena, including neural development, as discussed by Robert Sapolsky, adds a new dimension to how we now think about evolution.