A short selection from Essay Thirty-four in Darwin, Dogen, and the Extremophile Choice.
Wind back the tape of life to the early days of the Burgess Shale; let it play again from an identical starting point, and the chance becomes vanishingly small that anything like human intelligence would grace the replay. —Stephen Jay Gould 
Maybe Gould was right about the “vanishingly small” chance for human intelligence, but our late prophet of evolutionary contingency (his only reason for this comment by the way; there’s no evidence Gould would have approved of a Nature that ‘actively’ works against our kind of intelligence) didn’t recognize that, perversely it would seem, his and Eldredge’s punctuated equilibria might in fact favour such a supreme opportunist. Especially if a cycle of climatic ‘punctuations’ was also fast and unrelenting.  It could be argued that, even under chronic stress, the tirelessly healing resource partitions of the Paleolithic world might have had time, though balancing on the very edge of Promethean supra-ecological catastrophe,  to deselect unperfected language in the death-wake of out-competed bodies with over-reaching imaginations;  (See: https://www.extremophilechoice.com/2022/06/21/old-buddha-meets-young-buddha-part-3-when-we-see-the-difference-our-world-changes/ ) but the Natural and sexual ‘hands’ of selection would have exerted a drifting pressure in those times of advancing and retreating ice-sheets, of unsettled savannah and rainforest,  and they would have kept falling upon two fateful contingencies: 1 ‘intention’ already had an animal presence in that inchoate sprouting of motor-concept that our ancestors could feel as the sketchy covert rehearsal of familiar actions, and 2 the muscles of voice, being useless for fleeing danger, or in the case of diaphragm acting on larynx even for fighting or feeding, had already been set aside for innate signaling. So, when this ‘grunt-system’ also turned out to have very little use in exploration, manipulation and invention (jaws and lips optional), our ancestors’ tool-use (temporarily prolonged by the befuddlement of a diminished co-evolution) would have had an opportunity to take advantage of a set of traits pre-adapted to kick-start a ‘verbal selection process’ for their waywardly ramifying thoughts.
In our continuing evolutionary analogy, it’s not overt language, but covert activity in general that corresponds to the shadowy, abstracted, gene-pooled design space of an ecosystem’s non-somatic (germ plasm) chemistry. In fact, the implied correspondence between genetic ‘code’ and verbal code is misleading: the first is a chemical precursor for amino acid sequencing of proteins, and the second, a changeable convention that, to the extent its vocal details have no relevance as behaviours in the real world, assigns verbal behaviours to thought behaviours as arbitrary handles. It’s only because, at our accustomed scale of relating to Nature, the codons of DNA exhibit alternative sequencing, while sexually selected traits appear as a messy subset intrinsic to ‘fixed’ species, that we don’t recognize the latter as the properly correlated ‘conventions’ that handle Nature’s Darwinian work. Indirect verbal behaviour specifies the partial and tentative, but directly useful, covert behaviour  of which it is a subset, and so ‘thought’ unfolds bivalently according to the body’s own “universal grammar”.  Just so, to avoid tentative reproduction, sexual traits, not directly related to survival, are selected ‘as a convenience’ to decisively speci-fy traits that are.
1. Gould, Stephen Jay. 1989. Wonderful Life: The Burgess Shale and the Nature of History. New York: W. W. Norton & Company. p.14.
2. Tattersol, Ian. Sept. 2014. If I Had a Hammer. Scientific American, vol. 311, no. 3, pp. 55-59. This from p. 56.
3. See: https://www.extremophilechoice.com/2022/07/17/young-buddha-at-home-part-4-lifting-the-lid/
4. Wong, Kate. Sept. 2014. The Human Saga. Scientific American, vol. 331, no. 3, pp. 37-39. “Arguably, no chapter of the human odyssey has been so dramatically rewritten as the one detailing the ascent of H. sapiens. Far from being a slam dunk, destined for world domination from the outset, the fossil record now paints a picture of a species that had no sooner debuted than it nearly went extinct as a result of climate change.”—p. 39.
5. deMenocal, Peter. B. Sept. 2014. Climate Shocks. Scientific American, vol. 311, no. 3, pp. 48-53. “There was no one-time habitat switch from forests to grasslands but rather a rapid succession of wet-dry cycles that moved, in distinct steps, toward dryer conditions.” —p. 50. These swings reflected the known sensitivity of African and Asian monsoonal climates to Earth’s orbital wobble, which occurs as a regular 23,000-year cycle. However, overlaid on this more general trend, deMenocal says there were two “major shifts in African climate … roughly a million years apart, that mark significant changes in our family tree. The first evolutionary shakeup happened between 2.9 million and 2.4 million years ago. The famous ancestral lineage of ‘Lucy’ and her ilk (Australopithicus afarensis) became extinct, and two other, quite distinctive, groups appeared. One of them had the hints of some modern-looking traits, including larger brains. The owners were the very first members of our own genus, Homo. The first crude stone tools appeared near these fossils. The other group besides Homo that emerged at this time looked different: a stoutly built, heavy jawed and ultimately unsuccessful lineage known collectively as Paranthropus.” —p. 51.
“The second shakeup occurred between 1.9 and 1.6 million years ago. An even larger brained and more carnivorous species, Homo erectus (called Homo ergaster by some scientists), appeared on the scene. Its taller, more lithe skeleton was nearly indistinguishable from that of modern humans. This species was also the first to leave Africa to populate South-east Asia and Europe. Stone tool technology also got a major upgrade: the first hand axes showed up, with large blades carefully shaped on two sides. …While these broader shifts were happening, the climate whipsawed rapidly between wet and dry periods, so to thrive, our ancestors had to adapt to rapidly changing landscapes. …Rick Potts, a paleontologist at the Smithsonian Institution, calls the role of flexibility in making us what we are ‘variability selection.’” —p. 50.
6. Stix, Gary. Sept. 2014. The “It” Factor. Scientific American, vol. 311, no. 3, pp. 72-79. On p. 76 Stix quotes Michael Tomasello criticizing the linguistic contention that grammar is genetically hard-wired: “Language is such a complicated thing that it couldn’t have evolved like the opposable thumb.”
7. Chomsky, Noam. 2002. Adrianna Belletti and Luigi Rizzi, ed., On Nature and Language. New York: Cambridge University Press. pp. 11-17.