There are two distinct but in their own silos widely agreed explanations of how we humans came to be as we are. One silo calls itself Cultural Evolution and the other calls itself Evolutionary Psychology. Both are in error.
Cultural evolution is my main interest, and I’m pretty sure that the best explanation of the evolution of Homo sapiens, and indeed all the humans before us, will be a Darwinian account of an obligate symbiosis between hominins and their extended phenotype, starting about three million years ago. However what is known in academia and by the Cultural Evolution Society as Cultural Evolution ignores evolutionary science altogether, and is otherwise riven with error, such as an exclusionary and dogmatic assertion of the utility of group selection theory. I’ll go into detail at a later date.
A prominent example of the pitfalls of the second silo is Yuval Harari’s enormously successful Sapiens. Its intellectual infrastructure is the fantastical story-telling of Evolutionary Psychology. Now I believe that Steven Pinker’s demolition of the notion of group selection is one of the most cogent and elegant essays in contemporary scientific writing, but I also think that the totality of Evolutionary Psychology belongs to narrative fiction, not science; and no better primer than Harari’s Sapiens. The book’s phylogeny is Cartesian, and it continues the great dislocation Descartes finalised between the body as brute automaton, and the rational soul which is, according to Descartes’s own assertion, in many ways coterminous with the One God creator. For rational soul Harari substitutes an undefined and ahistorical miracle, the Cognitive Revolution, which is where I have picked up the Capitalisation Habit.
As I have tweeted, there is on-line an excellent summary http://bit.ly/2uMqOKB of the papers of the Royal Society conference ‘Major transitions in human evolution’ http://rstb.royalsocietypublishing.org/content/371/1698 , which came to the clear conclusion that there were no, repeat no major transitions in human evolution (not even thresholds). What a group of various specialists under the aegis of the Royal Society B concludes is not by definition irrefutable fact, but it does deserve some attention.
The first page of Harari’s book is by the accounts of reviewers a masterpiece of concision, a jewel of insight. It is also nominalist smoke and mirrors, an attempt to suggest that by naming something and giving it capital letters you both describe it and account for its origins
The fourth paragraph asserts: “About 70,000 years ago, organisms belonging to the species homo sapiens started to form even more elaborate structures [than biological organisms] called cultures.”
There is no further reductionist, scientific account of what a culture is, not even an attempt to describe its extension, the shape of its existence in the world.
In place of explanation there is the suggestion that anatomically modern humans created something called culture out of nothing but “thought” and “imagination” as the result of a “Cognitive Revolution”, apparently with full consciousness of what it was they were doing, and therefore with forethought. It is a nakedly teleological account.
This created “culture” was apparently devoid of material content, in that Harari thinks unworthy of mention the three million years of development of the hominin extended phenotype, starting with the simple stone tools of Lomekwi, and weighing in at the thirty trillion tons of the present technosphere. He, and evolutionary psychologists in general, accord no function to this three million year evolving technosphere, all of which up to a few hundred years ago was exclusively mediated by human muscle contraction. It’s as if it were barely visible or palpable, a mere marginal detail. But each of us knows from our own material context that if the whole of the human extended phenotype, every bit of material culture, including practically everything that we eat, disappeared on the instant, we, the whole species, would be dead within days; and also that we think with material things, even as elusively material as the Higgs particle or the incommensurable diagonal of a square with sides of unit length, drawn in the sand by the followers of Pythagoras.
Put bluntly, there is no such discrete, intellectually manipulable entity (or whatever it’s supposed to be) as a human or any other culture. There is only our relationship, immeasurably complex, with the universe and our extended phenotype.
Harari at the bottom of the first page says: “The Cognitive Revolution kick-started history about 70,000 years ago”. What Harari means by “history” is impenetrable, but he is hostage to his own chronological quasi-precision. When he wrote the book, evidence suggested that the first humans arrived in Australia 45,000 years ago. This was increased since his publication to around 50,000 years, and then in the last few weeks to a possible >60,000, with the possibility that the earliest stone axe head with a ground edge emerged at around this time in the context of the first Australians.
It does not matter whether these dates are established. It merely demonstrates the historical fragility of Harari’s already vacuous assertion. If the first Australians did arrive there around 60kya, that was only ten thousand years after the “Cognitive Revolution”. Harari says; “The period from about 70,00 years ago to about 30,000 years ago witnessed the invention of boats”. However, the first Australians must have got there by some sort of boat. They did not swim. Harari’s fantasies do not allow for anything like a boat before 70,000 kya, because that would imply perhaps the evolution of boats over thousands, perhaps millions of years, from the first time a pre-human climbed astride a floating fallen tree. No, no no, boats were “invented”, without precursors, in the ten thousand years between the Cognitive Revolution and the first Australians; almost as if some proto-Archimedes had gone to sleep one night and woken up in the morning thinking, ah, if I could make something that could displace its own weight of water, leaving sufficient freeboard to carry a human being, and while we’re at it why not several, and, oh my goodness, cargo as well; why, then we could discover a big landmass what we wot not of just at the moment.
Okay, you could say, “all one needs to do is put the Cognitive Revolution a bit earlier, so there was plenty of time for boats to emerge in whatever form the first Australians used them”. But then, if the Cognitive Revolution is a moveable feast, why could it not be spread over the whole three million years of the evolution of the technosphere. Just as the Royal Society papers suggest.
This is merely a brief glance at page one of Harari’s Sapiens, but I’ll go out on a limb and suggest it applies to the whole edifice of Evolutionary Psychology; a Cartesian Just So Story, not a science.
Coming next, Cultural Evolution in its non-Darwinian form, as prescribed by Boyd and Richerson  and the Cultural Evolution Society.