About eight millions years ago, the scientific consensus goes, the lines that eventually led to humans and to the rest of the great apes diverged. This is probably clear only in retrospect. If an alien species stood surveying the Earth at the time, and for a few million years thereafter, our line would not have stood out as the one slated for more brains than we know what to do with.
We do know that average hominid brain size doubled within the last two million years whereas the average chimpanzee’s brain size remained unchanged. Human ancestors with skull-sizes in the modern range have been around for about a million years, give or take a few hundred thousand, and skulls as large as anything floating around today have been around for some 150,000 years, at least.
(Arthur Koestler theorized that the extremely rapid growth of the hominid brain contributed to humanity’s flaws in his grand summation, Janus. I urge everyone to read him though he may seem outdated.)
A rather more dubious scientific consensus holds that just 50kya (thousands of years ago) there was a great naissance in which culture, language and symbolic thought first erupted. Before this we were intelligent beasts. Afterwards we were primitive humans.
New archaeological finds, such as musical instruments, ochre pigment and art predating the 50kya cut-off are beginning to disturb this consensus. Common sense also dictates against it. What the —- were our ancestors doing and thinking during this 70ky, at the least, period? What were they doing and thinking during the millions of years before? Did symbolic thought take them over like a mind-virus? (This I actually find almost plausible. Memes and all that.)
We now know that chimpanzees murder, wage war and have inherited cultures. They do these things with the brain case our ancestors had more than two million years ago. Just this past summer a dog was reported to be able to bring a new toy from a stack by figuring out which ones already had names.
Dogs are also better than chimps, truly wild dogs (feral for thousands of years) and wolves at guessing human intentions. Gorillas and chimps can develop vocabularies of hundreds of words (remember, a working human vocabulary may contain as few as 800 words). Coco the Gorilla had an IQ score in the 80s and that was even though they deducted points for such obvious species specific things as preferring to be in the woods rather than a house when the thunderstorm hit.
Dolphins and birds (birds?!) have demonstrated their own versions of intelligence and culture. Many animals have proven to be capable of deception and subterfuge. Even more remarkable, some animals have shown that they are capable of empathy. Blue jays will look behind a curtain for something hidden, something that does not occur to human infants until they are a few years old.
What I am getting at is that intelligence and culture have been around for hundreds of millions of years and that our culture and intelligence is an outgrowth of this older stuff. I do not believe that it is possible to truly understand humanity unless one understands the antiquity of its origins. If you don’t accept evolution, you can not really understand human nature.
This was a riff. If you want me to fill it out with links and documented facts and stuff, I will do so with pleasure, so long as there is interest. As far as I know, all the material above is factually correct. Please advise me if not.