Evolution and humans: multi-facited development (Evolution)

by David Turell @, Friday, March 10, 2017, 19:12 (865 days ago) @ David Turell

This article enumerates how complex human development was, and how intelligence was enhanced by the changes in body plan from the ape body plan:

https://www.quantamagazine.org/20151110-evolution-of-big-brains/?utm_source=Quanta+Maga...

"Although the mechanics of the human brain’s expansion have long been mysterious, its importance has rarely been questioned. Again and again, researchers have cited the evolutionary surge in human brain size as the key reason for our exceptionally high degree of intelligence compared to other animals. As recent research on whale and elephant brains makes clear, size is not everything, but it certainly counts for something. The reason we have so many more cortical neurons than our great-ape cousins is not that we have denser brains, but rather that we evolved ways to support brains that are large enough to accommodate all those extra cells.

"There’s a danger, though, in becoming too enamored with our own big heads. Yes, a large brain packed with neurons is essential to what we consider high intelligence. But it’s not sufficient. Consider, for a moment, what the world would be like if dolphins had hands. Dolphins are impressively brainy. They have demonstrated self-awareness, cooperation, planning and the rudiments of language and grammar. Compared to apes, though, they are severely limited in their ability to manipulate the world’s raw materials. Dolphins will never enter the Stone Age; flippers cannot finesse.

"Similarly, we know that chimps and bonobos can understand human language and even form simple sentences with touch-screen keyboards, but their vocal tracts are inadequate for producing the distinct series of sounds required for speech. Conversely, some birds have the right vocal anatomy to flawlessly mimic human speech, but their brains are not large enough or wired in the right way to master complex language.

"No matter how large the human brain grew, or how much energy we lavished upon it, it would have been useless without the right body. Three particularly crucial adaptations worked in tandem with our burgeoning brain to dramatically increase our overall intelligence: bipedalism, which freed up our hands for tool making, fire building and hunting; manual dexterity surpassing that of any other animal; and a vocal tract that allowed us to speak and sing. Human intelligence, then, cannot be traced to a single organ, no matter how large; it emerged from a serendipitous confluence of adaptations throughout the body. Despite our ongoing obsession with the size of our noggins, the fact is that our intelligence has always been so much bigger than our brain."

Comment: These are enormous changes in an eight-million-year period. Certainly looks directed. Note my entry describing genes and brain development in early humans (Friday, March 10, 2017, 01:47) :

https://cosmosmagazine.com/biology/evolving-a-human-brain?utm_source=Today+in+Cosmos+Ma...


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