Brain expansion: different theories about rapid expansion (Evolution)

by David Turell @, Tuesday, December 15, 2020, 18:56 (151 days ago) @ dhw

A professor's Darwinian take in a book review:

"Scientists have long posited that time and evolution stratified the human brain, with the oldest and crudest lizard layer lurking at the bottom, followed by the mammalian limbic system, which controls emotion, and topped by the uniquely human neocortex, which guides rational thought. This theory not only suggests that humans are the most evolved creatures, given our deluxe add-ons, but also explains the tug of war between our animal impulses and logical ambitions—an inner struggle Plato observed more than 2,000 years ago.

"But according to Lisa Feldman Barrett, a professor at Northeastern University, the idea that the human brain developed a way to rein in our inner lizard is one of the most persistent and widespread errors in all of science.


"More dramatically, Ms. Barrett writes that scientists have recently discovered that the brains of all mammals—and most likely all vertebrates—follow a single manufacturing plan. This means every brain has the same essential ingredients but with species-specific mutations to aid survival in different environments. This, argues Ms. Barrett, undermines the idea that the human brain stands apart as the pinnacle of natural selection. Sure, our brain seems impressive, but we are simply one animal among many with a noodle adapted to the task of survival. “Other animals are not inferior to humans,” Ms. Barrett writes. “Your brain is not more evolved than a rat or lizard brain, just differently evolved.”


"Perhaps the biggest misconception, Ms. Barrett writes, is that our brains evolved for thinking. Sure, our fancy brains are responsible for everything from suspension bridges to “Infinite Jest,” but these are byproducts of its main purpose: to regulate our physical resources to ensure our survival. Every brain essentially manages what Ms. Barrett calls a “body budget,” tracking resources like water, salt and glucose. “Every action you take (or don’t take) is an economic choice,” she explains, and our brains are engaged in constant guesswork about when it’s best to eat or flee.


"The human brain is essentially “under construction” for the first 25 years, Ms. Barrett writes. Babies are born with many more neural connections than they need, and it is the job of caregivers to help strengthen necessary connections and remove unnecessary ones—a process Ms. Barrett calls “tuning and pruning.” Our impressively adaptable brain is what allows humans to thrive in places as diverse as the desert and the Arctic, but it comes at a cost. Caregiver neglect or inadequate nutrition can seriously harm a nascent brain, with lasting consequences.


"As Ms. Barrett admits, “there are still many more lessons to learn.” Why, I wondered, are our brains so much more complex than those of other animals? Does survival alone explain human ingenuity? And what is the use of those brain-based experiences that tax our body budget with little upside, such as anxiety and depression? “Our kind of brain isn’t the biggest in the animal kingdom, and it’s not the best in any objective sense,” Ms. Barrett concludes. “But it’s ours. It’s the source of our strengths and our foibles . . . It makes us simply, imperfectly, gloriously human.'”

Comment: another silly model of the human brain to diminish our pinnacle position. Darwin, not God.

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