"Our brain’s cerebral cortex—the seat of higher thought—is eerily similar to a clump of neurons inside
the head of the lowly marine ragworm. The ragworm’s brain, which
evolved some 600 million years ago, is so similar to the cortex that
humans and worms must share a common ancestor..."
When
scientists "compared the worm’s cells with those in a vertebrate
cerebral cortex, they found they were too similar to be of independent
origin....."
"...these
tests challenge the standard notion that the ability to think evolved
from complex vertebrate behaviors like predation.... that now appears to
spring from something far more basic, he argues, like the ability “to
distinguish between food and nonfood”—a feat the ragworm accomplishes
with aplomb."
My Comment:
For
years, I'd considered fear of predation to be our most primitive
instinct. I'd missed the obvious. It's not merely eat or be eaten. It's
knowing what is food and what is not that's the most basic instinct.
Though, of course, photo-sensitivity and other visceral senses are more
basic -- still, I'm referring to instincts.
Food attracts.
Fear repels. And the three basic defense mechanisms interplay ( run, hide, fight).
On the psychological level, it's a combination of various psychological defense mechanisms.