Tuesday, July 31, 2012

Nature’s Brains, Part 4

July 8, 2012
Bob Fiske

Nature’s Brains, Part 4

(Note: I invite you to read Part 3 before you dive into this part.)

Sooner or later, in nature’s tinkering with brain designs, a truly superior model was bound to come along.  The simian family lays claim to this prize.  Scientists don’t really understand how this happened, yet we see many descendent species alive today that clearly show the innovative features that formed over time.

One of these innovations was exquisitely fine motor control.  This capability appears to have co-evolved with body characteristics that could express new types of movement.  For instance, all monkeys and apes possess a finger-based hand that shapes itself with greater precision than is given to clawed or hooved mammals.  Also, some of these species are endowed with long limbs and tails that give them the arboreal advantage to swing, climb and hang.  Of course, living in trees also requires balance, eyesight and hearing to match the motor skills.  These are jobs handled by the new brain, and they couple well with this brain’s superior learning ability.

Courtesy of e-mail, I once watched a film of a gibbon teasing a pair of tiger cubs.  (You may watch it here, though be warned that the film quality is low.)  If ever I saw a gymnastic wizard, this little gibbon was it.  It is a remarkable testimony of the superior level of body-and-brain coordination possible using a simian brain.

Other capabilities emerged in the simian brain.  A brain that can learn is a brain that can teach.  Thus, it is possible to pass brain-encoded patterns from generation to generation without relying only on the DNA hard-wiring of behavior.  By the way, the teaching of new generations is not a monopoly owned just by simian brains.  Bears teach their cubs how to forage, and many types of young male birds must learn their songs from older males of the same species and geographic location.  Nonetheless—as we well know—the simian brain would push the ability to learn and teach to new heights.

The most recent brain innovations are sported by the hominids, or great apes.  Some of our less intellectual cousins, chimpanzees and gorillas, show that they, too, carry the seeds of the type of intelligence that flourished in the Homo (human) line.  Chimps have been observed to make simple tools such as using sticks to fish out ants from a nest for eating.  These species show other “human” traits such as problem-solving, concern for the welfare of others, and self-awareness.

And, surprisingly, both chimpanzees and gorillas have revealed that they possess previously unsuspected symbolic language skills.  Given the right expressive media (American Sign Language, computer screens or colored shapes), hominids in research settings have amassed sizeable vocabularies and have shown that they can fashion novel “utterances” to express, wants, needs and general observations.

Finally in this discussion of the “advanced design” hominid brain, I wish to mention a series of brain structures that are loosely bundled under the term “the limbic system”.  The limbic structures lie at the base of the cortex, at the juncture where it surrounds the “old brain”.  In fact, these structures (the hippocampus, the amygdala, the nucleus accumbens, and others) appear in other mammalian brains of less intellectual stature than the hominid brain.  In spite of this fact, it is probable that, in hominid brain design, limbic structures were enhance and pressed into service to perform more complex functions.  Limbic functions are thought to play a role in reward, fear, addiction, emotional memories and memory formation in general.  Perhaps that’s too much anatomy.

The idea I want to paint about the new-and-improved hominid brain might be better conveyed using broader brush strokes.  This brain permitted a new level of behavioral and thought patterns, patterns that were the product of emotions, punishments, rewards and social transactions.  In ape communities we see such things as exchanging grooming services, currying favor and shifting dominance hierarchies.  However, in human communities an entirely new social reality was called into existence.  Its final metamorphosis would be expressed in human culture.  In this culture the social, emotional, symbolic, political, artistic, economic and intellectual components could take on reality as  by-products of a marvelously large brain.

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