Neuroscience: Human brains are unique, neuroscientist observes

Are human brains unique?, Dr. Michael Gazzaniga asks and - in more news that shouldn't surprise anyone - decides that the answer is yes:

I always smile when I hear Garrison Keillor say, "Be well, do good work, and keep in touch." It is such a simple sentiment yet so full of human complexity. Other apes don't have that sentiment. Think about it. Our species does like to wish people well, not harm. No one ever says, "have a bad day" or "do bad work" and keeping in touch is what the cell phone industry has discovered all of us do, even when there is nothing going on.

There in one sentence Keillor captures humanness. The familiar cartoon that makes its way around evolutionary biologists circles shows an ape at one end of a line and then several intermediate early humans culminating in a standing tall, erect human. We now know the line isn't so direct but the metaphor still works. We did evolve and we are what we are through the forces of natural selection. And yet I would like to amend that cartoon. I see the human turning around with a knife in his hand and cutting his imaginary cord off, in being liberated to do things no other animal comes close to realizing.

This is, of course, an introduction to his forthcoming book, Human: The Science Behind What Makes Us Unique (Ecco; June 24, 2008), in which he tries to mesh his insights with materialism. He especially needs to believe that the human brain can be explained entirely in terms of natural selection. That's wildly improbable, but watching him try will likely be interesting.

One interesting topic Gazzaniga addresses is the importance of brain size:

From my own perspective on this issue, I have never been taken with the brain size argument. [= bigger is better] For the past 45 years I have been studying split-brain patients. These are patients who have had their two hemispheres of the brain surgically separated in an effort to control their epilepsy. Following their surgery, the left brain can no longer communicate meaningfully with their right brain, thus isolating one from the other. In effect, a 1340 gram interconnected brain has become a 670 gram brain. What happens to intelligence?

Well, not much. What one sees is the specialization that we humans have developed over years of evolutionary change. The left hemisphere is the smart half of the brain. It speaks, thinks, and generates hypothesis. The right brain does not and is a poor symbolic cousin to the left. It does, on the other hand have some skills that remain superior to those on the left, especially in the domain of visual perception. Yet, for present purposes, the overarching point is that the left hemisphere remains as cognitively adept as it was before it was disconnected from the right brain, leaving its 670 grams in the dust. Smart brains are derived from more than mere size.

I'm skeptical that the right brain is as useless as Gazzaniga thinks. But a reductionist always needs to leave a pile of stuff on the cutting room floor.

Fred on everything, including evolution: Hot air about big brains

Columnist Fred Reed offers a send-up of speculative theories about the evolution of large brains in humans, “Circling the Paradigm: Protecting the Theory at Any Cost” (April 21, 2008):

A standard theory among a large school of evolutionists is that intelligence is low among people in sub-Saharan Africa, where humanity apparently originated, because life in tropical climates doesn't impose great intellectual demands; when people migrated to colder climates, as for example in Europe, they had to evolve higher intelligence to survive. To most people it seems obvious that higher intelligence would be useful anywhere at all, so why, they ask, didn't it arise below the Sahara?

Hart replies that larger brains carry not only benefits but also costs and, by implication, that in some places the costs are greater than the advantages. The costs of larger brains are, he says:

1) Larger brains require larger amounts of energy.

2) Larger brains require larger heads, which create strains on the muscular and skeletal structure.

3) Larger brains (and larger heads) require wider female pelvises and the wider pelvises result in less efficiency in walking and running."
This is evolutionary boilerplate, and also absurd. The two are often seen keeping company.

I won’t even try to keep up with Fred in debunking the “big brains” nonsense, but here is an interesting fact: Size of brain does not necessarily correlate with intelligence in humans. See these Mindful Hack stories, for example:

How much brain does a man really need? Not much.

Also: How much brain do you need? Could you use that space for something else?

While we are here, it is worth noting that some creatures, like whales, have much bigger brains than humans, but have not used them to develop thinking faculties similar to humans.

My own view is that when people believe in mechanistic theories, they tend to reach for them as an alternative to other theories, whether they are useful or not. Where they are not useful, they spin them out a little more, as in Fred’s hilarious examples. Here is more of Fred on Everything.