SERMON: “Our Shrinking Brains” by the not-so-reverend bob

I’m not sure how I feel about the fact that we modern humans have brains about ten percent smaller than our ice-age parents.  Because that’s what science is telling us.  After millions of years of growing our huge brains, they are now moving in the opposite direction.

I can look around on any given day and find any number of current human behaviors to blame on this cranial shrinkage: bad driving, talk radio, Sarah Palin.  But in the biology of life — in the “progression” of evolution through natural selection — things are never quite so simple.

The obvious fact is that there is a reason we have been able to dispense with ten percent of our brain.  Otherwise, we’d still have it.  Conversely, if our lives had become steadily more challenging, it’s a pretty sure thing our brains would actually be growing.  But what has changed so much that has changed us so much?  For in nature, there is pretty much never an evolutionary change that is not a selection for a better-adapted trait in a changing environment: if environments aren’t changing, species won’t change.  It takes the introduction of a new variable to push animal evolution: a new and invasive species, a climate shift.

In our case the best explanation seems to be our own domestication.

Now when we think of domesticated animals, we think of cows and sheep, dogs and cats and married men.  But the reality is that we humans have been domesticating our social selves for quite a while now.  Think about it: there was no New York City in the Pleistocene.  In those days we lived mostly in blood-kin bands of hunter-gatherers.  And no matter how much we’d like to make a comparison between the violence of our modern American culture and that “brutish and short” world of our Ice-Age forebears, the fact is that we humans manage a near miraculous daily feat of living cheek to jowl with masses of our fellow creatures with an historically unprecedented lack of person-to-person violence.

The n.s.r. bob ponders our shrinking brains...

In short, as we’ve learned of the enormous (mostly economic) benefits of living together, dividing our labors and extending trust to strangers, we have been submitting our genes to the selective forces of evolution.  It may turn out that we humans turn out to be even greater domesticators then we’ve given ourselves credit for by virtue of performing that task upon ourselves.

This fact confronts — in a broader sense — our continued mass denial of the reality of the evolutionary process.  A great deal of this resistance is based in belief, with most of that religious in nature.  Such belief holds that seeing ourselves as “merely” organisms adrift in some random natural process will strip us of all human dignity, and undermine any sense of universal (and therefore enforceable) morality.

To the first point, there is no “merely” about the evolutionary process.  And neither is anything at all about our biology “simple” or “base”.  I would argue that it is only ignorance that allows us to regard reductionist bronze age mysticism as a superior intellectual stance in the face of the actual wonder and mystery of life in the universe.

As to the argument for human dignity, the presupposition is that animal life is somehow worthy of disdain in any form other than human.  So the problem is not that we debase ourselves if we abandon our “special status” as divinely-created superbeings, but that we have constructed a false hierarchy for purely egotistical reasons.  For how does it truly lower us to recognize that we are walking, talking ecosystems of bacteria, viruses and cells whose chemical and electrical processes are facilitated by the metals and minerals that were born in the births and deaths of ancient stars?  (The writers of ancient holy books would have peed their pants were they to have had any inkling of such ideas to incorporate into their cosmology!)

And what of morality?  This is the big one.  The religious insist that our sense of right and wrong is divinely given.  Of course it’s not.  It’s clear from nature that morality exists in all social species.  And that is the key here: we are a social species.  Which means that if God were to vanish tomorrow (and with Him, all religious belief) there would indeed be many who would feel a certain freedom to pursue their hedonistic fantasies without restraint.  They would, however, immediately run up against the true barrier to dissipation: other humans.  The genuine control on human behavior is our own social natures: our desire — nay, our need — to be part of the group.

(The only humans truly free of this need are the psycho- or sociopath — and this is a genetic disorder, leaving those humans devoid of certain critical wiring that would normally make them give a shit about what their fellow humans think of them).

In short, were we to lose religion tomorrow, nothing at all about human morality would change.  Every single one of our human-to-human transactions would still require the same negation it does now.  Say hello to the new boss, same as the old boss.

Another unanswered question about evolution in our time is the effect of sexual selection on the species — now that women have had access to both better education and more control over their reproductive lives.  We already surmise that women are the most likely force behind producing the human male that has a larger penis (by body size) than any other primate.  And there is surely no difference between the human selection process for attractiveness or fitness and that of the bower bird or the peacock.  And now that technology is progressing at an ever more incredible rate, there is no reason to think that it, too, will not soon add its own selective pressures on the species.

Obesity is another evolutionary issue.  For there is nothing about our evolutionary past that endowed our entire species with the tools for resisting the brain-altering cravings that unlimited sugars trigger (the same parts of the brain hijacked by alcohol and other addictions).  To the end that we may be experiencing a rather dramatic selection process where a great many humans (that are prone to obesity under our modern industrialized diet) may soon be selected “out” of the gene pool.  There’s no reason not to expect that a mutation (or series of mutations) that give one a capacity for functioning well on the crap we now eat may soon spread through the population, giving those individuals that slightly-higher-than-average success rate that translates into thriving young.

All of this gets back to something I said in my very first sermon on Charles Darwin’s birthday: “Because of Darwin, life on earth makes sense”.  The theory of evolution has proven to be the best means of making sense of life on both a global and personal level.  And though it can be impossible to observe in an individual life, we have now accumulated enough data and insight to see evolution in action.  In scientific terms, we call it a theory.  The religious read that to mean “a man-made idea that’s not really true”.  What it means to scientists is a description of reality that has yet to be proven false.  Quite a difference, that.

The religious like to trot out the old aphorism that “Just because you don’t believe in God doesn’t mean He doesn’t exist”.  But the same can be said of evolution and natural selection.  The difference between the two, of course, is that evolution is the description of reality that is actually based in reality and evidence, and therefore does not deserve to be compared on equal terms with belief-based explanations for life.

But then, after these last twenty-thousand years of evolution the belief centers of our brain seem not to have diminished by even that (above-mentioned) ten percent.  But then, it may be that our capacity for religious belief was one of the traits that helped in our domestication.  Maybe it’s a cognitive leftover of evolution, like my tailbone, or my appendix, or that weak spot in my lower back that still isn’t quite used to walking upright.  And maybe I’ll just have to keep using the ninety-percent of brain I still have left to work around it.

t.n.s.r. bob

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