The Brain and Life Span

I posted a blog on 3/31/14 titled “Monogamous Dummies,” wherein I described a then-current result of studies of fruit flies, which had made the surprising discovery that polygamous male fruit flies demonstrated themselves to be more intelligent than monogamous males. Another surprising finding of this study was that monogamous males lived longer than their polygamous cohorts.

The researchers had no explanations for these results, other than to note that, within a given species, those individuals possessing a larger brain (and thus who are usually more intelligent) did not live as long as their smaller-brain comrades. A possible reason offered is that the brain of any critter demands a significant proportion of that critter's energy. Thus, big-brained creatures may sort of run out of energy sooner and expire before their dumber fellows.

It is a fact that the species which immediately preceded us Homo sapiens, the Cro-Magnon, had a bigger brain than we do (about 10% larger). Thus, as we humans have evolved, our brains have shrunk a little. Does this say that we are dumber than Cro-Magnon? That's very difficult to say, but the life of modern humans is certainly easier than that of our deep ancestors. While they had to work hard to forage for food, we walk into the supermarket and leisurely fill our cart with oodles of goodies. While they had to keep a sharp lookout to avoid being eaten by large predators, we have either done away with most of those predators or locked them up in zoos.

And what about the life span of Cro-Magnon, compared to modern humans? That's also not an easy question to answer, but it is surely affected by technology and availability of high-quality food. Our modern healthcare tools can be very effective at extending the life of people. Cro-Magnon did not have access to antibiotics, dentists, or surgical techniques. So maybe we H. sapiens live longer, not because we're dumber, but because of our modern medicine?

These findings also suggest a reason why evolution has gradually decreased the size of our brain. If we don't need the brain power we once had (because we have smart machines to care for us), why not let the brain shrink a bit—especially if it lengthens our life span? Is this not a wise trade-off that evolution has made?

That possibility is a little disconcerting, however. What might happen when we develop super-smart artificial intelligence machines? Will our brains shrink to the point that our dogs will someday be teaching us simple tricks and taking us to the vet to be neutered?