What Keeps Us Human

I’ve been reading the latest analyses of paleolithic hominin DNA and from what I’ve gathered it seems to be the case that the present human population is a non-homogeneous collection of various hybrid populations between Homo sapiens (“modern” humans) and Homo neanderthalensis, Homo denisovensis and very likely Homo erectus.

Of course, human evolution is such a hot-button topic today that getting paleontologists to use words like hybrids to describe human lineages makes them squeamish and nervous.  Everyone is afraid of the accusation of racism to erupt if someone hints that human beings of different ancestries aren’t all exactly the same.  But they really should all calm down.  Hominin species have been walking the Earth for something like seven million years and during that time various groups have become isolated, evolved different characteristics and then just as easily recombined and formed hybrids that in turn become isolated and start the process all over again.

The latest information I’ve seen shows that there is a strong correlation between Neanderthal DNA and modern populations in northern Europe and northwesten Asia.  And there are strong correlations between Denisovan DNA and modern populations of Australian aborigines and Papuan New Guineans.

The ancient DNA that has been found is restricted to specimens that existed in cooler climates so the complicated story of hominin mixing and isolating in Africa and other tropical areas may never be reconstructed (although recent work with fossil protein materials may change that in the future).  But I think it’s clear that humans have in the past and will continue in the future to recombine their populations in various ways in reaction to local conditions that select for fitness.

Of course, those selection pressures have changed drastically over the geologic time our genus has existed.  Human society has also evolved and culture has as much to do with evolution now as climate had in the past.  Human behavior is now dictated by things like propaganda, government policy, industrial planning, resource scarcity and even internet influencers.

But hopefully men and women will still try to find mates that will allow their offspring to have the best chance of surviving and carrying on the race.  It still makes sense for a man to want a woman with empathy for his children and enough sense to teach her children to obey their parents and follow the simple rules written on those stone tablets that have guided our civilization for the last several thousand years.

And it makes sense for a woman to want a man who isn’t too lazy or selfish to provide for his family and who enjoys coming home from the hunt and retires to the fire in his cave and tells his little tribe about the mammoth that he hunted and the saber-tooth tiger that hunted him.  And draws a picture on the walls of his cave to celebrate that story.

And the most important trait that both men and women should be selecting their mates for is their minds.  Our brains have been our hallmark for millions of years.  Homo habilis; the tool maker.  That’s us.  We’re the monkeys that came down from the trees, stood up straight and looked at the world straight on and began changing it to our liking from day one.  Fire.  The wheel, the wagon, the chariot, the ship, the saddle, the plow, the heat engine, automobiles, airplanes, rockets. Stone weapons, saws, knives, hammers, axes, levers, firearms, lasers.  Gold, silver, copper, tin, iron, steel, uranium, the atom bomb, the hydrogen bomb.  Wheat, oats, millet, rice, maize, cattle, horses, sheep, goats, donkeys, chickens, ducks, white mice, guinea pigs, rhesus monkeys, yeast, mammalian cell culture, CRSPR gene editing, bioengineering.

Let’s just hope that our “civilization” never forgets what keeps us human.