crisis

A change in direction?

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On the other hand, during the last fifty thousand years or so, evolution seems to be taking us toward diversity, rather than versatility, in at least some respects.

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For instance, the constantly increasing brain sizes of the last two million years, which enabled our ancestors to become more and more versatile, no longer characterizes our evolution.  Instead, current brain-size evolution has turned into random drift.  This is probably because of a combination of features of modern life:

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1. New birthing procedures enable mothers to successfully give birth even when the infant has an extra-large head.

2. Good nutrition has been a fact of life for most human populations in recent times so that large brains no longer compete for scarce resources that are needed by other tissues, such as muscles.

3. Human societies have become so large and interconnected that people no longer have to be versatile in order to pass on their genes.

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Not only do big brains not necessarily contribute to survival, but in the last fifty thousand years they have increasingly become a handicap, and average brain sizes have tended to decline.  This decline of average brain size would most likely be most pronounced in the most modern societies if nutrition had not improved overall.  In other words, modern life seems to support an evolutionary trend toward smaller brain sizes, and we may be following in the footsteps of Homo naledi.

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What about taking charge?

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It has been suggested that we should take steps to stop evolution altogether.  This might be safer than letting blind chance rule our future course of evolution, but it calls to mind Adolph Hitler's quest to eliminate genetic characteristics that he thought were inferior (or, in fact, if he thought they might be superior in some ways to his planned Master Race).

The future

So, what surprises lay hidden in future time?  Chances are that Florida will disappear, and major metropolises around the world will sink beneath the waves.  Most of the animals and plants that we find on Earth today will be squeezed out of existence by Homo sapiens.  In short, another existential crisis is staring us in the face, as our population, technology and habits squeeze the life out of our planet.  Again, we find ourselves unable to come to a consensus as to what to do to save ourselves.  But now, the group that needs to agree about the problem and take concerted action consists of all of humanity.  What is clear is that present trends are unsustainable, so I will end my story with this question:  Are we ultimately winners or losers?