Maladaptation and Human Evolution
Species evolve when they are “maladapted” to their environment, which occurs when the environment changes. A species’ genetic composition at any given time can be modeled based on the species previous genetic composition with the addition of a set of evolutionarily induced changes (which are a function of how different a species’ actual genome is from a theoretically optimal genome for it’s environment). Now lets look at what this way of looking at evolution means for humans.
You may or may not have heard of something called Moore’s law. Essentially what Moore's law says is that human technology “improves” (for our purposes that simply means changes) at an exponential rate. This has been happening, arguably, ever since the renaissance. By technology I don’t just mean iphones and computers, I mean everything we produce and live with. That includes beds, desks, art, and medicine. This exponential change in technology translates into an exponential change in our immediate environments. Our surroundings, our environment, the thing which interacts with our genomes to determine each of our reproductive success is changing at an ever increasing rate.
Moore's Law Graph
While the technological change is small, we can evolve quickly enough to be reasonably well adapted to our environments. As the change grows, however, the human genome becomes more and more maladapted to it’s environment. This causes more rapid evolution and, if continued long enough, maladaptation beyond our species extinction threshold (which is probably quite low due to our long generation time).
Evidence of our growing maladaptation is all around us. Lets look at a few examples. One pretty obvious one is the overabundance of calories available to us. Our bodies have evolved to utilize most effectively a 1000-2000 calorie per individual environment. Now, though, we have access to many more calories, but our bodies don’t utilize them effectively (as evidenced by obesity in the western world, and its deleterious effects).
We have to go back
Another example, and one which is really much more damning to our species’ fitness, is birth control. Organisms have evolved for hundreds of millions of years on the basis that sex translates into offspring. A recent (less than one hundred years) change in our environment, however, has destroyed this connection for humans. Our genome hasn’t had the time to evolve to cope with this monumental change, and the decline in fitness is obvious and dramatic: individuals in countries with widespread access to birth control are markedly less fit (have fewer children per capita and lower population growth overall) than those in countries without access.
The final, and to me most interesting, example is human moral maladaptation. Our deepest moral convictions are derived genetically, not culturally. Humans universally feel that infanticide is wrong, for example, because we are genetically predisposed to do so (believing infanticide is wrong makes us more fit because we won’t kill our own offspring). We have not had time, however, to evolve the appropriate (most fit) moral responses to certain recent technological changes. For example, abortion (the functional equivalent of infanticide) is not at all viewed with the same universal distaste as infanticide is. We have not had time as a species to evolve a moral opposition to this hugely unfit behavior because it is such a recent addition to our environment.
Will the Maladaptation of our Technological Environment lead to faster evolution or extinction?
Extinction or Rapid Evolution
As our technology (environment) continues to increase exponentially, our maladaptation to our environment will continue to increase. Such rapid environmental change over such a short timescale will lead to extinction or extraordinarily fast evolution. Considering the speed at which our environment is changing relative to our long generation time as a species, my bet is on extinction.