There’s a really really dumb article getting a lot of attention in the media about the future of human evolution. Razib has a deprecating post about it, but I thought I’d add my two Australian cents (=0.006 US cents) worth.
Let’s look at the major claim: that humans will subspeciate. I can’t think of anything less likely among a species that has major gene flow between all its populations on a scale of thousands of generations. Species aren’t formed by selection for differing adaptive traits within a population, but by the interruption of the gene flow that is caused by migration or invasion between populations. Take a look at human gene flow over the past 10,000 years – massive amounts of interbreeding and invasive gene flow. Not a hint of the sorts of isolation required for a mammalian species to speciate in sight. Not even the Tasmanian aborigines, who were isolated for about 10,000 years. Not even the San or M’buti. Nada.
So why would we think that it will happen in the future? What possible “trend” is observed that could indicate this? The “genetic haves” are already among us – they are the people whose genes allow them to fight off certain pathogens like plague or HIV, those whose genes allow them to ingest dairy products when dairy industry is ubiquitous, those whose genes allow them to fight off malaria (but who become “have nots” when they are no longer in a malarial region, because the homozygotes die young). The entire premise of there being some sort of genetically privileged pure strain is biologically implausible.
What about the “reliance on technology reducing our ability to fight disease”? This is classical eugenics. The exact same arguments against medical treatment were made in the 1910s and 1920s. And it was false then, too. Medical technologies allow those who might succumb to some diseases to live, but that doesn’t affect our genetic constitutions all that much for (you guessed it) tens of thousands of generations. Is it likely that we will manage to maintain medical treatments consistently for that long – 30,000 years or so? On what possible reading of cultural history can we make that claim?
And what’s this “physical peak” we are supposed to reach? Where in biology is it written that any species has a “physical peak? Adaptive peaks are defined by the conditions in which a species lives, and if our environment happens to include the products of industrial and medical technologies, then that is what defines our “peak”. Evolution doesn’t aim for classical Greek ideals or the standards of Playboy. It in fact is generated by the environment and organisms’ behaviours, and if it turns out that your genetic fitness is best increased by being ugly, short and squat, to quote the Monty Python hymn, then that is where it will go.
This scenario is based on little biology and the idea that human society is the driving force of human evolution. Biology will surprise us – it cares nothing for the transitory fashions and institutions of human culture, except when that culture persists for a very long time or the influence on genetic evolution is striking (like the introduction of agriculture and dairy farming). That “damage”, if that’s how you want to see it, has already been done. We evolved resistance to a slew of diseases the hard way, and we will continue to do so. Medicine can ameliorate the impact, but not stop evolution in any way. The very idea that our immune systems will somehow deteriorate through lack of use shows how little this guy understands about immunology, epidemiology, evolution or history.
Articles and claims like this are responsible for a host of misunderstandings by the ordinary person about biology and evolution. The ideas it espouses were out of date in 1930. Even then, they were known to be wrong, but were still accepted by the uneducated. But to argue that there even could be long term trends that we can predict about evolution, when we don’t know enough about the boundary conditions of culture or the environment, and history, if it teaches us anything, teaches us that there are no certainties in history, is to make stupidity a virtue.
Now it’s entirely possible that Curry is in fact not saying any of these things, but merely speculating for a popular TV show, in which case everything I just said applies to the PR people and the journalists, but whether he said it, or not, the ideas are ridiculous, unbiological, unhistorical and implausible. Such claims make us all a little bit stupider.
Late note: See John Hawks’ smackdown too.