The Future of Human Evolution

The January SCIENTIFIC AMERICAN, a special issue on Darwin and evolution, contains an article called “What Will Become of Homo Sapiens?” It addresses the widespread belief that the physical evolution of our species has stopped. I admit I’ve tended to assume that’s the case, at least for the foreseeable future. Thanks to technology, many of the physical differences that would have affected individuals’ survival under primitive conditions have become irrelevant. People who once would have died in infancy grow up to reproduce. And someday gene therapy will enable most couples to have children without worrying about genetic defects they might otherwise pass on to descendants.

This article undercuts the assumption that Homo sapiens has reached a stable plateau in evolution. It mentions changes that have occurred in the time since modern human beings arrived on the scene (a mere instant in terms of geological eons)—for instance, the development of racial differences; varying disease resistance among ethnic groups; the capacity for some population groups to digest milk after childhood. (It’s easy for Americans of European descent to forget that “lactose intolerance” is the norm, not the exception.)

Will a new human species ever arise? The article points out that speciation depends mainly on isolation of some kind. Separated groups tend to drift apart genetically, so that if they eventually reunite, they find they have become too dissimilar to interbreed. Globalization has made us members of a single worldwide breeding population. Special circumstances might produce the isolation necessary to spawn new types of humanity, though, such as colonies on distant worlds unable to communicate easily with Earth or a global disaster that breaks up the survivors into small, widely separated groups.

And then there’s genetic engineering. If biological science develops the ability to design preferred traits into human embryos, parents with access to this technology will inevitably use it. A division might arise between the classes who can afford custom-designed offspring and those who can’t. Would the differences become wide enough to engender separate species, though? The article also poses the possibility of symbiosis with machines, leading to the development of a new kind of human race sufficiently different from us to be thought of as a distinct species.

I’m more intrigued by genetic engineering, however, which of course reminds me of the Sime-Gen universe. Although we’re never told how the change occurred, it seems likely that artificial tampering with genes was involved. The development over a mere thousand or so years of a whole new energy-producing system, not to mention visible features such as tentacles, is radically more extreme than developing immunity to a particular disease; it seems to require artificial intervention. Remember the short-lived TV series PREY? It had an exciting premise of a new human species living secretly among us. In execution I found it disappointing. For one thing, the new species didn’t literally prey on us in any way (wouldn’t it have been cool if they’d been energy vampires?), and their hostility toward us didn’t have any rational motive that I recall. I don’t think closely related species of birds or mammals kill each other on sight; unless they’re competing directly for the same resources, they’re more likely to ignore each other. More important, the cause of the new species’ evolution was ridiculously attributed to global warming since the late nineteenth century. That’s far too short a time for a separate species to evolve, and the planet has experienced much greater temperature variations since the advent of Homo sapiens, with no species differentiation as a result. Now, wouldn’t a TV series based on the Sime-Gen books be not only more logical but more fruitful of intriguing plotlines? Well, we can dream.

Margaret L. Carter (www.margaretlcarter.com)