Mammal species tend to come and go rather rapidly, appearing, flourishing and disappearing in a million years or so. The fossil record indicates that Homo sapiens has been around for 315,000 years or so, but for most of that time, the species was rare—so rare, in fact, that it came close to extinction, perhaps more than once.
Thus were sown the seeds of humanity’s doom: the current population has grown, very rapidly, from something much smaller. The result is that, as a species, H. sapiens is extraordinarily samey. There is more genetic variation in a few troupes of wild chimpanzees than in the entire human population. Lack of genetic variation is never good for species survival.
The signs are already there for those willing to see them. When the habitat becomes degraded such that there are fewer resources to go around; when fertility starts to decline; when the birth rate sinks below the death rate; and when genetic resources are limited—the only way is down. The question is “How fast?”
Related on the SLP
I suspect that the human population is set not just for shrinkage but collapse—and soon. To paraphrase [singer Tom] Lehrer, if we are going to write about human extinction, we’d better start writing now.
