How We Evolve:
A growing number of scientists argue that human culture itself has become the foremost agent of biological change.
When the previous generation of life scientists was coming up through the academy, there was a widespread assumption, not always articulated by professors, that human evolution had all but stopped. It had certainly shaped our prehuman ancestors — Australopithecus, Paranthropus, and the rest of the ape-men and man-apes in our bushy lineage — but once Homo sapiens developed agriculture and language, it was thought, we stopped changing. It was as though, having achieved its aim by the seventh day, evolution rested. “That was the stereotype that I learned,” says population geneticist and anthropologist Henry Harpending. “We showed up 45,000 years ago and haven’t changed since then.”
[…]But since the turn of the millennium, genomics has undergone a revolution. With the completion of such landmark studies as the Human Genome Project and the publication of HapMap, scientists finally have access to the particles of evolution. They can inspect vast stretches of DNA from people of all ethnicities, and the colossal amount of information suddenly available has spurred a revision of the old static picture that will render it unrecognizable. Harpending and a host of researchers have discovered in our DNA evidence that culture, far from halting evolution, appears to accelerate it.
Does human culture evolve via natural selection, as our genes do?
Biologists have a pretty good idea of both how flies become resistant to DDT and how humans and primates have diverged over time. That’s because the mechanism underlying these processes is the same. Using evolution we can understand how organisms generally change their stores of genetic information (DNA and RNA), alter their observable characteristics, and diversify.
We do not understand how cultures evolve nearly so well. The majority of human evolution does not involve changes in our DNA, but rather alterations in the gigantic library of nongenetic information, the culture, that our species possesses. This library is orders of magnitude larger than that of our genetic information, and the elements on its diverse shelves usually have meaning only in connection with other elements. Indeed, there has been a long, bitter debate about whether it is sensible even to use the term evolution to describe changes in culture. After all, culture is composed of overlapping phenomena from languages, religions, institutions, and socially transmitted power relationships to the information embodied in artifacts ranging from potsherds to jumbo jets. The study of cultural change encompasses not only the disciplines of biology and the social sciences, but areas of the humanities as well.
We’ve Seen The Future, And It Is Us
As we drive the evolution of species, humans may be building a future with ever more diverse pests and pathogens and without the creatures we value most.
Human habitation has been, and is increasingly, playing a direct role not only in the extinction of species, but in their evolution. By our own actions, we may be accompanied into the future by ever more diverse pests and pathogens, and may leave behind what we value most—elephants, tigers, and others of the earth’s great megabeasts.
Evolution is often thought of as a slow process relative to our life spans, one that we have played no part in. We imagine it to have occurred in the far distant past. Until recently, the study of big evolutionary changes has rested on an examination of fossil remains and molecular evidence of the deep past. But, from a biological perspective, we can see that evolution is actually happening now and more quickly than we had previously assumed. Moreover, the new centers of evolution are neither tropical forests nor east African lakes but, instead, those habitats and resources most closely allied with us—our human habitats and ourselves.