Over the last 50,000 years, modern humans have been subjected to enormous evolutionary pressures, in part from the consequences of their own social culture. They explored new ranges and climates and developed new social structures. Fast adaption, particularly to new social structures, was required as each population strove to exploit its own ecological niche and to avoid conquest by its neighbors. The genetic mechanism that made possible this rapid evolutionary change was the soft sweep, the reshaping of existing traits by quick minor adjustments in the sets of alleles that controlled them. But what began as a single experiment with the ancestral human population became a set of parallel experiments once the ancestral population had spread throughout the world. These independent evolutionary paths led inevitably to the different human populations or races that inhabit each continent.

More and more — as this, and so many of the discoveries discussed in this book illustrate — the once slow and passive process of natural selection is being transformed into one rapid and proactive: evolution by human direction. This means, over the next century, technological acceleration may do more than just disrupt industries and institutions, it may actually disrupt the progress of biologically based intelligence on Earth.

But if humans can make new varieties of plants and animals, must not nature do so also? This related process is called natural selection. That life has changed fundamentally over the aeons is entirely clear from the alterations we have made in the beasts and vegetables during the short tenure of humans on Earth, and from the fossil evidence.

If artificial selection can make such major changes in so short a period of time, what must natural selection, working over billions of years, be capable of? The answer is all the beauty and diversity of the biological world. Evolution is a fact, not a theory.

The recent discoveries that human evolution has been recent, copious and regional severely undercut the social scientists' official view of the world because they establish that genetics may have played a possible substantial role alongside culture in shaping the differences between human populations.

Whether or not we choose to watch, evolution is shaping us all.

Thus human culture has been as much a product of the process of natural selection as the human species. We are not merely clockwork oranges, the clockwork itself, the social programming which determines our “repertoires of behavior,” how we respond to the world around us, is itself the product of a blind deterministic process.

It is natural human impulse to think of evolution as a long chain of improvements, of a never-ending advance towards largeness and complexity — in a word, towards us. We flatter ourselves. Most of the real diversity in evolution has been small-scale. We large things are just flukes — an interesting side branch.

Scientists are advancing a theory that human beings have stopped evolving because we've interfered with natural selection. Thousands of years ago, the fittest of the species endured, while the weakest stumbled into tar pits or got eaten by saber-toothed tigers. That doesn't happen much anymore, and consequently—these experts assert—humans are actually devolving, getting dumber and less fit. The hypothesis is bolstered by the popularity of daytime talk shows and psychic hotlines. More empirical evidence is supplied every Fourth of July, when alcohol and explosives are freely distributed among the populace.

About all these things physics can tell us nothing. The idea of natural selection, which, as we shall see, is uaully called in to account for this vast creative surge, is already looking increasingly inadequate to explain evolution. The main trouble is, I think, best explained in the analogy of coffee. Natural selection is only a filter, and filters do not provide the taste of coffee that pours through them. Similarly, the range of evolutionary alternatives between which selection takes place has to be already in matter. How it comes to be present there is the real mystery about creation.

As breeders of domestic animals, when they choose certain varieties in preference to others to breed from, speak technically of their method as that of 'selecting,' Mr. Darwin calls the combination of natural causes, which may enable certain varieties of wild animals or plants to prevail over others of the same species, 'natural selection.'

Natural selection, as it is actually used in evolutionary population biology, serves mainly as an optimization process. In fact, the reasoning that underlies much evolutionary biology often strikes social scientists as strongly reminiscent of neoclassical economics.

Considering that we live in an era of evolutionary everything — -evolutionary biology, evolutionary medicine, evolutionary ecology, evolutionary psychology, evolutionary economics, evolutionary computing — -it was surprising how rarely people thought in evolutionary terms. It was a human blind spot. We look at the world around us as a snapshot when it was really a movie, constantly changing.

The fact that human evolution has been recent, copious and regional is not widely recognized, even though it has now been reported by many articles in the literature of genetics. The reason is in part that the knowledge is so new and in part because it raises awkward challenges to deeply held conventional wisdom.