Which brings us to the genome of one critical tame animal: ourselves, humans. The Nobel Prize-winning zoologist Konrad Z. Lorenz once suggested that humans were subject to the same dynamics of domestication. Our brain and body sizes peaked during the end of the last ice age, and declined with the spread of agriculture.

Instead of poring over the meager fossil record, we can survey patterns of variation across tens of thousands of living individuals. Genomics now provides evidence that humans have been subject to a great deal of natural selection over the past 10,000 years. A beautiful example is the ancestors of Tibetans’ absorption of small portions of the genome of ancient human relatives adapted for living at high altitude.

Our cultural flexibility and creativity since the end of the ice age have not freed humans from evolutionary forces, but have opened up novel and startling paths. Thinking of domestication as an evolutionary process that occurs through “artificial” selection creates a false dichotomy of nurture and nature that plays into a conceit of human exceptionalism. In fact, the idea that we are apart from nature, that it is ours to tame and exploit, is an outmoded approach.

A more useful interpretation is that over the past 10,000 years, humans fashioned their own ecosystem. We were part of a natural process that altered the landscape. In that light, we can think of the domestic cat as an ecological response to the emergence of parasites (rodents attracted by early Neolithic granaries). The same forces that reshaped the genomes of our domesticates also reshaped ours.

No longer roving in small bands subsisting on game and unprocessed plants, we settled down in villages, harvesting the same crops year after year. For millenniums, peasants fed on what we might today term porridge, of various types. Our teeth became smaller — indeed, both dogs and humans show evidence of adaptation to starchy diets.

Just as the fur of our mammalian domesticates, freed from the constraint of needing to fade into the landscape, became a riot of diverse colors, human pigmentation started to change and many populations became light-skinned. With a cheek-by-jowl existence, humans and their animals began sharing diseases, remolding the immunity of whole populations, but leaving those who did not experience this co-evolution untouched and vulnerable. Possibly, some pathogens incubated in cats, like Toxoplasma gondii, may even alter human behavior.