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rfmcdonaldWired's Nick Stockton writes about the evolutionary pressures which resulted in domesticated housecats, as revealed by a study examining genetic differences between domestic housecats and their wildcat relatives.
Cats are different than other domesticated animals. Unlike other species tamed for either food or labor, cats specialized in becoming mooches. Sure they catch mice, but it’s not like they do it for our sake. Despite these differences, many scientists believe that cats, like all domesticated animals, inherited certain genetic mutations from ancestors who were unafraid of humans. A new study identifies some of the genes that may be responsible for the differences between house cats and their wild ancestors.
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By comparing the wildcat and house cat genomes, and looking for places where the house cat genome had undergone rapid changes, the researchers found three possible genetic links to that change in temperament. Compared to wildcats, house cats have more mutations on genes known to mediate aggressive behavior, form memories, and control the ability to learn from either fear or reward based stimuli. Cats with these traits would have mated with each other, repeatedly passing them along from parent to kitten until a significant population became distinct from their still-aggressive cousins.
“There’s a big difference between house cats and wildcats,” said Stephen O’Brien. “A house cat will sit on your lap, but a wild cat will hand you your behind.” These genes were most active in the neural crest, a group of embryonic cells that become the spinal cord in adult vertebrates.
Not all of the genetic differences were related to behavior. Living with humans put other selective pressures on cats, including the addition of vegetables to their diet. “Wildcats are pretty unique in the mammal world because they are hyper carnivores,” said Carlos Driscoll, a researcher at the National Institutes of Health and co-author of the study. “It’s not just that they don’t like eating non-protein foods, but it doesn’t seem to do them any good if they do.” House cats, on the other hand, do eat some plant matter, which probably came about from picking through our ancestors’ rubbish. This is reflected not only physiologically—house cats have a slightly longer large intestine than wildcats—but also in genes that control the digestion of fatty plant matter, which are more active in domesticated cats.
