Cat Genome Reveals Clues of Domestication

The genome of cats, which did not split off from wild cats until fairly recently, is revealing surprising clues of domestication, according to a new study.

Cats and humans have shared the same households for at least 9,000 years, and yet we still know very little about how our feline friends jumped from wild cats to lap cats. News research published in the journal Proceedings of the National Academy of Sciences aims to answer that question.

As part of the cat genome sequencing project, which started in 2007 and is funded by the National Human Genome Research Institute, researchers aimed to understand the genetics of domestication. By comparing DNA from wild cats and house cats, looking for places where the house cat genome had undergone rapid changes, the team found certain genetic links that can explain the change in temperament.

House cats contain genetic mutations involved in in behaviors such as memory, fear and reward-seeking, as well as mediating their normally aggressive nature.

"Humans most likely welcomed cats because they controlled rodents that consumed their grain harvests," senior author Wes Warren said in a statement. "We hypothesized that humans would offer cats food as a reward to stick around."

This incentive lead cats to abandon their solitary lifestyle in the wild for the comfortable couches of people's homes, causing them to become more docile over time.

However, not all of the genetic changes were related to behavior.

For instance, certain fat-metabolizing genes found in carnivores such as wild cats (and tigers) were not present in the genome of their domesticated brethren. Living with humans, researchers from Washington University in St. Louis suggest, may have put 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," Carlos Driscoll, a researcher at the National Institutes of Health and co-author of the study, told Wired. "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."

In addition, traits like floppy ears, curlier tails, or white spotting, which are not actively selected for, seem to be linked to domestication.

And given that domestic cats have hereditary diseases similar to those that affect humans, scientists hope the complete cat genome could improve understanding and treatment of the more than 250 genetic diseases.