When Did Cats Become Companion Animals?

Is that a mouse? Image source: morgueFile.

I am unabashedly a cat person, heavily influenced, I suspect, by the ever-fluctuating population of cats that roamed the family farm. Most of these outdoor cats were skittish around humans, but sometimes there were friendly female cats with a litter of kittens that were fun to chase, pick up and stroke. While the farm’s clowder of cats would eagerly await table scraps my mom would put out in the evening, there was plenty of opportunity for the felines to hunt vermin around the farm. It is this function—rodent control—that may be the reason that many of us share our homes with cats. One hypothesis to explain the association between cats and humans is rodents were stealing from human grain stores and cats could control rodent populations. However, there was not much data to confirm this hypothesis. Recent archeological evidence from China seems to support this view of cat domestication as reported in the Proceedings of the National Academy of Sciences.

Hu et al. studied felid bones that had been found in refuse pits at a Neolithic farming village excavated at the Quanhucun site in Shaanxi, China. These remains spanned more than one layer, and based on carbon dating of bone fragments taken from two different remains in different strata, the remains were about 5,300 years old, spanning about 200 years. This time period is interesting because while there is ample evidence of the close relationship between humans and felines as demonstrated in Egyptian art about 4,000 years ago, the earliest evidence of the association between humans and cats was a grave in Cyprus about 9,500 years ago where a wildcat was buried next to a human. The felid remains found in China lie between these two time points and offer an opportunity to look at the transition to domestication that is heavily featured in 4,000-year-old Egyptian art.

With the time frame established for the remains, Hu et al. compared the size of eight specimens definitively identified as felid with measurements of equivalent bones from modern European wildcats (assumed to be similar to wildcats from 5,300 years ago) and modern European domestic cats as well as cat humerus and pelvis specimens from two ancient Egyptian sites. There is a great size difference between wildcats and domesticated cats, and based on this difference, the skeletal remains can help define how domesticated the Quanhucun felids were. Based on measurements for the eight skeletal items available, some data suggested the felids were too small to even be on the low end of the wildcat range but with the qualification that there is no data for wildcats contemporary with the Quanhucun felids, and some skeletal measurements fit within the range of domestic cat measurements. Therefore, the scientists tentatively concluded the felids at Quanhucun were domesticated cats, not wildcats.

To better understand the association between cats and humans in the Neolithic farming village at the Quanhucun site, scientists undertook isotope analysis of bones from herbivores both wild and domesticated, rodents, felids, humans and dogs all excavated from the Chinese village. Isotope analysis is useful because it can help scientists learn what kind of diet an individual had consumed. The ancient villagers stored millet at the Quanhucun site and based on the burrows near grain storage sites and construction of rodent-deterring storage vessels, rodents were consuming the stored grain. Millet differed from the native vegetation in that it used C4 photosynthesis rather than C3. This would affect the carbon balance of any animal that consumed millet. The carbon and nitrogen isotopes measured in herbivores like deer and hare were the lowest of all the animals, reflecting their primarily C3 plant-based diet. For the domesticated pigs and dogs as well as those pesky rodents, the carbon and nitrogen values were higher, consistent with consumption of the C4-based millet grain. Human remains also had a similar carbon measurement but with more nitrogen than pigs or dogs, reflecting greater meat consumption. As for the felids, their carbon and nitrogen isotopes were closer to humans, dogs, pigs and rodents, suggesting that they were eating the rodents that were eating the grain that humans, dogs and pigs also consumed.

Interestingly, there are some hints of old and infirm cats in the ancient Chinese village. Based on the worn teeth on one jaw bone, one felid was quite old. A set of remains used in the isotope analysis had higher carbon and lower nitrogen isotope amounts compared to the others, reflecting a greater grain consumption. In addition, the felid bones uncovered at Quanhucun spanned a few hundred years, suggesting an ongoing cat population. Therefore, a probable reproducing population of cats that included older animals and some individual cats, possibly infirm, surviving on bits of grain means even if they weren’t contributing to rodent removal, they were still allowed in the village, possibly even actively fed and cared for by humans.

So what does this all mean? Hu et al. show evidence that cats were domesticated in China around 5,300 years ago. Cats were performing useful work in keeping down rodent populations near human grain stores and due to their close proximity to humans, eating some of the waste and leftovers from human dinners. As a result, the felid diet starts to look more like the already domesticated pig and dog. This work shows us a glimpse of cat domestication in China by analyzing what kind of food the cat was consuming. The possibility that ancient felids, especially old or infirm cats, had a diet that was rich in grain supports the hypothesis that humans were caring for them. Regardless, I am glad domesticated cats are part of the human realm, and I appreciate that my ancestors recognized their value as companions as well rodent hunters.

Reference
Hu, Y., Hu, S., Wang, W., Wu, X., Marshall, F.B., Chen, X., Hou, L. and Wang, C. (2013) Earliest evidence for commensal processes of cat domestication. Proceedings of the National Academy of Sciences of the United States of America, PMID:

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Sara Klink

Scientific Communication Specialist at Promega Corporation
Sara is a native Wisconsinite who grew up on a fifth-generation dairy farm and decided she wanted to be a scientist at age 12. She was educated at the University of Wisconsin—Parkside, where she earned a B.S. in Biology and a Master’s degree in Molecular Biology before earning her second Master’s degree in Oncology at the University of Wisconsin—Madison. She has worked for Promega Corporation for more than 10 years, first as a Technical Services Scientist, currently as a Scientific Communication Specialist. Sara is camera shy but may succumb to peer pressure and post an image.

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