Several readers sent me a link to or news report about a new paper in Proceedings of the National Academy of Sciences by Yaowu Hu and colleagues (reference and link at bottom). The paper reports the discovery of cat remains associated with a 5200-5500-year-old human settlement in east-central China. Since the earliest domesticated cats from China were previously known from only 2000 years ago, this pushes Chinese cats back a considerable distance.
The question is to determine whether these really were semi-domesticated cats, and that’s the main problem of this paper. The evidence is suggestive, but not super-compelling. But first let me tell you what we know about the history of cat domestication. Rather than rewrite the paper’s introduction, I’ll just present it verbatim, as it’s clear enough.
Studies of mitochondrial DNA from modern wildcats and domestic cats demonstrate that ancient populations of Near Eastern wildcats (Felis silvestris lybica) were the maternal ancestors of domestic cats. A wildcat phalanx from the site of Klimonas shows that they were introduced to Cyprus 11000–10500 B.P. (all dates are reported in calibrated years before present), providing the earliest connection between humans and cats. The earliest cat to demonstrate a close association with humans is also from Cyprus, where a young wildcat was interred next to a human at the site of Shillourokambos ca. 9,500 y ago. Isolated cat bones have been found at Near Eastern sites, such as Jericho, but little is known about the crucial period for cat domestication between 9,000 and 4,000 y ago. Healed fractures on the forelimbs of a young swamp cat (Felis chaus) buried in a ca. 5,500-y-old grave at Hierakonpolis in Upper Egypt indicate that wildcats were actively cared for by ancient Egyptians. However, the first evidence for domestic cats is based on Middle Kingdom Egyptian art dated to ca. 4000 B.P. Trade in cats was prohibited in ancient Egypt, but they were nevertheless exported to Greece around 3,000 y ago and from there to Europe. Cats were thought to have first appeared in China around 2,000 y ago. Claims for earlier cats in the region have been made (Table S1), but without precise dates or detailed biometric measurements these have been difficult to evaluate.
The authors hypothesize that some subspecies of Felis silvestris (perhaps native, or perhaps a semi-domesticated immigrant from the Middle East) was becoming more domesticated by associating with the people from this site, who raised and ate grain (the authors found remains of millet and a bit of rice). Because the bowls for storing grain at the site were shaped in a way to discourage rodents, and because the authors also found rodent bones at the site (including the Chinese “zokor”), the idea is that cats domesticated themselves by hanging around the settlement nomming the grain-attracted rodents. Then, the story goes, they became tamer, their flight distance became reduced, and, at least in China, humans began feeding them grain. This is not a new story: it’s the old idea that cats weren’t domesticated by humans, but domesticated themselves.
At any rate, here’s a sketch of one of the anti-rodent pots, taken from the paper’s “supplemental material.” I guess zokors couldn’t climb up the outward-sloping sides:
More evidence for domestication: the authors found 8 cat bones at the site (mandible, humerus, pelvis, tibia, and femur) from at least two individuals (though, curiously, the graph below suggests three). One of the jawbones—”A” in the figure below—showed a “worn fourth premolar and first molar.” The authors imply that aged cats mean semi-domesticated and well-fed cats, though I’m sure some cats in the wild can live long enough to get worn teeth. Carbon-14 dating put the cat bones at about 5300 years old.
The third piece of evidence is based on body size. The cat from the Chinese site (they measured just one set of bones) is larger than modern house cats measured in Czechoslovakia, but smaller than modern European wildcats, although this intermediacy is not uniform. The pelvis of the Chinese cat, for instance, is 79 mm in “GL” (not sure what that means, though perhaps “girth left,” since they measured only the left side), compared to a mean of 44 mm for modern Czech cats and 53 mm for modern European wildcats from the Carpathians. The cat is also a tad smaller in some bone measurements than cats from ancient Egyptian sites.
From the intermediacy of these measurements between modern house cats and modern wild cats, they conclude that the data “are suggestive of domesticated cats.” But I don’t find this at all convincing. They’re implying that domestication leads to smaller cats, which may be true, but size is also determined by nongenetic factors like health and nutrition. Moreover, if there was an ancient subspecies of Felis silvestris in China that was smaller than the modern European wildcat, these could be pure wildcats that were hanging around the settlement. I find the size measurements unconvincing evidence for domestication.
Finally, the authors give isotope data (carbon and nitrogen) taken from bone collagen collected from specimens at the site. From this they try to infer something about diet. Here are the plots for δ13C (the ratio of C13/C12) and δ15N (the ratio of N15/N14) for each animal measured, including humans. Here are the plots. The cats (why are there three dots instead of two?) show intermediate values for the nitrogen ratio and higher values for the carbon ratio. Sadly, no pure carnivores were measured, as there were none at the site.
From these data the authors conclude—well, nothing that I can sign onto. For example, it’s clear that the cats weren’t eating the same stuff as deer and fish, but since cats are carnivores and neither fish nor deer are, that’s not surprising. But they also say that the high δ13C ratio for humans “suggested that the individual consumed a large amount of C4-based animal protein”. Just a few paragraphs later, though, they say that “the common Chinese zokor [a rodent] had a high δ13C value, indicative of the consumption of millet products”. Well, which is it? The data also suggested to the authors that the cats were eating millet, too. But cats are carnivores, and why weren’t they eating rodents? Will cats eat millet if they can get it, or are fed it by humans? Do the data even suggest that cats were eating millet?
In the end, I can’t make heads or tails of the isotope data (though it may be simply reflect my own ignorance). Nevertheless, interpreting that data seems to involve a lot of speculation. The authors say, for instance:
Together, the spread of millet farming and commensal rodent populations attracted cats and provided incentives for farming communities to support them. The cat population at Quanhucun survived for several hundred years, with one of the individuals that we studied living to a considerable age, suggesting a favorable environment for cat survival. One animal stands out from the others, with a high δ13C value (−12.3‰) and low δ15N value (5.8‰), suggesting that it ate large quantities of agricultural products and did not rely as heavily as expected on rodents or other small animals for food. These data are intriguing, raising the possibility that this cat was unable to hunt and scavenged for discarded human food or that it was looked after and fed by people.
That is a LOT of speculation. Had I been the editor of this paper (it was Dolores Piperno from the Smithsonian), I would have suggested that the authors need to clarify a lot of things, and avoid so much speculation. If I can’t understand the isotope data after two readings, then neither will the average reader.
But the paper is still valuable in other ways. It gives evidence, for instance, that cats were living in at least loose association with humans more than 5,000 years ago in China, just at the time when they were supposed to be getting domesticated in the Middle East. (Mitochondrial DNA tells us that all modern housecats descend from Felis silvestris lybica from the Middle East.) So if these are domesticated cats, and ones not domesticated in situ in China, how did they get from the Middle East to Shaanxi? There are Asian subspecies of F. silvestris, too, and perhaps those were domesticated independently and later acquired their mitochondrial DNA by hybridizing with cats brought from the Middle East. (Mitochondrial DNA introgresses rapidly between subspecies and species, while nuclear DNA can remain distinct.)
What this all tells us, I think, is the unsatisfying but common conclusion that “more work needs to be done.” The problem is that it’s very difficult to look at nuclear DNA from bones, and I’m not sure how much to trust the isotope data. At any rate, we’re not justified in concluding either that cats were originally domesticated in China (which some newspapers have suggested), or that the cats domesticated themselves in China, eating both grain and rodents. That must await further work.
Hili, are you reading this?
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Hu, Y., S. Hu, W. Wang, X. Wu, F. B. Marshall, X. Chen, L. Hou, and C. Wang. 2013. Earliest evidence for commensal processes of cat domestication. 10.1073/pnas.1311439110 Proceedings of the National Academy of Sciences, early edition.
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I always used to be make jokes about our cat being an Egyptian. But now it seems that my old joke is not that accurate anymore?
Perhaps the cats in the Middle East were given as gifts or trade (forbidden or not). I’m pretty sure there was trade between the middle east and China so they would know each other. If there were corresponding records for this type of thing that would be helpful.
I doubt such trade would have been direct? Usually it would mean things were traded on by intermediaries & there were many gaps along the way. The Sumerians appear to have traded with the Harappans though so perhaps you are right.
If I had to guess as a non-expert I would say that this self-domestication arose in several places where conditions – that is arable farming – developed.
I wonder if anyone has looked at cats in the Indian subcontinent? Half way between China & Egypt & with early agriculture along the great rivers of the north like the Harappan on the Indus where famously there are paw prints of a cat on tiles found at Chanhu-daro, though there it is supposed to have been Felis viverrina.
Just this week I was watching a documentary about cat domestication, in which the researchers collected saliva samples from domesticated cat populations all around the world. The aim was to find the population with the greatest genetic diversity, as this would indicated the geographical region where cats were domesticated the longest. The conclusion was pretty clear that it was in the fertile crescent. Perhaps the documentary and the above paper were discussing the same DNA study.
The documentary pointed out that cats in other areas had less genetic diversity, and this included areas in Asia. This would occur if they were descended from smaller populations brought in by trade.
I do not think that any of this precludes that cats could self-domesticate in more than one area, but even if they did their genetic traces might be eliminated by the relative flood of new DNA coming in by trade.
Everybody has this the wrong way round. Cats domesticated humans not the other way around.
😉
Jerry, a quick question: You state that neither deer nor fish are carnivores. I thought that some species of fish are carnivorous. Yes, no? L
Piscivore (fish eaters) rather than carnivores. I’m not sure if piscivores have a carbon ratio and nitrogen ratio similar to carnivores.
Thx. L
I was operating under a broader definition of carnivore too, Linda. Glad you asked.
…one of the anti-rodent pots, taken from the paper’s “supplemental material.” I guess zokors couldn’t climb up the outward-sloping sides:
Not until the cat walks by and knocks it over.
Many cats would object to the term “domesticated”
Baihu wishes for me to remind y’all of his own origins:
http://en.wikipedia.org/wiki/White_Tiger_(China)
and, in particular, to note that Africa is west of China.
Cheers,
b&
Isn’t neoteny closely associated with becoming tame? And could it be assessed from such meager bone samples as these?
Yes, but probably only in certain breeds of cats and dogs that were descended from breeds that were already domesticated. The shorter faces were generally bred for in stocks used as companions (pets), so that they looked cuter. Domestication would have started for more utilitarian purposes, like vermin control in the case of cats. No need for widdle pushed in faces and big round eyes just then. 🙂
You’re saying neoteny was selectively bred by humans out of a desire to have cuter pets. Perhaps. My understanding was:
1) Neoteny was a natural adaptation in response to semi- or fully domesticated environments — looking immature elicited parenting/nurturing responses;
2) The genes ‘for’ neoteny and those for lower fear/aggression ‘travel’ together.
I see what you mean, but to me what you are saying versus what I was saying was a matter of emphasizing different agents involved in artificial selection. The way I put it, humans consciously selected for traits of neoteny in some breeds, once they found it. But your way of putting it is also quite valid, and it had a little more flourish since it equates this case of artificial selection to selection in general.
The two aren’t mutually exclusive — neoteny could have first been naturally selected because semi-wild cats or dogs with childlike features received better treatment/greater acceptance; then much later, breeders artificially accentuated it.
If childlike features are indeed linked with childlike behavior/docility, then the individuals that were best suited behaviorally to domestication would by default end up displaying the greatest neoteny. I suspect both features and behavior were factors.
Checking finds, like this one in China, for signs of neoteny might prove interesting, though.
Cats admittedly have shorter jaws than dogs, for example, but I have not heard before of the suggestion that it could be due to selection for life-long neoteny so that juveniles could induce better parental care in the wild. Carnivores tend to have short jaws as juveniles, and this is popularly thought to induce parental care b/c they look cute, but that particular selection value goes away as individuals grow up and become independent for their parents.
So why might cats as a group keep short jaws as adults, but other carnivores develop long jaws? My first thought, and I am only guessing here, is that cats retain short jaws b/c they do not fill them up with the different kinds of teeth as they grow up. Canids and bears grow in a variety of meat shearing teeth and crushing teeth, and they need longer jaws for all of that equipment. Cats are dedicated carnivores, and amazingly they have only 3 meat shearing teeth behind their canines. The shearing effect of those teeth are actually pretty cool to see. Everyone should try to check them out on a docile cat.
Domesticated neotenous dogs can have problems with their bite b/c their teeth no longer mesh, but some breeds have managed to lose some teeth.
“Everyone should try to check them out on a docile cat.”
Emphasis on the “docile.” 😀
It seems to me the distinction between “natural” and “artificial” selection of domesticated animals is itself somewhat artificial. In either case, individuals that appeal to humans for whatever reason enjoy greater reproductive success. Whether the humans in question are conscious of their role as agents of selection seems largely irrelevant.
Agreed, but it can still help to make the distinction. You can point to it and say, “We know this happened because here’s the paper trail,” as opposed to the indirect methods of observation necessary in most other cases.
b&
“Domesticated” cats? (O.o)
But, no gratuitous LOLcat? Then I may try to embed the one from Ars’s article, I hope it is permissible. (But also the link, since my embeds usually fail here.)
Not now. My domestication story is very long.
[ http://arstechnica.com/science/2013/12/earliest-evidence-of-cat-domestication-found-in-china/ ]
Feasibly it could either indicate spread by a repeat measurement since they unhelpfully leave them out of the graph (and perhaps the text), or a modern reference which also unhelpfully seems lacking in the graph. The former would be nice to assess what the data can say, the latter would be nice to assess what the data can say on “eating millet”.
Embed fail, so people have to go for the link for the lolzy cat.
Also, I meant to day on the “there … are … three … dots!” [obligatory Star Trek reference] that the text pretty much precludes my first hypothesis with “One animal stands out from the others,”.
Using sophisticated creationist dating methods, this implies that Noah must have had two cats; or, if they’re considered ‘clean’, he had 14 of the critters.
So how come the Ark is still depicted in creationist books without a cat flap? Checkmate, creationists!
Then, as now, they no doubt meowed at the door and Noah or someone would open it to let them out on the deck. The cat would then just sit in the doorway and look outside.
Well, of course. With all that rain going on outside, you don’t think they’d actually go out there and get wet, do you?
b&
I think all pets might do this, rain or shine. This is just like my beloved dog, Percy. 70 pounds of pure muscle, he will still sit and sniff hesitantly at our back door after having asked repeatedly to go out. I sometimes have to gently sweep him out with my foot.
I have to shovel paths in the snow. Leading to more broadly shoveled areas so they can choose the right spot…
If the carbon ratio is skewed in the rats wouldn’t that be reflected in the cats too if they are primarily or exclusively consuming those rats? I don’t see why this would suggest the cats droppeda trophic level and are millet directly.
I believe the claim is that the different stable-isotope carbon ratios from C4 and C3 plants are maintained upward in the food chain. So the ratio seen in rodents feeding on millet would be maintained in carnivores feeding exclusively on these rodents.
By the way, you had me at “wildcat phalynx” — first thought was some battle scene from MiddleEarth..
Wouldn’t there also be undigested millet in the guts of the rats being eaten?
I was curious to see the Chinese zokor</a., as I have not heard of it before. Not sure if this is the only species, but it is not what I expected!
Link closure fail. Sorry.
I think that is a Mongolian or Steppe Zokor, not a Chinese Zokor, but I’m having trouble figuring out if they’re the same thing or not. I have seen a quite ratty looking animal labeled a Chinese Zokor as well as the more mole-like rodent you linked to. Zokors are not well-known apparently, though I did read that they are not generally pests.
I’d think cats would have to be pretty desperate to eat millet!
Absolute bloody pseudoscience, cats were created by Professor Ceiling Cat in their perfectly domesticated form 6000 years ago.
What these scientists will dream up to deny Creationism knows no bounds.
[youtube=http://www.youtube.com/watch?v=z681qCmmUvc&w=420&h=315]