Elite kin groups down the generations

By Razib Khan | December 27, 2011 1:59 pm

The Pith: The purported sons of great men often are really the sons of great men. Another case of “Conan was right”.

Dienekes points me to a neat new paper, Present Y chromosomes reveal the ancestry of Emperor CAO Cao of 1800 years ago, which attempts to validate the claims to descent from a particular ancestor by a set of Chinese clans. The Chinese clan system is based on direct paternal descent by and large (and there has been a history of aversion to adoption from outside the kin group), and so aligns perfectly with the phylogeny of Y chromosomes, which are passed from father to son to son to son. That’s the ideal. What’s the reality? People are adopted. Or, some sons of a purported father are actually not the biological sons of that father. And finally, there are cases where individuals may fabricate ancestry and interject themselves into a lineage group through deception.

The individual in this case flourished 72 generations ago. Additionally, there is some controversy as to the relationship of this individual to others of their lineage. Here is the important section from the paper:

Here, we typed 100 Y chromosome single-nucleotide polymorphisms (Supplementary Table 1) as listed in the latest Y-chromosome phylogenetic tree…on 280 individuals of 79 Cao clans or clan clusters from different locations throughout the China…and 446 individuals of different clans with other surnames. A clan cluster may consist of several simplex clans if they carry different Y-chromosome haplotypes. Thus, we studied overall 111 simplex clans of CAO (Supplementary Table 2). According to their stemma records, 15 of the CAO clans claimed to be descendants of Emperor CAO. These 15 clans distributed in different provinces and never knew the existence of each other. Their Y chromosomes comprise six haplotypes…Only one of these six haplotypes can be Emperor CAO’s type. The other haplotypes found in the claimed clans might be introduced by other sources such as adoption, acceding to mother’s surname, nonpaternities, and so on…Here we need to recognize the most probable Emperor CAO’s haplotype by examining the haplotype distribution among the clan groups.


The strategy here is simple. You have a set of individuals who claim descent from a putative ancestor down the male line. If the social ideal matched the biological reality these individuals would share the same Y chromosomal lineage (diverged by mutations in direct proportion to time since the last common ancestor). Reality never matches the social ideal. But if that reality has any basis in fact you will see an over-representation of one lineage among the diverse set of lineages. That’s because the interjected lineages should be a relatively random sample from the population, slowly replacing the ancestral lineage. The authors found that pattern. In addition, they noticed that there was a different lineage prominent among those who were of the broader Cao clan, but not descended from Cao Cao. Therefore, they concluded from these results that Cao Cao himself was not a genuine member of the Cao clan, though many of those claiming descent from him are genuine. He was a case of fabrication of ancestry, witting or unwitting. Here’s a table illustrating the results for the marker hypothetically associated with Cao Cao:

Number of Clans in the clan groups P-value for pairwise OR claimed & reference (95% CI)
Haplotypes Claimed Unclaimed General pop Claimed vs ref
O2-M268 6 5 22 9.32 × 10−5* 12.72 (4.22–38.32)
O3-002611 1 21 79 0.952 0.32 (0.04–2.43)
O1-P203 2 6 65 0.607 1.02 (0.23–4.62)
O3-M117 3 15 67 0.408 1.40 (0.39–5.08)
C3-M217 2 5 25 0.211 2.63 (0.57–12.17)
O3-P164 1 2 13 0.358 2.51 (0.31–20.34)
Others 0 42 175 NA 0

I assume that with a deeper sequencing of the Y chromosome this sort of analysis will get much better. From a population genetic perspective this isn’t interesting really. But from a social historical perspective it is. There are many groups around the world which claim descent from a male founder. The distribution of genuine vs fictive groups could give us a sense of the persistence of prestige across the generations, and the ability of a given kin group to defend its exclusive prestige against newcomers who might attempt to erode or co-copt it. It is notable that 6 out of 15 clans who claim descent from this individual 72 generations in the past are actually descendants! If you assume that 40% of the hypothetical descendants are actual descendants then you have a fidelity of ~99% generation. That’s pretty impressive, but is about typical for high status males in terms of rates of cuckoldry today.

Hopefully we’ll be checking for the Sayyids in the near future. I suspect that there’s been a lot more obscuring of the genetic signal in this case for various reasons. As more and more “elite lineages” get typed we can modify our assessments of the likelihoods of prior results, such as that of Genghis Khan.

Citation: Journal of Human Genetics, doi: 10.1038/jhg.2011.147

Image credit: Wikipedia

CATEGORIZED UNDER: Anthroplogy, Genetics, Human Genetics
  • Eze

    Hopefully we’ll be checking for the Sayyids in the near future.

    The Sharifs project at FTDNA seems to suggest that the haplogroup of the genuine Sayyids/Quraishi/Banu Hashim seems to be J1c3d2

    http://www.familytreedna.com/public/sharifs/default.aspx?section=yresults

  • iron0037

    Sorry, but as a non-expert in your field, I need clarification to understand the table you present. What is “number of Clans in the clan groups?” Is this the number of individuals examined in the study broken down those claiming to be or not to be a member of the clan? If so, then what is the general population column mean? Shouldn’t that be included in the unclaimed column? I have taken a probability class, and I can read on Wikipedia what a p-value is. But what am I looking at the p-value for? And what on earth does “OR claimed & reference (95% CI)” mean?

    I like your entries and I try to read them on a regular basis. But I might humbly suggest that if you want to appeal to more casual geneticist enthusiasts, then you should provide a background explanation into what you’re presenting. Look at a recent blog I wrote (link below). I don’t just say that the “function converges on the optimal solution to the traveling salesman problem by employing a genetic algorithm” and leave it to the reader to implicitly fathom that statement. I think such a change would increase your return readership.

    http://blogs.mathworks.com/pick/2011/10/14/traveling-salesman-problem-genetic-algorithm/.

  • SeekTruthFromFacts

    I second iron0037. It’s your blog – you can write whatever you fancy – but the lay readership would be grateful for the clarification.

  • AG

    Wow, wonderful post about Cao Cao. According to history, he was adopted by Eunuch and advanced in the imperial court. With genetic evidence, the story become even more complicated.

  • John Emerson

    It is well known that Cao Cao’s father Cao Song was the adopted son of the eunuch Cao Teng. One source also says that Cao Song’s father was originally from the Xiahou clan, which was later favored by the Cao Cao when he became powerful.

    Thus, Cao Cao father founded one Cao clan, which was basically part of the Xiahou clas, and Cao Cao’s grandfather was a member of a different “authentic” Cao clan.

    There is a possibility of overlap, because (according to my Chinese teacher) adopted sons were often adopted from related clans, so that the eunuch Cao Teng (and his birth-family Caos) may well have been related to the Xiahou clan — sometimes two families would intermarry for generations on a systematic basis.

    Despite Cao Cao’s acknowledged adoptee status, his biographies carefully calculate his Cao lineage back to ancient times.

    To sum up: first there were two clans, which may have been intermarrying clans. Then one individual from one of the clans was renamed Cao, and another Cao lineage rose from him. At the beginning at least Cao Cao’s lineage would have the genes of the second lineage (whether Xiahou or some other).

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This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at http://www.razib.com

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