November 25, 2008

Origin of ancient Chinese horses from ancient DNA

From the paper:
To shed light on the origin of the diverse haplogroups, we studied the distribution of the seven haplogroups in 17 modern populations, and showed that only F and D have a significant geographical pattern (Table 3 and Fig.2). Haplogroup F is prevalent in East Eurasian populations and its frequencies declines from east to west, consistent with the results of previous studies (McGahern et al., 2006). Based on our findings in Chinese horses older than 4000 years, we propose that haplogroup F is an ancient haplogroup of East Asian origin.

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we suggest that the origin of Chinese domestic horses is more complex than previously thought, and that both indigenous breeds and introduced maternal lineages were involved in the process of domestication. Thus, our data fail to support either of the two previous hypotheses on the domestication of horses in China.

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Phylogenetic analysis revealed that the Przewalski fell into cluster A2, distinct
from Chinese ancient horses and modern horses. Genetic distance analysis indicated that the Przewalski were far from the ancient horses, suggesting that the Przewalski horse and the domestic horse should be considered sister taxa with a common ancestor, and that the Przewalski horse is not the wild ancestor to the Chinese domestic horse. However, this conclusion should be viewed with caution, as the Przewalski horse underwent a severe genetic bottleneck: all present individuals descend from only 13 survivors, with only four maternal lineages (Volf & Kus, 1991).

Related: Wikipedia article on Przewalski's horse. Also, Lippold & Hofreiter from ISBA3:
We sequence 600 bp of mtDNA from the mitochondrial D-Loop of different individuals obtained from different locations. Our initial results indicate tremendous genetic diversity, but no phylogeographic pattern within this marker. The genetic distribution of these ancient samples also falls within the broad diversity range apparent in recent horses.

It would be interesting to see more ancient DNA results for wild and domestic horses, especially from the Eurasiatic steppes where they are believed to have undergone domestication.

Journal of Archaeological Science doi: 10.1016/j.jas.2008.11.006

Ancient DNA provides new insights into the origin of the Chinese
domestic horse


Dawei Cai et al.

Abstract

Domestic horses played a pivotal role in ancient China, but their exact origin remains controversial. To investigate the origin of Chinese domestic horses, we analyzed mitochondrial DNA (mtDNA) from 35 horse remains, aged between 4000 and 2000 years, excavated from nine archaeological sites in northern China. The Chinese ancient horses exhibited high matrilineal diversity, falling into all the seven haplogroups (A-G) observed in modern horses. These results suggest that several maternal lines were introduced into the gene pool of Chinese horses in the past. Haplogroup A and F were more prevalent in ancient horses than the other haplogroups. Interestingly, only haplogroups A and F were present in the samples older than 4000 years, while the more recent horses (between 2000 and 3000 years BP) fell into all seven haplogroups. Comparison with DNA data of present-day horses suggests haplogroup F is like to be an ancient haplogroup of East Asian origin. These analyses also suggest that the origin of Chinese domestic horses is complex, and external mtDNA input occurred after initial domestication. Our results indicate that the Chinese ancient horses are more related to the modern Mongolian horses. Lastly, our results cannot support cannot support the previous hypothesis that early Chinese domestic horses were derived from the Przewalski horse.

Link

4 comments:

Antigonos said...

So there is a chance that the Przewalski horse belongs even in a different taxon than the domestic horses!
Interesting, since even if they belong in different taxa they can mate and produce fertile offspring!
Not like the donkey and the horse that produce sterile offspring, the mule!
That comes as no surprise since even different species can mate and produce fertile offspring, like the camel and the lama!
That perhaps could be said for humans too. Both in the case of the Neanderthalian-EHS mixing and in the case of present races.
There is a global common belief that just because human races can mate and produce fertile offspring they belong to the same species, gradient, etc.
Is it so?
I have my doubts!
Someone might say of course that the differentiation in the case of the Przewalski is obvious from the DNA. DNA is subject to positive selection. It is also affected by genetic drift and severe bottlenecks, that might have erased the archaic Homo egnarts from our DNA. The great rate of growth of the human population might have affected it too.
Finally there are some things in our blood that show traces of archaic contribution from other Homo relatives.
Time alone will show if we all belong in a single species or not and until then we should all keep an open mind!

eurologist said...

Time alone will show if we all belong in a single species or not...

I for one, am a legal alien, and will Antagonize you because of your circum-neanderthal mindedness.

Antigonos said...

"I for one, am a legal alien, and will Antagonize you because of your circum-neanderthal mindedness."

First of all being an allien doesn't imply that you're smarter than Neanderthals!
More so when you don't think on your own, but you ruminate "political correct cliche" by which you have been brainwashed since your birth.
Except of course if you are aquainted with Neanderthals and you know them by personal experience!!

Crimson Guard said...

You guys should stay away from chinese horse breeding...