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Wednesday, July 08, 2020

Where did your chicken come from?

Scientists have sequenced the genomes of modern domesticated chickens and compared them to the genomes of various wild pheasants in southern Asia. It has been known for some time that chickens resemble a species of pheasant called red jungle fowl and this led Charles Darwin to speculate that chickens were domesticated in India. Others have suggested Southeast Asia or China as the site of domestication.

The latest results show that modern chickens probably descend from a subspecies of red jungle fowl that inhabits the region around Myanmar (Wang et al., 2020). The subspecies is Gallus gallus spadiceus and the domesticated chicken subspecies is Gallus gallus domesticus. As you might expect, the two subspecies can interbreed.

The authors looked at a total of 863 genomes of domestic chickens, four species of jungle fowl, and all five subspecies of red jungle fowl. They identified a total of 33.4 million SNPs, which were enough to genetically distinguish between the various species AND the subspecies of red jungle fowl. (Contrary to popular belief, it is quite possible to assign a given genome to a subspecies (race) based entirely on genetic differences.)

The sequence data suggest that chickens were domesticated from wild G. g. spadiceus about 10,000 years ago in the northern part of Southeast Asia. The data also suggest that modern domesticated chickens (G. g. domesticus) from India, Pakistan, and Bangladesh interbred with another subspecies of red jungle fowl (G. g. murghi) after the original domestication. These chickens from South Asia contain substantial contributions from G. g. murghi ranging from 8-22%.

Next time you serve chicken, if someone asks you where it came from you won't be lying if you say it came from Myanmar.


Image credits: BBQ chicken, Creative Common License [Chicken BBQ]
Red Jungle Fowl, Creative Commons License [Red_Junglefowl_-Thailand]
Map: Lawler, A. (2020) Dawn of the chicken revealed in Southeast Asia, Science: 368: 1411.

Wang, M., Thakur, M., Peng, M. et al. (2020) 863 genomes reveal the origin and domestication of chicken. Cell Res (2020) [doi: 10.1038/s41422-020-0349-y]

2 comments :

  1. Subspecies(race) ? They are confused about what species much less subspecies. What stops the divisions or fixes them? What is a race?
    Probably chickens come from those areas but creationists should question the dNA trails suggested. We should see options for populations to simply change bodyplans from influences working with the dna and then like results come about. so a option the DNA is just simply a replica but not a trail. For example the Giant panda and the Red panda both developed thier long bony thumb though they are not the same creature. So it could be they both have the same DNA score for the thumb.

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  2. "(Contrary to popular belief, it is quite possible to assign a given genome to a subspecies (race) based entirely on genetic differences.)"

    Like so many things this depends on definitions. Certainly it is possible to assign human ethnicity (which is where I suspect you are going with this) via genetic differences, but that is rather more specific than the idea of "race" that claims that all humans can be neatly categorized into three arbitrary categories.

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