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View Full Version : Decline of genetic diversity in ancient domestic stallions in Europe



markozd
25-04-18, 22:48
Abstract:


Present-day domestic horses are immensely diverse in their maternally inherited mitochondrial DNA, yet theyshow very little variation on their paternally inherited Y chromosome. Although it has recently been shown thatY chromosomal diversity in domestic horses was higher at least until the Iron Age, when and why this diversitydisappeared remain controversial questions. We genotyped 16 recently discovered Y chromosomal single-nucleotidepolymorphisms in 96 ancient Eurasian stallions spanning the early domestication stages (Copper and BronzeAge) to the Middle Ages. Using this Y chromosomal time series, which covers nearly the entire history of horsedomestication, we reveal how Y chromosomal diversity changed over time. Our results also show that the lack ofmultiple stallion lineages in the extant domestic population is caused by neither a founder effect nor randomdemographic effects but instead is the result of artificial selection—initially during the Iron Age by nomadic peoplefrom the Eurasian steppes and later during the Roman period. Moreover, the modern domestic haplotype probablyderived from another, already advantageous, haplotype, most likely after the beginning of the domestication.In line with recent findings indicating that the Przewalski and domestic horse lineages remained connectedby gene flow after they diverged about 45,000 years ago, we present evidence for Y chromosomal introgressionof Przewalski horses into the gene pool of European domestic horses at least until medieval times.

This is very interesting, as it clearly suggests that horses were domesticated by various cultures of the Neolithic. The earliest domestic horses came from northern Anatolia (2700-2200 B.C.E.), followed by Portuguese Zambujal culture whose population seems to have domesticated horses who carried Przewalski Y-DNA haplotypes. There are several Y-DNA turnovers before the emergence of modern domesticates. The Y-DNA haplotypes of modern domesticates first appears in the Hatvan culture of Slovakia in the Bronze Age.

https://d8v5jhqx5tv4l.cloudfront.net/wp-content/uploads/2018/04/horses-y-chromosome-map.png


The supplement includes 3 Y-DNA haplogroups from Andronovo horses. These are associated with Anatolia (n=2) and Slovakia (n=1)

Link: http://advances.sciencemag.org/content/4/4/eaap9691

Expredel
25-04-18, 23:51
The earliest domestic horses came from northern Anatolia (2700-2200 B.C.E.), followed by Portuguese Zambujal culture whose population seems to have domesticated horses who carried Przewalski Y-DNA haplotypes. There are several Y-DNA turnovers before the emergence of modern domesticates.
I don't think it's a coincidence that R1b showed up in Iberia around the same time Przewalski stallions showed up.

markozd
26-04-18, 00:20
I don't think it's a coincidence that R1b showed up in Iberia around the same time Przewalski stallions showed up.

Yes, a wild horse from north-eastern Romania and another one from Germany carry the same Y-DNA-haplotype. We don't know if they were actual Przewalski horses however, or if they were on the clade leading to modern domesticates with some introgression from eastern wild horses on the male line. The Iberian horses seem to mostly disappear after the Bronze Age in any case.

holderlin
27-04-18, 04:52
This is very interesting, as it clearly suggests that horses were domesticated by various cultures of the Neolithic. The earliest domestic horses came from northern Anatolia (2700-2200 B.C.E.), followed by Portuguese Zambujal culture whose population seems to have domesticated horses who carried Przewalski Y-DNA haplotypes. There are several Y-DNA turnovers before the emergence of modern domesticates. The Y-DNA haplotypes of modern domesticates first appears in the Hatvan culture of Slovakia in the Bronze Age.


Thanks for the post, this is good stuff.

I'm seeing earliest domesticated Horses in Romania and Ukraine 4300-3600BC, and the earliest Y-HT-1 in Slovakia in 2700BC. Where are you getting Northern Anatolia? There are Y-HT-3 in Northern Anatolia in 2700-2200BC, is that what you mean?

holderlin
27-04-18, 04:55
Checking on these cultures, but I'm pretty sure the Ukraine sample is Sredny Stog

holderlin
27-04-18, 05:02
Thanks for the post, this is good stuff.

I'm seeing earliest domesticated Horses in Romania and Ukraine 4300-3600BC, and the earliest Y-HT-1 in Slovakia in 2700BC. Where are you getting Northern Anatolia? There are Y-HT-3 in Northern Anatolia in 2700-2200BC, is that what you mean?


OK, that's a Przewalski in Romania, which makes the first domesticated horse Ukraine Eneolithic. That sounds very familiar to my own banter :)

I don't ask for much. Maybe a small procession of chariots and trumpeting with some horse sacrifices and excessive feasting into the evening. Just give me like a gallon of wine with some fine Scythian Cannabis.

Expredel
27-04-18, 14:41
Yes, a wild horse from north-eastern Romania and another one from Germany carry the same Y-DNA-haplotype. We don't know if they were actual Przewalski horses however, or if they were on the clade leading to modern domesticates with some introgression from eastern wild horses on the male line. The Iberian horses seem to mostly disappear after the Bronze Age in any case.
The article is misleading, check this link:

http://www.lipizzan-online.com/download/files/%7BCAD6A9DF-D3A7-4319-99EF-D1FFA0024ABC%7D/Identification%20of%20Genetic%20Variation%20on%20t he%20Horse%20Y%20Chromosome.pdf

While HT1 is the most common lineage nowadays, HT2, HT3, and HT4 still occur among modern breeds.

So what we're seeing is not the replacement of wild horses with domesticated horses, but something else. The Roman empire may have favored HT1, it may have been carried into Europe by the Huns as well. It'd be interesting to see UK and North African samples.

markozd
27-04-18, 18:04
Thanks for the post, this is good stuff.

I'm seeing earliest domesticated Horses in Romania and Ukraine 4300-3600BC, and the earliest Y-HT-1 in Slovakia in 2700BC. Where are you getting Northern Anatolia? There are Y-HT-3 in Northern Anatolia in 2700-2200BC, is that what you mean?

Yeah those samples are classified as wild in table S2 in the supplements, the earliest domesticated samples being Anatolia & Portugal. The haplotypes in the Portuguese samples is very eastern though, so I doubt they are native. Not sure about the Anatolian samples - the culture in question is near Troy, which has unambiguous connections with Bulgaria in the EBA.

holderlin
27-04-18, 18:37
Yeah those samples are classified as wild in table S2 in the supplements, the earliest domesticated samples being Anatolia & Portugal. The haplotypes in the Portuguese samples is very eastern though, so I doubt they are native. Not sure about the Anatolian samples - culturein question is near Troy, which has unambiguous connections with Bulgaria in the EBA.

Ah missed that. Cancel the procession. Northern Anatolia/Balkans makes just as much sense though.

I'm glad we finally have some data like this. No more speculating.