miniwhinny
Well-Known Member
- Joined
- Jan 24, 2005
- Messages
- 1,445
- Reaction score
- 0
There's an awesome program on this evening by Nat Geo tracing the migration of the human species from it's roots in Africa to where we are today...and how we're all 99.99% genetically identical (I know - we all know that already lol) I've been looking forward to it for quite a while now.
But it got me thinking about a study that was done on the horse a few years ago.
Just wanted to share...
As many of you know I'm a major science nut
A number of years ago I was fortunate enough be asked to take part in a European Study tracing the mtDNA patterns of the domestic horse to find out once and for all scientifically how many maternal lines our modern horses descended from and when. Scientists wanted to know if the domestic horse descended from just one maternal line in just one area or more than one in various areas. The domestication of the horse is so intregal and intertwined in the migration and cultures of humans. At the time I raised a very rare American mustang horse that had been genetically isolated for the 500 years they had been here in America. Genetically they clustered in the Iberian breed group D1 so samples from my horses were requested and submitted.
mtDNA is passed in the maternal lines only. Male horses carry mtDNA of their mothers but cannot pass it on. Only the female lines can pass mtDNA.
Here's a very brief synopsis of the results from the scientists involved with the study.
The place and date of the domestication of the horse has long been a matter for debate among archaeologists. To determine whether horses were domesticated from one or several ancestral horse populations, scientists sequenced the mitochondrial D-loop for 318 horses from 25 oriental and European breeds, including American mustangs. Adding these sequences to previously published data, the total comes to 652, the largest currently available database. From these sequences, a phylogenetic network was constructed that showed that most of the 93 different mitochondrial (mt)DNA types grouped into 17 distinct phylogenetic clusters. Several of the clusters correspond to breeds and/or geographic areas, notably cluster A2, which is specific to Przewalski's horses, cluster C1, which is distinctive for northern European ponies, and cluster D1, which is well represented in Iberian and northwest African breeds. A consideration of the horse mtDNA mutation rate together with the archaeological timeframe for domestication requires at least 77 successfully breeding mares recruited from the wild. The extensive genetic diversity of these 77 ancestral mares leads us to conclude that several distinct horse populations were involved in the domestication of the horse.
We pooled the mtDNA sequences, covering 15,494–15,740, domestic horses (626 sequences),
Przewalski's horses (14 sequences), 1,000- to 2,000-y-old samples from archaeological sites in southern Sweden and Estonia (4 sequences). 12,000- to 28,000-y old Alaskan permafrost remains (8 sequences), a total of 652 sequences (93 mtDNA types).
We reconstructed the unrooted evolutionary network and then identified the root of the network by using the most closely related equid outgroups, namely Equus grevyi, Equus kiang, and Equus hemionus. The root turned out to be the central horse node A6, which implies that the Alaskan fossil equids are within the Eurasian mtDNA variation. To calculate phylogenetic time estimates, we postulated within the network one most parsimonious tree of the 641 modern horses; that is, we disregarded the ancient Alaskan and Scandinavian horses. The mtDNA root type traced to be between 342,000 ± 74,000 and 1,198,000 ± 260,000 years old. The large uncertainty is caused by the poor calibration of the mtDNA mutation rate. This root type is well distinguished from any other modern equid root type and multivariates into about 13 horse mtDNA branches. [SIZE=10pt]This means 300,000 years ago approximately represents the latest possible date for the first modern caballine horse[/SIZE].
Pretty cool
But it got me thinking about a study that was done on the horse a few years ago.
Just wanted to share...
As many of you know I'm a major science nut
A number of years ago I was fortunate enough be asked to take part in a European Study tracing the mtDNA patterns of the domestic horse to find out once and for all scientifically how many maternal lines our modern horses descended from and when. Scientists wanted to know if the domestic horse descended from just one maternal line in just one area or more than one in various areas. The domestication of the horse is so intregal and intertwined in the migration and cultures of humans. At the time I raised a very rare American mustang horse that had been genetically isolated for the 500 years they had been here in America. Genetically they clustered in the Iberian breed group D1 so samples from my horses were requested and submitted.
mtDNA is passed in the maternal lines only. Male horses carry mtDNA of their mothers but cannot pass it on. Only the female lines can pass mtDNA.
Here's a very brief synopsis of the results from the scientists involved with the study.
The place and date of the domestication of the horse has long been a matter for debate among archaeologists. To determine whether horses were domesticated from one or several ancestral horse populations, scientists sequenced the mitochondrial D-loop for 318 horses from 25 oriental and European breeds, including American mustangs. Adding these sequences to previously published data, the total comes to 652, the largest currently available database. From these sequences, a phylogenetic network was constructed that showed that most of the 93 different mitochondrial (mt)DNA types grouped into 17 distinct phylogenetic clusters. Several of the clusters correspond to breeds and/or geographic areas, notably cluster A2, which is specific to Przewalski's horses, cluster C1, which is distinctive for northern European ponies, and cluster D1, which is well represented in Iberian and northwest African breeds. A consideration of the horse mtDNA mutation rate together with the archaeological timeframe for domestication requires at least 77 successfully breeding mares recruited from the wild. The extensive genetic diversity of these 77 ancestral mares leads us to conclude that several distinct horse populations were involved in the domestication of the horse.
We pooled the mtDNA sequences, covering 15,494–15,740, domestic horses (626 sequences),
Przewalski's horses (14 sequences), 1,000- to 2,000-y-old samples from archaeological sites in southern Sweden and Estonia (4 sequences). 12,000- to 28,000-y old Alaskan permafrost remains (8 sequences), a total of 652 sequences (93 mtDNA types).
We reconstructed the unrooted evolutionary network and then identified the root of the network by using the most closely related equid outgroups, namely Equus grevyi, Equus kiang, and Equus hemionus. The root turned out to be the central horse node A6, which implies that the Alaskan fossil equids are within the Eurasian mtDNA variation. To calculate phylogenetic time estimates, we postulated within the network one most parsimonious tree of the 641 modern horses; that is, we disregarded the ancient Alaskan and Scandinavian horses. The mtDNA root type traced to be between 342,000 ± 74,000 and 1,198,000 ± 260,000 years old. The large uncertainty is caused by the poor calibration of the mtDNA mutation rate. This root type is well distinguished from any other modern equid root type and multivariates into about 13 horse mtDNA branches. [SIZE=10pt]This means 300,000 years ago approximately represents the latest possible date for the first modern caballine horse[/SIZE].
Pretty cool
