Saturday, April 29, 2017

There's Huge Science in Loving Horses - Science

The heritage of various lines of horses is known intimately for exceptionally long periods and best known for it are the Bedouins with their line of Arabians which is likely the breed of horse a novice will be able to identify first due to the shape of its forehead and its upright tail.  Here are some Scythian horse breeders and they were doing excellent work with domesticated horses in the 9th Century B.C.  (Science Daily:  Scythian horse breeding unveiled: Lessons for animal domestication)

Note:  BC is often called BCE these days and I thought that was Before Current Era but actually it means Before Common Era and that's not political correctness; that's just bloody insulting.  To identify the Common Era as the one beginning almost in-sync with the birth of Christ seems almost deliberately calculated to be offensive.  I'm not a Christian but there's C / NC (Cool / Not Cool).

Moving along ...


These are Kazakh horses in North Central Kazakhstan.

Credit: Ludovic Orlando, Natural History Museum of Denmark, CNRS.


Nomad Scythian herders roamed vast areas spanning the Central Asian steppes during the Iron Age, approximately from the 9th to the 1st century BCE (Before Common Era). These livestock pastoralists, who lived on wagons covered by tents, left their mark in the history of warfare for their exceptional equestrian skills. They were among the first to master mounted riding and to make use of composite bows while riding. A new study published in Science led by Professor Ludovic Orlando and involving 33 international researchers from 16 universities, now reveals the suite of traits that Scythian breeders selected to engineer the type of horse that best fit their purpose.

- SD

The sophistication of what they were doing is difficult to accept since humans were still meandering out of the Stone Age back then yet here they demonstrate a significant knowledge of equine genetics.


The exercise for the interested student on this one is comparing the timelines of the development of the Scythian and the Arabian bloodlines since the latter history is ancient as well.  The hard-core horse lovers may well do that but I just like to look at them plus Hopalong Cassidy rode one when I was a kid.  His horse, Topper, was an Arabian and the white hair is a giveaway but I still looked to be sure.


The study took advantage of exceptionally preserved horse remains in royal Scythian burials, such as the site of Arzhan, Tuva Republic, where over 200 horses have been excavated but also at Berel', Kazakhstan, where no less than 13 horses were preserved in a single, permafrozen funerary chamber. Applying the latest methods in ancient DNA research, the researchers could sequence the genome of 13 Scythian stallions. These were 2,300-2,700 years old and included 11 specimens from Berel' and two from Arzhan. The researchers also sequenced the genome of one 4,100 year-old mare from Chelyabinsk, Russia, belonging to the earlier Sintashta culture, which developed the first two-wheeled chariots drawn by horses.

- SD

Applied genetics maybe going back four thousand years or more ... or longer.  See below.


The genome data set generated in the study also reveals important lessons for the history of horse management, which started some 5,500 years ago, and animal domestication as a whole. By contrasting patterns of genetic variation in ancient and present-day horses, the authors found support for a significant demographic collapse during the last 2,300 years, which resulted in an important reduction of genetic diversity within horse domesticates. During the same time period, reproductive management has involved an increasingly reduced number of stallions, up to the point that, today, almost all domesticates virtually carry the same, or highly similar, Y-chromosome haplotype(s).

- SD


The above theme continues in demonstrating the deleterious aspects of so much reduction in the genetic diversity in the equine genome and the interested breeder may wish to continue with it.


Genetic diversity is an inherent casualty in breeding thoroughbreds and it's not without expense.  That's something future breeders probably need to take into account since the basic genetic approaches of 'purifying' some trait are by father-daughter / mother-son breeding and the specific purpose of that is reducing genetic diversity.


It seems there's high value in preserving ancient horse genomes and maybe the wild horses in America are old enough and unchanged enough.

No comments: