Origin of domestic horses finally established

Date:
October 20, 2021
Source:
CNRS
Summary:
The modern horse was domesticated around 2200 years BCE in
the northern Caucasus. In the centuries that followed it spread
throughout Asia and Europe. An international team of 162 scientists
collected, sequenced and compared 273 genomes from ancient horses
scattered across Eurasia to come up with this finding.



FULL STORY ========================================================================== Horses were first domesticated in the Pontic-Caspian steppes,
northern Caucasus, before conquering the rest of Eurasia within a few centuries. These are the results of a study led by paleogeneticist
Ludovic Orlando, CNRS, who headed an international team including
l'Universite' Toulouse III -- Paul Sabatier, the CEA and l'Universite'
d'E'vry. Answering a decades-old enigma, the study is published in Nature
on 20 October 2021.


==========================================================================
By whom and where were modern horses first domesticated? When did they
conquer the rest of the world? And how did they supplant the myriad
of other types of horses that existed at that time? This long-standing archaeological mystery finally comes to an end thanks to a team of 162 scientists specialising in archaeology, palaeogenetics and linguistics.

A few years ago, Ludovic Orlando's team looked at the site of Botai,
Central Asia, which had provided the oldest archaeological evidence of
domestic horses.

The DNA results, however, were not compliant: these 5500-year-old horses
were not the ancestors of modern domestic horses1. Besides the steppes of Central Asia, all other presumed foci of domestication, such as Anatolia, Siberia and the Iberian Peninsula, had turned out to be false. "We
knew that the time period between 4,000 to 6,000 years ago was critical
but no smoking guns could ever be found" says CNRS research professor
Orlando. The scientific team, therefore, decided to extend their study to
the whole of Eurasia by analysing the genomes of 273 horses that lived
between 50,000 and 200 years BC. This information was sequenced at the
Centre for Anthropobiology and Genomics of Toulouse (CNRS/Universite'
Toulouse III -- Paul Sabatier) and Genoscope2 (CNRS/ CEA/Universite'
d'E'vry) before being compared with the genomes of modern domestic horses.

This strategy paid off: although Eurasia was once populated by genetically distinct horse populations, a dramatic change had occurred between 2000
and 2200 BC. "That was a chance: the horses living in Anatolia, Europe,
Central Asia and Siberia used to be genetically quite distinct" notes
Dr Pablo Librado, first author of the study. Then, a single genetic
profile, previously confined to the Pontic steppes (North Caucasus)3,
began to spread beyond its native region, replacing all the wild horse populations from the Atlantic to Mongolia within a few centuries. "The
genetic data also point to an explosive demography at the time, with no equivalent in the last 100,000 years" adds Pr Orlando.

"This is when we took control over the reproduction of the animal
and produced them in astronomic numbers." But how can this rapid
population growth be explained? Interestingly, scientists found two
striking differences between the genome of this horse and those of
the populations it replaced: one is linked to a more docile behaviour
and the second indicates a stronger backbone. The researchers suggest
that these characteristics ensured the animals' success at a time when
horse travel was becoming "global." The study also reveals that the
horse spread throughout Asia at the same time as spoke-wheeled chariots
and Indo-Iranian languages. However, the migrations of Indo-European populations, from the steppes to Europe during the third millennium BC
could not have been based on the horse, as its domestication and diffusion
came later. This demonstrates the importance of incorporating the history
of animals when studying human migrations and encounters between cultures.

This study was directed by the the Centre for Anthropobiology and
Genomics of Toulouse (CNRS/ Universite' Toulouse III -- Paul Sabatier)
with help from Genoscope (CNRS/CEA/Universite' d'E'vry). The French laboratories Arche'ologies et sciences de l'Antiquite' (CNRS/Universite'
Paris 1 Panthe'on Sorbonne/ Universite' Paris Nanterre/Ministe`re de la Culture), De la Pre'histoire a` l'actuel : culture, environnement et anthropologie (CNRS/Universite' de Bordeaux/Ministe`re de la Culture)
and Arche'ozoologie, arche'obotanique : socie'te's, pratiques et
environnements (CNRS/MNHN) also contributed, as did 114 other research institutions throughout the world. The study was primarily funded by
the European Research Council (Pegasus project) and France Genomique (Buce'phale project).

Notes 1 Unsaddling old theory on origin of horses, (press release on 22 February 2018).

2 Genoscope is a department of CEA-Jacob.

3 The Pontic steppe is the western part of the Eurasian steppe. The home
of the modern domestic horse is thought to be in the Don and Volga basins,
east of the Dnieper.

========================================================================== Story Source: Materials provided by CNRS. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Librado, P., Khan, N., Fages, A. et al. The origins and spread of
domestic horses from the Western Eurasian steppes. Nature, 2021
DOI: 10.1038/s41586-021-04018-9 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211020135922.htm

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