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Domestic animals have played
a key role in the history of humankind. However, the origins of many of
these animals remain to a large extent mysterious. According to the studies
carried out by researchers from the CNRS and the University of Grenoble
1 on the mitochondrial* DNA of several hundred goats
from 44 countries of the Old World, domestic goats have three different
maternal origins and might have played a greater role in the development
of agriculture in the Neolithic period than other domestic animals. These
findings were published in the May 8 issue of the Proceedings of the
National Academy of Sciences.
Domestic goats are still the
main economic resource of many developing countries. Their importance
hails back to the Neolithic age: indeed, they may have played a crucial
role in the spread of agriculture at that time. Goats are more likely
to follow humans in their travels than other domestic animals, and they
are much less fussy about their food.
In order to better understand the role of goats in the development of
agriculture, the researchers of the Laboratoire de biologie des populations
d'altitude (Biology of altitude populations Laboratory) (CNRS – University
of Grenoble 1 – Grenoble), studied their genetic data in search of
information about their origins. They succeeded in collecting over 400
tissue samples belonging to 88 breeds from all over the Old World (44
countries), from Portugal to China, from Norway to South Africa. For each
individual tissue, they sequenced 481 pairs of mitochondrial DNA bases.
Their DNA, present in the mitochondria of all the cells, can only be transmitted
by females. The phylogenies established thanks to this DNA have made it
possible to trace the evolution of these goats. This type of molecular
marker has been widely used in research on the history of population groups.
The first significant result is the presence of three distinct mitochondrial
lineages. This proves that today's domestic goats are the descendants
of at least three female ancestral stocks. The largest proportion probably
corresponds to the initial domestication of goats in the Fertile Crescent
(Near and Middle-East), around 10,000 years ago. The other two lineages
are less polymorphous and would thus seem to be more recent (between 6,000
and 2,000 years old). They could either be the descendants of groups that
were domesticated separately, or the result of genetic exchanges with
wild populations. Available data on other domestic animals (cows, sheep,
pigs, horses) also tends to show multiple maternal origins.
The second important finding is the near absence of geographical structure
at the intercontinental level. This means that in terms of mitochondrial
DNA, European goats do not differ from Asian or African goats. This result
is surprising, since cows and sheep are highly structured at the intercontinental
level. For this reason, researchers believe that goats must have played
a specific role, different from that of other domestic animals, at the
time agricultural practices developed. The weak phylogeographic structure
in domestic goats could be attributed to the fact that, unlike other domestic
animals, goats followed humans in their travels.
*
mitochondria are contained in every cell of the body and produce most
of its energy.
Reference:
Luikart G, Gielly L, Excoffier L, Vigne J-D, Bouvet J, Taberlet P (2001)
Multiple maternal origins and weak phylogeographic structure in domestic
goats. Proceedings of the National Academy of Sciences of the United
States of America, 98, 5927-5932.
Researcher
Contacts:
Gordon Luikart
Tel: + 33 4 76 63 56 07
E-mail: gordon.luikart@ujf-grenoble.fr
Pierre Taberlet
Tel: + 33 4 76 51 42 78
E-mail: Pierre.Taberlet@ujf-grenoble.fr
Press Contact:
Martine Hasler
Tel : +33 1 44 96 46 35
e-mail : martine.hasler@cnrs-dir.fr
Department of Life Sciences Contact:
Thierry Pilorge
Tel: + 33 1 44 96 40 26
E-mail: thierry.pilorge@cnrs-dir.fr
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