Like Mice Off a Not So Sinking Ship

19 03 2012
House_mouse_Mus_musculus

The humble house mouse (Mus musculus), traveling the globe with man. Image is courtesy of Wikimedia Commons and is in the public domain.

An international team of researchers led by scientists at the University of York in the United Kingdom have used mitochondrial DNA to show that the timeline of house mice migration across the upper north Atlantic through Scotland and the Scottish Islands, to Iceland, Greenland, and Newfoundland closely matches that of the Viking invasion.

The Vikings, who fought, raided, and explored their way across the north Atlantic from the late eighth to the mid-tenth centuries were the scourge of most of Europe at that time, raiding, killing, and pillaging large swaths of the continent, not just the areas above, but also parts of England, Wales, the Isle of Man, and Ireland.  They established the first cities in Ireland.  They founded the duchy of Normandy, in France, and they even established a kingdom in Sicily in the Mediterranean Sea.

It seems that where they went, their house mice (scientific name Mus musculus) went with them, at least on the northern part of their journey.

According to a press release (see here) the research team, made up of members from the UK, US, Iceland, Denmark, and Sweden, used techniques designed to characterize genetic similarity, and thereby infer the relatedness of one population, or one individual, with another, in order to determine a mouse colonisation timeline.

They obtained modern samples of house mic DNA and compared them to ancient samples dating mostly from the 10th to 12th centuries.  Samples were collected from nine sites in Iceland, Narsaq in Greenland, and four sites near the Viking archaeological site, L’Anse aux Meadows, in Newfoundland.  Ancient samples came from the Eastern and Western settlements in Greenland and four archaeological sites in Iceland.

When analyzed, the samples showed that house mice traveled with the Vikings to Iceland in the early 10th century , either from Norway or the northern part of the British Isles.  From Iceland the mice continued their journey on Viking ships to settlements in Greenland.  However, while descendants of these stowaways can still be found in Iceland, the early colonizers in Greenland have become extinct and their role has been filled by Danish house mice (same species) brought much later by a second wave of European human immigrants.

Of significance is the fact that no evidence of house mice was found in the Viking settlement in Newfoundland, nor was there any evidence of ancestral Viking house mice DNA in modern house mice there.  So, it seems that if the mice made if as far as Newfoundland, they became extinct before they could contribute to the modern house mice lineage on the island.

Replica of a Viking Long Ship

Replica of a Viking long ship. Photograph by archiwum własne wikingów, Jarmeryk, from Wikimedia Commons.

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Ancient Horse Mother Found

1 02 2012

A team of geneticists, paleontologists, and archaeologists have identified the ancient mother of all the horses alive today, according to a paper (link here) published in the Proceedings of the National Academy of Sciences, January 30.

The study, led by Alessandro Achilli, of the Dipartimento di Biologia Cellulare e Ambientale, at the Università di Perugia, in Perugia, Italy, determined that the common ancestral mare to all living horses trotted the earth between 130,000 and 160,000 years ago, with a date of approximately 140,000 years being most likely.  More importantly, the study also identified 18 major clusters of genes called haplogroups, that were involved in the domestication of horses.

Torroni and his colleagues examined 83 modern horse genomes from the Americas, Asia, Europe, and the Middle East.  While the generalities of horse domestication are broadly understood, the specifics of time and location are not.  This study sheds significant light on these aspects of the horse’s natural history.

The study indicates that horses were domesticated over a broad area of Eurasia with multiple incidents of domestication occurring at different times.  This differs from many other domestic animals, such as cattle and sheep, which were domesticated from a handful of animals at very specific locations and then spread through trade and capture.  At least one of these domestication events took place in Europe, with Iberia being a possible location for it.

Horses have an extended and close relationship with humans.  They have played a major role in human history.  Horses were widely used in warfare until the end of World War I, and were still used to some extent even in World War II.  In civilian use, millions of horses were engaged for transportation and to haul goods until the 1920s, when they were largely replaced by trucks and automobiles.  They were still a common sight on many American roads until the 1940s.

In addition to its general scientific interest, the paper points out that the results of the study can also be used to classify fossil horse remains, identifying where they belong on the horse family tree; better define and understand modern horse breeds and their ancestry; and evaluate the role of maternal ancestry in racehorse performance.

Bhimbetka_Rock_Paintng_Man_Riding_Horse

A 30,000 year old rock painting from Bhimbetka in north central India, showing a man riding a horse. This image comes from Wiki Commons and is used under the GNU Free Documentation License