The Fertile Crescent of the Middle East has long been identified as a "cradle of civilization" for humans. In a new genetic study, researchers at the University of California, Davis, have concluded that all ancestral roads for the modern day domestic cat also lead back to the same locale.
Findings of the study, involving more than 11,000 cats, are reported in the January issue of the journal Genomics.
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Earlier archaeological evidence and research on the evolutionary history of cats has suggested that domestication of the cat originated about 5,000 to 8,000 years ago in the Fertile Crescent, a region located today in the Middle East. This is the area around the eastern end of the Mediterranean, stretching from Turkey to northern Africa and eastward to modern day Iraq and Iran. This domestication of the cat occurred as humans transitioned from nomadic herding to raising crops and livestock.
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From the DNA analysis, the researchers found that the cats were genetically clustered in four groups that corresponded with the regions of Europe, the Mediterranean basin, east Africa and Asia.
They discovered that randomly bred cats in the Americas were genetically similar to randomly bred cats from Western Europe. They also found that the Maine coone and American shorthair -- two breeds that originated in the United States -- were genetically similar to the seven Western European breeds. This suggests that cats brought to the New World by European settlers have not had sufficient time to develop significant genetic differentiation from their Western European ancestors.
Second, rats (Rattus rattus), from the 6 February issue:
DNA of the common Black Rat has shed light on the ancient spread of rats, people and diseases around the globe. Studying the mitochondrial DNA of 165 Black Rat specimens from 32 countries around the world, an international team of scientists has identified six distinct lineages in the Black Rat’s family tree, each originating from a different part of Asia.
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The six different lineages originated in India, East Asia, the Himalayas, Thailand, the Mekong Delta, and Indonesia.
The Indian lineage spread to the Middle-East around 20,000 years ago, then later to Europe. It reached Africa, the Americas and Australia during the Age of Exploration. The East Asian lineage moved from Taiwan to Japan, the Philippines, and Indonesia, arriving in Micronesia only 3,500 years ago.
The other four lineages have not become so widespread but they could be set to expand their ranges in the future.
And third, blue-eyed people (Homo sapiens), from the 31 January issue:
New research shows that people with blue eyes have a single, common ancestor. A team at the University of Copenhagen have tracked down a genetic mutation which took place 6-10,000 years ago and is the cause of the eye colour of all blue-eyed humans alive on the planet today.
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“Originally, we all had brown eyes”, said Professor Eiberg from the Department of Cellular and Molecular Medicine. “But a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a “switch”, which literally “turned off” the ability to produce brown eyes”. The OCA2 gene codes for the so-called P protein, which is involved in the production of melanin, the pigment that gives colour to our hair, eyes and skin. The “switch”, which is located in the gene adjacent to OCA2 does not, however, turn off the gene entirely, but rather limits its action to reducing the production of melanin in the iris – effectively “diluting” brown eyes to blue. The switch’s effect on OCA2 is very specific therefore. If the OCA2 gene had been completely destroyed or turned off, human beings would be without melanin in their hair, eyes or skin colour – a condition known as albinism.
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