In an island north of the eastern tip of Siberia, a small group of woolly mammoths became the last survivors of their once thriving species…[G]eneticists have now deciphered the probable reason for the population’s demise.
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The real reason, [scientists] concluded, after examining lake bed sediments, was simply a lack of fresh water. Elephants are heavy drinkers and mammoths, their close cousins, were probably even more so…During dry periods, only one lake on St. Paul was available and this seems to have failed as thirsty mammoths destroyed the plant cover around its shores.
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The mammoths of Wrangel, a much larger island, survived for some 1,600 years longer and seem to have met a different fate. A team led by Eleftheria Palkopoulou and Love Dalen of the Swedish Museum of Natural History [analyzed] the whole genomes of two individuals…[and found that] the Wrangel mammoth’s genome carried so many detrimental mutations that the population had suffered a “genomic meltdown.”

The mammoth had lost many of the olfactory genes that underlie the sense of smell, as well as receptors in the vomeronasal gland, which detects pheromones…Loss of such genes…could disrupt mate choice and social status.
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