The woolly mammoth went extinct about four centuries ago, lasting about six thousand years longer than their other mammoth relatives did. And with scientists having come up with some new theories on why these modern elephant ancestors faded away from existence, the hope is that the findings could help improve conservation efforts for endangered species in present times.
A new study, which was published Thursday in the journal PLOS Genetics and cited on reports by the likes of the Christian Science Monitor, posits that "genomic meltdown" may have resulted in the woolly mammoth's extinction. This was based on the analysis and comparison of DNA belonging to two ancient mammoths – one approximately 4,300-years-old and found in remote Wrangel Island between the Chukchi Sea and East Siberian Sea, and the other a mainland mammoth estimated to be over 45,000-years-old.
According to the Christian Science Monitor, mainland mammoth populations had gone extinct about 10,000 years ago, as a result of climate change transforming their grassland habitat into forests, and the arrival of humans, who would use the beasts' meat for food and clothing. The woolly mammoth, however, didn't go extinct right away, as two populations survived for several thousand more years. One population on St. Paul Island in Alaska had lasted until about 5,600 years ago, when they disappeared due to a lack of fresh water. Another population on Wrangel Island had lasted a bit longer, going extinct about 4,000 years ago.The DNA analysis carried out by a team of Swedish scientists suggests that the mainland mammoth that lived 45,000 years ago came from a breeding population of about 13,000 — that's 43 times larger than the 300 mammoths that remained on Wrangel until the species fully became extinct. They also discovered that the island genome was "damaged" – this means that the gene pool's integrity may have "broken down" due to a lack of diversity among woolly mammoths.
The extinction, as a team of University of California, Berkeley researchers believe, may have been caused by "genomic meltdown," or the deletion of individual genes. According to the New York Times, UC-Berkley's Rebekah Rogers and Montgomery Slatkin studied the Swedish research at the gene level, and discovered that a good number of mutated genes that would have rendered proteins useless by preventing synthesis before the process could be completed. This resulted in the woolly mammoth losing its keen sense of smell, which would consequently have an impact on their choice of mates and social status among other animals of the species.
In addition, the two UC-Berkeley scientists had found a second damaged gene, one that affects the consistency and structure of the animals' hair. Typically, woolly mammoths have thick coats that kept them warm in cold weather situations, particularly during the Ice Age. But if the gene in question – FOXQ1 – is damaged, this results in hair becoming shinier and smoother. As such, the Christian Science Monitor wrote that this may have led to woolly mammoths transforming into "satin mammoths" on Wrangel.Love Dalen, an evolutionary genetics professor at the Swedish Museum of Natural History, led the original DNA analysis of the woolly mammoths. He told BBC News that the UC-Berkeley gene deletion findings make for a "very novel result," and one that could have an impact as scientists try to figure out ways to improve the prospects of threatened and endangered species.
"If this holds up when more mammoth genomes, as well as genomes from other species, are analyzed, it will have very important implications for conservation biology."The New York Times wrote that the new study might not bode well for modern-day endangered species – as proven by the woolly mammoth extinction theory, genomic meltdown appears to be irreversible. But if it's any consolation, Rogers noted that it may have taken "hundreds of generations" on Wrangel before this phenomenon truly became evident.
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