By the time of their demise, woolly mammoths' genomes held mutations that even affected their ability to smell, Gizmodo reports.
Woolly mammoths flourished during the Pleistocene, but their numbers dwindled in the Holocene, likely due to a combination of the end of the ice age and corresponding loss of habitat, predation by humans, and other factors, it adds. But two small, isolated woolly mammoth populations on St. Paul Island and Wrangel Island held on until about 5,600 and 4,000 years ago, respectively, it adds. Researchers led by the University at Buffalo's Vincent Lynch sequenced the genome of one of the Wrangel Island woolly mammoths that lived about 4,300 years ago.
As they report in Genome Biology and Evolution, the researchers found through their comparison with older woolly mammoths and modern elephants that the Wrangel Island woolly mammoth's genome harbored a number of mutations. In particular, this woolly mammoth had putatively deleterious alterations to genes including HYLS1, NKD1, NEUROG3, and OR5A, which are associated with developmental defects, reduced male fertility, diabetes, and the detection of floral scents, respectively. When they tested these mutations in cell cultures, they appeared damaging.
"These data suggest that at least one Wrangel Island mammoth may have suffered adverse consequences from reduced population size and isolation," the researchers write in their paper.