Bring up the woolly mammoth at a cocktail party and the questions will probably be about what you are drinking and will the species ever be recreated using DNA. Ask Jelle Reumer, a paleontologist at the Natural History Museum of Rotterdam and Utrecht University, and he’ll steer the conversation to new evidence that the extinction of the wooly mammoth was caused by an extra rib.

Dr. Jelle Reumer pointing to location of extra rib

Fossils of mammoths found near the North Sea and dating to the late Pleistocene, about 12,000 years ago, are believed to be the last of the species. Many have cervical or extra ribs along the neck vertebrae which are congenital abnormalities.

In an article in the open-access journal PeerJ, Reumer reports that a search through the mammoth fossils of the Natural History Museum of Rotterdam and the Naturalis Biodiversity Center in Leiden, Netherlands, found a high percentage of them had cervical ribs.

In humans, cervical ribs indicate the presence of other severe abnormalities that often result in death in the womb or within the first year after birth. Reumer believes the extra ribs in the mammoths could have been the result of inbreeding which caused deadly genetic defects. Another possibility is that they point to prenatal stress caused by famine or disease which weakened the pregnant mothers, their fetuses and their newborns.

Whatever the cause of the cervical ribs, Reumer says the effect was the same.

The vulnerable condition may well have contributed to the eventual extinction of the woolly mammoths.

Baby mammoth found in Siberia

Plans to recreate a woolly mammoth using DNA from remains found frozen in Siberia are already underway in Russia. Let’s hope they can prevent the cervical ribs so it doesn’t return only to see extinction again.