Woolly Mammoths' Extinction Due to Inbreeding and Bad Climate

A new finding uncovered the secret behind the ultimate extinction of the woolly mammoth suggesting that inbreeding and unfavorable climatic conditions led to their disappearance.

The hairy enormous woolly mammoth is the most famous prehistoric elephant of the Pleistocene epoch. A lot of information has been uncovered about these animals based on the analysis of their fossil remains. Over recent years, researchers noticed an unusual pattern in the fossils of the mammoths that were unearthed near the North Sea.

These fossils, about 12,000 years old, were found to have extra ribs along their neck vertebrae. This deformity on its own though was not a threat but it definitely did indicate that the development of the animal was not normal.

A study conducted earlier in 2006 looked at the presence of such extra cervical ribs in humans and found that nearly 78 percent of the fetuses with such deformity die before birth and 86 percent of babies with these cervical ribs die before completing an year, reports LiveScience.   

In most mammals this deformity is linked with stillbirths and multiple congenital abnormalities that have a damaging impact on the lifespan.

In the current study, researchers from Rotterdam Museum of Natural History and the Naturalis Biodiversity Center in Leiden noticed that the cervical ribs were 10 times more common in the woolly mammoths from the North Sea when compared to 3.3 percent in the modern elephants. The researchers based their conclusion after examining the mammoth and modern elephant's cervical ribs that are housed at several European museum collections.

"It had aroused our curiosity to find two cervical vertebrae, with large articulation facets for ribs, in the mammoth samples recently dredged from the North Sea. We knew these were just about the last mammoths living there, so we suspected something was happening. Our work now shows that there was indeed a problem in this population," Jelle Reumer, one of the authors of the study, said in a statement.

When compared to the modern sample, the presence of abnormal cervical vertebrae in mammoths is higher, strongly indicating the vulnerability in the species.  Most often the development of this rib is based on the genetic and environmental factors existing during the pre embryonic development.

In the case of the mammoths, the researchers point at inbreeding as a major cause due to the small population size and also climatic conditions like famine, disease outbreak, or cold that disturbed the embryonic and fetal development that completely wiped out the species. It is the developmental abnormalities that gradually pushed these vulnerable creatures to extinction.

The finding was documented in the journal Peer J.