Abnormality In Woolly Mammoth Remains Gives Clue To Their Extinction
Mammoths, the prehistoric ancestors of the modern- day elephant, once roamed the Earth in abundance. They are admired for their strength and size, yet the cause for their extinction still remains a mystery. There are many theories although no definitive answers as to why these gentle giants disappeared forever. A new study says that newly discovered mammoth remains found in the North Sea suggest that inbreeding and environmental stress played a role in the mammoth's extinction.
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Researchers at the Rotterdam Museum of Natural History and the Naturalis Biodiversity Center in the Netherlands noted that in a large number of woolly mammoth remains from the North Sea, the animals possessed a cervical rib. While this deformity is not necessarily life threatening, its presence usually indicates a disturbance had taken place during early embryonic development. This disturbance may have been from genetic or environmental stresses to the mother during the pregnancy. "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 explained in a recent press release.
All mammals, with the exception of sloths, manatee, and dugongs, have seven neck vertebrae which do not normally possess a cervical rib. In modern day mammals cervical ribs, or neck ribs as they are more commonly known as, are abnormalities associated with stillbirths or extremely serious abnormalities that will greatly shorten the newborn's lifespan.
The large amount of mammoth remains that had neck ribs would suggest that there was an outside threat which perpetuated this species' extinction. Inbreeding is a probable cause, based on the already small population of mammoths which existed during this time period. Other factors such as disease, famine, or even extreme cold could have caused disturbances in fetal development leading to the formation of the neck rib deformity. Based on the shortened lifespan of modern day mammals born with a neck rib, it would seem that mammoths with neck ribs faced a similar life expectancy. This could have significantly added to the extinction of these late Pleistocene mammoths.
It is difficult to narrow down the mammoth's extinction to one factor. This discovery is important in not only giving insight on the what caused the mammoth's extinction, but also it helps to give scientist an idea of the overall conditions that existed in this time period.
Source: Reumer JWF, ten Broek CMA, Freitson G. Extraordinary incidence of cervical ribs indicates vulnerable conditions in Late Pleistocene mammoths. Peer J PrePrints. 2014
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