Wednesday, April 2, 2014

Inbreeding in woolly mammoths: Clues about decline and eventual extinction

Woolly mammoths are one of those ancient creatures scientifically proven to have walked the Earth, but we can only imagine in picture books. Recently, researchers have made headway into the extinction of this species, collecting remains from the late Pleistocene age and about the North Sea. Mammals, including long-necked giraffes almost always have seven neck vertebrae, under examination scientists noted a cervical rib on the mammoth remains, which in modern day animals is attributed to inbreeding and harsh environmental conditions during the gestation period.

"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," said Jelle Reume. It was actually observed at a frequency 10 times higher, 33% versus 3.3.% in modern day elephants. The cervical rib is harmless to its host, however, as previously mentioned, is an indicator of environmental disturbances during embryonic development , but also stillbirths. The cervical rib is strongly associated with congenital abnormalities, negatively impacting the lifespan of an individual. In humans, approximately 90% of those possessing a cervical rib doe before reaching reproductive age, these rates are again attributed to major congenital abnormalities. For example, noting the number of cervical rib in humans, an incidence higher than 1% was only found in hospitals or isolated populations, 25% in children with leukemia, brain tumors, and neuroblastomas

In this study a total of 16 cervical vertebrates were looked at, 6 C6 and 10 C7 vertebrates, in comparison with 28 specimens of extant elephants. When identifying articulations for cervical ribs on the vertebrae, the following characteristics are of note: smooth, polished looking surface, visibly smoother than surround surface, surface has no vascular or nervous foramina. Once identified, size is an important characteristic as well, and those of the woolly mammoth were visibly larger than those found on elephants, and in mice was found to be negatively correlated with fitness. Low fitness, harsh conditions during a period of great climate changes, in an unstable and changing ecosystem acting on a vulnerable organism, in this case the woolly mammoth seems like the perfect recipe for eventual extinction

Posted by Thomas Flores (B)


  1. Not only is it amazing to be able to find information like this about extinct organisms, but also ingenious to discover one of the reasons for extinction of the mammoth with such precision. I wonder if anyone(maybe even this research group?) has any hypotheses as to why the mammoths were suffering from inbreeding and harsh environmental conditions. One would think that such a creature built for harsh terrain would be able to handle it, perhaps not though.

    Posted by Michael Dailing

    1. Researchers, and those involved with this discovery hypothesized that the inbreeding was due to the harsh conditions. The mammoths were at the mercy of the late Pleistocene age, which was a time of climatic instability, resulting in those poor environmental conditions, which can also be confirmed through mineral deficiency tests. It would be great to believe that such a powerful, and almost mythical creature in our eyes could be strong as it is big, which in some respects it is; but the mammoths like any other organism needs proper nutrients, and drastic changes to their environmental can lead to crashes in a species viability for that niche.

      Posted by Thomas Flores