The last stand of the wooly mammoth

Angela

Elite member
Messages
21,823
Reaction score
12,325
Points
113
Ethnic group
Italian
See:
https://www.nytimes.com/2017/03/02/science/woolly-mammoth-extinct-genetics.html

"In a remote, mist-wrapped island north of the eastern tip of Siberia, a small group of woolly mammoths became the last survivors of their once thriving species. They fell extinct 4,000 years ago, having endured for some 6,000 years after the mammoths of the mainland had died off. From a message left in the tooth of a male mammoth, geneticists have now deciphered the probable reason for the population’s demise.The story is relevant to living populations of endangered species, because it supports the idea that as a population dwindles, natural selection becomes less efficient at purging bad mutations, leading to loss of genes and a slow meltdown of the genome. The implication is that once numbers fall below a certain level, genetic decline is irreversible.
Woolly mammoths once flourished from northern Europe to Siberia. As the last ice age drew to a close some 10,000 years ago, the mainland population perished, victims of climate change and human hunters. But some populations lived on for thousands of years, notably on two remote islands that had once been part of Beringia, the now foundered land bridge that joined Alaska to Siberia."

"the reasons for their extinction have long been a matter of speculation. Last August, a team led by Russell W. Graham of Pennsylvania State University ruled out all the leading candidates, including human predation, polar bears, increased winter snowpack, volcanic activity and changing vegetation.

Continue reading the main story
[h=2]RELATED COVERAGE[/h]






The real reason, they concluded, after examining lake bed sediments, was simply a lack of fresh water. Elephants are heavy drinkers and mammoths, their close cousins, were probably even more so, because they were adapted to the cold but were trying to survive in the post-ice age climate. During dry periods, only one lake on St. Paul was available and this seems to have failed as thirsty mammoths destroyed the plant cover around its shores.'

"The mammoths of Wrangel, a much larger island, survived for some 1,600 years longer and seem to have met a different fate...The dwindling population during this 40,000 year period suffered a reduction in genetic diversity of some 20 percent, the Swedish team reported, suggesting that the lesser fitness of the Wrangel mammoths might have contributed to their extinction.

In fact, the Wrangel mammoth’s genome carried so many detrimental mutations that the population had suffered a “genomic meltdown,” according to Rebekah Rogers and Montgomery Slatkin of the University of California, Berkeley. Analyzing the Swedish team’s mammoth data at the gene level, they found that many genes had accumulated mutations that would have halted synthesis of proteins before they were complete, making the proteins useless, they report Thursday in PLOS Genetics.
The mammoth had lost many of the olfactory genes that underlie the sense of smell, as well as receptors in the vomeronasal gland, which detects pheromones, hormonally active scents that influence the behavior of other individuals. Loss of such genes, to judge by the situation with elephants, could disrupt mate choice and social status.
Another damaged gene is called FOXQ1, which affects the structure and translucency of hair. Mammoths had thick, rough hair that provided essential insulation in ice age climates. Damage to FOXQ1, at least in some mice and rabbits that carry the same damaged form of the gene, causes hairs to become less stiff and shiny, taking on a satin appearance. A herd of Wrangel mammoths in moonlight might have shimmered like ghosts, but any compromise to their insulation would have jeopardized survival.'




 
archeologists believe most HG were exogame
there is a theory that endogame HG went extinct long time ago
and that remote small tribes who were unable to find partners from other tribes became unfit for survival
you can reverse this reasoning : appearantly diversity among HG was sufficient for survival, at least in the specific biotopes they lived in

I doubt that mammoths were heavy drinkers like elephants
during LGM the tundras of eastern Siberia were very arid and mammoths survived that

so the mammoths on Wrangel Island would have become extinct because of remoteness
that is not the reason why mammoths went extinct on the European and Siberian tundras

in paleolithic Europe mammoths went extinct, Gravettians hunted mainly reindeer
new mammoths arrived into Europe from time to time, but their DNA has shown they were descendants from Siberian and even Beringian herds
 

This thread has been viewed 2111 times.

Back
Top