Post by Admin on Jun 29, 2024 10:05:53 GMT
The planet's last surviving mammoth population was killed by a random and sudden mystery event, a new study has revealed.
The population, isolated from the rest of the world for 6,000 years on Wrangel Island in what is now extreme northern Russia, was previously believed to have been slowly wiped out by genetic inbreeding.
But a new study has found that the population — which grew from at most eight individuals to 300 before its demise 4,000 years ago — did not go extinct for genetic reasons. This leaves an even bigger mystery as to what actually happened. The researchers published their findings June 27 in the journal Cell.
"We can now confidently reject the idea that the population was simply too small and that they were doomed to go extinct for genetic reasons," study senior author Love Dalén, an evolutionary geneticist at the Centre for Palaeogenetics in Stockholm, said in a statement. "This means it was probably just some random event that killed them off, and if that random event hadn't happened, then we would still have mammoths today."
From about 300,000 to 10,000 years ago, woolly mammoths roamed the frigid plains of Europe, Asia and North America. As the ice across these northern regions melted, the Arctic tundra that the giant pachyderms relied on for food disappeared. This caused the mammoths' range to shrink until they eventually disappeared.
A number of species have recently recovered from near-extinction. Although these species have avoided the immediate extinction threat, their long-term viability remains precarious due to the potential genetic consequences of population declines, which are poorly understood on a timescale beyond a few generations. Woolly mammoths (Mammuthus primigenius) became isolated on Wrangel Island around 10,000 years ago and persisted for over 200 generations before becoming extinct around 4,000 years ago. To study the evolutionary processes leading up to the mammoths’ extinction, we analyzed 21 Siberian woolly mammoth genomes. Our results show that the population recovered quickly from a severe bottleneck and remained demographically stable during the ensuing six millennia. We find that mildly deleterious mutations gradually accumulated, whereas highly deleterious mutations were purged, suggesting ongoing inbreeding depression that lasted for hundreds of generations. The time-lag between demographic and genetic recovery has wide-ranging implications for conservation management of recently bottlenecked populations.
Temporal dynamics of woolly mammoth genome erosion prior to extinction
www.cell.com/cell/fulltext/S0092-8674(24)00577-4
We don’t have the woolly mammoth with us any longer, but we aren’t sure exactly why. Christopher Moore, an archaeologist at the University of South Carolina, blames a massive meteor—even if he doesn’t have a crater to prove it.
However, Moore and and his team believe that we may not need a crater to prove the extremely controversial Younger Dryas impact hypothesis—the idea that roughly 12,800 years ago, the climate took a sudden shift in the northern hemisphere that helped wipe out the woolly mammoth. Instead, they’ve been thinking something else will fit the bill: a meteor shockwave.
In a new study published in the journal Airbursts and Cratering Impacts, the team presents evidence that he believes points to a major meteor exploding near Earth—possibly not actually striking Earth physically—that would have caused the kind of rapid climate change throughout the northern hemisphere that would lead to a complete shift in our world.
“They explode in the air before they hit the ground,” Moore said about comets in a news release, “but if they’re low enough, the shockwave and heat can hit the ground and melt sediment, produce microspherules, and shock the quartz. We’re being hit by these things more than most people think.”
Evidence from Greenland’s ice cores show elevated levels of combustion aerosols, which indicate that a large, prehistoric fire raged at the proposed beginning of the climate event. Add in high levels of platinum found from Syria to South Carolina—rare in Earth’s soil, but incredibly common in comets—and the location of both magnetic balls of iron known as microspherules and shock-fractured quartz that melted into silica in different areas, and the researchers believe that a convincing picture is beginning to take shape.
www.scienceopen.com/hosted-document?doi=10.14293/ACI.2024.0003
The population, isolated from the rest of the world for 6,000 years on Wrangel Island in what is now extreme northern Russia, was previously believed to have been slowly wiped out by genetic inbreeding.
But a new study has found that the population — which grew from at most eight individuals to 300 before its demise 4,000 years ago — did not go extinct for genetic reasons. This leaves an even bigger mystery as to what actually happened. The researchers published their findings June 27 in the journal Cell.
"We can now confidently reject the idea that the population was simply too small and that they were doomed to go extinct for genetic reasons," study senior author Love Dalén, an evolutionary geneticist at the Centre for Palaeogenetics in Stockholm, said in a statement. "This means it was probably just some random event that killed them off, and if that random event hadn't happened, then we would still have mammoths today."
From about 300,000 to 10,000 years ago, woolly mammoths roamed the frigid plains of Europe, Asia and North America. As the ice across these northern regions melted, the Arctic tundra that the giant pachyderms relied on for food disappeared. This caused the mammoths' range to shrink until they eventually disappeared.
A number of species have recently recovered from near-extinction. Although these species have avoided the immediate extinction threat, their long-term viability remains precarious due to the potential genetic consequences of population declines, which are poorly understood on a timescale beyond a few generations. Woolly mammoths (Mammuthus primigenius) became isolated on Wrangel Island around 10,000 years ago and persisted for over 200 generations before becoming extinct around 4,000 years ago. To study the evolutionary processes leading up to the mammoths’ extinction, we analyzed 21 Siberian woolly mammoth genomes. Our results show that the population recovered quickly from a severe bottleneck and remained demographically stable during the ensuing six millennia. We find that mildly deleterious mutations gradually accumulated, whereas highly deleterious mutations were purged, suggesting ongoing inbreeding depression that lasted for hundreds of generations. The time-lag between demographic and genetic recovery has wide-ranging implications for conservation management of recently bottlenecked populations.
Temporal dynamics of woolly mammoth genome erosion prior to extinction
www.cell.com/cell/fulltext/S0092-8674(24)00577-4
We don’t have the woolly mammoth with us any longer, but we aren’t sure exactly why. Christopher Moore, an archaeologist at the University of South Carolina, blames a massive meteor—even if he doesn’t have a crater to prove it.
However, Moore and and his team believe that we may not need a crater to prove the extremely controversial Younger Dryas impact hypothesis—the idea that roughly 12,800 years ago, the climate took a sudden shift in the northern hemisphere that helped wipe out the woolly mammoth. Instead, they’ve been thinking something else will fit the bill: a meteor shockwave.
In a new study published in the journal Airbursts and Cratering Impacts, the team presents evidence that he believes points to a major meteor exploding near Earth—possibly not actually striking Earth physically—that would have caused the kind of rapid climate change throughout the northern hemisphere that would lead to a complete shift in our world.
“They explode in the air before they hit the ground,” Moore said about comets in a news release, “but if they’re low enough, the shockwave and heat can hit the ground and melt sediment, produce microspherules, and shock the quartz. We’re being hit by these things more than most people think.”
Evidence from Greenland’s ice cores show elevated levels of combustion aerosols, which indicate that a large, prehistoric fire raged at the proposed beginning of the climate event. Add in high levels of platinum found from Syria to South Carolina—rare in Earth’s soil, but incredibly common in comets—and the location of both magnetic balls of iron known as microspherules and shock-fractured quartz that melted into silica in different areas, and the researchers believe that a convincing picture is beginning to take shape.
www.scienceopen.com/hosted-document?doi=10.14293/ACI.2024.0003
