How the woolly mammoth, an Ice Age ambassador, ended up confined to modern-day Wrangel … [+]
Rising sea levels about 10,000 years ago turned Wrangel Island into a final refuge for woolly mammoths, isolating them from their mainland counterparts. As the world’s climate continued to warm and habitats changed, Wrangel Island became one of the last viable environments where these mammoths could survive, setting the stage for their final chapter.
Four millennia ago, Wrangel Island was a frozen refuge, the last ice box where woolly mammoths … [+]
A prevailing theory for the extinction of isolated populations such as woolly mammoths on Wrangel Island often points to inbreeding. Inbreeding can reduce the genetic variability of a population and increase the spread of deleterious genetic mutations, leading to reduced survival and reproduction rates. A striking example is the Tasmanian tiger, or thylacine, which suffered from reduced genetic diversity due to heavy inbreeding before its extinction in the 20th century.
However, this popular theory of blood relatedness leading to extinction may not be valid for Wrangel Island’s woolly mammoths, according to a June 2024 paper published in Cell.
There was a ‘close’ event, but the mammoth was on his way to recovery
The study analyzed 21 genomes from Siberian woolly mammoths and found that when the mammoth population experienced a significant bottleneck—an event that greatly reduces the size and genetic diversity of a population—it recovered well. In the case of woolly mammoths on Wrangel Island, the stranding event occurred when rising sea levels and climate change caused their numbers to decline sharply as they became isolated on the island.
This drastic reduction in population size limited their genetic diversity and could have made them more susceptible to environmental stresses and changes.
The study found that while the Wrangel Island mammoth population started with just eight individuals, it grew to around 200 to 300 and remained stable until their extinction. Over time, the worst genetic mutations became less common because mammoths with these deleterious traits were less likely to reproduce.
This suggests that, contrary to expectations, inbreeding did not lead to the accumulation of deleterious mutations that could have caused their extinction. Instead, the isolated mammoth population was able to purge these harmful mutations over generations, challenging the traditional view that genetic degradation was the primary factor in their extinction.
Did we have something to do with the disappearance?
New genetic data on woolly mammoths suggests the bloodbath was just one small part of a larger storm brewing. While mammoths faced genetic challenges due to their isolation, the real threats to their survival likely came from a combination of known and unknown environmental changes and, most likely, human interference.
The last woolly mammoths became extinct 4000 years ago. Around this time, human civilization was advancing technologically and expanding geographically. Early humans had reached various remote parts of the world, including areas near Wrangel Island.
This period marked significant changes in human hunting practices and land use, which may have affected local ecosystems in profound ways. Although direct evidence of humans hunting the last mammoths on Wrangel Island is still elusive, the overlapping timelines suggest that human activity may have played a role in stressing mammoth populations, either through direct hunting or by altering habitats. theirs.
This hypothesis is consistent with broader patterns observed in other species extinctions, where human expansion and environmental impact have often been critical factors. A similar scenario unfolded with the Tasmanian tiger, which faced relentless hunting, habitat loss due to agricultural expansion, and diseases introduced by invasive species. These factors combined led to her conceiving problem and subsequent disappearance.
The dodo bird is another example of extinction driven by human activity. Originally from Mauritius, the dodo was unaccustomed to predators, making it vulnerable when humans arrived. The introduction of invasive species, habitat destruction and outright hunting by sailors drove the dodo to extinction by the end of the 17th century.
Once a native of Mauritius, the dodo bird became extinct prematurely due to human activities, from … [+]
In both cases, as with the woolly mammoths, it was not just one factor, but a combination of human influences and environmental changes that led to their demise. Only time will reveal the specifics of how the last woolly mammoths to roam the earth met their end, but finds like these put things into perspective for us. They remind us that most species are resilient, built to withstand various challenges. It often takes a series of unfortunate events for a species to become extinct.