“It really surprised me,” Bataille says of these ranges, which were much larger than he expected. “It definitely begs the question: Why? What happened? Why is he doing this? Why is it moving like this and so fast? ”
This indication that mammoths needed a very large habitat for development could give us clues as to why they became extinct, says David Nogués-Bravo, an associate professor of historical biogeography at the University of Copenhagen who was not involved in the research. During the life of this mammoth, somewhere at the very end of the last ice age, the Earth warmed up. Boreal forests began to take over the home of mammoths on grassy plains. Maybe people showed up and started hunting them. Approximately 6,000 years after the death of this mammoth, the species was almost extinct. It is difficult for scientists to discern how different stressors could have collided to wipe out mammoths, but having this basic information about their range and how far they moved could help them build models to recreate what could have happened.
Nogués-Bravo says techniques like isotope mapping are a big step forward because they could help scientists monitor the extinction process. “It really opens a big window that will help us understand why species are extinct,” he says. This could ultimately help scientists predict what could happen to other large animals, such as elephants, in the coming years as climate change and human interference limit their habitats.
But there are limits to how beautiful a picture data from this tusk can paint. Nogués-Bravo says these maps are probably quite accurate in giving an insight into where the animal was at all. But they are not GPS. “I’m more skeptical about the specific routes they’ve tried to model,” he says. To track those routes, researchers would need really accurate isotope data from every square mile of the area, a level of detail that their rodent-based map lacks.
Yet, although the portrait is a bit blurry, it is an unprecedented view of what one mammoth did during its lifetime. For example, as Wooller and Bataille examined the tusk base, they began to see signs of trouble. Strontium isotope patterns revealed that the animal moved less and less, stayed in a relatively small area, and did not migrate the hundreds of miles it had before. Scientists estimate that mammoths usually live in their 60s or 70s, but at just 28, this mammoth began to die. In the last years of his life, the level of nitrogen isotopes in his tusk began to rise, a pattern that indicates starvation of mammals. “It was like we caught what caused his death,” Wooller says why the mammoth stopped moving and normal eating is still a mystery.
Now researchers would like to apply this technique to the tusks of other mammoths. Wooller is curious about whether other males behaved similarly to the one they followed and whether females had different migration patterns than males. He also wonders how these movements have changed as the planet has been constantly warming, so he wants to examine the tusks of mammoths that have lived in different time periods. This could offer more clues as to whether they changed their range in response to the progression of the boreal forest or due to the presence of humans. This technique can also be used on the teeth and horns of other species that were alive at the time, such as caribou or musk oxen, to see how each animal reacted to this changing world.
“What we’re showing here is that there’s a very rich and wonderful record here that can be set with this tusk,” Wooller says. Each is a storehouse of information, a whole life story waiting to be read.
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