Being confronted with a pack of wolves is bad enough, but if you happened to be in Alaska some 12,000 years ago, things would be much, much worse. Back then, the icy forests were patrolled by a sort of super-wolf. Larger and stronger than the modern gray wolf, this beast had bigger teeth and more powerful jaws, built to kill very large prey.
This uber-wolf was discovered by Jennifer Leonard and colleagues from the University of California, Los Angeles. The group were studying the remains of ancient gray wolves, frozen in permafrost in eastern Beringia, a region that includes Alaska and northwest Canada. These freezer-like conditions preserved the bodies very well, and the team found themselves in a unique position. They could not only analyse the bones of an extinct species, but they could extract DNA from said bones, and study its genes too.
For their first surprise, they found that these ancient wolves were genetically distinct from modern ones. They analysed mitochondrial DNA from 20 ancient wolves and none of them was a match for over 400 modern individuals. Today’s wolves are clearly not descendants of these prehistoric ones, which must have died out completely. The two groups shared a common ancestor, but lie on two separate and diverging branches on the evolutionary tree.
The genes were not the only differences that Leonard found. When she analysed the skulls of the Beringian wolves, she found that their heads were shorter and broader. Their jaws were deeper than usual and were filled with very large carnassials, the large meat-shearing teeth that characterise dogs, cats and other carnivores (the group, not meat-eaters in general).
This was the skull of a hypercarnivore, adapted to eat only meat and to kill prey much larger than itself using bites of tremendous force. Leonard even suggests that the mighty mammoths may have been on their menu.
Did our ancestors exterminate the woolly mammoth? Well, sort of. According to a new study, humans only delivered a killing blow to a species that had already been driven to the brink of extinction by changing climates. Corralled into a tiny range by habitat loss, the diminished mammoth population became particularly vulnerable to the spears of hunters. We just kicked them while they were down.
The woolly mammoth first walked the earth about 300,000 years ago during the Pleistocene period. They were well adapted to survive in the dry and cold habitat known as the ‘steppe-tundra‘. Despite the sparse plant life there, the woolly mammoths were very successful, spreading out in a belt across the Northern hemisphere.
Their fortunes began to change as the Pleistocene gave way to the Holocene. The climate around them started to become warmer and wetter and the shrinking steppe-tundras greatly reduced the mammoth’s habitats. The species made its last stand on the small Wrangel Island in Siberia before finally succumbing to extinction.
But climate change isn’t the whole story. About 40,000 years ago, those relentless predators – human beings – started encroaching into the woolly mammoth’s range in northern Eurasia. Which of these two threats, climate change or human hunters, sealed the mammoth’s fate?