Why Was This Ancient Tusk 150 Miles From Land, 3,000 Feet Deep?


Mammoth tusks that are over 100,000 years old are “extremely rare,” Mr. Mol added, and studying one could give scientists new insights about the Lower Paleolithic, a poorly understood era of Earth’s history.

Scientists know that around 200,000 years ago Earth was experiencing a glacial period and our ancestors were migrating out of Africa. But they don’t know exactly how the planet’s changing climate affected mammoths and other large animals during this time. What is also unclear is how arrival to North America altered the genetic diversity of mammoths.

“We don’t really know much of anything about what was happening during that time period,” Dr. Fisher said. “We don’t have access to a lot of specimens from this time period and that’s due in large part to the fact that getting access to sediments of this age is difficult.”

Mammoths, the furry, small-eared relatives of modern elephants, first appeared around five million years ago and became extinct around 4,000 years ago. The first mammoths came out of Africa and spread north, evolving into distinct species along the way, until they had colonized much of the Northern Hemisphere.

The earliest mammoths to venture into North America were known as Krestovka or steppe mammoths. These mammoths came from Eurasia 1.5 million years ago and did so by marching across the Bering Strait, which wasn’t covered by water like it is today. Hundreds of thousands of years later, another species of mammoth, the woolly mammoth, also crossed the Bering Strait and joined their cousins in North America. The two hybridized to produce the Columbian mammoth, but no one knows exactly when. A recent study estimated that the hybridization event occurred at least 420,000 years ago, but more research is needed to confirm this.

If the tusk is as old as scientists suspect, it “could really help clarify the timing of this hybridization event,” said Pete Heintzman, an associate professor at the Arctic University Museum of Norway who studies the DNA of mammoths and other ice age creatures.

Although exposure to saltwater can be destructive to biological tissue, the deep sea can be ideal for DNA preservation.

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