[ISL] "Last mammoths on Alaska island likely died of thirst"

[rfmcdonald]

CBC reported on the grim findings of the researchers who determined why the mammoths of Alaska's Saint Paul Island, last of their kind, died out.

St. Paul Island's mammoths were a vulnerable population that probably never numbered more than 30, [one researcher] estimates. Pinpointing the cause of their extinction "just sort of underscores the precariousness of small island populations to what seems like fairly subtle environmental change."

Even today, the crater lake that the researchers studied is only a metre deep. The researchers drilled through the ice in winter, into the layers of sediment deposited on the bottom of the lake over thousands of years.

There they found mammoth DNA, spores of fungi that can only live in the fresh dung of large mammals like mammoths, and the remains of aquatic insects that contain chemical information about water levels over the lake's history.

Together, the data pinpoint the time of extinction at 5,600 years ago — about 900 years after the date of the youngest mammoth remains ever dug up on the island — and chronicle the deterioration of the lake during the last days of the mammoths.

The result doesn't just solve a longstanding mystery about a puzzling extinction.

It may also be a warning about the seriousness of a problem that has never been linked to extinctions in the past, but is relevant for human communities in our own age of rapid climate change, rising seas and a coastal flooding[.]