Cometary Wipeout of Mammals

Join Our Community of Science Lovers!

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

Roughly 12,900 years ago a global-cooling anomaly contributed to the extinction of 35 mammal species, including the mammoth. In some areas, average temperatures may have dropped as much as 15 degrees Celsius (27 degrees Fahrenheit). New evidence, in the form of diamonds several nanometers wide, supports a theory proposed last year that a comet collision or a similar explosive event threw up debris and caused the cooling.

Nanodiamonds occur only in sediment exposed to high temperatures and pressures, such as that produced by a cometary impact. Researchers uncovered them in six sites in North America: Murray Springs, Ariz.; Bull Creek, Okla.; Gainey, Mich.; Topper, S.C.; Lake Hind, Manitoba; and Chobot, Alberta. Preliminary searches in Europe, Asia and South America have also turned up similar finds in sediments of the same age, showing that the event had global reach. But it was definitely not as large as the one that wiped out the dinosaurs 65 million years ago. The study landed in the January 2 Science.

It’s Time to Stand Up for Science

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.

I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.

If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.

In return, you get essential news, captivating podcasts, brilliant infographics, can't-miss newsletters, must-watch videos, challenging games, and the science world's best writing and reporting. You can even gift someone a subscription.

There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.

Thank you,

David M. Ewalt, Editor in Chief, Scientific American