Nuclear Tests Marked Life on Earth With a Radioactive Spike

Posted on by Lori Jia

The Atlantic, March 2, 2020

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On the morning of March 1, 1954, a hydrogen bomb went off in the middle of the Pacific Ocean. John Clark was only 20 miles away when he issued the order, huddled with his crew inside a windowless concrete blockhouse on Bikini Atoll. But seconds went by, and all was silent. He wondered if the bomb had failed. Eventually, he radioed a Navy ship monitoring the test explosion.

“It’s a good one,” they told him.

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Ghost DNA Hints at Africa’s Missing Ancient Humans

Posted on by Carl Zimmer

The New York Times, February 12, 2020

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Scientists reported on Wednesday that they had discovered evidence of an extinct branch of humans whose ancestors split from our own a million years ago. The evidence of these humans was not a fossil. Instead, the researchers found pieces of their DNA in the genomes of living people from West Africa.

Arun Durvasula and Sriram Sankararaman, two geneticists at the University of California, Los Angeles, described this so-called ghost archaic population in the journal Science Advances. Their discovery may shed light on human genetic diversity in Africa, which has been hard to chart until now because the fossil record is sparse.

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Friday’s Elk, February 1, 2020

Posted on by Matt Kristoffersen

Happy Groundhog Day’s Eve!

I wanted to start off with a note to Friday’s Elk readers in the Los Angeles area. On Thursday, February 6, I will be speaking in the Aloud Series at the Library Foundation of Los Angeles. I’ll be in conversation with Sean Carroll, Caltech physicist, author, and podcaster extraordinaire. We’ll be at the Mark Taper Auditorium-Central Library. Hope to see you! You can register here.

This past month, I took a look at evolution’s imprint on us, as well as a great step that took place two billion years ago to our level of complexity. Continue reading “Friday’s Elk, February 1, 2020” →

Neanderthal Genes Hint at Much Earlier Human Migration From Africa

Posted on by Carl Zimmer

The New York Times, January 31, 2020

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In recent years, millions of people have been astonished, even thrilled, to learn from those popular genetic tests that their DNA is laced with Neanderthal genes.

Those genes were first discovered in 2010, in a study of Neanderthal fossils. From DNA recovered from the bones, researchers deduced that modern humans interbred with Neanderthals some 60,000 years ago, after leaving Africa.

As a result, the genes of non-Africans today are 1 percent to 2 percent Neanderthal. People of African ancestry, it was thought, have little to no Neanderthal DNA.

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Ancient DNA from West Africa Adds to Picture of Humans’ Rise

Posted on by Lori Jia

The New York Times, January 22, 2020

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In October 2015, scientists reconstructed the genome of a 4,500-year-old man who lived in Ethiopia. It was the first time that anyone had created a complete genetic snapshot of an African from an ancient skeleton.

Since then, other researchers have recovered DNA from skeletons unearthed in other regions of the continent. Now researchers have found the first genetic material from West Africa. On Wednesday a team reported that they had recovered DNA from four individuals in Cameroon, dating back as far as 8,000 years.

These ancient genomes contain vital clues to the history of the continent that have largely disappeared in the past few thousand years. Taken together, they are giving scientists a new vision of our species since it arose in Africa.

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