In a cave in the Philippines, scientists have discovered a new branch of the human family tree.

At least 50,000 years ago, an extinct human species lived on what is now the island of Luzon, researchers reported on Wednesday. It’s possible that Homo luzonensis, as they’re calling the species, stood less than three feet tall.

The discovery adds growing complexity to the story of human evolution. It was not a simple march forward, as it once seemed. Instead, our lineage assumed an exuberant burst of strange forms along the way.

Our species, Homo sapiens, now inhabits a comparatively lonely world.

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In 2011, Dr. Dena Dubal was hired by the University of California, San Francisco, as an assistant professor of neurology. She set up a new lab with one chief goal: to understand a mysterious hormone called Klotho.

Dr. Dubal wondered if it might be the key to finding effective treatments for dementia and other disorders of the aging brain. At the time, scientists only knew enough about Klotho to be fascinated by it.

Mice bred to make extra Klotho lived 30 percent longer, for instance. But scientists also had found Klotho in the brain, and so Dr. Dubal launched experiments to see whether it had any effect on how mice learn and remember.

Continue reading “One Day There May Be a Drug to Turbocharge the Brain. Who Should Get It?” →

Before dawn on April 4, 1994, Abigail Alling and Mark Van Thillo slipped across the foothills of Arizona’s Santa Catalina Mountains. They made their way to a looming monument of geodesic domes and pyramids known as Biosphere 2. The three-acre complex contained a miniature rain forest, a mangrove, a desert and a coral reef — along with seven people who had been sealed inside for a month.

Ms. Alling and Mr. Van Thillo had recently emerged from a two-year stay in Biosphere 2. Later, after they were arrested, they told reporters that they feared for the safety of the people inside. They were determined to bring the mission to an end.

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On Thursday, 41 scientists published the first worldwide analysis of a fungal outbreak that’s been wiping out frogs for decades. The devastation turns out to be far worse than anyone had previously realized.

Writing in the journal Science, the researchers conclude that populations of more than 500 species of amphibians have declined significantly because of the outbreak — including at least 90 species presumed to have gone extinct. The figure is more than twice as large as earlier estimates.

“That’s fairly seismic,” said Wendy Palen, a biologist at Simon Fraser University who is a co-author of a commentary accompanying the study. “It now earns the moniker of the most deadly pathogen known to science.”

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