Thirty-four years ago, doctors in Los Angeles discovered that some of their patients were succumbing to a normally harmless fungus. It soon became clear that they belonged to a growing number of people whose immune systems were hobbled by a virus, eventually known as human immunodeficiency virus, or H.I.V.

To date, an estimated 78 million people have become infected, 39 million of whom have died.

As the true scale of the virus’s devastation began to emerge, a number of scientists set out to investigate its origins. Piece by piece, year after year, the scientists reconstructed its history. Their research slowly revealed that the virus did not make a single leap from animals, but several.

Continue reading “Two Strains of H.I.V. Cut Vastly Different Paths” →

The turquoise killifish lives in a fleeting world: the ponds that appear only during the rainy season in East Africa.

As a new pond forms, turquoise killifish eggs buried in the mud spring from suspended animation. The eggs hatch, and in just 40 days the fish grow to full size, about 2.5 inches. They feed, mate and lay eggs. By the time the ponds dry up, the fish are all dead.

Even when hobbyists pamper them in aquariums, turquoise killifish survive only a few months, making them among the shortest-lived vertebrates on Earth. So the turquoise killifish may not seem the best animal to study to discover the secrets of a long life.

Continue reading “In Short-Lived Fish, Secrets to Aging” →

In 2010, scientists made a startling discovery about our past: About 50,000 years ago, Neanderthals interbred with the ancestors of living Europeans and Asians.

Now two teams of researchers have come to another intriguing conclusion: Neanderthals interbred with the ancestors of Asians at a second point in history, giving them an extra infusion of Neanderthal DNA.

The findings are further evidence that our genomes contain secrets about our evolution that we might have missed by looking at fossils alone. “We’re learning new, big-picture things from the genetic data, rather than just filling in details,” said Kirk E. Lohmueller, a geneticist at the University of California, Los Angeles, and co-author of one of the new studies.

Continue reading “A New Theory on How Neanderthal DNA Spread in Asia” →

In 2010, a graduate student named Tamar Gefen got to know a remarkable group of older people.

They had volunteered for a study of memory at the Feinberg School of Medicine at Northwestern University. Although they were all over age 80, Ms. Gefen and her colleagues found that they scored as well on memory tests as people in their 50s. Some complained that they remembered too much.

She and her colleagues referred to them as SuperAgers. Many were also friends. “A couple tried to set me up with their grandsons,” Ms. Gefen said.

Continue reading “Studying Oversize Brain Cells for Links to Exceptional Memory” →