In the early 1970s, Sarah Blaffer Hrdy, then a graduate student at Harvard, traveled to India to study Hanuman langurs, monkeys that live in troops, each made up of several females and a male.

From time to time, Dr. Hrdy observed a male invade a troop, driving off the patriarch. And sometimes the new male performed a particularly disturbing act of violence. He attacked the troop’s infants.

There had been earlier reports of infanticide by adult male mammals, but scientists mostly dismissed the behavior as an unimportant pathology.

Continue reading “Unraveling Why Some Mammals Kill Off Infants” →

Milk is not just food. The more closely scientists examine it, the more complexity they find.

Along with nutrients like protein and calcium, milk contains immune factors that protect infants from disease. It hosts a menagerie of microbes, too, some of which may colonize the guts of babies and help them digest food. Milk even contains a special sugar that can fertilize that microbial garden.

Now, it turns out, milk also contains messages.

Continue reading “In a Mother’s Milk, Nutrients, and a Message, Too” →

About 50,000 years ago, humans from Africa first set foot in Europe. They hunted woolly mammoths and other big game — sometimes to extinction. Eventually, they began grazing livestock and raising crops.

They chopped down forests and drained swamps, turning villages into towns, then cities and capitals of empires. But even as they altered the Continent, Europeans changed, too.

Their skin and hair grew lighter. They gained genetic traits particular to the regions in which they lived: Northern Europeans, for example, grew taller than Southern Europeans.

Continue reading “From Ancient DNA, a Clearer Picture of Europeans Today” →

Even as American hospitals prepare for new cases of Ebola, they must brace for a more familiar invader. The flu season will arrive soon — although exactly when, scientists cannot say.

Unlike Ebola, the influenza virus is truly airborne. And if recent history is any guide, it will kill thousands in the coming months.

Flu viruses and Ebola viruses take different routes to the same biological goal: to get into new hosts and replicate. Scientists have learned a great deal about the devious ways in which they manage to do it.

Continue reading “As Ebola Spreads, So Have Several Fallacies” →

Scientists have reconstructed the genome of a man who lived 45,000 years ago, by far the oldest genetic record ever obtained from modern humans. The research, published on Wednesday in the journal Nature, provided new clues to the expansion of modern humans from Africa about 60,000 years ago, when they moved into Europe and Asia.

And the genome, extracted from a fossil thighbone found in Siberia, added strong support to a provocative hypothesis: Early humans interbred with Neanderthals.

Continue reading “Man’s Genome From 45,000 Years Ago Is Reconstructed” →