In Tanzania, not far from the Serengeti, live the Hadza, a community of about 1,300 people. For such a small group, they attract a lot of scientific attention.

Many of the Hadza live solely on the animals they kill, along with honey, berries and a few other wild foods. For the first 95 percent of our species’ history, there was no other way to live.

So the Hadza have been closely scrutinized for clues about the hunter-gatherer way of life: how they find their food, how much energy they use — even how much sleep they get.

Continue reading “Gut Bacteria Can Fluctuate With the Seasons” →

There are some questions in biology that you’d think were settled long ago. For instance: How many types of cells are there in the human body?

“If you just Google this, the number everyone uses is 200,” said Jay Shendure, a geneticist at the University of Washington. “But to me that seems absurdly low.” A number of scientists like him want to build a more complete catalog.

Yet there are an estimated 37 trillion cells in the human body. The traditional ways to identify cell types — such as carefully tracing the shape of individual cells under a microscope — are too slow and crude for the job.

Continue reading “A Speedier Way to Catalog Human Cells (All 37 Trillion of Them)” →

The Mesozoic Era, from 252 million years ago to 66 million years ago, is often called the Age of Dinosaurs. To generations of paleontologists, early mammals from the period were just tiny nocturnal insect-eaters, trapped in the shadows of leviathans.

In recent years, scientists have significantly revised the story. Mammals already had evolved into a staggering range of forms, fossil evidence shows, foreshadowing the diversity of mammals today.

In a study published on Wednesday, a team of paleontologists added some particularly fascinating new creatures to the Mesozoic Menagerie. These mammals did not lurk in the shadows of dinosaurs.

Continue reading “When Dinosaurs Ruled the Earth, Mammals Took to the Skies” →