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” →

With fossils and DNA, scientists are piecing together a picture of humanity’s beginnings, an origin story with more twists than anything you would find at the movie theater.

The expert consensus now is that Homo sapiens evolved at least 300,000 years ago in Africa. Only much later — roughly 70,000 years ago — did a small group of Africans establish themselves on other continents, giving rise to other populations of people today.

To Johannes Krause, the director of the Max Planck Institute for Human History in Germany, that gap seems peculiar.

Continue reading “In Neanderthal DNA, Signs of a Mysterious Human Migration” →

Mark D. Zabel wants to set some fires.

Dr. Zabel and his colleagues are developing plans to burn plots of National Park Service land in Arkansas and Colorado. If the experiments turn out as the researchers hope, they will spare some elk and deer a gruesome death.

Across a growing swath of North America, these animals are dying from a mysterious disorder called chronic wasting disease. It’s caused not by a virus or bacterium, but a deformed protein called a prion.

Continue reading “Fire May Be the Only Remedy for a Plague Killing Deer and Elk” →

A common genetic mutation is linked to an increase in life span of about 10 years among men, researchers reported on Friday.

The mutation, described in the journal Science Advances, did not seem to have any effect on women. Still, it joins a short list of gene variants shown to influence human longevity.

By studying these genes, scientists may be able to design drugs to mimic their effects and slow aging. But the search for them has been slow and hard.

Continue reading “Scientists Discover a Key to a Longer Life in Male DNA” →