For generations, scientists looked to the East African savanna as the birthplace of our species. But recently some researchers have put forward a different history: Homo sapiens evolved across the entire continent over the past several hundred thousand years.

If this Africa-wide theory were true, then early humans must have figured out how to live in many environments beyond grasslands. A study published Wednesday shows that as early as 150,000 years ago, some of them lived deep in a West African rainforest.

Continue reading “Early Humans Thrived in Rainforests” →

The viruses we know best are the ones that make us sick — the influenza viruses that send us to bed and the smallpox viruses that may send us to the grave.

But healthy people are rife with viruses that don’t make us ill. Scientists estimate that tens of trillions of viruses live inside of us, though they’ve identified just a fraction of them. A vast majority are benign, and some may even be beneficial. We don’t know for sure, because most of the so-called human virome remains a mystery.

Continue reading “Trillions of Viruses Live in Your Body. A.I. Is Trying to Find Them.” →

Scientists have long struggled to understand how human language evolved. Words and sentences don’t leave fossils behind for paleontologists to dig up.

A genetic study published on Tuesday offers an important new clue. Researchers found that, between 250,000 and 500,000 years ago, a gene known as NOVA1 underwent a profound evolutionary change in our ancestors. When the scientists put the human version of NOVA1 into mice, the animals made more complex sounds.

Continue reading “The Gene That Made Mice Squeak Strangely” →

Louis Pasteur was at his most comfortable when working in his Paris laboratory. It was there that he had some of his greatest scientific triumphs, including experiments that helped confirm germs can cause disease. “Everything gets complicated away from the laboratory,” he once complained to a friend.

But in 1860, years before he became famous for developing vaccines and heating milk to kill pathogens, Pasteur ventured to the top of a glacier, on a remarkable quest for invisible life.

Continue reading “Louis Pasteur’s Relentless Hunt for Germs Floating in the Air” →

In 1786, a British judge named William Jones noticed striking similarities between certain words in languages, such as Sanskrit and Latin, whose speakers were separated by thousands of miles. The languages must have “sprung from some common source,” he wrote.

Later generations of linguists determined that Sanskrit and Latin belong to a huge family of so-called Indo-European languages. So do English, Hindi and Spanish, along with hundreds of less common languages. Today, about half the world speaks an Indo-European language.

Continue reading “Ancient DNA Points to Origins of Indo-European Language” →