BOSTON — David Reich wore a hooded, white suit, cream-colored clogs, and a blue surgical mask. Only his eyes were visible as he inspected the bone fragments on the counter.

Dr. Reich, a geneticist at Harvard Medical School, pointed out a strawberry-sized chunk: “This is from a 4,000-year-old site in Central Asia — from Uzbekistan, I think.”

He moved down the row. “This is a 2,500-year-old sample from a site in Britain. This is Bronze Age Russian, and these are Arabian samples. These people would have never met each other in time or space.”

Continue reading “David Reich Unearths Human History Etched in Bone” →

Gregor Mendel discovered fundamental rules of genetics by raising pea plants. He realized that hidden factors — we now know them to be genes — were passed down from parents to offspring.

It wasn’t until the early 1900s, long after Mendel’s death, that doctors discovered that humans weren’t so very different. Some diseases, it turns out, are inherited — they’re Mendelian.

Today, scientists have identified over 7,000 Mendelian diseases, and many are discovered with screenings of children and adults. But a new study suggests that many disorders go undetected.

Continue reading “What’s Behind Many Mystery Ailments? Genetic Mutations, Study Finds” →

Thousands of years ago, a special child was born in the Sahara. At the time, this was not a desert; it was a green belt of savannas, woodlands, lakes and rivers. Bands of hunter-gatherers thrived there, catching fish and spearing hippos.

A genetic mutation had altered the child’s hemoglobin, the molecule in red blood cells that ferries oxygen through the body. It was not harmful; there are two copies of every gene, and the child’s other hemoglobin gene was normal. The child survived, had a family and passed down the mutation to future generations.

Continue reading “How One Child’s Sickle Cell Mutation Helped Protect the World From Malaria” →