Nearly 25 years after scientists completed a draft human genome sequence, many of its 3.1 billion letters remain a puzzle. The 98% of the genome that is not made of protein-coding genes — but which ...

In the 1990s, Lee Sweeney, a physiologist at the University of Pennsylvania, demonstrated that inserting the gene encoding insulin-like growth factor 1 (IGF-1) into the muscle cells of mice increased ...

Studying the process of brain formation illuminates just how much of development is a series of tiny miracles. Only a few weeks after a human egg is fertilized, a sheet of cells called the neural ...