After scientists had a handle on how many chromosomes humans have, other researchers began exploring whether certain ailments might be caused by chromosomal abnormalities. To this end, a French cardiologist discovered that Down syndrome was caused by the presence of an extra chromosome in humans. But a colleague stole credit for her work, and the battle over their legacies continues to this day, in part because the colleague is on track to become a certified Catholic saint.

It seems like a simple question: how many chromosomes do human beings have? But getting an accurate count proved surprisingly hard for much of last century. In fact, virtually every textbook once cited an incorrect number, until in 1956, a fiery Indonesian scientist finally determined the true count—and had to battle his boss over who would receive credit for this legacy-making discovery.

The 1910 return of Halley’s comet was greeted with rapture around the world—at least at first. Due to irresponsible speculation by scientists about the theoretical dangers of a close encounter with a comet, many people grew terrified of Halley’s approach and took drastic measures. They fled their homes, hid out in wells or caves, even committed suicide. It’s a grave reminder of scientific communication gone very wrong.

It’s the 80th anniversary of the Dutch Hongerwinter during World War II, which led to widespread starvation, and an inadvertent breakthrough in treating deadly celiac disease.

After 40 years of studying snakes, Karl Schmidt finally suffered his first bite. And when he did, he kept a gruesome diary to document the suffering and danger—right up to the edge of death...

Parasites can force animals to do nefarious things by manipulating their minds—including, uncomfortably, the minds of human beings.

In refusing to approve the drug thalidomide, FDA scientist Frances Oldham Kelsey spared thousands of babies from deadly birth defects and revolutionized drug research. But was her legacy all good?

Japanese physicist Fusa Miyake has sparked a revolution in archaeology by studying radioactive tree rings—work that also terrifies astronomers, who fear it foretells doom for our civilization.

A woman who drowned in Paris became one of the most famous faces in the world as the model for CPR dummies, saving millions of lives and inspiring artists from Pablo Picasso to Michael Jackson—all while remaining completely unknown.

In the early 1800s, the first Egyptian mummies in Europe served as a crucial test for evolution—a test that, according to people then, evolution flunked.