The One Basic Fact About History That Time Travelers Always Forget

One of the staples of time travel stories is the idea that our heroes will visit earlier geological periods in Earth's history. Of course — because they'll want to see dinosaurs with ostrich feathers and giant millipedes. But they generally forget something very important about Earth's past. » 10/31/14 11:30am Yesterday 11:30am

Want to Stay Healthy? You'll Need to Become a Human-Animal Hybrid.

Biologists have been mixing the DNA of different animals since the 1970s, but the idea of injecting the genes of animals into humans remains taboo. Called transgenics, it's a practice that could cure illness in the future — and eventually reshape our species. Here's what you need to know about it. » 10/15/14 11:25am 10/15/14 11:25am

Why Do Your Pupils Get Larger When You're On Drugs?

Normally, our pupils dilate in response to changing light; as it gets darker, our pupils get larger. But they expand in size for other reasons as well, including when we're sexually aroused and when we're performing complex cognitive tasks. But it's also known that certain medications — including illicit drugs — can… » 9/29/14 11:20am 9/29/14 11:20am

You Are Alive Today Thanks to the Symbionts in Your Body

Mitochondria float around in the goo of your cells, tirelessly making the molecules that power your body. But these mitochondria used to be independent of your body; they were bacteria, floating free in the world. You are, at a fundamental level, the result of symbiosis — the interdependence of two life forms. » 9/23/14 11:27am 9/23/14 11:27am

Though It Seems Crazy Now, the Neutron Bomb Was Intended to Be Humane

Until the day he died, physicist Samuel Cohen declared that his invention, the neutron bomb, was a "moral" and "sane" weapon that would kill enemy combatants, while sparing civilians and cities. But, despite the support of fans like Ronald Reagan, this weapon of not-as-much mass destruction proved to be a hard sell. » 9/19/14 11:00am 9/19/14 11:00am