As sperm swim they transform chemical energy into motion, the way a car’s engine uses gas to propel you down the road. Like that engine, the process is complicated—if just one part stops working, the whole system can grind to a halt. This idea might lead to a contraceptive for men that’s reversible.
For years we've been told that teenagers should drink three glasses of milk a day or the equivalent in dairy foods to build up bone reserves that help prevent osteoporosis and bone fractures later in life. But a comprehensive new study throwing this conventional wisdom into serious question.
Calcium supplements—previously thought to help prevent heart disease and stroke—have now been shown to almost double the risk of heart attack. Doctors are now warning that such supplements should be taken with caution, and even then only for vital medical reasons.
About 600 million years ago, life on Earth was pretty much just a homogeneous bunch of simple, soft-bodied species. But in an evolutionary blink of an eye, that all changed. A longstanding geological mystery could explain why our distant ancestors suddenly developed skeletons.
Calcium is everywhere in your body, not just your bones and teeth. In fact, this mineral is crucial to countless biological processes, from regulating your hormones to aiding muscle function. And when you don't have enough of it, the results can be disastrous.
Currently there are two known causes for supernovae. But an exploding star spotted in 2005 defies the understood explanations. The theory of how it ignited could explain something unexpected: Why we have calcium in our bones.