Most girls around the world have periods, but how and why do periods happen? Periods are part of the menstrual cycle, which is an essential part of the female reproductive system.
Our biological sex affects the way we look in some obvious ways, like deciding what body parts we are born with. But, it also has effects on a range of other sexual traits that you might not expect.
In Yellowstone National Park, winters are getting shorter and there is less food for scavengers. That’s bad news for scavengers like bears, but could wolves help?
Estrogen and testosterone are two hormones that cause puberty. But what happens when the body doesn’t produce the amounts of hormones that it usually does?
You might think that people can be born only as either males or females. In fact, lots of people are born with a blend of male and female traits. We call this being “intersex,” and it happens more often than you may think.