Scientists believe modern humans have lived on the Earth for 200,000 years. We've made our mark – for good and bad – more than any other living thing. In the beginning, people...

Thousands of years ago, few people lived on the planet. The people who were here lived a nomadic life, moving from place to place in search of food. They probably kept just a few things – clothing, tents, tools and weapons. They...

Think about how you feel when your room is a mess. Maybe there are socks and dirty clothes piled on the floor. An old banana peel sits on the dresser and juice from a tipped over juice box drips down the side. How does your room feel? Do you like spending time there? Probably not. You might...