How do humans evolve?

What answers can we find in a skull?
What answers can we find in a skull?

Despite the long lines outside of technology stores anytime a new gadget is released, there was a time not so long ago when people in the United States actually went about their days minus cell phones, personal computers, electronic readers and televisions. Glance back even further in our history, and you'll see yourself in a horse-drawn buggy instead of an automobile. These are just examples of recent human advances;we've been evolving for millions of years. First, our early ancestors led the way in human evolution. Then, a couple hundred thousand years ago, the first true "us," also known as Homo sapiens, took over the reins.

Take a minute to think about all we've gained in recent years that we think we can't live without, and then rewind our history. How much do you love animals? If you can't get enough of our animal friends, then be thankful you didn't live longer than 10,500 years ago, before humans started domesticating them. Or, as fun as camping may be, would you want to live outside permanently? Give a cheer to our ancestors 400,000 years ago; they were the ones who first started making shelters [source: Smithsonian Museum of Natural History].

Thinking about this long history, you might wonder how humans got to here from there -- and where we're headed.

First, let's back up to get a general idea of how evolution works. At its simplest definition, evolution is gradual change from one generation to the next. Just as your parents passed along their genes to you -- maybe giving you an affinity for math or natural inclination to sports -- early humans passed their genetic makeup on to their children.

Selection of these genes appears to occur in two ways: natural selection and genetic drift. In natural selection, members of a species that adapt to their environment have a better chance of surviving and reproducing [source: Futuyma]. For example, an early human who was a great hunter would have a better chance of eating over someone who came home empty-handed. This ability would ensure his or her survival. By surviving, this top-notch hunter would have an improved chance of having children and passing on certain attributes, such as strength or endurance, to the next generation. On the other hand, in genetic drift, completely random genetic variations are passed along without real significance to chance of survival [source: Futuyma].

Now that you have a little background, let's take a look at our early history. Click on over to the next page to learn about our ancestors, when we spread our wings and started traveling the globe, and how we've evolved.