These articles explore evolution - the changes seen in the inherited traits of a population from one generation to the next. Evolution is one of the great mysteries of biology, since it is a slow process and difficult to study.

Depending on whom and when you ask, everything from same-sex smooching to punk music portends the end of Western civilization. Do any of these cultural commentators have a case?

Imagine a time in Earth's far-flung past when organisms didn't swim through the oceans or populate the lands. Even the mighty dinosaurs hadn't arisen. Will the planet ever return to that lifeless state?

Over the past few years, scientists have noted thousands of species disappearing from the face of the planet. Are we undergoing another mass extinction? What's causing it? Can it be stopped?

"It is as hard to see one's self as to look backwards without turning around," wrote Thoreau -- an odd quote from someone who's known for living alone in the woods. "Know thyself"? As it turns out, it's harder than it sounds.

Variety is the spice of life. Absent the amazing diversity of organisms that calls Earth home, it would be a deadly boring place. How did we get to a point where Komodo dragons, giraffes and butterflies all compete for space on the same planet?

When a basketball superstar makes a 3-pointer, the multimillion-dollar paychecks go into his or her bank account. But why don't his or her parents get the glory? After all, didn't they provide the DNA that allowed for such incredible success?

You stub your toe, and it begins to throb almost immediately. You wince as the pain takes hold for a moment and you can't concentrate on anything else. But is some pain just in your head?

We don't admit to breaking up with someone because of his looks, or that we've read our boss's private e-mails. We answer "fine" when someone asks how we are, even if we're not fine at all. Why is polite society all about the big fib?

Why do we dream? Why do we believe? Why are we curious? During the 60-part documentary series, "The Curiosity Project," Discovery Channel investigates and tries to answer many of life's great questions.

Everyone knows that humans require food, water and shelter, but what about knowledge? It turns out that we have an innate, unquenchable need to seek out new things and new stimuli. Aren’t you curious?

On May 19, 2009, researchers unveiled a fossil called Ida. Within hours, headlines were abuzz with news of the missing link. But a day later, many scientists weren't so sure.

What do we have in common with these guys? A lot. At some point in our shared past, paleoanthropologists think we both sprang from the same forefather. What was that long-gone relative like?

Everything has to start somewhere, including us humans. But where? Was it Africa, or were there multiple ground zeros for humanity's explosive growth and eventual world domination?

A gulf of difference may separate our human world of empires, science and spirituality from the animal wilds of the other great apes. But the genetic differences are pretty meager.

The Galapagos Islands may have played a grand role in Darwin's theory of evolution, but they're notable for more than their finches. What strange species populate these remote islands?

If wisdom teeth are so wise, why do they keep sprouting in the gums of people who don't need them anymore? Should a lack of wisdom teeth give you bragging rights as a highly evolved human?

If you swim like a fish or run like a cheetah, you may understand biomimicry better than you realize. The practice involves imitating models in nature to improve technology and design.

When Australia became separated from the other continents, its species evolved in isolation. And yet, some of the Australian animals evolved in exactly the same way as the other animals in the world. How?

Whether they're big or small, extinctions change the world. And while extinctions themselves are all about change, the study of extinction is all about uncertainty. Anything that lives can become extinct, but how do scientists know when it happens?

One kind of flatworm doesn't have a working mouth, because the algae that lives inside of it makes food for the worm. Symbiosis is crucial to the survival of many species. In fact, you're a symbiote yourself.

Have you ever done something for someone else just because it was a nice thing to do? Do people perform unselfish acts because it feels good or is it just something society wants us to do?

If nature is red in tooth and claw, then "survival of the fittest" sounds like a fight to the death. Natural selection is what drives evolution. Is it true that only the strong survive?

According to DNA research, we may all have a common ancestor, an African woman who lived thousands of years ago. How did scientists reach this conclusion? Is it even possible?

Polar bears evolved to blend in with the terrain so they could hunt better. What causes one group of animals to split off from the rest of the species and develop new genetic traits?

Where did humanity begin, and how did we get to where we are now? Did we really all begin in Africa? What made us leave?