Who Peopled the Planet?
Prehistorians really agree that all of us originally came out of Africa. It's the details that cause a paleoanthropological donnybrook.
by Joann C. Gutin
Is Anyone Out There?
Surely, out of the countless spheres in the universe, one harbors something that can say hello.
How Did Life Start?
Earth could have been just another empty chunk of rock. But something happened here, and it may have taken place on a stage of clay.
How Many People Can Earth Hold?
Our urge to go forth and multiply could, a century and a half from now, leave earth with more than 694 billion people--some 125 times our current populations.
How Big Is the Universe?
The short answer: astronomers don't know which is why some of them are abandoning their old step-by-step approach and are trying to take the measure of the cosmos in one fell swoop.
Can We Wipe Out Disease?
There's no doubt that we are smart enough to conquer many diseases. But like it or not, we are also part of the process that produces them.
What is Consciousness?
Defining it is hard enough--giving it to a computer is even harder.
What Drives Climate?
From ice age to hothouse, Earth seems to change its temperature by adjusting its blanket of CO2.
Does Chaos Rule the Cosmos?
Chaos surrounds us, and yet so do orderly patterns. Scientists are now trying to discover how they can coexist.
How Does a Single Cell Become a Whole Body?
It remains one of biology's deepest enigmas. How does an egg, a tiny squishy blob of a cell, grow into a fully formed organism--a sinuous worm, a delicate fly, a perfect human baby?
