Everything has a beginning, and NPR's TED Radio Hour takes a look at origins, both the origin of the universe and of humans.
"This is one of those deep human questions that I feel like we as a species should be trying to answer," Spencer Wells, the director of the Genographic Project at the National Geography Society, tells NPR's Guy Raz.
After historian David Christian describes the Big Bang and the expanse of time that followed before even the first single-celled organism appeared, paleontologist Louise Leakey — the granddaughter of Louis and Mary Leakey — takes up the question of when and where people arose. She notes that until the 1940s, paleontologists thought that humans arose in Asia, but then her grandmother Mary found a 1.75 million-year-old hominid skull in Africa, much older than any of the Asian hominid fossils, and placed human origins there.
As Wells then adds, people began to spread out from Africa. He suspects weather may have influence why people suddenly started to leave Africa — there was an ice age going on that not only meant that sheets of ice were covering parts of the planet, but also that it was leeching moisture out of the air, making the Sahara larger and drier than it is now, and there was a large volcanic eruption that blotted out the sun for a time. People, he says, likely went in search of better food and water supplies.
"And humans have remarkably little genetic variation for a species of large ape," Wells adds. "We're highly inbred. And it's because the population size around the time of that volcanic eruption dropped down to maybe as few as 2,000."
But we've more than bounced back. Although people have only been around for some 200,000 years, Louise Leakey notes the human population has ballooned to 6.5 billion. Neanderthals, Raz points out, lived for about 500,000 years before dying out.
"Evolutionarily speaking, we are just a blip. We're sitting on the edge of a precipice," she adds. "We have the tools and the technology at our hands to communicate what needs to be done to hold it together, today. Will we do that, or will we just let nature take its course?"