Mammoth Mystery

Scientists have long debated one of the greatest mysteries of science. What caused the mass extinction of mammoths around 13,000 years ago? a look at science in the making, National Geographic follows a team of investigators as they assemble one theory for what might have happened to the mammoths, which reigned over the landscapes of North America for more than 1 million years. Could the clues point to the biggest cosmic impact humans have ever witnessed?