WASHINGTON— Even before the dawn of agriculture, people may have caused the planet to warm up, a new study suggests.
Mammoths used to roam modern-day Russia and North America, but are now extinct, and there's evidence that around 15,000 years ago, early hunters had a hand in wiping them out. A new study, accepted for publication in Geophysical Research Letters, argues that this die-off had the side effect of heating up the planet.