Lake Malawi is one of the world’s largest lakes today, but it has dramatically fluctuated in size across the ages. For instance, around 164,000 years ago in southern Africa, people likely used fire to heat stone to render it more malleable for toolmaking. Scientists hypothesize that humans 50,000 years ago used fire in a dense tropical forest near that location to foster the growth of specific plant species. Other studies propose similar activities about 45,000 years ago in New Guinea and 40,000 years ago in Australia. The ancient people appear to have left another impression on the landscape near Lake Malawi.