A combination of climate change and hunting by humans may be a possible explanation for their extinction. "Homo erectus" is known to have consumed mammoth meat as early as 1.8 million years ago, though this may mean only successful scavenging, rather than actual hunting. Later humans show greater evidence for hunting mammoths; mammoth bones at a 50,000-year-old site in South Britain suggest that Neanderthals butchered the animals, while various sites in Eastern Europe dating from 15,000 to 44,000 years old suggest humans (probably "Homo sapiens") built dwellings using mammoth bones (the age of some of the earlier structures suggests that Neanderthals began the practice). However, the American Institute of Biological Sciences notes that bones of dead elephants, left on the ground and subsequently trampled by other elephants, tend to bear marks resembling butchery marks, which have allegedly been misinterpreted as such by archaeologists.