The ability to control fire was a dramatic change in the habits of early humans. Making fire to generate heat and light made it possible for people to cook food, simultaneously increasing the variety and availability of nutrients and reducing disease by killing organisms in the food. The heat produced would also help people stay warm in cold weather, enabling them to live in cooler climates. Fire also kept nocturnal predators at bay. Evidence of cooked food is found from , although fire was probably not used in a controlled fashion until 400,000 years ago. There is some evidence that fire may have been used in a controlled fashion about 1 million years ago. Evidence becomes widespread around 50 to 100 thousand years ago, suggesting regular use from this time; interestingly, resistance to air pollution started to evolve in human populations at a similar point in time. The use of fire became progressively more sophisticated, with it being used to create charcoal and to control wildlife from 'tens of thousands' of years ago.