Clearly, the controlled use of fire to cook food was an extremely important element in the biological and social evolution of early humans, whether it started 400,000 or 2 million years ago.
The lack of physical evidence suggests early humans did little to modify the control and use of fire for cooking for hundreds of thousands of years, which is quite surprising, given that they developed fairly elaborate tools for hunting during this time, as well as creating some of the first examples of cave art about 64,000 years ago.