Comment 8 by katy Cordeth

Isn't it quite probable that the first cooked food that early man ate on a regular basis would have been prepared by immersing raw meat into hot springs - boiling it rather than broiling it?

It is possible to use hots springs, but there are serious limitations.
1. They are often heavily contaminated with chemical minerals.
2. A flowing spring washes away the nutrients.
3. A small fixed pool cannot be cleaned after earlier meals.
4. Hot water is difficult to transport without modern containers, and cools rapidly.

Naturally occurring volcanic springs would have provided a much more reliable and permanent source of heat and wouldn't have required him to sit around twiddling his opposable thumbs waiting for a forest fire or a lightning strike to occur.

Where there are hot springs, there are usually volcanic sources of fire, which will start natural fires, and from which burning material can be moved to a safe distance.

On the link I give @7 they actually run a barbecue directly from the volcanic heat, without combustible material being used at all.