When did humans first tame fire?

It depends what you mean by "tame". Keeping a fire going is old: perhaps a million years or more. The oldest sure sign of lighting one from scratch is much younger: about 400,000 years. The first human fires were probably embers taken from lightning wildfires. People carried them back to a shelter and kept them alive.

The best early clue is Wonderwerk Cave, South Africa. Its name means "miracle" in Afrikaans. Deep inside, too far for any wildfire to reach, lie charred bones. They date to between about 1 and 1.79 million years ago. A recent study suggests hominins there tended natural fires rather than lighting their own.

Older claims are shaky. At most very early sites, a natural blaze could explain the burning too. That sure sign comes from a Neanderthal site in England. It has burnt soil, heat-cracked tools and lumps of pyrite for striking sparks. After 400,000 years ago, hearths turn up far more often. By about 120,000 years ago, fire was almost everywhere modern humans lived.

Why did fire matter? It gave warmth and light, and kept predators away at night. It also cooked food. The cooking hypothesis says cooked food fed the growth of bigger brains. It's a compelling idea, but still debated. Critics say cooking alone can't explain the brain boom.