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From beyondveg.com:

When was fire first
controlled by human beings?

So the next question is obvious: How long have fire and cooking been around, then, and how do we know whether that length of time has been long enough for us to have adapted sufficiently?

Let's take the question one part at a time. The short answer to the first part of the question is that fire was first controlled by humans anywhere from about 230,000 years ago to 1.4 or 1.5 million years ago, depending on which evidence you accept as definitive.

Evidence for very early control of fire is sparse and ambiguous. The earliest evidence for control of fire by humans, in the form of fires at Swartkrans, South Africa and at Chesowanja, in Kenya, suggests that it may possibly have been in use there as early as about 1.4 or 1.5 million years ago.[100] However, the interpretation of the physical evidence at these early sites has been under question in the archaeological community for some years now, with critics saying these fires could have been wildfires instead of human-made fires. They suggest the evidence for human control of fire might be a misreading of other factors, such as magnesium-staining of soils, which can mimic the results of fire if not specifically accounted for. For indisputable evidence of fire intentionally set and controlled by humans, the presence of a hearth or circle of scorched stones is often demanded as conclusive proof,[101] and at these early sites, the evidence tying the fires to human control is based on other factors.

Earliest dates for control of fire accepted by skeptical critics. At the other end of the timescale, these same critics who are only willing to consider the most unequivocal evidence will still admit that at least by 230,000 years ago[102] there is enough good evidence at at least one site to establish fire was under control at this time by humans. At this site, called Terra Amata, an ancient beach location on the French Riviera, stone hearths are found at the center of what may have been huts; and more recent sources may put the site's age at possibly 300,000 years old rather than 230,000.[103]
Somewhat further back--from around 300,000 to 500,000 years ago--more evidence has been accumulating recently at sites in Spain and France[104] that looks as if it may force the ultraconservative paleontologists to concede their 230,000-year-ago date is too stingy, but we'll see.

And then there is Zhoukoudian cave in China, one of the most famous sites connected with Homo erectus, where claims that fire may have been used as early as 500,000 to 1.5 million years ago have now largely been discredited due to the complex and overlapping nature of the evidence left by not just humans, but hyenas and owls who also inhabited the cave. (Owl droppings could conceivably have caught fire and caused many of the fires.) Even after discounting the most extreme claims, however, it does seem likely that at least by 230,000 to 460,000 years ago humans were using fire in the cave[105], and given scorching patterns around the teeth and skulls of some animal remains, it does appear the hominids may have done this to cook the brains (not an uncommon practice among hunting-gathering peoples today).[106]

The most recent excavation with evidence for early use of fire has been within just the last couple of years in France at the Menez-Dregan site, where a hearth and evidence of fire has been preliminarily dated to approximately 380,000 to 465,000 years. If early interpretations of the evidence withstand criticism and further analysis, the fact that a hearth composed of stone blocks inside a small cave was found with burnt rhinoceros bones close by has provoked speculation that the rhino may have been cooked at the site.[107]

Crux of the question: first control of fire vs. earliest widespread use. Now of course, the crucial question for us isn't just when the earliest control of fire was; it's at what date fire was being used consistently--and more specifically for cooking, so that more-constant genetic selection pressures would have been brought to bear. Given the evidence available at this time, most of it would probably indicate that 125,000 years ago is the earliest reasonable estimate for widespread control.*[108] Another good reason it may be safer to base adaptation to fire and cooking on the figure of 125,000 years ago is that more and more evidence is indicating modern humans today are descended from a group of ancestors who were living in Africa 100,000-200,000 years ago, who then spread out across the globe to replace other human groups.[109] If true, this would probably mean the fire sites in Europe and China are those of separate human groups who did not leave descendants that survived to the present. Given that the African fire sites in Kenya and South Africa from about 1.5 million years ago are under dispute, then, widespread usage at 125,000 years ago seems the safest figure for our use here.
Sequence of stages in control: fire for warmth vs. fire for cooking. One thing we can say about the widespread use of fire probable by 125,000 years ago, however, is that it would almost certainly have included the use of fire for cooking.* Why can this be assumed? It has to do with the sequence for the progressive stages of control over fire that would have had to have taken place prior to fire usage becoming commonplace. And the most interesting of these is that fire for cooking would almost inevitably have been one of the first uses it was put to by humans, rather than some later-stage use.*

The first fires on earth occurred approximately 350 million years ago--the geological evidence for fire in remains of forest vegetation being as old as the forests themselves.[110] It is usual to focus only on fire's immediately destructive effects to plants and wildlife, but there are also benefits. In response to occasional periodic wildfires, for example, certain plants and trees have evolved known as "pyrophytes," for whose existence periodic wildfires are essential. Fire revitalizes them by destroying their parasites and competitors, and such plants include grasses eaten by herbivores as well as trees that provide shelter and food for animals.[111]

Opportunistic exploitation of animal kills by predators after wildfires. Fires also provide other unintended benefits to animals as well. Even at the time a wildfire is still burning, birds of prey (such as falcons and kites)--the first types of predators to appear at fires--are attracted to the flames to hunt fleeing animals and insects. Later, land-animal predators appear when the ashes are smoldering and dying out to pick out the burnt victims for consumption. Others, such as deer and bovine animals appear after that to lick the ashes for their salt content. Notable as well is that most mammals appear to enjoy the heat radiated at night at sites of recently burned-out fires.[112]

It would have been inconceivable, therefore, that human beings, being similarly observant and opportunistic creatures, would not also have partaken of the dietary windfall provided by wildfires they came across. And thus, even before humans had learned to control fire purposefully--and without here getting into the later stages of control over fire--their early passive exposures to it would have already introduced them, like the other animals, to the role fire could play in obtaining edible food and providing warmth.