Why Are Humans The Only Animals That Cook Their Food? An Evolutionary Biologist Explains

Cooking is so embedded in our daily lives that it’s very easy to overlook just how strange it is. As ordinary as it might seem, from an evolutionary perspective, a human standing over a flame and deliberately transforming food with heat is exhibiting an unprecedented behavior.

Throughout the animal kingdom, we’ve uncovered countless species that have evolved dazzlingly complex ways of finding, processing and consuming their food. Some crack nuts with stones; others ferment, cache or chemically defend their meals. But only our lineage crossed a very particular threshold: we learned how to cook.

Given how many of us take warm, cooked food for granted, this distinction might not seem meaningful when taken at face value. But it is. As an ever-growing body of evolutionary research increasingly suggests, cooking changed so much more than just our diets. It fundamentally changed who we are as a species.

Are Humans Really The Only Animals That Cook?

Cooking, at least in the strict biological sense, requires a precise combination of three specific abilities:

• The controlled use of an external heat source, usually fire
• The intentional application of said heat to food
• An understanding, whether implicit or learned, that this process transforms the food itself

There are plenty of animals that come close to certain parts of this sequence. Chimpanzees, for instance, are known for using tools to crack open nuts. Japanese macaques have been observed to wash sweet potatoes before eating them. Some birds even eat rocks (and keep them in their stomachs) to break down their food without the need for teeth.

These behaviors are, without a doubt, clever; they’re sometimes even culturally transmitted. But each one of them stops short of cooking because they lack one essential ingredient: control of fire. There isn’t a non-human animal on the planet that is known to produce or manage fire reliably, nor are there any that systematically apply heat to alter their food before consuming it.

That said, some animals are still known to enjoy cooked food — only, we cook it for them. A 2008 study published in the Journal of Human Evolution tested whether great apes, our closest living relatives, show any latent inclination toward cooked food. Across several captive populations, the researchers found that apes tended to prefer cooked food over raw, though not universally and not without exceptions.

This preference matters, as it suggests that the appeal of cooked food (i.e., softer texture, enhanced flavor, easier chewing) didn’t arise after we began cooking our food. Instead, it likely existed beforehand.

Cooking may have “exapted” a pre-existing bias toward high-quality, easily processed foods (like ripe fruits or tender meat), which would have proven advantageous in terms of energy gain and efficiency before we even discovered fire. In other words, early hominins may not have needed to be convinced that cooking was beneficial; they may have already felt it.

But perhaps more provocatively, this notion also challenges the long-standing assumption that the control of fire significantly preceded cooking. However, if our ancestors already preferred cooked food, then the motivation to cook — and to control fire for that explicit purpose — may have emerged in tandem.

Even so, the preference for cooked food alone isn’t enough, as there are many animals that might benefit from cooked food. We are the only species that ever crossed the threshold into actually producing it.

How Heat Reshaped The Human Body

Most people are already aware that cooking is a uniquely human behavior, which is why many might still wonder why it matters. To illustrate this importance, evolutionary biologists often turn to what’s known as the cooking hypothesis, most prominently developed by Richard Wrangham and supported by experimental and genetic research.

At its core, the hypothesis argues that cooking was not a cultural afterthought. He argues instead that it was a significant biological turning point in which our anatomy, metabolism and cognition were fundamentally reshaped.

A key piece of evidence comes from a 2016 study in Genome Biology and Evolution. Through controlled feeding experiments, researchers demonstrated that cooking alters the manner in which our bodies process it at a molecular level. This aligns with earlier physiological work, including a 2003 study in Comparative Biochemistry and Physiology Part A, which outlines several mechanisms through which cooking may have transformed the human lineage.

First, cooking increases the energetic and caloric availability of food. Heat denatures proteins, gelatinizes starches and breaks down plant cell walls. In turn, food is rendered much easier to digest and metabolize. Calories that would otherwise pass through the body unused become accessible.

Second, cooking appears to have reshaped the human body. Compared to other primates, humans have much smaller teeth, reduced jaw musculature and shorter digestive tracts, particularly a diminished large intestine. These are features that are consistent with a diet requiring less mechanical breakdown and microbial fermentation. This means, in simple terms, that cooking has essentially externalized parts of the digestive process.

Third, cooking may have enabled brain expansion. The human brain is, metabolically speaking, a very expensive organ; it consumes a disproportionate share of the body’s energy in relation to its size.

As such, by increasing our caloric yield and reducing our digestive costs, cooking would have freed up the energy necessary for supporting a larger, more complex brain. Importantly, this idea also aligns well with what we’ve seen from archaeological timelines, in which increased brain size roughly coincides with our ancestors’ use of fire.

Finally, and perhaps most strikingly, there’s also genetic evidence of an adaptation to cooking. The 2016 Genome Biology and Evolution study discovered that some of our genes associated with metabolism respond differently to cooked versus raw diets, and that some of these genes show signs of positive selection in humans.

This suggests that our bodies are, to some extent, designed for eating cooked food, as opposed to merely being tolerant of it. Together, these lines of evidence tell us that, beyond being the only animals that cook, we’re also a species that has been biologically shaped by cooking.

Why Didn’t Other Animals Besides Humans Evolve Cooking?

Many might still wonder: If cooking is so advantageous, then why don’t any other animals do it? The simplest answer is also the most constraining: cooking requires fire, and fire is difficult to control.

More specifically, fire demands ignition, fuel management and sustained attention — each of which are abilities that, while aren’t totally inconceivable in other species, just haven’t evolved elsewhere.

However, the more robust answer to the question lies in a convergence of traits that appears to be uniquely human. Cooking depends on three very specific cognitive traits, namely:

• Planning (waiting for food to transform or be “ready” for consumption)
• Causal reasoning (demonstrating an understanding that heat is what beneficially changes the properties of food)
• Social learning (passing techniques across generations)

While there are, indeed, many animals that display fragments of these abilities, we are the only species that has successfully combined them in flexible and cumulative ways.

There’s also an element of evolutionary path dependence. That is, once our ancestors began cooking for the first time, even sporadically, the benefits would have set off a feedback loop. Cooked food provides more energy. More energy supports larger brains. Larger brains improve tool use and fire control. Better fire control enables more consistent cooking.

Other animals lacked the initial foothold — control over fire — which meant that they never entered the loop.

Finally, there is the question of necessity. The vast majority of animals are already perfectly adapted to raw diets: their teeth, guts and metabolic systems are tuned to extract energy from uncooked food. So, while cooking might be advantageous for them, it is in no way essential to their survival.

Humans, on the other hand, seem to have moved in the opposite direction. As our bodies adapted to softer, higher-quality diets, we became increasingly reliant on cooking in turn. In a sense, the innovation of cooking may have actually become a constraint.

In the eons since its conception, cooking has become an inseparable part of humanity and culture. It’s a behavior that has blurred the line between biology and technology, and in doing so, has substantively reshaped both — arguably for the better. We are the only animals that cook. But more than that, we may be the only animals that need to.

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