But where chimps might merely poke over the ashes, our lineage at some point took the next step in promoting and even domesticating the flames perhaps picking a smoldering stick from the edges of one grassland, and lighting the grassland in the next valley over. The energetic returns to foraging in this sparse landscape suddenly soared.
Slowly and tentatively at the dawn of the Pleistocene, and then suddenly around 1.9 million years ago, with the rise of the even brainier Homo erectus, and as grasslands reached their peak, we had become the fire ape.
Today the entire industrialized world is held up by the energy released by oxidizing organic carbon back to CO2. Fire, in other words. We just happen to be burning all the plant matter in Earth history that we can get our hands on, buried in the crust. But it's a trick we learned early, and it's essential to our nature. We are what's known as an "obligate pyrophile." We need fire to survive. We are "wholly dependent on fire for survival and reproduction," in the words of a study led by the archeologist Christopher Parker. In fact, as we'll see, it's written in our very anatomy.
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With small guts but big, energy-hogging brains, these creatures were apparently performing much of their metabolism outside of their bodies in order to subsidize their intelligence. This is because there simply aren't enough hours in the day to forage and digest raw foods sufficient to support brains as energetically expensive as our own, contra many a modern paleo-diet guru. Cooking is the only way. This is because brains are ravenous for glucose, an energy-dense sugar synthesized by photosynthesis that we combust with a perpetual metabolic bonfire of oxygen to keep us conscious at every waking moment. But to get at glucose, we first need to cook our plants- wheat, barley, rice, millet, lentils, peas, chickpeas, bitter vetch, cassava, sago, yam, taro, plantains, breadfruit, sweet potato, etc.—in order to explode little packets of starch within them and unravel the long, dense polymers stitched together from glucose. This unlocks the sugar for a much easier metabolism, allowing us to skip the painstaking, energy-intensive step of breaking down these starches in our guts ourselves, and allows us to extract far more energy from these staple foods at lower cost.
— The Story of CO2 is the Story of Everything, by Peter Brannen
utterly delighted by the term ‘obligate pyrophile’ 🥺❤️🔥
