A living organism is a machine that constantly channels energy through itself and converts it into heat. This internal cycle is called internal entropy production (a measure of energy dissipation). But about 2.5 million years ago, our ancestors switched on a second loop — an external one. They picked up a sharpened stone, and then a burning branch.

Archaeologists know: it was then that the hominid brain began to expand rapidly. The authors link this leap not to diet or climate, but to the need to negotiate. Maintaining a fire required coordinated action among several individuals. So grew self-awareness and awareness of others, and with it, the brain. The external entropy generated by a group around a fire proved more powerful than the internal entropy produced by a solitary organism.

A mathematical model shows: the size of a group capable of cooperation initially grew very slowly — characteristic time on the order of 20 million years from some critical point. But this process triggered something irreversible. Within humans, two types of "energy furnaces" coexist — the ancient, cellular one, and the new, collective one. The conflict between them creates psychological tensions familiar to everyone. And global warming, viewed through the lens of this theory, is not just a technical problem but a direct consequence of that very external entropy production that once made us human.

So the ancient fire continues to burn — only now on a global scale.