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.
as written by the authors arXiv:2606.19066
Ancient human beings started "external entropy production" in a late stage of evolution, in addition to the internal entropy production by which energy was dissipated within the body of life, as previously described consistently with the birth of life by maximum entropy production principle. In this paper, the mechanism for development of external entropy production, which is strongly related with use of tools and controlling fire, is theoretically investigated. Archaeological data show that the brain size of ancient human beings started rapid increase around 2.5 million years ago when the usage of tools and control of fire started. It may be natural to assume that the rapid growth of brain size is related to the growth of awareness which helped cooperation with the other human beings for control of fire. Coupled equations for the growth rate of brain including awareness and for growth rate of size of the interacting human beings are analyzed. The external entropy production per one human being which is directly related to the group size of cooperating human beings is estimated to increase as about 20 million years in the beginning from the critical time. This evolution created coexistence of internal entropy production of traditional multi-cellular life and new external entropy production of multi-body life. A psychological problem due to the coexistence of two kinds of entropy production mechanism in human being and concept of technologies based on the present thermodynamic evolution theory are discussed. It is suggested that the evolutionary understanding of the origin of global warming based on the external entropy production may be important to create an useful countermeasure.
Over 2.5 million years, the human brain tripled in size — from 400–500 cm³ in australopithecines to 1300–1400 cm³ in modern humans, and the main surge coincided with the appearance of the first hearths.
In José Saramago's novel "The Cave," a pottery kiln becomes the center of a new world — a metaphor for external entropy that reshapes not only clay but society.