Other than humans, rhesus macaques are Earth’s most widespread primates, and both species are generalists whose ability to adapt has been responsible for their success. Rhesus macaques are , about twice that of dogs and cats, and nearly as much as chimpanzees. Rhesus macaques have what is called Machiavellian social organization, in which everybody is continually vying for rank and power is everything. Those with rhesus power get the most and best food, the best and safest sleeping places, mating privileges, the nicest environments to live in, and endless grooming by subordinates, whom the dominants can beat and harass whenever they want, while those low in the hierarchies get the scraps and are usually the first to succumb to the vagaries of rhesus life, including predation. It is the . But even the lowliest macaque will become patriotic cannon fodder if his society faces an external threat, as even a macaque knows that a miserable life is better than no life at all. The violence inflicted seems economically optimized; within a society the violence is mostly harassment, but when rival societies first come in contact, the violence is often lethal, as the initially established dominance can last for lifetimes. Within a society, killing a subordinate does not make economic sense, as that subordinate supports the hierarchy. Potentates rely on slaves. The human smile evolved from the teeth-baring display of monkeys that connotes fear or submission.
For this essay’s purposes, the most important ecological understanding is that the Sun provides all of earthly life’s energy, either (all except nuclear-powered electric lights driving photosynthesis in greenhouses, as that energy came from dead stars). Today’s hydrocarbon energy that powers our industrial world comes from captured sunlight. Exciting electrons with photon energy, then stripping off electrons and protons and using their electric potential to power biochemical reactions, is what makes Earth’s ecosystems possible. Too little energy, and reactions will not happen (such as ice ages, enzyme poisoning, the darkness of night, food shortages, and lack of key nutrients that support biological reactions), and too much (such as , ionizing radiation, temperatures too high for enzyme activity), and life is damaged or destroyed. The journey of life on Earth has primarily been about adapting to varying energy conditions and finding levels where life can survive. For the many hypotheses about those ancient events and what really happened, the answers are always primarily in energy terms, such as how it was obtained, how it was preserved, and how it was used. For life scientists, that is always the framework, and they devote themselves to discovering how the energy game was played.