Scat No More—The Temperamental Journey, From Prey to Predator to Domesticator Extraordinaire

The May issue of Natural History, has a short account of the discovery of prehistoric human hair found in a cave in South Africa that may be 250,000 years old. The strands came from the head of someone (Homo sapiens or H. heidelbergensis) who was having the ultimate bad hair day. It was found in the fossilized dung of an equally ancient brown hyena.

The ancient scat is a humbling reminder that for our hundreds of thousands of years our hominin ancestors were mere dinner for the stronger, faster, deadlier animals that surrounded and vastly out numbered them. This evolutionary reality dictated everything about the way their bodies and minds worked. Creatures that are preyed upon are quite sensibly paranoid. Any unfamiliar, sudden noise, sound, smell, or sight is instantly registered as threat and triggers the full fight/flight response. And yet we somehow overcame our overwhelming preyful fear to become the top predator of our world-a shift in behavior that hints at a major change that was going on deep in our brains.

The hair found in that cave covered a human skull that encased a brain that was growing and reorganizing its proportions and priorities. What were these big brains up to? Not language or better tools, not yet anyway. No, the first evidence of major brain change shows up in a shift in human personality, temperament, and behavior. Our ancestors slowly became more curious, more confident, and more cooperative. Mutual trust and generosity fostered better baby care and stronger kinship bonds. The growing sense of camaraderie and bravado created bands of newly minted brothers-a combined force that dared to face old enemies together.

The new understanding of the emergence of a social brain, fueled by ancient brain chemicals that can inhibit the defensive fight/flight reflex while promoting a calmer more receptive response to new people and new ideas, explains how we began our temperamental journey from prey to predator. This neurochemistry that promotes calm and confident social interaction runs through all social mammals which helps to explain why some early humans may have felt the urge to reach out to the most approachable wolves, and why those wolves would have found that touch tolerable. And since touch can trigger this social brain chemistry in both humans and canines, those first innocent close encounters could have ignited a synergistic neurobiological feedback system that folded animals into the expanding idea of family.

From prey to predator to domesticator-these are all transformations that must be neurologically instigated and rewarded. And now our big brains are beginning to understand the brain chemistry that drew us into the ever-tightening spiral that's drawn us from the wariness of watchers, to predators pushing the edge of the flight zone, ushering us ever closer to animals until they became ours-and we became theirs.

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