Why do horses snort? Sometimes, at the approach of a stranger or the appearance of a plane high above the pasture, a horse will widen its eyes, flare its nostrils and send a stuttering column of air out into the world. On other occasions, horses have been known to snort for no reason besides their own boredom. By suddenly creating a sound, the slack-minded horse elicits an automatic “startle response”  flooding its brain with chemicals, delivering a jolt of excitement and relieving, at least for a moment, the monotony of a long day in an empty field. The horse has in effect fooled its own nervous system  and benefited from the self-deceit.

If horses can alter their own brain chemistries at will (and have good reasons to do so), what about human beings? In “On Deep History and the Brain,” Daniel Lord Smail suggests that human history can be understood as a long, unbroken sequence of snorts and sighs and other self-modifications of our mental states. We want to alter our own moods and feelings, and the rise of man from hunter-gatherer and farmer to office worker and video-game adept is the story of the ever proliferating devices  from coffee and tobacco to religious rites and romance novels  we’ve acquired to do so. Humans, Smail writes, have invented “a dizzying array of practices that stimulate the production and circulation of our own chemical messengers,” and those devices have become more plentiful with time. We make our own history, albeit with neurotransmitters not of our choosing.

Historians by and large take biology and the deep past for granted: natural selection endowed our ancestors with their impressive bodies and brains, and then got out of the way. These days, it’s chiefly nonhistorians like Jared Diamond and Tim Flannery who seek to trace the long arc of the species and write macrohistory in a scientific key. Smail, who teaches medieval history at Harvard, would like his peers to join their company. If historians have become accustomed to studying midwives and peasants, the marginal and often illiterate members of recent societies, why shouldn’t they extend their curiosity to the most peripheral human subjects of all  the prehistoric? Even today, Smail laments, the curriculum is shaped by the prejudice that history began only when our ancestors started to write or to farm or to think of themselves as actors in a grand pageant of historical change. The presumption is curiously convenient. In the schema of “sacred history,” history began with the expulsion of Adam and Eve from the Garden of Eden  that is, in Asia, a few thousand years before Christ. In the modern schema, history begins in much the same place, at much the same time. “The sacred was deftly translated into a secular key,” Smail writes, as “the Garden of Eden became the irrigated fields of Mesopotamia and the creation of man was reconfigured as the rise of civilization.”

Image Credit... Joel Holland

Taking Paleolithic man seriously, Smail argues, requires us to understand that history and biology always shape each other  there is no ascent from the tyranny of brute instinct to the freedoms of civilization. Some evolutionary theorists stress that cultural innovation allows human beings to overcome the blind stumblings of natural selection: we deliberately solve a problem and pass on that solution to our descendants, who improve on it in turn. Smail takes a different tack. The imperfect copying of past behavior and small, often unconscious preferences can push a society in a new direction, even without anyone aiming toward a particular goal. It’s possible, for instance, that early men decided to make sharper spear points with the intent of drawing more blood from their prey; Smail would rather suppose that these spear points were created by accident, and then spread because the hunters who used them proved to be better hunters, even if they didn’t know why. Cultural evolution can be rapid and it can help human beings adapt to their environment, but it needn’t be intended or progressive.