January 7th, 2015
It’s a truism that you are what you eat. But what-we-eat — once we get done with the growing, gathering and moving of it all — also shapes the world we inhabit. Maintaining our inner state has immense and inescapable effects on the outer states we inhabit, so it’s not a stretch to consider our diet as a kind of dialogue between our physiology and the life of the planet, the two forming and informing each other.
Take, for instance, the genetic history of the AD4H enzymes that most modern humans carry around. These are a group of enzymes which help metabolize ethanol, otherwise known as drinking alcohol. Now, the dose makes the poison, but still, without the ability to metabolize alcohol — that is, break it down into benign substances — it’s nothing but toxin. The AD4H enzymes are the key that turns poison into something more.
Overripe fruit will naturally ferment and it’s likely that this is the start of humankind’s relationship with alcohol. The mutation of the AD4H allowed our foraging ancestors to eat fruit that had, for many other animals, become poisonous — a survival advantage for sure. What’s startling about this mutation is its date: AD4H made its fateful transformation 10 million years ago. That means the homo family has been an alcohol specialist for a lot longer than we’ve been human. Longer, even, than we’ve been walking on two feet.
Ten million years ago, the anthropologists tell us, we were coming down from the trees and learning to live on the ground. It probably wasn’t by choice. Animals don’t give up the survival strategies that have served them thus far, unless there’s really no alternative.
So, there “we” were, minor apes adapted to living in trees, suddenly treeless. This was a moment of species-level peril to be sure. It was dangerous down on the ground and what’s more, our favorite tree-top food, fruit, was now out of reach. Fruit falls, but once fallen, almost anyone can get at it and what’s more, oftentimes the only fruit left was old and rotting. That’s where the AD4H mutation came in handy, enabling our ancestors to eat more rotting fruit and not die in the process. Furthermore, alcohol easily evaporates, and the scent carries. A fermented-fruit specialist had it easier finding dinner with his or her nose.
Our ancestors began by wanting fresh fruit and putting up with the fermenting stuff when they had no choice. But somewhere along the line, fetal-alcohol syndrome be damned, the proto-humans who were better at metabolizing alcohol produced more children and we, as a species, changed from being able to survive fermented fruit to craving it; the oldest surviving recipe is a recipe for beer, a product of the very first agricultural society.
But what’s still mysterious is why we became agricultural in the first place. The archaeological record is unambiguous; when mankind converted to agriculture, we became shorter, sicklier, and endured lives of grinding labor. Life as a hunter-gatherer was better in all ways, with more leisure time and better food. So the question is why?
The obvious hypotheses — overpopulation, habitat destruction — have proven surprisingly difficult to find evidence for. Which means that we might be looking in the wrong place. One alternative explanation for our transformation into farmers is that it was to enable the deliberate production of alcohol. After all, we’ve got Gilgamesh stating outright that intoxication is the thing which transforms the “wild man” into civilized man and the very first agricultural civilization rose from fields of barley.
But there’s another way to look at this, focused less on culture and more on survival. For all its psychoactive effects, alcohol is a toxin with a difference in that it’s also a bouquet of calories and nutrients. What’s more, the reason that S. cerevisiae converts food to alcohol is because very few other microorganisms can tolerate alcohol. In other words, it’s a preservative. Alcohol is impossible to disinter from beneath the cultural strata that have gathered around it it, but if we squint we see the outlines of a remarkable and perhaps epochal survival strategy — a high-energy, nutrient-rich, self-preserving food that would either kill or render hapless any vermin trying to pilfer it. Is it any wonder that most modern humans now carry livers where one out of every ten enzymes is geared to metabolize alcohol? (And doesn’t it make you wonder if maybe Gilgamesh wasn’t being metaphoric by telling us that alcohol transforms wild man into the civilized form?)
So, there you have it, a remarkable, one-of-a-kind mutation which enabled our distant ancestors to survive what might have been a lethal transition. Except it wasn’t one of a kind. A parallel shift happened in Europe about 7,500 years ago, when a single mutation allowed people there to metabolize another kind of toxin — milk.
Dairying had been part of human culture for thousands of years prior to this, but only children were drinking milk. That was because children almost inevitably stopped producing lactase — the enzyme needed to break down the milk sugar lactose — around the age of eight. Without lactase, milk is a kind of anti-food, provoking a dietary dysentery in adult humans.
The reason that dairy cows were kept was to produce yogurts and cheeses, forms of milk where microorganisms had done the work of digesting the undigestible lactose. But the mutation that arose in Europe (and other hotspots in West Africa and around the Arabian Peninsula) changed that. The lactase persistence allele meant that adults could continue to metabolize lactose and the effects were dramatic. Suddenly, here was access to an amazingly rich new food source and researchers estimate that people with the mutation produced 19% more fertile offspring — “among the strongest (effects) seen for any gene in any genome.” The result was that the mutation became dominant in Europe’s genome and even today, most adults who can tolerate milk are of European descent.
Looking backward, it all seems so inevitable, that alcohol became inextricably enmeshed in the entire human project, that milk became a gargantuan element of the Western diet. But these were in no way foreordained. They were accidents that became radical changes of direction that became essential mechanisms of survival.
It’s curious, to say the least, to see the cow-centric farmland of the United States, or the bucolic hillside vineyards of Burgundy and realize that we are looking at landscapes made in response to a coding error, a jumbling of nucleic acids. I find this a hopeful thought, especially when I hear people dissemble “yes, it’d be nice” to any notion of changing our food system into something less destructive/more humane/more equitable/more sustainable. The DNA drama of firewater and its dairy sideshow make it inescapably clear that if you don’t change the system, then the system will just up and change you.