We have programmed into us a system where consuming certain substances changes our neurological settings in one way or another. People take for granted the fact that you can take an anti-depressant to improve your mood, but there’s no reason an organism must be built that way. Why can you swallow a pill and have it change your emotions? If all your digestive system does is take plant parts and animal flesh, and break them down into building blocks for the body and usable energy, then why can you put a small object containing certain chemicals in your stomach, and have it change your mental parameters? Why do mind-altering drugs work? Clearly there’s something more involved going on in your digestive system.
In fact, it’s not only drugs like anti-depressants that have mind-altering properties, but also many foods as well. If you switch from a grain-based diet to a diet containing only meat, fish, and non-starchy vegetables, you’ll find that your neurological settings change. For me personally, one of the most noticeable effects is that my disgust sensitivity plummets to nearly zero.
To explain why this happens, let’s go back to the ancestral environment. It would make sense if there’s a biologically evolved system where, for example, a man who eats a lot of meat from big game animals becomes strong, steady, and fearless, simply because becoming that way makes him more likely to be able to tap into that food source in the future as well. The more the man kills and consumes large, dangerous animals, the more his body can assume that it makes sense to invest in building the physiological, neurological, and ultimately personality-related settings useful for getting more of that type of food.
And it seems like this is exactly how it works. It’s no coincidence that eating a lot of red meat is traditionally perceived as fitting for a masculine man, while eating a vegan diet is traditionally perceived as being at odds with masculinity. To develop a masculine disposition, tradition tells you to eat red meat. And to be an ancestral hunter, a masculine disposition is required. It’s no mistake that a particular food is traditionally understood to pair well with the exact type of personality that would be required to obtain that food in the ancestral world. Red meat is masculine because in the Paleolithic era only the masculine were adept at getting red meat.
Humans are able to survive in a wide variety of climates and eat a wide variety of foods. We can catch fish in icy lakes to survive the winter, or hunt big game animals in the scorching heat of summer. Putting aside what’s optimal for health, we can live on a strict vegan diet, an exclusively carnivorous diet, or anywhere in between. While koalas, for example, live always in the same environment and consume nothing but a single special type of leaf, humans are able to thrive on whale blubber in the Arctic no less than on fruit in the tropics. As a result, the human body and mind must be flexible. What we eat, and what elements we’re exposed to, change our physical and mental parameters; and this system functions as a way to adapt us to our environment.
If a man eats a lot of large, dangerous animals, his body incorporates the hormones as if they’re his own. He builds muscle. His risk tolerance increases. As I mentioned above, he becomes strong, steady, and fearless. On the other hand, if he consumes only plants, he doesn’t get these effects. Instead, his body avoids burdening his agility with superfluous muscle. He develops a healthy concern for hazardous choices. He becomes fast, stealthy, and careful. In other words, the more he hunts, the more he builds a body and mind adapted to that life; and the more he sticks only to foraging for plants, the more adapted he becomes to that life. A predator must be daring in the face of danger and ready to go to battle, while an herbivorous human must retreat at the first sign of danger. Popular culture knows that vegans are generally gentle, sensitive, and risk aversive. Tradition knows that veganism isn’t a good path toward a masculine disposition. This is exactly what we’d expect, given this evolutionary analysis. Eating a vegan diet transforms you into the sort of human would would do well within a tribe specializing in gathering plants. Veganism isn’t as much of a health choice as it is a personality type. Vegan culture is compatible with how a vegan diet affects the human body and mind.
Now, in the Paleolithic era humanity had comparatively little influence on the environment. It was mostly a matter of humans molding themselves to their surroundings, rather than humans actually acting to change their surroundings. Hunter-gatherers constructed shelter, crafted tools, and so on, certainly, but they hunted the animals that happened to live in their region and gathered the plants which Mother Nature put in their area. Before the agricultural revolution, the environment was largely just a given, and humans had to adapt themselves to it. Different climates pose different challenges, both because the elements are different and also because the types of animals and plants are different. It takes a different type of human to hunt polar bears in the Arctic than to gather fruit in the tropics. Built into us is a system where climate and diet affect our settings; this works to mold the hunter-gather to his environment, no matter how how far his nomadic tribe migrates north or south, or how much things change from one generation to another.
But once the Neolithic era came around, humanity gained much more power to change the environment. What we ate stopped being simply what happened to be available. Our diet was no longer restricted to plants and animals that were created largely by forces which were outside of our control. Selective breeding of plants and animals completely transformed the food supply. Picture a wolf and then picture a Chihuahua. That’s how different any given food could become over the course of many years of artificial selection.
With biological evolution having put into place a system where different diets have different effects on our psychology, and now with cultural evolution having the power to change the food supply, you might be able to see where this would lead. If cultural evolution can have profound influence on the food supply, and diet has significant effects on how the human body and mind work, then cultural evolution is able to start using artificial selection to change the food supply in a direction that molds humans not only to the natural environment as created by Mother Nature, but also to the societal conditions as produced by Civilization. While it was nothing new that diet affected psychology, the agricultural revolution allowed cultural evolution to gain control of this switchboard and start changing humans in accordance with group-level interests.
Basically, groups which chanced upon agricultural practices which led to a food supply that better molded their psychology to the requirements of civilized life were more likely to proliferate. Eventually, societies where the diet-related traditions supported the mental parameters needed to adapt people to the division of labor within industrial conditions had a decisive advantage in war.