Thread by @krishashok

You can read your entire evolutionary history in what your body does to food. Every gene you carry is a note your ancestors left about what they ate. And what we eat today has left no note yet, because we haven't had time to adapt to it

Start 100 million years ago. Our monkey ancestors ate insects. We still carry chitinase, the enzyme that breaks down insect shells, except ours barely works now. The leftover capability is also why people with shellfish allergies also tend to have dust-mite allergies

60 million years ago, our monkey ancestors started eating fruit. Almost every animal makes its own vitamin C. We don't. A gene called GLO broke in our primate ancestors and never got fixed, because fruit gave us vitamin C for free. That broken gene is why scurvy exists and why we need citrus in our diets

Around the same time, another gene broke - the one that produces Uricase, which clears uric acid. With it gone, fructose from fruit gets stored as fat and pushes uric acid up. Great for a primate fattening up before winter. Less great when you drink 1 liter of fruit juice without pulp

2 million years ago, our ancestors started eating more meat, and specifically cooked meat. This is the big one. Cooking pre-digests large, complex protein, so we could afford smaller guts and spend that energy on a bigger brain. Our brain roughly doubled, we got bipedal endurance, tool-using hands and that scene from 2001: A Space Odyssey

Fish came later. If your ancestors lived on the coast, your body is a bit better at turning the omega-3 in plants into the kind your brain actually uses. People far from the sea had to get iodine from other foods, which is why we now add it to salt, and also why influencer idiots promoting iodine-free Himalayan Pink Salt are a public health menace.

12,000 years ago we started farming, and eating a lot of starch: rice, wheat, millet. Your spit contains an enzyme that starts breaking down starch before you swallow. Some people have 2 copies of the gene for it, some have 13. More copies, easier you digest starch. Indians mostly have a lot

8,000 years ago, milk. Most humans stop digesting it after childhood, like most animals do. But some kept the ability to digest milk into adulthood. This happened on its own in a few different places: North Europe, East Africa, the Middle East...and North India

7,000 years ago, with grains came alcohol (yeast will ferment grains into ethanol). Your body uses a gene called ADH to break it down. Many East Asians have a version that works too fast and makes them go red and feel sick after one drink. It's unpleasant, and that's the point: people who feel sick drink less, so they're less likely to become alcoholics

Notice the pattern. It takes tens of thousands of years, sometimes millions, for the body to write a gene around a food. Insects, fruit, meat, starch, milk.

But our modern day diet with refined sugar, flour & oils, ultraprocessed to be ultrapalatable is about 100 years old. We have zero evolutionary adaptation and are eating food with bodies that have no instructions for it

In general, traditional cuisines tend to encode solutions for geographically specific diet problems, and it's tempting to listen to the "eat like your grandmother" advice. It's mostly good advice but only if your lifestyle, sleep, physical activity & air quality also matched hers