One of the most important aspects of nutrition is the functioning of the brain. The human brain developed and grew as a result of years and years of evolution. Two researchers (Leslie Aiello and Peter Wheeler) coined the term the “Expensive-Tissue Hypothesis.” Over the past 2 million years, the human brain has grown from about 400 grams (austral opithecus robustus) to roughly 1500 grams (homo sapiens sapiens). Now we need to ask ourselves. Why did this happen? Compared to other mammals, humans have a huge brain in relation to body size. When you have a larger brain, it gives you an improved ability to survive and continue finding better food sources. In turn, the higher quality food will give the body more energy to grow the brain even larger. According to the Expensive Tissue Hypothesis, the research has shown that although human brain size has increased, the human gut size has decreased.
Now, we are going to define what exactly a high-quality diet is. To define a high-quality diet, it must support the growth of society and human survival. It must support the growth of the brain. Our ancestors needed to be smart to survive. Scavenging for nuts and berries all day wasn’t going to cut it. As you may already know, plant foods were secondary sources of nutrition when it came to survival. There are several reason why plant foods were considered lower quality to our ancestors. Plant foods are secondary for several reasons, that being:
- Plant foods are deficient in key nutrients
- They are less calorie-dense
- Large quantities are required to sustain survival
- They lack a complete amino acid profile
- More fermentation is required by the gut to breakdown fiber
Going back to the Expensive Tissue Hypothesis, our bodies only have a finite ability to digest fiber due to our shrunken gut size. Remember, our guts were a lot larger millions of years ago. But as we have progressed over time, our brains have grown and our guts have shrunk. In layman’s terms, our ability to eat fiber has gotten significantly worse over time.
Now we’re going to address the question you’ve all been waiting for. What led to the massive increase in brain size for humans? History seems to indicate that it was hunting wild game and eating animal foods. Contrary to plant foods, meat provides the body with all of its essential nutrients. Animal foods are also calorie-dense and have a complete amino acid profile. The amino acid profile is essential to maintaining and building muscle. Protein promotes muscle. Muscle promotes survival. It’s as simple as that. A skeptic might ask “So what evidence was there that people were hunting at the time?” Simple. Stone tools. There are spearheads known as Acheulean tools that date back as far as 2 million years ago. This was precisely around the time human brains were getting significantly bigger. There is also evidence for butchering. Anthropologists have found cut marks on animal bones that date back roughly to the same period.
Why do we assume that plants are good for us? What if we consider the opposite? Plants have evolved to contain defense chemicals which include phytoalexins (soy), oxalates (spinach), gluten (wheat), lectins (beans), and the list goes on and on. This is the chemical warfare that’s been going on between plants and animals for millions of years. Animals use claws to defend themselves and on the contrary, plants use chemicals. Plants don’t want to be eaten so some create fruit that they do want to be consumed. All-in-all, both plants and animals want to live. Neither want to be eaten. Like we’ve discussed before, it’s all about survival.
Now let’s talk about polyphenols. Companies in America rave about the benefits. But let’s look at the facts. There are zero polyphenols made in human biochemistry. In other words, polyphenols are not produced in the human body. It doesn’t necessarily mean they are bad for us. But they are foreign to the human body and by no means essential toward optimal living and survival.
Here’s a cool fact for you. Phytoalexins are plant pesticides. Except not the kind you spray on plants, but the kind plants produce internally. There are 49 natural pesticides found in cabbage. I’m not saying that they’re bad for us. But are pesticides essential for an optimal diet? Probably not.
One of the greatest misconceptions is the notion that plant molecules act directly as antioxidants. And they just don’t. They do not act in human biochemistry directly. They change human biochemistry by acting as prooxidants. The 49 pesticides found in cabbage are not vitamins and do not participate in our biochemistry. This cabbage doesn’t want to be eaten. It has those pesticides for that very reason.
People will usually argue. What about hormesis? Isn’t stress in small increments healthy? Like a cold plunge or a sauna. Yes and no. There are different kinds of hermetic stress: environmental hormesis and molecular hormesis. Environmental hormesis would be spending short periods of time saunas or ice tubs to help the body build a resistance to stress. On the other hand, molecular hormesis come from ingesting molecules from plants in small amounts to produce small amounts of stress. One form of stress is external – environmental. One form is internal through what we ingest – molecular. If molecular hormesis were a thing, wouldn’t drinking alcohol and smoking cigarettes in small amounts be seen as healthy?