The Ecology of Humans – Diet


The belly rules the mind. ~ Spanish proverb

It is astonishing that nutrition can be a controversial subject. It remains so because of widespread ignorance.

Simply, the best diet consists entirely of organic vegan produce: a variety of fruits and vegetables, with a smattering of seeds (nuts, grains, and legumes).

A healthy diet is high in carbohydrates, with a modest amount of protein, and the fat found in otherwise nutritious fruit, such as nuts and avocado.

Eating the right kinds of difficult-to-digest food – dietary fiber – is essential to health. This seems something of a paradox. It is instead sharing the wealth.

The gut flora that digest what we eat need sustenance. If microbes in the stomach cannot consume all that comes to them, those in the lower tract have something to chew on. Otherwise these lower denizens starve, and the digestive system suffers.

For healthy digestive microbial communities throughout the digestive tract, dietary fiber, such as resistant starch, must be eaten. Resistant starch comprises carbohydrates that pass through to the large intestines undigested. Many natural foods contain resistant starch.

From a health standpoint, the term vegetarian is an oxymoronic combination: vegan (fruits, vegetables, and seeds) and dairy. Dairy clogs the system with its excessive protein and unseemly fat. It gives an otherwise healthy diet a bad name. Veganism is the healthy choice. Vegetarianism is not.

Meat, especially mammal flesh, presents serious digestive difficulty. Its regular consumption accelerates aging.

Nominally healthy seafood has been seriously polluted by worldwide industrialization. Fatty fish, such as tuna, have become more toxic than nutritious.

What most people eat – processed foods – barely sustains the body. What tickles the taste buds for so many, while doing the most damage, is sugar and its artificial substitutes.

The Descent of Diet

Tell me what you eat, I’ll tell you who you are. ~ French politician Anthelme Brillat-Savarin

All primates are primarily frugivores: fruit eaters. A few species are also folivorous: leaf eaters. The human digestive tract is adapted to fruit and vegetable consumption, as are teeth and jaw muscles.

Humans evolved by their diet. The trend in early hominid species was toward larger teeth and thicker enamel, but that later reversed.

Homo habilis had teeth somewhat like australopiths: a bit smaller but lacking the heavy wear from the diet of tough, coarse foods that sustained australopiths. H. habilis was eating better: fruit, vegetables (including tubers), and nuts; very little, if any, meat.

H. erectus, a tool-making hunter and gatherer, had even smaller teeth; partly a product of cooking food, and so tenderizing it somewhat. Gathering brought fruit, nuts, and vegetables, which varied seasonally and by locale. Meat became a larger part of the diet with more successful hunting.

The hunting that brought down red meat, though perhaps satisfying, was never the best nutrition. Humans, while omnivorous, thrive on a variety of the ready energy sources found in plant-based carbohydrates. For optimal nutrition, meat has always had, at most, a limited place on the hominin menu.

The menus of little early humans were partly supplied from shifting shorelines. The earliest settlements were near bodies of water. Ancient lakes, rivers, and the oceans yielded a rich supply of nutrients more readily than a diet reliant upon cultivation of crops. Aquatic foods offered a varied, nutritious diet. This included grasses, papyrus shoots, algae, seaweed, fish, snails, mollusks, and shrimp.

Shellfish, loaded with omega-3 fatty acids crucial for healthy brains, may have fueled smarter Homo. Human mental powers were enhanced at the water’s edge.

The agricultural revolution that started some 6,000 years ago resulted in some tooth reduction, spurred by the frequent practice of cooking, which turned tough food soft and more easily chewed. Besides the ease of intake, cooking vegetables releases nutrients otherwise locked in cellulose.

Cooking also renders as ready fuel tubers that are otherwise difficult to chew and digest (unless mashed using stone tools: a hominid practice for millions of years). Some foods, such as sorghum, cassava, manioc, and linseed, become edible only by cooking, as they contain cyanogenic glycosides.

Cereal grains retain abrasive particles even when cooked, so tooth wear increased with the onset of agriculture. That has been reversed in recent times, to deleterious effect, by common consumption of highly processed foods.

Cooking promoted brain development in hominins by improving nutrient intake, as fruit is seasonal and varies widely by locale. Improved nutrition also allowed gastrointestinal organs to shrink – effectively trading brains for guts.


Since the invention of farming, we have been breeding varieties with progressively fewer beneficial phytochemicals, partly because many taste bitter or astringent. ~ American nutritionist Jo Robinson

Phytochemicals are nutrients found in plants. 25,000 phytonutrients have been identified.

Phytonutrients are critical for development and cell health in every bodily system. Some phytochemicals even inhibit and retard the progress of cancer.

Several phytochemicals promote longevity through cellular detoxification. These are often a molecular compound containing sulfur, which gives vegetables, such as garlic and onions, their characteristic odor. In keeping the body healthy, the immune system is a significant sulfur consumer.

Antioxidants are an exemplary phytonutrient that acts as potent agent for good health.


When we consume plants, we also consume the antioxidants in those plants. And they serve us just as faithfully and effectively as they serve the plants, protecting us from free radicals and slowing down the aging process in our cells. ~ American biochemist Colin Campbell

An antioxidant is a molecule that inhibits the oxidation of other molecules. There are a multitude of antioxidants. Many are abundant in leafy green vegetables. All are beneficial.

Oxidative stress damages cells, so a diet of fruits and vegetables that offers antioxidant activity is well advised. In contrast, eating meat creates oxidative stress.

A good thing can be taken too far. Taking antioxidant supplements may exacerbate cancer, even as cancer cells generate higher levels of oxidative stress (ROS) to help feed their abnormal growth.

It has been proposed that reactive oxygen species (ROS) cause mutations, and thus cancer, and that antioxidants counter this effect, but studies suggest that antioxidants do not prevent cancer and may accelerate it. These findings may be due to the cellular location of ROS targeted by antioxidants. ~ Indian American biochemist Navdeep Chandel & American oncologist David Tuveson

This is an example of a cautionary note that high-dose supplements generally ought not be taken without consideration of health condition. There is no substitute for a healthy diet of varied fruits and vegetables.

We are left with a delicate balancing act. Both too many and too few free radicals spell trouble. ~ English nutritionists Aidan Goggins & Glen Matten


Lycopene is a carotenoid phytonutrient. Carotene is a pigment produced in plant cells, yielding the vivid colors of fruits and vegetables.

Cooking tomatoes increases the concentration of bioavailable lycopene in this fruit. Watermelon and red citrus, such as pink grapefruit, are also high in lycopene. As carotenoids are pigments, coloration signifies lycopene content.

Regular consumption of foods rich in lycopene are beneficial in warding off prostate cancer. Lycopene is an active antioxidant.


The contribution of foods to nutrition has 3 categories: carbohydrates, proteins, and fats.

Fruits are rich in healthy carbohydrates. Other than potatoes, which are a near-ideal balance of carbohydrates and proteins, vegetables tend to offer abundant protein. Nuts and seeds offer healthy fats.

Seafood, especially fish, is extraordinarily rich in protein, as are eggs. Meat is a mixture of protein and unhealthy animal fat, as is dairy.

There are other essential nutrients, albeit in small quantities: vitamins and minerals. We begin with these, so that the described foods can be better appreciated for their nutritional qualities.

Vitamins are organic molecular micronutrients. In contrast, dietary minerals are inorganic elements which are combined into forms that are biologically useful. Both are nutritionally essential, albeit in tiny quantities.