Evolution of our diet

Are humans naturally herbivores, omnivores or carnivores?

Distinct facts to remember about the evolution of the human diet

There is a significant difference between the food that is best for us and the food that our digestive system features are most likely to have evolved to handle. In other words, the foods that our ancestors had to eat are not necessarily the foods we should still be relying on now.

However, our ancestry may have some answers to diet-related questions we’re facing today. 

In order to understand what is healthy and what is beneficial in terms of dieting and food we need to look at our ancestor’s diet and recent changes in food production.

If you think about living in the wild, it is tough and we’re the descendants of those who were able to counter the elements, avoid predators, live through disease, and survive disasters such as floods and droughts and seasonal depletion of resources and food scarcity.

Our ancestors had to be opportunistic about the food, as such they became omnivores, able to eat both meats and greens. Excess food had to be stored for future use.

At some stage of our evolution, we started cooking and perhaps sharing food, which means that it helped our brains develop as neural processes require a lot of energy.

At another stage, our ancestors’ jaws and teeth became smaller as brains got even larger.

Our ancestors?

The closest relatives to humans in the animal kingdom are primates, specifically great apes such as chimpanzees, gorillas, and orangutans.

Their diets vary depending on the species and their environment. Generally, great apes are omnivorous and consume a range of foods such as fruits, leaves, seeds, nuts, insects, and occasionally small animals. Chimpanzees, for example, have been observed to hunt and eat small mammals, while gorillas mainly consume leaves, shoots, and stems. Orangutans mainly feed on fruits but also eat leaves, bark, and insects.

Over time humans have evolved to have a more diverse and flexible diet compared to other primates, which has allowed us to consume a wider range of foods and adapt to different environments. This was hugely advantageous for humans as a species.

Our original primate ancestors

Opportunistic: able to eat a lot and store for later
Omnivores: able to chew and extract nutrients from most food sources
Scarcity resistant: scarce resources mean periods of fasting and seasonal changes in body shape
Active in search for food: physically demanding daily regime of looking for food during the daytime
Adaptable: animals and plants disappear, and early humans migrated and adapted to different foods

Technology changed our diet further

There were three distinct and very important technological advancements that had a massive effect on the diet of our ancestors.

First tools, fire, and agriculture. Each had given tremendous help in preserving resources and saving time, allowing the human species to advance and prosper. Each of these advancements had a real effect on human lifestyle and diet in particular.

The first tools: 3 million years ago: 

The history of technology begins arguably even before the beginning of our own species. Razor-sharp flakes of stone were used as knives which allowed our ancestors to hunt more effectively, to cut meat into smaller pieces instead of relying on chewing them. The larger unshaped stones were used as hammers and anvils have been uncovered at Lake Turkana in Kenya. The tools were made 3.3 million years ago and thus were likely used by an ancestor such as Australopithecus to create further tools and perhaps to create some kind of resemblances of homes.

The invention of tools allowed our ancestors to carve up fruit and meat into smaller pieces, to fend off larger predators. This allowed our ancestors to have more free time, which may have been a contributing factor in further technological advancements such as fire and cooking.

Perhaps the discovery of tools eventually pushed humans to the top of the food chain, with a wider choice of foods to consume.

Fire and cooking: 1 million years ago

Fire and cooking had a life-changing effect on the digestibility of food and it had a massive effect on the bioavailability of nutrients.

Fire and cooking make food more digestible, meaning that humans who had access to the fire were able to find more spare time for activities other than foraging and hunting. Perhaps fire and cooking helped humans to develop language and culture, as cooking may have been a social activity, due to both consumptions of cooked foods and the heating effect of open fire pits. 

The heating effect is especially important at night when the temperature drops and in the colder periods of the year. By having a source of heat our ancestors, as we do now, spend fewer resources on heating our own bodies. This allows more resources to be spent on other activities.

Furthermore, fire is something that scares all the animals if you remember watching the Jungle Book, so it would have been used for protection against ferocious predators. The masters of fire would have become the masters of their environment.

Agriculture (Neolithic Revolution): 20,000 to 15,000 years ago 

The development of agriculture was a massive step toward the society that we have today. The appearance of organized agriculture followed by the introduction of irrigation (6000 years ago) – lead to a massive increase in the availability of plant foods and livestock feed. 

Farming and irrigation of large areas allowed humans to concentrate in larger population clusters around rivers. Crops such as rye, barley, wheat, and rice became a significant part of the human diet. Mead and the usage of grapes to make alcoholic beverages also added to the diversity of cultivated crops. 

The adaptation of wild plants into crops made us less reliant on previously strictly-seasonal foods. The collections of harvests in particular in the steady climate of Africa and the middle east made humanity prosper like never before. This step in the evolution of our culture coincided with animal husbandry.

Domestication of animals: 13,000 years ago

Whilst the populations in flat areas adopted agriculture and irritation to their needs, the inhabitants of more mountainous regions preferred to herd sheep, horses, goats, and other animals. Some animals were raised for their skins, others for their meat or milk. This also diversified the pool of available foods further. 

It is unknown when the plentiful fish and other sea products joined meats from herded animals on our ancestors’ menu. It most likely also played a role in increasing both the size of the menu and the size of the portions for individuals, leading to the development of a larger brain due to animal organs being more nutritious.

Further advancement in animal husbandry allowed for improvement of the selective quality of animals and to breed sought-after features for more meat and fat.

Our menu today

The choice of food sources increased steadily through the ages. Today the food is mixed, altered, enhanced, heated, and cooked. Vitamins are added to cereals, and sugar is added to almost everything. 

However, the majority of food is processed, low-quality, nutrient-scarce, and calorie-rich. It is readily available in quantities and variety unimaginable to our ancestors.

Opportunistic omnivores to modern human diet

The fire changed everything, it put our ancestors onto the path of what we are today and we still cook, unlike our closest primate relatives such as chimpanzees and other apes. Continuous use of cooked foods allowed us to gain more micro and macronutrients. This was the turning point for our digestion as well, it is hard to imagine a widely-adopted diet that does not feature uncooked foods. Our digestion evolved alongside our ability to cook and the introduction of farmed crops and animals expanded it to the point where you could probably not find many similarities between our day-to-day meals and the meals of our ancestors before the invention of fire.

At this point looking at whether our digestion is similar to that of herbivores, omnivores, and carnivores is irrelevant. Other animals have to suffice with what nature provides them with, humans can cook, can farm, and can plan the storage of food. From opportunistic hunter-gatherers, humans turned into far-planning organizers of crops and animals and built whole chains of food manufacturing. Food has become more available but that comes at a cost too.

If you consider for a moment that cooking is unnatural, i.e. not replicated by other species in nature – it would lead to suggest that we have evolved beyond the standard set of rules set for nature. Since cooking and further technological advancements have been a part of our ancestors’ lives for many generations we have to use other methods to distinguish what is good and what is bad for us in terms of diet. Our ancestors, rightfully being opportunistic omnivores in the harsh and unforgiving nature gave us the necessary flexibility to adapt our diet accordingly. 

Modern methods of analysis allow us to distinguish between different food sources.

Our evolution

The cost of modern foods for our physiology and health

Our ancestors were opportunistic omnivores, meaning that they ate a wide variety of foods, including plants, fruits, nuts, seeds, and animal-based foods such as meat and fish. They were also constantly on the move, searching for food and experiencing periods of scarcity and abundance.

This lifestyle required our ancestors to develop physiological traits that helped them to store and conserve energy, such as the ability to store fat and the tendency to crave high-energy foods. These traits were beneficial for survival in an environment where food was scarce and unpredictable, as they helped our ancestors to store energy during times of abundance and use it during times of scarcity.

However, in the modern world, where food is abundant and easily accessible, these physiological traits can become a problem, leading to issues such as obesity, type 2 diabetes, and other health problems related to overconsumption of high-energy foods.

One of the main reasons for this is that the modern food environment is vastly different from that of our ancestors. We now have access to a wide variety of highly palatable, energy-dense foods that are designed to be appealing and satisfying, leading to overconsumption and a positive energy balance.

Furthermore, the modern sedentary lifestyle, which involves less physical activity than that of our ancestors, further exacerbates this issue, as it reduces the amount of energy that we expend and increases the likelihood of weight gain.

While our physiological traits evolved to help us survive in an environment of scarcity and unpredictability, they can become a problem in the modern world, where food is abundant and highly palatable. Adapting to this modern food environment requires conscious effort and a commitment to making healthy choices that support long-term health and well-being.

The changes in our faces – a smaller jaw

If you consider changes to human physiology over the years, in particular jaws and teeth then you’d see evidence of teeth and jaws becoming smaller. This is because humans no longer need to spend as much time chewing, as cooked and cut food is easier to chew. This is not actually very healthy, as our chins often do not develop fully.

If you look at the preserved teeth of our ancestors, and most animals we see in the world today, they have almost perfectly aligned, symmetrical teeth. The dentist industry thrives due to the limitations of our modern-day diet. The term Standard American Diet, abbreviated as SAD (very telling) is an example of such a limited if not detrimental diet for our whole bodies but teeth specifically.

Our ancestors and our closest relatives in the primate world today spend many more hours chewing and developing their jaws and if you look at chimps and gorillas – the evidence of the change of lifestyle becomes apparent. We are no longer our ancestors, it is important to recognize that and to adapt our diet to our modern bodies.