Meat Eating – An Evolutionary Perspective

Editor’s note: Diet is obviously a very contentious topic, especially here on the Tribune. Sinead has promoted the “Starch Solution“, with which many people have had great success, while Angelo recently advocated a paleo raw vegan diet, which has also worked for some, but obviously not all. This article argues that eating meat played a crucial role in our evolution, leading to increased intelligence. Read it, think about it, and come to your own conclusions, then let us know what you think in the comments.


There is a lot of talk back and forth with regards to diet and specifically the feasibility of consuming meat on a regular basis, if at all. I must state the consumption of meat, whether for or against is a personal decision, which can only be made at the individual level. This essay is merely a response via an evolutionary perspective. Just because we evolved to eat meat does not make it a necessity in this modern age of very high quality vegetarian protein blends. One must simply acknowledge that we evolved eating high quality animal foods, along with high quality animal fats, plus the addition of plant material. If you can find an excellent vegetarian protein, which mimics closely animal protein via amino acid profiles, go for it. I consider Adolf Hitler to be one of the greatest men to have ever lived, as he led the German folk away from the hangman’s noose, thereby restoring their dignity and honor. Few men, if any, can compare to this great man and he was a vegetarian.

Personally, I love the flavor and texture of animal flesh in my mouth and I love how it makes me feel because we evolved as a species to consume it. I am a pagan man and I will not deny my body what it desires. Though, all things are good in moderation does apply here, as the human body can only digest approximately 30 grams of protein per sitting (every 2-3 hrs. is optimal), which is about the size of your palm.  I consume 5 whey protein shakes per day and only one solid meal, as this allows the body to do other things besides constantly digesting meat.  Also, I eat fat with every meal (coconut oil, olive oil, hemp oil, fish oil and whatever fat naturally occurs in my one ‘solid’ meal per day. And finally, as a northern European I do NOT need to eat large amounts of carbohydrates, as this is a myth formulated by the grain and potato industries. Carbs are most important after a workout (60 to 90 grams via carb loading) and otherwise it is up to you. I eat 1 banana and/or 1 apple, maybe a sweet potato and whatever carbs I ‘accidently’ ingest while consuming other foods, such as yogurt. Remember, carbs are an addictive substance and you will fool yourself into thinking you need them just like any junky believes it needs its fix. I hope you enjoy this brief essay on our evolutionary past, which made us what we are today.

1. Introduction

A high quality diet based on animal products, such as meat, organ meat and animal fats, was crucial to the evolution of hominids, including the hominid brain, thus selecting for increased intelligence. I will argue a plant only based diet for hominids has not existed for the last 4.4 million years, as increases in hominid brain size directly correlate with increased animal consumption as witnessed via hominid morphology, archaeological data and isotope analysis. To further this discussion, I will use Ardipithecus ramidus, Australopithecus, Homo habilis, Homo erectus and Homo sapiens as examples, as they clearly represent a long, unbroken line of increasing brain size within the EEA (environment of evolutionary adaptedness). Hunter-gatherer societies have been studied for decades and this data suggests a definite preference for animal products when available, as animal meat, organs and fat provide the greatest bang and value when it comes to energy requirements. This data further suggests upwards of 65% to 85% of hunter-gatherer diets are animal based with the remainder being made up of plants, insects and honey (see Ache of Paraguay). To reconstruct our evolutionary ancestors diet I will use various scientific studies of key skeletal, tooth and gut morphology, encephalization, isotope analysis and other archaeological evidence, such as cooking.

2. Evidence for Ancestral Diets

The Optimal Foraging Theory (OFT) predicts how an animal will behave when foraging for food. This theory argues that the most economically advantageous foraging pattern will be selected for in a species through natural selection (the process whereby organisms better adapted to their environment tend to survive and produce more offspring). Thus, one may conclude, that all things being equal in our ancestral environment (EEA), an individual will take into account the amount of energy available in any food item versus the amount of energy expended in taking in and processing that food item (cost/benefit analysis). Plants, such as root vegetables, require more time to gather and process and are low in energy density when compared to high quality foods, such as animal meat, organs and fat. Ripe fruit and honey are excellent sources of energy, but are often difficult to acquire. Plant material does not have sufficient energy to be beneficial in the long term and therefore cannot be the primary source of energy for evolving hominids. Larger game animals fit the Optimal Foraging Theory perfectly, as they are rich in meat, organ meat and fat. Large prey animals are an excellent source of amino acids, vitamins, minerals and other nutrients crucial to a hominid diet. An excellent example is the Ache tribe of Paraguay.  hese hunter-gatherers prefer a diet high in meat, organ meat and fat to the abundant plant life that is readily available.

2.1 Ardipithecus ramidus/Australopithecus

Ardipithecus ramidus existed from approximately 5.8 to 4.4 mya and had a brain size that averaged 325 cm3. The genus Australopithecus existed from approximately 4.4 mya to 2.25 mya and had a brain size between 400 to 500 cm3 depending upon the species. Australopithecus evolved into both gracile and robust forms, having been influenced and shaped by various ecological factors, including an increasingly higher quality diet including some animal products. Evidence of early hominid diets can be studied via skeletal remains, such as tooth size, tooth shape, enamel structure, dental microwear and jaw biomechanics. Ardipithecus ramidus’ teeth had thin enamel (1.1 to 1.2 mm) and little shearing ability. They would have been more reliant on a softer plant tissue diet, such as specific leaf buds, flowers and fruits that were easy to penetrate.

Australopithecus had thicker tooth enamel and flat, blunt molars, which had difficulty shearing through meat. Australopithecus tooth and jaw structure varied between species, suggesting a varied diet of plant based foods. Even though they had not yet adapted a tooth designed to process meat on a regular basis, isotope analysis suggests that Australopithecus did in fact eat large amounts of meat. The Australopithecus ability to eat a variety of hard and soft foods gave them an adaptive edge over a more specialized diet, as they now had the ability to fill a variety of ecological niches and this more generalized diet, which included meat and fat allowed for greater access to energy sources which in turn allowed for an increase in brain size.

2.2 Homo habilis

Homo habilis can be dated from 2.5 mya to 1.8 mya. Looking at skeletal remains, such as tooth or jaw morphology, it is apparent that Homo habilis used an omnivorous diet strategy, thereby adapting to a more open environment of grassland with varied resources spread over a large territorial range. The adaptation towards bipedalism, which freed the hands, along with a larger brain had given Homo habilis the ability to acquire meat through scavenging or hunting. A diet in game meat, organ meat and fat would have allowed Homo habilis to feed a larger brain (640 cm3), which in turn allowed for a more socially complex animal to evolve. The earliest tools and bone cut marks date to 2.4 mya. This suggests a correlation between meat eating and tool use for at least 600,000 years. Tool use further opens the range of edible foodstuffs that can be collected and processed. Homo habilis had large front teeth and large molars with thicker enamel suggesting they ate a mechanically more demanding diet. Also, evidence for meat eating correlates nicely with an evolving brain.

2.3 Homo erectus

Homo erectus (brain size: 900cm3) can be dated from approximately 1.9 mya to 250 kya (thousand years ago) and they lived in Africa, Asia and Europe. Homo erectus was the most adaptive of early Homo species and is considered the only hominid species to have become human-like in behavior. Homo erectus achieved an advanced tool kit and lived increasingly social lives as hunter-gatherers, perhaps creating the first division of labor (cooperating individuals who perform specific tasks and roles). Homo erectus used fire to cook with and used an advanced tool system to hunt animals and gather food. This created a feedback loop, as a high quality protein diet via meat (plus organ meat and fat) allowed for larger brains, greater intelligence and increasingly complex social systems. In fact, many evolutionary psychologists argue that increasingly complex social systems selected for higher IQ’s as hominids had to be at their best social game, thereby outwitting, outlasting and outcompeting the hominid next door, thus ensuring it was their genes being passed on to the next generation.

Evidence to support Homo erectus’ diet is found in skeletal remains and through direct archaeological evidence, such as cave sites, where faunal remains are found.  These remains show evidence of burn and cut marks.  Tooth physiology is an excellent guide to Homo erectus’ diet.  Homo erectus tooth enamel is the thinnest of all hominids to date.  Their teeth have excellent shearing ability for the processing of meat and they have the smallest jaws in comparison to Australopithecine or Homo habilis.  This data suggests, Homo erectus on occasion ate hard, brittle foods but most likely relied on advances in tool use and cooking to make food easier and less taxing to consume. Homo erectus would have relied on game meat, organ meat, animal fat and some plant material for the majority of its diet, thereby fuelling an ever-increasing brain size.

3. Evidence for Homo Sapiens High Quality Diet with an Emphasis on Animal Consumption

Homo sapiens evolved to consume an omnivorous diet. Average brain size for Homo sapiens is 1300 cm3, though it has been steadily shrinking for the past 28 000 years. In fact, our European ancestors, the Neanderthal, had an average brain size of 1650 cm3. Evidence indicates hunter-gatherers consumed 68% of their diet in fish, wild game, organ meat and animal fat, with plant foods making up the remaining 32% (though this varies). For example, the Ache of Paraguay acquired 80% of the energy in their diet via animal sources, 10% from palm, 10% from insects and honey and 1% from fruit. Plant matter in the human diet is important, providing carbohydrates, vitamins, minerals, fiber and other valuable phytonutrients but it cannot provide the necessary energy as required in the environment of evolutionary adaptedness. Evidence suggests humans have always consumed a majority of animal products because brain tissue is metabolically expensive.

3.1 Brain Size versus Gut Size

There is a direct correlation between hominid diet, brain size and gut size. Splanchnic organs consume as much energy as the brain and small guts are compatible only with exceptionally high quality diets incorporating animal products.  Therefore, a smaller gut with a high quality diet became the key to the evolution of the hominid brain. The consumption of animal meat, organ meat and animal fats allowed the brain to grow without the need to raise the basic metabolic rate. Raising the basic metabolic rate would require more intensive feeding behaviors and increased competition for limited resources within a finite environment. The addition of cooking (applying heat to improve the nutritional quality of food) allowed humans to consume and extract more nutrients from available dietary sources and had the added benefit of tenderizing meat, making it easier to chew, which lead to smaller jaw and teeth sizes.

3.2 Isotopic Analysis and Tooth Morphology

Isotopic analysis of skeletal remains suggests humans have consumed a large percentage of their daily diet in animal products. Isotopic percentages in ancient human remains were found to be equal to other predators, such as wolves and arctic foxes.  Homo sapiens have seen a reduction in tooth and jaw size suggesting humans have turned to a high quality diet of cooked animal products and processed plant matter.  Softer food selected for smaller teeth and a smaller jaw. For example, Australopithecus had upwards of 4 to 5 times the crushing power of modern humans. Furthermore, tooth enamel thickness decreased and meat shearing ability increased, further suggesting a move towards an animal based diet with the addition of plant matter, insects and honey (or anything children and females can scavenge safely via an energetic cost/benefit analysis and predator avoidance strategy).

4. Conclusion

The high quality diet of hominids up to and including Homo sapiens has been a crucial factor in the development of extreme encephalization.  It has been clearly demonstrated that a high quality diet with a heavier reliance upon animal products selected for larger brains, increased complexity within human social systems and higher levels of intelligence. A steady progression of hominid morphology through time coupled with other evidence, such as isotopic analysis, further demonstrates a steady reliance on animal products, such as meat, organ meat and fat reaching as far back as 4.4 mya. Studies of modern hunter-gatherers (Ache of Paraguay) show a preference for animal products over plant material even when the latter is readily available in the immediate environment. Studies involving vegetarians have shown they have a lower Body Mass Index and experience low energy and impaired reproductive function, which would have created an intolerable and unforgiving situation in the environment of evolutionary adaptedness.  Meat, organ meat and animal fat provide valuable vitamins, minerals, amino acids and other nutrients essential to proper health and evolutionary processes.


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