Cooking also made us human

Cooking is a distinctive and unique feature of our species. After the success of Eating meat made us human, we continue delving into the nutrition of our ancestors as one of many factors that led us to Homo sapiens. We will analyze the contributions of our readers in the previous post on the importance of carbohydrates and the use of fire.

THE OPPORTUNIST OMNIVOROUS

In the previous post we learned that one factor that contributed to the fast growth of the brain was the increased intake of meat by H. habilis, that allowed them to save energy in digestion (Aiello, L. Wheeler, P, 1995). Another factor that allowed saving energy to dedicate to brain growth, since Lucy, was bipedalism (Adrienne L. Zihlman and Debra R. Bolter, 2015).

One of the things that gave us evolutionary success is our ability to take advantage of almost any food, allowing our expansion around the globe. Current diets are varied and traditionally linked to the availability of the geographical area or time of year, which changed with the development of agriculture and livestock. Human groups studied in historical period without agriculture or livestock, hunt, fish and gather very different foods, but no groups exclusively carnivorous or exclusively vegetarian have been found (except Eskimos, who have traditionally fed on hunting and fishing because of the characteristics of their environment, frozen during almost all the year).

Hazda people returning from hunting. The Hadza are a small African tribe of about 1500 hunter-gatherers. Photo: Andreas Lederer

The first tools, possibly used by Australopithecus but obvious since H. habilis, allowed our ancestors to get food that otherwise would have been impossible to get: drilling and tearing flesh, breaking the hard shells of nuts, and later crushing and grinding grain. Thus, the basis of our current supplies are hard cereal grains (e.g. rice, wheat) and the dried seeds of legumes (e.g. lentils), because our needing of protein intake is low, although meat is consumed in excess in the First World countries.

But before the advent of agriculture, our ancestors ate what they found: Neanderthals in hostile areas had to base the diet with meat and supplement it with vegetables when they were available, while in milder climate zones, like the Mediterranean , make use of aquatic resources as molluscs, turtles and fish. Furthermore, by its robust body and increased muscle they needed more protein intake.

Neanderthals collecting mussels in Gibraltar, one of the last settlements of this species. Photo: DK Discover

THE ORIGINS OF THE CUISINE

As we have seen, seeds are very nutritious because they are rich in carbohydrates (especially starch), but low in protein; in addition, legumes must be cooked to be assimilated. No other animal, except us and our ancestors, prepare food or cooks. Cooking is an unique human trait which opened an infinite number of possibilities in our nutrition.

CONTROL OF FIRE

The first traces of use of fire date back 1.6 million years ago in Africa, although the first reliable evidence is a hearth 0.79 million years old. The responsible: Homo erectus, but those who used fire continuously, especially for cooking, were a later species: Neanderthals.

Homo erectus, American Museum of Natural History. Photo: Mireia Querol Rovira

The advantages of controlling fire were numerous and very important, but in this post we will delve into the first one:

• Cooking and food storage
  
• Better hunting and scavenging: fire allowed them to obtain prey hunted by large carnivores or direct theirs to natural traps .
  
• Protection from predators
  
• Heat: increased survival when temperatures fell.
  
• Light: they could extend its tasks when night had fallen, favouring social skills and later, the development of language. In addition, changing the circadian rhythm (24h internal clock) could have extended the reproductive period .
  
• Access to new territories: burning areas of dense vegetation to take dead animals and make use of new areas and encouraging migration to cooler places.
  
• Improved tools: wood tools made with fire are more durable.
  
• Better hygiene: burning waste avoided infections.
  
• Medicine: after H. erectus, the fire has been used as disinfectant and instrument sterilizer and for the preparation of remedies based on medicinal plants, as inhalation of vapors or preparing of  infusions.

  

  Homo erectus surprised by the strength of his spear warmed with fire. Figure by Elisabeth Daynès, CosmoCaixa. Photo: Mireia Querol Rovira

  ADVANTAGES OF COOKING FOOD

  • Variety in the diet: certain foodstuff is indigestible raw or difficult to chew (especially for individuals with dental problems). Stewed food is softer and easier to digest, allowing H. erectus expand their diet respect their ancestors, accessing food of higher nutritional value (Richard Wrangham, 2009). Cooking improves the palatability and increases the assimilable carbohydrate availability in tubers, vegetables… and therefore it gives them more energy value. According to Wrangham and other experts, raw foodism can be harmful to health, because our body is adapted to this “pre-digestion” in the stoves, which allows us to be the primate with the shorter digestive system in relation to the body.
  • Reduction of the teeth: tusks and teeth could have been reduced due to consumption of cooked food. A tooth that has to bite a boiled potato instead of a raw one can be 82% smaller. Less space were needed for chewing muscles and teeth in the skull, so the mouth and face became smaller. This free space can be dedicated to accommodate an increasingly large brain. H. erectus had a brain 42% larger than H. habilis.
  • Less energy consumption: energy and time dedicated to chew and digest cooked food is less, so the number of final calories obtained increases. This energy can be devoted to brain development rather than digesting food.
    
    Possible Neanderthal diet. Photo: Kent Lacin LLC/The Food Passionates/Corbis.
  • Fewer diseases: raw food, especially meat, may contain potentially pathogenic or deadly bacteria and parasites. But from certain temperatures, many of these bacteria die, so eating cooked rather than raw, our ancestors increased their survival significantly.
  • Less poisoning: some plants, fungi and tubers are toxic if are consumed raw, like some edible mushrooms, sweet potato or potatoes with green areas.
  • Food preservation: by smoking meat, it could be kept in good condition for longer and take advantage of it in times of scarcity. In addition, cooked food lasts longer than raw food.

CONCLUSION

In short, cooking was another factor involved in the brain development and cognitive abilities of our ancestors, allowed energy savings to digest and chew food, decreased masticatory apparatus, allowed the young become earlier independent from their breast-feeding mothers (who could mate more often), improved immune system… Even improved social skills: left more free time so they could dedicate it to other tasks, such as cooperation to keep the fire, planning the collection or capture of food, distribution of food in the group acoording to range and health of individuals… intelligence enhanced cooking techniques, which in turn enhanced the intelligence, in an infinite wheel that still exists today.

REFERENCES

• Mateos A, Rodríguez J (2010). La dieta que nos hizo humanos. CENIEH, Burgos.
• Arsuaga J L, Martínez I (2006). La especie elegida. La larga marcha de la evolución humana. Booket divulgación.
• The Importance of Dietary Carbohydrate in Human Evolution
• Butchered bone suggests earlier start to eating meat
• El dominio del fuego
• La cocina nos hace humanos
• Boniato o batata cruda y dioscorina
• Cooking up bigger brains
• cover picture by Mauricio Antón

Eating meat made us human

Currently some of the world’s population can choose their diet: omnivorous, vegetarian, vegan, raw foodism, carnivorous, paleodiet… but what ate our ancestors?  Which diet is more suited to the one of our ancestors? Without going into polemics, we will discuss one of the crucial facts of the evolution from Australopitechus to Homo: the meat intake.

WHAT DID OUR RELATIVES EAT ?

One of the reasons given to follow a strict vegetarian or vegan diet is that as “we are apes”, they feed on fruits and plants, and moreover, a more “natural” diet  is achieved. Currently and traditionally the base of the world diet are the seeds of cereals (rice, wheat, corn, etc.) and legumes (beans, lentils…), which often require processing (flour, for example) and have nothing to do with their wild ancestors. Since agriculture and livestock was invented and we have selected the best varieties for human consumption, the label “natural” loses all meaning. Although transgenic food is now on everyone’s lips, we have been using the genetic modification for thousands of years.

In the top row, wild ancestors of lettuce, carrot and corn. Below, domestic varieties. Source

That we are apes and the natural thing is to eat vegetables, is also not entirely true. As primates have evolved in trees, hominids have a strict diet or mainly folivorous -leaves- and frugivorous -fruit- (gorillas, orangutans), while gibbons also complete their diet with invertebrates. Our closest relatives however (bonobos, chimpanzees) are omnivorous as they eat vegetables, fruits, invertebrates and even small mammals and other primates (althought in less proportion than vegetables).

Chimpanzee eating meat. Populations of chimpanzees have been described  hunting with spears made by themselves. Photo Cristina M.Gomes, Max Planck Institute.

No wonder then that our direct distant ancestors as Australopithecus Lucy, ate leaves, fruits, roots and tubers as the basis of their diet. Some species, in addition to vegetables, also fed on invertebrates and small vertebrates, similar to modern chimpanzees.

HERBIVOROUS AND CARNIVOROUS

Fruits have more sugars, although they are not very abundant in comparison with leaves and stems. But leaves have less nutritional value because they contain many fibers we can not absorb, such as cellulose. Legumes contain more protein than grains, but some essential amino acids and vitamins (such as B12) are absent or in a few proportion in vegetables and easily assimilable iron (hemo iron) is found only in food with animal origin.

In short, vegetables are harder to digest compared to animals, so mammalian herbivores have longer digestive systems, or compartmented stomachs, chew over long periods of time and some are ruminants, while carnivores have digestive systems with lower absorption surface and require little chewing of food.

Digestive systems of non-ruminant herbivores, ruminants, insectivores and carnivores. Unknown author

 

WHY OUR ANCESTORS STARTED EATING MORE MEAT?

2.6 million years ago, climate change made our planet cooler and drier. In Africa the savanna dominated much of the territory, so hominids had to deal with hard leaves, leaves covered with wax, hard or thorny stems, roots… these difficult to digest resources were utilised by Paranthropus, with large teeth and powerful musculature in the jaw to crush, although they had a similar brain to Australopithecus. They became extinct a million years ago.

Paranthropus boisei. Reconstruction by John Gurche, photo by Chip Clark.

But another group of hominins found a kind of resources that offered them more energy in smaller quantities, and were easier to chew: meat. Homo habilis was the first to eat meat at higher rates than the rest of relatives and also meats with more fat. It was an opportunist: they ate almost anything edible, instead, Paranthropus were specialists, so if their food was scarce, they had more possibilities to die.

BIG BRAINS …

While Australopithecus and Paranthropus had a cranial capacity of 400-500 cm ³, Homo habilis had up to 700 cm ³. This increased brain size allowed them greater versatility and ability to improvise to find food.

One thing that clearly differentiates us from other primates and animals is the large size of our brain. As you have noticed, H. habilis and is classified within our genus,  Homo, due to that great leap of brain size, among other things.

Skull comparison between Australopithecus, Homo habilis and Paranthropus. Credit: Peter S. Ungar et al, 2011.

But a large brain also has drawbacks: 25% of our body’s energy is consumed by the brain at rest, H. habilis brain consumed 15% and Australopithecus only 10%. In addition to quantity, this energy also has to have quality: some fatty acids for proper brain function only are found in some nuts, but especially in animal fat, easier to achieve if vegetables were scarce.

Homo habilis reconstruction by Elisabeth Daynès, Cosmocaixa (Barcelona). Photo by Mireia Querol

…SMALL INTESTINES …

The only way to dedicate more energy to brain function is to reduce the size of other high energy consumer organs (Aiello, L. Wheeler, P, 1995). Heart, kidney, liver, they are major consumers of energy, but vital, so the solution is to reduce the gut and that’s only possible with the change of an almost exclusively vegetarian diet (Australopithecus) to another of easier assimilation with more protein and animal fat (H. habilis).

Comparison between high energy consumer organs between humans and other primates. Image by J. Rodriguez

…AND TOOLS

A large brain also gave another advantage to H. habilis. Despite his appereance (small, no large fangs or claws) they could make use of a great variety of meat (first as scavengers and later as hunters) due to the use of tools. Australopithecus probably used some sort of simple tools, mostly wooden made, but we know for sure that early manufacture of stone tools (archaeological industry) belong to H. habilis. This allowed them to take advantage of the inside of the bone marrow of large prey killed by carnivores when all the flesh had been eaten by other animals. Currently only hyenas and bearded vultures can access this resource without tools. Besides, by not requiring such large teeth and jaws, the skull can accommodate a larger brain.

H. habilis scavenging a rhino. Source; DK FindOut

CONCLUSION

In short, the increase of the brain of Homo was possible by changing diet, which allowed a shorter digestive tract and smaller masticatory apparatus. In turn, to achieve these more energy foods more intelligence is required, resulting in more complex behaviors such as the use of manufactured tools (Oldowan lithic technology, Mode 1).

Our digestive system is the result of millions of years of evolution as opportunistic omnivores. Some current strict diets (vegetarian or almost carnivorous) are in contradiction with this biological heritage and the abuse and access to all kinds of food carry us all kinds of allergies and food problems. The secret remains following a balanced and varied diet.

REFERENCES

• Roberts A (2002).  Evolución: historia de la humanidad. Akal, UK.
• Mateos A, Rodríguez J (2010). La dieta que nos hizo humanos. CENIEH, Burgos.
• Arsuaga J L, Martínez I (2006). La especie elegida. La larga marcha de la evolución humana. Booket divulgación.
• Potts, Richard. Sloan, Christopher (2010). What does it mean to be Human? Ed. National Geographic Society.
• Vegetarianismo – Aspectos nutricionales a tener en cuenta cuando te planteas ser vegetariano
• Paleodieta: hábitos prehistóricos para otra dieta milagro (OCU)