Stevie Argyll said:
zlyja
I am back looking at another hypothesis.
The cooked food factor
In 1930, research was conducted to demonstrate the effect of food (cooked/processed vs. raw/natural) on the immune system. It was tested and documented at the Institute of Clinical Chemistry in Lausanne, Switzerland, under the direction of Dr. Paul Kouchakoff.
Probably the best way to look at food - what people eat and how they eat it, and what large scale effects it has - is to look at it archaeologically. Martin Jones, a professor of archaeological science at Cambridge, specializing in the study of the remains of early food, wrote an interesting book entitled "Feast - Why Humans Share Food."
book blurb said:
When you next share a meal with family or friends, ask yourself why humankind partakes of a ritual that to most species would be anathema. The human tendency to sit together peacefully over food is an extraordinary phenomenon. ... how did this strange and powerful behaviour become part of the human way of life?
When you think about it, that may be a key to a lot of things: the sharing of food/resources. Think of "The Last Supper" and its significance. That is an idea that has exercised me to no end. What was so blasted important about sharing a meal that it became the centerpiece of a religion? Was there something about it that was older than Christianity as we know it?
I know what Gurdjieff and others had to say about it - the esoteric meaning - but frankly, that isn't satisfactory. I think it may be a ritual that was handed down as a clue to reveal who was and was not pathological. Those who share willingly and generously are not, those who don't, those who seek to assimilate resources, to "own" things, are.
For most species, fire spells threat. So does direct eye contact and the opening of the mouth and the exposure of teeth. Combine these elements with the placing of food between a group of individuals other than parent and child, and you have a recipe for conflict and violence in any other species.
At some point, some group of humans turned all of these signals around and transformed them into the very essence of humanity. This change in behavior is evidenced by central hearths with clear spaces around them where diners gather in a circle. In the sharing of food and the accompanying courtesies, humans exhibit their fundamental distinction and separation from the animal kingdom.
So, was the "last supper" something like: "eat together in remembrance of me - you are not animals, you are spiritual beings."
Of all the things that humans do, sharing food is the LEAST "evolutionary." No other species followed this path of mutual sharing and support which required being able to conceptualize space and time abstractly. What logic of nature, as we witness it in the animal kingdom, would follow such a trajectory so foreign to the natural world?
These issues penetrate to the most fundamental differences between views about humanity and the world at large. Perhaps they bear witness to those having a soul and those who do not?
But, getting back to cooking food: The earliest evidence of cooking goes back as far as 180,000 years and a few other candidates for signs of cooking that go back even further - in a number of sites, they are attested as far back as 500,000 years. Certainly, Neanderthal was cooking his food though he did not have central hearths and did not given evidence for free sharing of food. The evidence at Neanderthal sites is more like the sharing systems of apes and chimpanzees who DO share food in a hierarchical sort of way. There is limited evidence that they cared for the elderly and infirm and a lot of evidence that women and children (and infirm and elderly) were given the offal and less desirable parts to eat; but it WAS a primitive sharing, if you want to call it that.
What is cooking for?
The entire rest of the animal kingdom seems to do quite well without it - in fact, seems to prefer to do without it. Humans enjoy a lot of raw food and we even consider some of these to be haute cuisine.
Among the MATERIAL changes brought about in the archaeological record by cooking is the changing size of teeth and crania in fossil remains. As teeth got smaller, brains got bigger. It seems that cooking serves to reduce the COST of digestion.
Alongside the fossil record of teeth getting smaller and brains getting bigger is the modern physiological record of living mammals that reveals a corresponding pattern in the organs of the gut. Not only are human teeth small in relation to overall body size, we also have a relatively small gut. Our bodily eating machinery has shrunk, jus as the brain has grown. Shrinking guts may have a great deal to do with growing brains.
Different parts of our bodies do different kinds of work and use up a lot of energy doing so. Some tissues have relatively low running costs, other organs, the liver, gut and brain, burn up a lot of energy. There is a limit to how big and active they can get and how efficiently they can run, determined by how much food any animal can consume and release as sugar/nutrients. By looking across the mammal kingdom and measuring the mass of different organs, one can arrive at a mammalian norm. When we compare that norm with the respective masses in our own bodies, we discover that the modern human brain is two to three times as large as what would be predicted from looking at mammals as a group.
When we think about this, we naturally have to think about the energy economy of the body: the need to balance the books in terms of energy. With a big brain that uses a lot of sugar/nutrients, something else has got to get smaller. The two other big spenders of energy in the body are the liver and the gut. The liver can't get smaller because it is tasked with managing the chemical balance of the body, detoxing, etc. So it seems that, in humans, it was the gut that got smaller, becoming half the size of that which would be predicted by mammalian norms.
So, archaeologically speaking, the record seems to show that the change to cooking enabled humans to grow massive brains by reducing the size and energy consumption of the gut.
The really economic nature of this can be considered in perspective: a cow turns grass into beef with a suite of four specialist stomachs, one with an army of bacterial guest-workers that also need feeding. The grass can be chemically dismantled almost entirely.
The human gut does a poor job with fiber. Yes, it can sweep our gut because it remains undigested, but it is very poor at meeting our nutritional needs.
Digesting meat is not as energetically costly as digesting cellulose. Animal tissue can supply energy and protein in a concentrated and unoccluded form. Another way to ease the workload of the gut is to do some of the digestion OUTSIDE the body: cooking.
Digestion is a chemical process in which large, indigestible molecules are tuned into small easily absorbed molecules, and can be achieved in a variety of ways including fermentation: getting yeast and bacteria to do part of the job of digestion first.
Brain capacities have been measured or estimated for a broad range of hominid fossils and it is possible to track key periods in which the brain increased in size substantially. Obviously, we can't measure the gut in fossils but we CAN measure the teeth. Reduction in tooth size very likely marks the easing of pressure on internal digestion.
A surge in brain size coincides with the earliest evidence of ashes, burnt bone, and charcoal in conjunction with hominids, and the subsequent appearance of hearths coincides with tooth reduction as well.
Cooking required a certain amount of brainpower and brainpower required cooking. Which drove the development?
It seems that stresses in the environment demanded solutions and finding solutions exercised the brain and those who could find solutions - including cooking - survived. The activities involved with getting food in a stressful environment placed demands on intelligence and the brain and quite possibly, the most imperative demand was that of cooperation and social cohesion which demanded the expansion of the neo-cortex. This could only happen with the reduction of something else: the gut. In short, the link between brain complexity and external digestion created a positive feed-back loop. The more effective external digestion became in reducing demands on the gut, the larger the potential size of the brain. Larger brains enabled more external digestion ideas/technologies, enhancing the cycle.
The building of a brain requires a LOT of protein, a great deal of energy (sugar), and an extensive suite of vitamins and minerals. In primates, this work is done by the placenta before birth and at birth, the great majority of its brain growth has already been accomplished. Most mammals give birth to "toddlers" that are able to take on some fairly grown-up tasks within minutes of birth. Human babies have a lot of growing to do still. So, a large part of brain growth in humans depends on mother's milk and, ultimately, the diet of the mother at a stage in her life when she is least able to compete for food.
Beyond proteins and sugars, a lot of brain growth and development depends on fats and rather specific fats at that. One of the most common fatty acids in myelin - the sheathing of neurons - is oleic acid which is the most abundant fatty acid in human milk. Two other fats crucial to optimal development of the brain and eyes are called DHA and AA. DHA is the most abundant fat in the brain. Mother and child can manufacture both DHA and AA from two other fats, but these two source fats cannot be synthesized in the human body. They have to be consumed as part of the diet. That is why they are called "essential fatty acids" (EFAs).
EFAs are "nature's antifreeze." They are important in keeping the flesh of cold ocean fish supple however cold the environment. Thus, the oil from cold water ocean fish is one of the best sources of EFAs. In the plant world, they are found in leafy vegetables and oily seeds such as walnut, hemp, and flax.
Not only do we need EFAs for our brain, we need them in the right balance: there are two kinds: omega 3 EFAs and omega 6 EFAs. A mixed diet of meat, fish and vegetables will take care of this balance. Too much meat without balancing fish and veggies, and you get too many omega 6 EFAs.
Interestingly, one source of fat that has the right balance of EFAs is the soft, oily fat of the horse.
Cooking breaks down long-chain carbohydrates and other related molecules to simpler sugars. It also generates a series of more complicated molecules by chemically linking carbohydrates and proteins.
Cooking tenderizes meat and generally softens food and this is of benefit to two vulnerable groups of people: the very young and the elderly.
Cooking also alters the nutritional quality of the food. The thermal breakdown of molecules does not just soften food; it also causes those molecules to be rearranged, sometimes for the better in nutritional terms, sometimes for the worse. In the case of plant foods, cooking performs the important task of breaking down toxic substances. Toxins are widespread in vegetation, and one of the principal means of a plant's natural defence against being eaten (lectins).
Even when cooking has a mixed or negative impact on overall nutritional quality, it has a positive effect on energetic costs of consumption. Cooking greatly enhances the profit margin by taking care of much of the chemical disassembly of the food outside the body and is, in the end, the key to the evolutionary advantages.
So, that is the long-view.
