Quote: (07-07-2018 06:01 AM)Beyond Borders Wrote:
Don't know how accurate the statements in the chart are but interested to hear comments. Some of it reads pretty biased, like the bit that claims it's "impossible" for humans to survive without animal protein.
That chart looks pretty accurate to me.
As for the claim that it's impossible for humans to survive without animal proteins, here is my take on it, (and not necessarily what the author had in mind). Of course it is possible to survive without animal protein, otherwise there would be a lot of dead vegans lying around. Vegans are able to obtain adequate amounts of protein through beans, nuts and to a lesser extent through vegetables. But this is only possible in a post agricultural world. Prior to the agricultural revolution it would have been extremely difficult if not impossible to gather and digest enough plant matter to fulfil our protein requirements, when you take into account availability of these plants and the capacity of our digestive systems. If we take the minimum protein requirements of a
sedentary male as 56g per day, that's about 300g of beans. Then take into account that modern day beans are nothing like their pre-agricultural ancestors, and were much less palatable and nutritious. Then take into account the availability of these pre-agricultural beans - there would have been much less beans lying around than grass and leaves which other herbivourous animals are able to digest. Then take into account that they wouldn't have been available year round in most climates. Then take into account the time and effort it would take to prepare these beans to make them edible. Fuck that! We obtained all our protein from animals. (And then there is the question of where did we get enough fats before the production of vegetable oils)? So in that context, I believe that it's true humans cannot survive without animal protein.
I think a more interesting comparison would be between humans and other omnivorous primates such as gorillas or chimpanzees. Although both these animals are able to digest animal protein (chimps and gorillas eat insects and chimps actively hunt monkeys), they obtain a vast majority of their nutritional requirements from plant matter. Chimps and gorillas have a much larger digestive tract than humans, (just look at their protruding bellies), and also the enzymes necessary to break down the cellulose in leaves and stalks. They also need to eat huge amounts of plants every day - gorillas eat about 20kg of plants a day. Back in our evolutionary past, our very distant ancestors also had the ability to do this, but as our brains grew larger and our digestive tracts got smaller, we were no longer able to digest such food and became increasingly, and eventually almost solely reliant on animals for our nutrition.
The theory is that we first begain to eat animals as scavengers, when we became smart enough to use rocks to crack open bones and skulls to eat the marrow and brains of animals already eaten by carnivores. This is important as we were now able to access much more nutrient and calorie dense food than plants. As meat became more prevalent in our diet, our guts gradually grew smaller and our brains were able to grow larger, and this is explained by the "expensive tissue hypothesis."
The expensive tissue hypothesis states that pound for pound all animals have the same metabolic requirements. For example if a squirrel were the size of an elephant, the squirrel would have the same energy requirements of an elephant. But there is a difference in how the energy is allocated throughout their body - if a large amount of energy is allocated to one part of the body, there is always a trade-off where less energy will be allocated to other areas. In the case of humans, 25% of our energy intake is designated to power our brains since they are so large and complex. But the trade-off for us was that in order for our brains to grow and thus require more energy, our guts could no longer be allocated as much energy and therefore needed to become smaller and less complex. So in order for us to become smarter, we were no longer able to efficiently digest plant matter as other primates can do.
It's my belief, as I stated in a post above, that nothing makes sense except in the context of evolution, and if we want to know our optimal diet we only need to look at our history as a species. It only makes sense to me that the food we should eat now is the food our bodies evolved over hundreds of thousands of years to thrive on. Of course it's POSSIBLE to live on other foods - it is POSSIBLE for a cow to survive on a diet of corn and soy, but nobody would claim that a cow is healthier eating these foods than it would be if it were eating grass as it evolved to do. Likewise, I believe that a meat based diet is optimal for our health, and I don't believe any studies that say we should be eating large amounts of foods which weren't present in our evolutionary past.