There's a good case to be made for humans being primarily meat eaters for much of our history and only eating plants as an alternative to starving - we certainly haven't had time to evolve to eat a vegetarian diet. Agriculture has only been around for a small fraction of our history and the skeletal record clearly shows how disasterous it was for our health.
The current 'plant based' fad diet recommendations are backed up by some very poor science and may be seriously unsuitable for humans and for children in particular, nutrition-wise. Animal agriculture is not even a major source of human emissions so to call for changes to our natural diet seems very premature.
Our stomach pH is very low, comparable to carrion eaters and some carnivores.
"It is interesting to note that humans, uniquely among the primates so far considered, appear to have stomach pH values more akin to those of carrion feeders than to those of most carnivores and omnivores"
https://journals.plos.org/plosone/article?id=10.1371/journal...
Our requirements for DHA and B12 indicate a diet rich in both - both found almost exclusively in animal foods
We wean our young for a very short amount of time compared to other apes.
"Our model indicates that carnivory has a specific and quantifiable impact on human development and life history and, crucially, explains why Homo weans so much earlier than the great apes."
Impact of Carnivory on Human Development and Evolution Revealed by a New Unifying Model of Weaning in Mammals
https://journals.plos.org/plosone/article?id=10.1371/journal...
We do require B12, but "found almost exclusively in animal foods" leaves out something important. B12 is produced by bacteria, and is found in natural, untreated water sources, as well as dirt. Our bodies are adapted to preserve B12 in a very elaborate way, (because it is a water-soluble vitamin), meaning that we can survive on the trace amounts found in untreated water and the dirt that sticks to vegetables. This is not to say that I'm recommending drinking untreated water or not washing vegetables. Vegans should absolutely supplement.
Like the article says, there's debate over whether this is enough, as the conversion is very inefficient. As I understand it, ALA and LA compete for the same pathway, meaning that excess of LA intake (an omega 6 fatty acid, abundant in nuts and seeds, and of course oils processed from them) will reduce our body's ability to produce DHA, so a human eating prehistoric diet would likely have a better conversion ratio than on a modern diet. Also, there's apparently evidence that if we don't eat a lot of DHA, our bodies convert more of our dietary ALA to it to compensate: https://www.ncbi.nlm.nih.gov/pubmed/20861171
But even taking all this into consideration, I'm not very sympathetic to arguments from nature. There's a big difference between saying "primal humans did X" and saying "modurn humans need to do X to be healthy". Even taking everything you said as given, there's overwhelming evidence that meat consumption is a big factor in for modern chronic health problems like heart disease and cancer. Eating whatever you can get your hands on (meat, eggs, fish, insects) makes sense when you just need enough calories to survive and reproduce, but that's not the problem now. We suffer from diseases of abundance. A plant-based diet with B12 and DHA supplementation is much healthier than an omnivorous one.
I do recommend the studies of the global burden of disease project as an authority for what is healthy [1]
Springman, cited on chapter 5 of the report, goes into depth relying on those evidences for modeling the potential diets. [2]
That is what the IPCC references. Great work, published in nature, peer reviewed and pretty solid science.
Sounds like a big ol' Paleo-esque Appeal to Nature argument.
> The current 'plant based' fad diet recommendations are backed up by some very poor science and may be seriously unsuitable for humans and for children in particular, nutrition-wise
Care to provide evidence to back that up? Your broad, evolutionary talking points and observations on stomach pH in your other response hardly backs up your strongly worded supposition.
Plant based diets have been practiced by not insignificant portions of the population beginning in the 6th-century BCE with Buddhism and Hinduism[1]. An estimated 20-40% of India is currently vegetarian[2]. Not sure "fad" is an accurate descriptor.
I'm sure you'd have a hard time refuting the unending amount of "poor science" that shows plant based diets are effective for longevity, treating obesity, diabetes, heart disease, and high blood pressure[3]. The AICR recommends a plant based diet to prevent cancer[4], and ten other major Nutritional Organizations recognize the health benefits[5].
"It is the position of the Academy of Nutrition and Dietetics that appropriately planned vegetarian, including vegan, diets are healthful, nutritionally adequate, and may provide health benefits for the prevention and treatment of certain diseases.
These diets are appropriate for all stages of the life cycle, including pregnancy, lactation, infancy, childhood, adolescence, older adulthood, and for athletes."[5]
>Plant based diets have been practiced by not insignificant portions of the population beginning in the 6th-century BCE with Buddhism and Hinduism. An estimated 20-40% of India is currently vegetarian. Not sure "fad" is an accurate descriptor.
In terms of human history, he's right. 6th-century BCE was not very long ago at all: that's less than a mere 3000 years. Humans have been around for over 2 million years.
Also, he's right about the skeletal record: archaeology shows that humans lost about 1 foot of height when they switched to agriculture. Yes, much of India is vegetarian, but Indians tend to be pretty short, but then when they emigrate to western nations and adopt more western diets, their kids end up dwarfing them.
I am Indian, I am vegan and was brought up vegetarian and I am not short. I am a foot taller than my parents. It has nothing to do with approximating western diets and everything to do with proper nutrition, vegetarian or not.
> everything to do with proper nutrition, vegetarian or not
Exactly. It's like the unending articles that point to negligent "vegan" parents as the cause of child deaths/underdevelopment when they fed them super extreme, restrictive diets that just happen to be able to fit into the rules of veganism. You can get poor nutrition and technically follow the rules of many diets, but that isn't necessarily a reflection on the diets themselves, but on poor nutrition awareness.
> In terms of human history, he's right. 6th-century BCE was not very long ago at all: that's less than a mere 3000 years. Humans have been around for over 2 million years.
3000 years is certainly long enough to take something out of "fad" status. I would challenge you to find another diet that follows specific rules that has been around for longer.
> Also, he's right about the skeletal record: archaeology shows that humans lost about 1 foot of height when they switched to agriculture.
Again - making broad, sweeping evolutionary correlations does not an argument make. You have absolutely no idea what specific shifts in eating, living or working habits resulted in skeletal changes. These are the same weak arguments proponents of the Paleo and Atkins diets make. Could you make a case for dietary changes effecting our evolution at the time? sure. Could you point to vegetarianism as the cause? Good luck with that.
> Yes, much of India is vegetarian, but Indians tend to be pretty short, but then when they emigrate to western nations and adopt more western diets, their kids end up dwarfing them.
Yet again with the generalizations. If we humor this for a moment, there is a much stronger argument for the correlation[3][4][5][6] of poverty levels[1] and height[2] than there is for levels of vegetarianism. In fact, there is data to show the opposite[7][8]. Poor diet in general results in impaired growth, not vegetarianism. I'm not even sure what you could argue would be missing in a vegetarian diet that would effect bone growth as most point to calcium in milk and vegetarians can drink milk...
Drinking milk is a Western thing, and not normal in India. Also, vegans don't drink milk at all; they're morally opposed to using animals products like that (eggs too), so they want to eliminate that as a calcium source.
From an evolutionary perspective, we have evolved: we use tools and process nearly anything we eat anyway. Plants are the only thing we eat with minimal preparation, and only some of those.
When was the last time you had raw beef? for me, it was beef tartare a few years ago...
Raw grain? Nope, that's all processed, either by boiling, or grinding and turning into something else.
Homo Erectus was thought to have subsisted on raw meat. There's evidence of intestinal parasites that suggests such a diet.
Apparently, at some point, we decided to cook our meat, which reduced the parasite load and removed the need for low pH comparative to other carnivores.
But not too long ago, humans did eat some raw meats. Primitive hunters sometimes ate raw hearts, and drinking fresh blood was not unheard of. 1,000 years ago, the Mongols would sometimes nick their horses and drink blood to sustain them on long journeys.
It's also usually prepared in some way, whether it's flash frozen or treated with vinegar.
But, I guess my point is that the evolutionary argument doesn't really make sense in a world where we evolved tools and have been eating processed food for a long, long time.
Also, evolution happens a lot faster than people give it credit for. Something I read somewhere is that the genes for lactose digestion only started remaining "switched on" in adults like 8,000 years ago, and yet a third of the world now has this gene.
That's a really short time! That's not far from when we develop writing (around 6,000 years ago).
Paleontologists believe that it was the shift from fruits and nuts to a high protein diet of meat that allowed our brains to grow dramatically compared to other primates. We are omnivorous, and our bodies require a certain amount of plant matter ideally, but clearly meat is an integral component of a healthy human diet.
>Our stomach pH is very low, comparable to carrion eaters and some carnivores.
Hmm... this is how you get into an argument where people talk past each other. You may be correct when it comes to that little nugget of information, but when it comes to the larger context, that piece of information will not make sense to someone who has other contradicting pieces of information. ( for example a vegan who thinks that humans ought to have huge canines to be a carnivore).
Anyway it's unfair of me to critique your style/content of your argument without offering an alternative. How about this?:
Ask the person who is into the 'plant based' belief to conduct an experiment of eating only meat for 2 months and then report the results. i.e if both of you agree that most 'science' and 'research' is flawed. Of course it goes without saying that you too should have performed this experiment on yourself.
Side note - I have been carnivore for 6 years ( 99% of my diet is red meat, eggs and dairy ).
The current 'plant based' fad diet recommendations are backed up by some very poor science and may be seriously unsuitable for humans and for children in particular, nutrition-wise. Animal agriculture is not even a major source of human emissions so to call for changes to our natural diet seems very premature.