1,2,3: -- All of these are comparing a human to an entirely different species, of which the common ancestor is in the neighborhood of 1.5 million years ago. By this same logic, bears and dogs (share a common ancestor of closer lineage, look at the muzzles of both species) should be compared. A grizzly is often strongly herbivoric, eating meat only seasonally when it is most available. Black bears almost never eat meat....yet they are pure muscle, one of the most powerful animals on Earth.
4. Our bodies don't have any traits of a carnivore.
-- Not true. Our dentition is poor for eating plants. We also have a small, more acidic stomach, no ruminant structures, no cud processing. Also our plant eating is very selective. Checkout what a bear or deer can eat that we cannot....pickup an acorn snack and see how that goes
5. Our digestive tracks represent that of a herbivore, not a carnivore.
-- See above. Not remotely true. I have gutted deer, bears, rabbits, elk, etc. The cud processing, compartmentalizing stomach is the evolved state of a herbivore. Eating constantly is the rule of the day for most herbivores, due to the low calorie content of most real-world vegetable matter. The digestive track is very long, especially in the beginning stomachs, usually multiple....a carnivore, like a wolf or lion, is longer on the BACK end, like our small and large intestines are.
6.We can survive off from meat. No problem. I'm sure other primates could too.
7. Meat was essential for survival in places and during times when plants weren't available.
-- Even though we CAME from equatorial Africa, many estimate that only a few thousand initially left. In other words, we were NOT yet a very successful species....what separated us as a species was the ability to thrive in cold, short growing season places, and to be strong hunters in the initial cradles of civilization. It is not that we ate meat "when plants were not available", as this would be about 60% of the year in most places outside the equator....and it is in these places where our population exploded. We lived that way for a very long time in between leaving the equator and civilization coming about, and we survived from hunting and gathering roots for a good part of the year. I haven't seen any research that proves we did otherwise on scale.
10. The story is that if we fast, the body ends up eating a little bit of muscle after glycogen runs out. Ok? So what happens if we don't have much protein, but maintain enough glycogen to run off? What is considered a lot? Why? Where are the numbers coming from? Says who? Have they identified a cause affect relationship?
-- I am a huge fasting advocate. I think the idea that we, as such successful mammals, start to CONSUME our own bodies in massive amounts if we go a day without food is without evolutionary basis. An animal that starts to lose "fitness" in the evolutionary sense if it goes a day without eating is an animal that won't be around for very long. It was likely very common for our ancestors to go days without food, even weeks in a bad season....and food would have been rationed to women and children first, so especially in the case of younger males, fasting and gorging was likely the rule most of the year.
11. Has anyone ever identified a cause affect relationship where something bad happens if you don't eat meat?
-- Yes, me.....I was a vegan for over 3 years, prior to going paleo....here is the unvarnished reality:
As a young male with the calorie requirements I have (and yourself), you have really 2 choices. Number one is that you stick to "real plant food". This means nothing processed, no shakes, no soy industrial trash, etc....If you do this route, as I learned the hard way, you will be a very weak, skinny guy with bad skin and low testosterone....option two is that you do a "hacked version" of vegan, whereupon you use all kinds of industrial food system loopholes to "stay vegan", whilst trying to be ripped up. This means a lot of soy shakes, eating 10 bananas at a sitting to refill glycogen after a workout, eating a lot of Tofurkey. If you do this, your gut will be roadkill, you will have a lot of muscle and also a lot of fat, and again have low T due to the soy intake.
I have yet to meet a young vegan male that doesn't fit one of those two approaches...if you are 55 and a female, with 1400 cal a day as your requirements, then yes, you can eat lettuce all day and probably feel fine. You will need to supplement with B and iron, but you won't be a tubby pale ball of cookie dough like I was as a vegan years ago
12. As discussed in PB, our ancestors got A LOT more physical activity in than we do today.
-- Yes, but it was selective from the research I have seen....the young and capable were likely tasked with doing everything, while those older (we didn't all die at 30) were likely much more lazy....also, this only speaks to the VERY high caloric needs of those in any given tribe that keep it running....see above for what this means.
As for the protein stuff, I have always considered that to be garbage. I eat a lot of protein, about 200g a day, but I do that because it is healthy and because protein is the preferred macro of the body. I don't think it's necessary to eat that much, but it is available to me in very lean form (rabbit) in abundance.
I enjoy the discussion as well though. Some of this stuff needs to get debated to help us see the forest a little more than the trees....if I see one more "carbs vs fat" discussion on here I am going to hang myself with dental floss.
"Carbs are the preferred macro due to the Krebs/Randle/Krusty the Clown cycle.....blah, blah, blah"
Don't eat for 18 hours, then go deadlift 3x bodyweight, then eat a Ribeye and some fruit, then shut the hell up and do it again tomorrow.
Done. Diet book written
"Man is born free.....but everywhere he is in chains."