Meat-eaters say that people must eat a lot of meat to stay healthy. The paleo diet, high in fat and protein, is really a meat-based diet. Bugs are out of the question, even though they are very nutritious and less costly to produce than traditional big farm animals, because it's unpopular among the target audience, which is most likely Westerners. On the opposite end, vegans say that people must eat a plant-based diet; that 100% plant-based is "ideal". I think they are both wrong. The most optimal human diet is somewhere in the middle, not vegan or meat-based, depending on biological adaptations and cultural conventions of different human populations that facilitate primarily carnivorous or herbivorous eating habits. This assumes that humans don't use any tools to facilitate a 100% plant-based diet.
Cats are obligate carnivores. They can't synthesize their own proteins. They must eat meat, because meat contains complete proteins. Humans can synthesize their own proteins from the amino acids provided from plants. This may suggest that humans naturally are herbivores, but the problem is, even though the human gut bacteria can synthesize vitamin B12, the vitamin B12 cannot be absorbed as the bacteria exist in the colon, not the small intestine, and thus the body will develop macrocytic anemia because of vitamin B12 deficiency. Eating solely from plant-derived foods is insufficient. Naturally, a grazing animal will pick up the bacteria, and the vitamin B12 will be absorbed into their bodies, and humans will eat the grazing animals. Unfortunately, this is not sustainable nowadays, because there are too many of us, and we really should not produce so many of them to feed us because of environmental issues and limited resources. Instead, we must find a new way to derive our vitamin B12, using fortified food products, supplements, or termites and grubs. Given that it's natural for humans to use tools, humans can rely more on their tools to facilitate a 100% plant-based diet. In other words, a well-managed vegan diet is natural for us, because it is the result of our reasoning and tool use proficiency. However, the same level of tool use is not widespread, so some humans may be able to go on a vegan diet, while other humans really should remain as flexitarian omnivores because of economics and limited resources in an area.
The Ethics of Eating Meat
Nature is amoral
Morality cannot be ascribed to nature. Nature is neither good nor evil. It is beyond the scope of morality.
We are wicked and selfish
Humans are born evil. They are selfish and self-centered, the exact opposite of altruism. But the good thing about morality is that it suppresses the evil natural state and forces humans to work together to achieve a common goal, putting the goals of the community above the goals of the individual. By working together, humans create civilization, peace, and harmony.
Killing animals for nutrition is not speciesism
Speciesism is belief that animals are inferior to humans in a sense that they are less important in the ecosystem. Many animals are very important in the ecosystem, and we humans depend on them for our survival like using bees to pollinate our plants. Transporting bees or pest predators (chickens) to an unknown location against their will may be a form of animal exploitation and injustice, but they provide an important role in the anthropogenic biome, also known as the farm. So, essentially we are being "cruel" to them simply because we are violating their free will, even though we place them in a position so we don't die because of crop failure due to unwanted pests.
The Negative Emotions of Taking Another Life
The YouTube video suggests that humans are not carnivores, because they get emotional when they have to take a life. However, I think the video is missing the point that humans are cultural as much as biological creatures. Maybe the women in the culture are conditioned to think that killing anything anthropomorphic is wrong. Personally, if it were my own mother, she'd have no qualms about killing, scaling, and de-gutting a fish; and when she was younger, she raised a chicken as a pet and used the chicken to lay eggs.
Pure altruism is unnatural
Altruism is natural, but pure altruism is not natural. Nature is not purely, completely altruistic. For altruism to occur in a species, there must be an implicit benefit to the species. For us to be altruistic, there must be an implicit benefit to us. If ethical vegans and animal rights advocates believe that humans must serve the welfare of animals, allowing them to live at the expense of human life, then humans might as well just kill themselves. Though, since some ethical vegans and animal rights advocates believe this, they should be the ones to kill themselves, because they would be doing a great favor for the animals. Less of humans, more of other animals. Simple as that.
The Three N's of Carnism
In the definition of carnism, meat-eating is natural, normal, and necessary. But even chimpanzees dig for termites. Does this mean that they view termites as inferior? No. Termites are important, necessary, normal, and natural. Termites also happen to contain vitamin B12, which is something that vegans often lack because they emphasize too much on not taking any animal's life. So, they take vitamin B12 from bacteria. Human gut bacteria do synthesize vitamin B12, but it isn't absorbed in the body. It's just released in the poop. Humans aren't coprophagic by nature, so eating their own poop is unreasonable and dangerous. If other animals pick up the vitamin B12, then there should be no reason why humans shouldn't eat the animals that pick up the vitamin B12. In this situation, eating meat is perfectly natural. How can something be inferior if humans biologically rely on it? We often take for granted that humans have free choice that we can pursue any kind of food, but in reality, this free choice is constrained by our own biology. That said, because termites are a rich source of vitamin B12 and chimpanzees just happen to eat termites occasionally, we should eat like the chimpanzees, our distant cousins in the evolutionary tree. We should end this taboo against bug consumption. We can't rely on factory-farmed animals, because they tend to live in filthy conditions and require antibiotics, which may also kill their gut flora. While pasture-fed meat does allow animals to eat more naturally, it is not sustainable for our big human population that demands more meat than necessary. Animal products are required in the diet, but our culture is overdoing it because of commercialism and consumerism. And thanks to modern tool use, animal products become unnecessary in the diet, thereby making veganism feasible.
We should end this taboo against bug consumption in Western culture.
Eat animals, but be mindful that it is immoral
Eating meat is undoubtedly immoral, because we humans have defined morality as "ending suffering in all living things". That is, our natural state is immoral, because we have to take another animal's life to feed ourselves. But don't worry. With our smart brains, we have invented a way to bypass our evil natural state. We just use vitamin B12 supplements derived from bacteria. Now, we can be moral, even though getting vitamin B12 from bacteria directly is not something humans are evolved to do, as humans aren't evolved to eat their own feces.
Nature is NOT morality.
Humans by nature are born evil. Empathy is innate, because of mirror neurons. But morality is not innate. It must be learned culturally to maintain social agreements among humans. Why is murder wrong? Some people may say that murder is wrong, because the victim is suffering. I say murder is wrong, because our mirror neurons enable us to feel pain in the victim, hence empathetic towards the victim, to protect ourselves from revenge. We know that when we are afflicted, we will try to take revenge on other people, so by minimizing harm to others, they will not harm us. Taking revenge on something requires the ability to remember the past and plan the future, and this cognitive ability, which exists in the prefrontal cortex, may not be present in other animals. So, animals can feel suffering, but they may not be able to plan for revenge for a previously felt pain. So, there is no social agreement between humans and animals based on the fear that animals can take revenge. Though, I think humans anthropomorphize non-human animals to the extent that, when an animal attacks a human, other humans would take revenge and kill the animal. Anyway, even though human nature is fundamentally evil, humans must strive for the opposite of that. Humans must strive for morality. In the past, we humans ate meat, because we didn't have a choice. We occupied a specific ecological niche in life, and that niche did involve animal products. But now, we know why meat was nutritious and can use this knowledge to circumvent our omnivorous biology, so that we don't have to eat meat and still live happy, healthy lives. Only in our current situation, meat is unnecessary for survival. Why eat meat when you can eat a well-planned vegan or flexitarian omnivorous diet? (I must mention "well-planned", because too many vegans on YouTube promote unhealthy fad diets, such as the RawTill4 diet. Those vegans are bad advocates for veganism.)