Humans aren't meant to eat meat

The argument

Human teeth did not evolve to eat meat. The anatomical comparison is the most direct evidence available about what a species is adapted to consume, because teeth are shaped by the diet an animal has actually eaten over evolutionary time. Carnivores such as dogs, tigers, and lions all have carnassial teeth, which are perfect for tearing and slicing meat. Humans do not have carnassial teeth at all. Although humans have canine teeth, they are not meant for processing meat — and the usual appeal to them collapses on inspection, since animals such as gorillas and deer have even larger and sharper canines while being vegetarian. The digestive evidence points the same way, and it is harder to dismiss than dentition because it concerns what the body does with food rather than how it is chewed. Our digestive systems are much more comparable to those of herbivores. In humans and other herbivores, salivary glands produce the enzyme amylase, which helps break down complex carbohydrates. However, there are no carbohydrates in meat, so carnivores do not produce this enzyme at all — digestion begins in the human mouth with a tool that meat gives it nothing to do. The rest of the tract is built on the same assumption. The human intestine is long and coiled in order to slow down digestion and absorb as many nutrients as possible from plant-based foods, whereas carnivores have short and straight intestines that move flesh through quickly. Carnivores also have the unlimited capacity to process and excrete cholesterol; humans do not have this capability, because plants do not have cholesterol and a plant-eating animal never needed a mechanism for disposing of it. Every structure from the mouth to the intestine is therefore specified for plants, which is why vegetarianism is not a deprivation but a return to the diet the human body was built for.

Premises

Counter-arguments

Without meat, we wouldn't have evolved to be the humans we are today. Humans probably were herbivorous at some point in the past, but a diet composed solely of vegetables and fruits isn't calorie-dense. The predecessor to Homo sapiens, Homo erectus, had "smaller teeth, reduced chewing muscles, weaker maximum bite force capabilities, and a relatively smaller gut" than earlier hominids. This can be explained by the increase of meat in their diet, which requires less force and time to chew than root vegetables. We don't need large carnassial teeth like other carnivores because we learned to process the meat instead of tearing muscle straight from an animal carcass. Our ability to process the meat probably led to structural changes in the skull and neck, including a larger, more developed brain. Moreover, cooking didn't exist until 500,000 years ago while Homo erectus have been around since two million years ago, meaning that we are capable of eating meat even without cooking it, which makes the meat even softer and easier to chew. Hence, humans are meant to eat meat and wouldn't have evolved to have the head and neck structure we have today without it.

Rejecting the premises

[Rejecting P1] Without eating meat, we wouldn't have evolved to be the humans we are today.