Meat-eaters: have claws
Herbivores: no claws
Humans: no claws
Meat-eaters: have no skin pores and perspire through the tongue
Herbivores: perspire through skin pores
Humans: perspire through skin pores
Meat-eaters: have sharp front teeth for tearing, with no flat molar teeth for grinding
Herbivores: no sharp front teeth, but flat rear molars for grinding
Humans: no sharp front teeth, but flat rear molars for grinding [we're talking about actually sharp teeth, not so-called human “canine” teeth]
Meat-eaters: have intestinal tract that is only 3 times their body length so that rapidly decaying meat can pass through quickly
Herbivores: have intestinal tract 10-12 times their body length.
Humans: have intestinal tract 10-12 times their body length.
Meat-eaters: have strong hydrochloric acid in stomach to digest meat
Herbivores: have stomach acid that is 20 times weaker than that of a meat-eater
Humans: have stomach acid that is 20 times weaker than that of a meat-eater
Meat-eaters: salivary glands in mouth not needed to pre-digest grains and fruits.
Herbivores: well-developed salivary glands which are necessary to pre-digest grains and fruits
Humans: well-developed salivary glands, which are necessary to pre-digest, grains and fruits
Meat-eaters: have acid saliva with no enzyme ptyalin to pre-digest grains
Herbivores: have alkaline saliva with ptyalin to pre-digest grains
Humans: have alkaline saliva with ptyalin to pre-digest grains
Source: A.D. Andrews, Fit Food for Men, (Chicago: American Hygiene Society, 1970)
The reason I asked for people to justify their eating of meat is that this is the first logical step in any of these debates. It is not up to me to tell you why your behavior is unjustified before you have even attempted to justify it yourself. Of course, whether or not humans evolved to eat is a separate question from whether or not it is moral to cause unnecessary suffering.
You can deride moral beliefs as mere "opinions," but moral propositions -- like all propositions -- contain ontological commitments. Those moral propositions that are founded upon false ontological propositions are bad moral propositions. Opinion doesn't come into that equation. Those who value their own suffering but do not value the suffering of others have breached logic and upheld falsehoods.