It would have been nearly impossible in most of the earth (availability of food sources) to follow a vegan diet and not starve before the age of the modern grocery store.
Veganism is a modern day and artificial life-style for childless, EV driving, inner city folks unsure about the gender. It makes them feel good or even feel superior by not killing animals and for environmental reasons (mostly philosophical, not health), the latter being all BS BTW. You don't put cows on prime agricultural land. In fact, as cows are fed and poop all over the crap land, they usually RAISE the quality of the soil (total opposite of what the environmental argument is).
We have canine and incisor teeth, stereo scopic vision for a reason, like all predators.
How can you tell if someone is a Vegan?
You don’t have to, they tell you.
The concept of avoiding animal products which is the religious basis for vegetarianism predates the term and practice of veganism but prohibitions against meat eating and animal sacrifice can be traced back to ancient times in various cultures. Vegetarianism has roots in ancient religions and philosophical traditions like Hinduism, Buddhism, and Jainism, as well as the ancient Greek philosopher Pythagoras. So are you talking about veganism or vegetarianism ?