Hey @Stewie, welcome to Fluther. It’s quite possible for humans to survive on a vegetarian diet. Majorities of populations worldwide did this for most of human history out of necessity. Very often, red meat was for rich people, only for the masses on special occasions and feast days. I know at least half of my ancestors were strict vegetarians going back many generations. I have been vegetarian for more than half my life. There are many vegetarian sources of protein. It can be found in lentils and beans, pasta, whole wheat bread, eggs, dairy products…and even vegetables themselves often have more protein than you would expect.