Vegetarianism started in ancient India and Greece. Now it is very widespread.
I wonder what was their reason for abstaining from meat  at that time
They didn't want to kill any animals and it was supported by religious groups.
thats great, it means it started out as a social cause
Exactly, although following Christianization of the Roman Empire vegetarianism almost disappeared from Europe.
Wow!, i can't believe that Christianization had such a profound event that shook even their social fabric
Yup, vegetarianism reemerged during the Renaissance and grew during the 19th and 20th centuries.
Amazing information, now im anxious about becoming a vegetarian