Can humans live without eating meat?

Never heard of vegetarians?

Vitamin B12 is a complicated vitamin with a unique absorption mechanism and a number of inactive analogues (molecules that appear to be active B12, but actually are not) that possibly interfere with its function. Vitamin B12 is generally found in all animal foods (except honey). Contrary to the many rumors, there are no reliable, unfortified plant sources of vitamin B12, including tempeh, seaweeds, and organic produce. One of the earliest studies conducted on vegans, from the U.K. in 1955, described significant vitamin B12 deficiency in the vegans with some suffering from nerve damage and dementia. This, as well as many case studies since then of vitamin B12 deficiency in vegans, and a great deal of other evidence detailed here, has led to the overwhelming consensus in the mainstream nutrition community, as well as among vegan health professionals, that vitamin B12 fortified foods or supplements are necessary for the optimal health of vegans, and even vegetarians in many cases. Luckily, vitamin B12 is made by bacteria such that it does not need to be obtained from animal products.

Despite the overwhelming evidnence that vegans without a reliable source of vitamin B12 are likely harming their health, some vegan advocates still believe that "plant foods provide all the nutrients necessary for optimal health," and do not address vitamin B12 when promoting the vegan diet. Other advocates acknowledge the need for B12, but only as an afterthought. And still others emphasize that humans need only small amounts of B12 and that it can be stored in the body for years.

While true that, at the time they become vegan, some people have enough B12 stored in their liver to prevent overt B12 deficiency for many years, people often misinterpret this to mean that you only need to consume a tiny amount once every few years. Actually, to build up such stores, it takes years of consuming B12 beyond one's daily needs (unless you are using supplements which can build up stores more quickly). Some people do not have large enough stores of B12 to be relied upon for optimal health even for short periods.

I invoke the wisdom of TSR to help me clarify this question. I hear some people saying that a healthy diet needs x component that can only be found in animals while others say that all components of a healthy diet can be found in non-animals. What's your stance? Can we live without eating meat?
Note: I am not asking whether or not we are designed to eat meat. I am asking if we can live without eating meat.
Make sure to back up your claims with empirical evidence.

Take a look at the following:
http://brown.edu/Student_Services/Health_Services/Health_Education/nutrition_&_eating_concerns/being_a_vegetarian.php

It was written by an educational institution so i'm confident that it is well researched.

A life without meat is not a life worth living.