Humans may not need meat but they definitely like it.

Most people when given the chance will choose mat rather than just vegetable alone .With increasing affluence the nations of the world are consuming in creasing amounts of animal products. But this does not
always mean that there is more usable protein in the diet. More often animal protein merely replace vegetable and cereal protein and dramatically increase the fat consumption of the diet.
All animal products are rich in fat .Not just the visible fat 'hat you see in the fat around a piece of steak or bacon even  a piece of lean beef has a fat content of 10 %  but did you ever see a fat vegetarian?Meat,pouetry  and fish were are not originally part of man's diet. Our teeth evoloved to deal with vegetables and not flesh. Our digestive systems are those of foragers ,not hunters. We cannot foage  ourselves on meat and than go without using for many days as other ....do  .
But meat is highly concentrated form of nutriment and is also among the most appetising of food in average diet .The flavour and smell of meat have encouraged many ways of eating.