Primate Evolution
Variation in the choices of food on a daily, seasonal, and yearly basis is one
of the greatest differences between primate species. Primate diets have
generally been divided into three main food categories-fruit, leaves and fauna
(including insects, spiders, and bird\'s eggs for the most part). The different
diets also are referred to as Frugivores, Folivores, and Insectivores (fruits,
leaves and insects respectively). These gross dietary categories are correlated
with aspects of primate activity patterns such as home range and group size.

There are different problems that have to be overcome in order to obtain a
balanced diet on a day-to-day basis. New leaves and mature leaves, for example,
may have different nutritional bases or availabilities. Some fruits appear in
large clumps while others are spread thinly over a larger area. Aside from diet,
primates have tended to either adapt through specialized dentition and digestive
systems or rely on a variety of different foods. Those that chose this second
route have tended to have larger brain sizes relative to their overall body
size. This may be due to the need to know where different types of food can be
found at different times throughout the year. Have you ever looked at a picture
of a gorilla or money that has what appears to be a "beer belly" look?

Those primates that specialize on eating large amounts of vegetation have
difficulty digesting their meals. Different solutions have been found including
double stomachs or multichewes, but the problem usually requires an individual
to sit back and let the digestive system work-and on the die expel gas. It
hasn\'t been until recently that it was realized that primates, who evolved in
the canopy, actually had a quite difficult time finding adequate nutrition. Due
to natural selection, which strongly favors those traits enhancing foraging
efficiency, and this difficulty finding sustenance, the characteristics regarded
as belonging to primates were evolved. Most primates species either maximize the
efficiency of their digestive track or maximize the quality and the volume of
food processed in a day. Also. Those species, which increase the volume of food,
consumed also tended to have larger brains because of a need to remember, not
only what, but also where good food sources are and when they are in season.

Knowing the trends of evolution, the next thing to do is to look at how it
relates to humans. It can be seen that out closest living relative, the
chimpanzee makes up 94% of his diet with plants. Most of this is fruit with high
sugar and fiber content, meaning that chimps take in hundreds of grams of fiber
per day; contrary to the 10 grams or less the advantage American consumes. This
suggests that our diet should be higher in vitamin C, pectin, and fiber like our
relatives in the wild. Ironically, the same natural selection, which favors the
most energy-dense and low fiber diets, may now be causing us to suffer from too
little fiber. Plants have been a major food eaten by primates. The primates were
almost exclusively herbivorous. A strong focus on plant foods is characteristic
of all primates-- and there is strong consensus that the primates were very
strongly herbivorous (Milton 1987, 1993). Many plants are lacking vital
nutrients, such as vitamins and the protein building blocks known as amino
acids, that the monkeys and other animals require. Some plants lack enough
carbohydrates to make them worthwhile as energy producers. Yet in all of these
cases the primates would still search for specific plants that exhibited one or
more of these traits, rather than just rely on the plant life that was within
easy reach. The fact that the primates would make an active search from a
variety of plants. One particular type of plant may have lacked was often
complemented by the positive aspects of another plant. For example, fruits are
low in fiber and protein and yet they are rich in valuable carbohydrates. If the
primates had relied solely on eating fruit then they would have lacked
sufficient protein and vital amino acids. To make up for that particular type of
shortage, the monkeys eat certain leaves that are high in protein and fiber and
that are also more abundant than the fruit. Together, the fruit and the leaves
make for a much balanced diet for the primates. In order for the primates to
rely on just one particular type of plant as a food source, the primates would
have to travel quite a distance to obtain enough food from multiple trees of the
same plant type. In addition, trees of a certain species tend