Adaptation
The key to evolution is that organisms are variable. Nothing is fixed. This is clear if you
look around the room- some have black hair, some red, some are tall, and others are
short. Normal variation in physical characteristics in a species can be very large.
Adaptations are the features possessed by organisms that suit them for a particular
function. So, primates have evolved binocular vision and large brains for dealing with
their varied forest environments. Many primates have long, powerful arms and grasping
hands and feet for holding on to branches and for swinging through the trees. The
grasping tail found in some monkeys is an adaptation for even better movement through
the trees. Adaptations are constantly changing as the environment in which a species lives
changes. If the temperature becomes colder, individuals with longer fur may have an
advantage and become more common.
Primates have forward facing eyes, giving a wide overlap of the visual fields. This
binocular vision enables them to judge distance with great accuracy, such as when
jumping from tree to tree. Prey animals, such as deer, have eyes on the sides of
their head, giving a very wide, but mostly monocular, field of view.