Reoriented Use of Senses

Primates have certain senses that are more important than others. The shape of the face and skull in primates reflects the senses that are most important. It is important to realize that the shape of an animal is related to the activities of the animal.

All primates rely more on sight than any other sense. As a result, primate skulls are shaped in a way to maximize their vision. The eyes of primates are located in the front of the face, rather than on the side of the head as they are in dogs or horses. Due to the forward position of the eyes, primates are capable of stereoscopic vision, and thus they have depth perception.

Stereoscopic Vision
Hold your pencil or pen in front of the top of the computer screen. Look at it first with one eye and then the other. Now look at it with both eyes. Did you see a difference? What were the differences you noted?

Why would stereoscopic vision be important to a primate? Would it be important to a cow? Can you think of any other animals who have stereoscopic vision? Why would it help these animals?

The eyes of primates are oriented to the front and protected by a relatively thick bone. The bone surrounding the lateral side and back of the eye is called a post-orbital wall. The amount of boney wall surrounding the eye varies between primates. In some primates, there is only a bar of bone on the lateral side of the eye. This is called a post-orbital bar. In other primates, the whole side and back of the eye is protected by bone, thus they have a post-orbital wall.

Reduced Emphasis on Smell
Since the main sense used by primates is vision, the physical features related to smell are reduced in size. Primates have a reduced snout and the area of the brain related to smell is much larger than that area in a dog. Primates use vision and touch to explore their environment.

What senses do you think cats rely most on?
Why?

Prosimians Pongids Gibbons New World Monkeys

Old World Monkeys Primate Anatomy Locomotion Reoriented Use of Senses

Larger Primate Brains Primate Environments Dentition Primate Diets

"Social organization" Primate Evolution Infant-Mother Bond and Childhood Diurnal and Nocturnal Behaviors

Dominance and Hierarchies Human Organization as Bands One Final Thought Introductory Page

Prosimians	Pongids	Gibbons	New World Monkeys
Old World Monkeys	Primate Anatomy	Locomotion	Reoriented Use of Senses
Larger Primate Brains	Primate Environments	Dentition	Primate Diets
"Social organization"	Primate Evolution	Infant-Mother Bond and Childhood	Diurnal and Nocturnal Behaviors
Dominance and Hierarchies	Human Organization as Bands	One Final Thought	Introductory Page