Ask A Scientist
Why is the human body the way it is, as in shape and form?
Asked by: Matt Johnson
School: Owego Elementary School
Hobbies/Interests: Building things and skateboarding
Career Interest: An architect or skateboarder
Answer from Michael A. Little
Distinguished professor of anthropology, Binghamto
Human adaptation to the environment
Pennsylvania State University
Swimming, choral singing, antique toys and books
Wife, Adrienne, and two grown children.
Web page address:
Humans are mammals, which means that we have hair, we are warm-blooded, and mothers can feed their newborns with milk that mothers produce themselves. As mammals that have evolved through time, we are closely related to the apes and share many characteristics with them. Some of the apes walk on all fours and some swing through the trees with their arms (to brachiate), but as humans, we are upright and walk and run on our legs. We also have hands and fingers that can carry objects while we walk and perform very precise tasks (such as using tools and playing musical instruments), a large brain that requires a lot of food energy to operate, and the need to balance our bodies in a vertical position while we sit, stand, walk or run. Both our outside form and our inside structure are adapted to one another because of these characteristics which are uniquely human. For example, because we walk on two feet, rather than four, the feet must be shaped to balance the body (we have big feet), and the muscles in the legs (which are attached to the leg and hip bones) must work together to keep us from falling over. Our big brain and nervous system send the muscles signals that allow for continual adjustments to our balance. Our big brain and our keen senses (stereoscopic vision, stereophonic hearing, and touch) also allow us to use our hands in complex ways by manipulating the muscles that move the fingers in ways that we want them to move. Our head, which has so great an ability to think, see, hear, taste, talk, sing, chew, and smell, must be balanced on the top of a spinal column with all sorts of muscles and nerves to hold it up. Since our internal organs are vertical rather than horizontal as they are in other mammals, they must be positioned in ways to pump blood, digest food, and do other things while in a vertical position. Our bodies are continually troubled by gravity, where our most stable position is lying down. The shape of our bodies varies for a number of reasons other than because we stand upright. Men have larger muscles than women and these contribute to the form of the body. Both women and men have body fat, which also contributes to our contours. But women have more body fat than men and this contributes to their differences in shape. It is believed that women have more body fat than men because they need the extra stored energy for when they are pregnant or producing milk. The characteristics are called "adaptive" because they are valuable in allowing humans to survive and reproduce. We also find these differences in form and shape to be attractive in the ways that they contribute to the beauty of the human body.