One of my favorite things to do is visit the zoo where I live in Knoxville when it first opens and the animals are most active. One recent weekend, the first thing I did was visit the chimpanzees.
Their breakfast was still scattered around the enclosure for them to find. Ripley, one of the male chimpanzees, quickly collected some fruits and vegetables, sometimes using his legs almost like hands. After he ate, he would grab fire hoses hanging around the enclosure with his feet and even hold pieces of straw and other toys in his toes.
I am a biological anthropologist who studies the biomechanics of the foot and ankle joint of modern humans.using the mechanical principles of movement to understand how forces influence the shape of our bodies and how people have changed over time. Your muscles, brain, and the way human feet evolved play a role in why you can't move your individual toes one after the other.
Comparing a person with a close relative
People primatesThis means that we belong to the same group of animals that includes apes such as Riley the chimpanzee. Actually, chimpanzee our closest genetic relatives, share almost 98.8% of our DNA.
Evolution is part of the answer to why chimpanzees have such dexterous toes while ours seem much more clumsy.
Our very ancient ancestors probably moved much like chimpanzees, using both arms and legs. But in time our bloodline began walking on two legs. Human legs must have evolved to help us maintain balance and support our bodies while walking upright. It has become less important for our toes to move individually than to keep us from tipping over as we move through the world in this new way.
Human hands have become more important for things like use of toolsone of the distinctive qualities of a person. Over time, our fingers became better at moving on their own. People use their hands to do many things, such as drawing, texting, or playing a musical instrument. Even typing this article is only possible because my fingers can make small, careful, controlled movements.
Humans' legs and arms have evolved for different purposes.
Muscles that move fingers or toes
Evolution has produced these differences by physically adapting our muscles, bones and tendons to better support walking and balance. The arms and legs have similar anatomy; both have five fingers and toes, which are driven by muscles and tendons. The human foot contains 29 muscles these all help you walk and maintain balance when you stand. For comparison, the arm has 34 muscles.
Most foot muscles allow you to point your toes down, such as when you stand on your tiptoes, or point them up, such as when you walk on your heels. These muscles also help the feet roll slightly inward or outward, which helps maintain balance on uneven surfaces. All of these movements work together to help you walk and run safely.
The big toe on each foot is unique because it helps propel the body forward when walking and has additional muscles just to move it. The remaining four fingers do not have separate muscles. Several core muscles in the bottom of the foot and calves move all four toes simultaneously. Because they share muscles, your toes can move, but not as independently as your fingers. The calf muscles also have long tendons that extend down to the foot; they're better at holding you and helping you walk than making tiny, precise movements.
Instead, six major muscle groups help move each finger. The fingers are separated by these muscles, which are located mainly on the forearm and are connected to the fingers by tendons. The thumb and little finger have additional muscles that make it easier to grasp and hold objects. All of these muscles are designed to enable careful, controlled movements such as writing.
So yes, I have more muscles that move my toes, but that's not the only reason I can't move my toes one by one.
Division of mental faculties
You also need to look inside your brain to understand why your fingers and toes work differently. A part of your brain called motor cortex tells your body how to move. It is made up of cells called neurons, which act as tiny messengers, sending signals to the rest of your body.
Your motor cortex produces many more neurons to control your fingers than your toes, so it can send much more detailed instructions to your fingers. Because of the way your motor cortex is organized, it takes more “brain power”—that is, more signals and more activity—to move your fingers than your toes.
Even though you can't grab things with your feet like Ripley the chimp can, you can see why.
This edited article is republished from Talk under Creative Commons license. Read original article.
