The Opposable Thumb
1991 Woodrow Wilson Biology Institute
The goal of this activity is to provide students with various opportunities to understand the physical importance of the opposable thumb among primates.
A discussion of primate characteristics is often included during units on human evolution. One of the characteristics most often identified as being typically primate and having played a role in human evolution is the opposable thumb. It is argued that the eye-hand coordination made possible by both stereoscopic vision and a grasping hand permitted primates to exploit arboreal habitats in a more efficient fashion. That same hand is used by humans today to manipulate tools and, in turn, the environment with a great deal of dexterity.
When students first hear or read about the opposable thumb during discussions of human evolution, they may perceive it as an anatomical fact with little seeming importance. In this activity, students will discover which of their simplest daily activities are possible only because of their opposable thumbs, which activities take longer without the use of an opposable thumb, and what sort of human activities would not be likely in the absence of an opposable thumb.
- masking tape
- paper clips
- zip-lock storage bag
- plastic fork and knife
- small amounts of food items to be cut
- stopwatch or clock with a second hand (optional)
Tape your thumbs to the sides of your hands. Then, try to complete the tasks that are listed below. Be careful not to use your thumbs. After completing each item, write out the answers to the following questions:
- A. Is the task more difficult with or without an opposable thumb?
- B. How did you have to change your usual technique in order to complete this task?
- C. Do you think organisms without opposable thumbs would carry out this task on a regular basis? Why or why not?
- Pick up a single piece of paper. Put it down on your desk.
- Pick up a pen or pencil from the table top. Use it to write your name on the piece of paper.
- Open a book. Turn single pages in the book.
- Pick up a piece of chalk. Write your name on the board.
- Use a fork and knife to cut a food item into small pieces.
- Tear off a small piece of tape.
- Turn on the water faucet. (Complete activity #8!) Turn it off.
- Moisten a paper towel and wash a table or part of the bench. Dry it.
- Sharpen a pencil.
- Cut a circle out of a piece of paper using scissors.
- Pick up all the scraps from activity #10 and throw them into the recycling box.
- Comb your hair.
- Put on make-up (optional).
- Pick up one paper clip. Clip a pile of papers together.
- Tie your shoelaces.
- Button several buttons.
- Zip up your jacket.
- Blow up a balloon and tie it.
- Put on earrings (optional).
- Close a zip-lock bag.
The preceding activities can be performed in a variety of ways depending on the amount of time available. Here are several possibilities:
- Students may work individually at their desks during a class discussion. Each student can choose one or two activities to perform on their own and report their findings orally to the group when complete.
- Students may work in groups of two or three. One student is responsible for recording the "results" (the answers to those questions listed in the directions)while the remaining students in the group perform the activities.
- Working in groups, students can use stopwatches to compare the amount of time it takes to complete these tasks with and without the aid of their opposable thumbs.