Have you ever wondered why we have thumbs? Do you think only humans have thumbs?  What if all animals had thumbs? Our thumbs are an example of an adaptation.  Our hands evolved over time (much like our eyes and other distinct features) to serve a purpose critical to our survival as a species.

Our thumb is what makes our hands so useful and distinct.  It is an opposable thumb, which means it can flex towards our other fingers, allowing us to hold and grasp objects. You can tell it is opposable because you can touch the tip of your thumb to each of your fingertips.  Your cat may have five toes on each paw, but their “thumb” is not in opposition to the other toes meaning your cat can’t grab things like you can. Some cats, called polydactyl cats, have more than 5 toes on their paws!

We evolved to have this type of thumb so that we could pick up and hold tools.  Tools were essential to our survival during our evolution because they helped us hunt, build, protect our families, etc.  Our closest animal relative, the chimpanzee, also has opposable thumbs as well as most ape species. They are able to use rudimentary tools, peel bananas, efficiently climb, and build shelters all thanks to their thumbs!

It isn’t just monkey’s and apes that have opposable thumbs. Koalas, giant pandas, opossum, and frogs in the Phyllomedusa family are some more examples of animals with opposable thumbs.  All these creatures have one thing in common:  they all climb!  Climbing was so important to their survival that the evolution of an opposable thumb was essential.  Having thumbs helps them in a lot of ways. Imagine a panda grasping some bamboo, their main food, and you can see how the thumb benefits them.  Opossums actually have thumbs only on their back feet specifically to help them climb super-fast.  This is helpful for avoiding predators.

Can you imagine what your pets could do if they had thumbs? Instead of fetch, you could play catch with your dog because he would be able to catch and throw! I bet he could turn the doorknob and let himself out in the yard by himself too!  Take a few minutes and imagine what life would be like if all our pets had thumbs! What about the opposite?  Is there anything you would no longer be able to do without a thumb?