In January 2014, the popular Youtube channel Vsauce (Michael Stevens) posted a video where he tackles the question, “Why is your BOTTOM called your bottom when it’s in the MIDDLE of your body?” Check out the video for yourself at the following link: https://youtu.be/xKg9Vl_Wg5U
Michael’s exposition of this topic grabbed my attention when he highlights the uniqueness of the bulbous human bottom and how it plays a dynamic role in why we humans walk upright on two feet instead of all fours. Our bodies are remarkably well suited for walking upright and our prominent bottoms helps us do this. Subsequently, the rear end is anything but the bottom of your body.
Let’s explore this linguistic conundrum. Using the word "bottom" to refer to your posterior is relatively new. The word “bottom” comes from words meaning; ground, foundation, the lowest part. If we consider our bottom to be the end of our body when we exclude the limbs, then indeed this does make a little more sense. The word “bum” predates the word “bottom” by quite a bit and is an onomatopoeia as it is echoic of buttocks slapping against a flat surface. Considering this, it is not too far of a stretch then to see where we get our American English slang “Bum” referencing to a person who sits around all day or, in other words, a lazy or useless person. r bodies are remarkably well suited for walking upright and our prominent bottoms helps us do this. Subsequently, the rear end is anything but the bottom of your body.
So back to why our human rear end is so magnificent! For one, its shape makes us different and unique within the vast animal kingdom. Its particular shape comes from the glut med and glut max muscles (and fat). Evolutionary psychology suggests that our attraction to full firm bottoms on potential mates was probably naturally selected. People in the past who probably liked big bottoms propagated their genes quite well and had reproductive success! A rear end full of shapely fat is a reflection of health and youth. And a great energy reserve. And reserve comes in handy with scarce food or during pregnancy or breastfeeding.
Secondly, our amazingly designed bottom allowing us to be bipedal gives us the great advantage to keep our torso balanced while moving. The requirements supporting this demand lend us to significantly larger muscles in our bottom thus making us the superior animal in mastering our upright posture.
Another reason our prominent backsides can be credited for our survival would be its remarkable endurance capabilities. Compared to horses and other quadrupeds, humans can reach impressive long distance aerobic endurance running speeds. In fact, the Man versus Horse Marathon held in the Welsh town of Llanwrtyd Wells every year has demonstrated that a human being can beat a horse in a race over a 22 mile distance (https://en.wikipedia.org/wiki/Man_versus_Horse_Marathon). Above and beyond other animals humans can sweat to release body heat, we have short toes for more efficient force over longer duration of running, we have short neck ligaments keeping our head perfectly stable while running, our uniquely designed Achilles tendon converts elastic energy into kinetic energy, and our tall narrow waists provide great counter rotation for our legs as they move through strides. When we consider our Neolithic ancestors and how hunting and gathering was likely necessary for survival we can thank our impressive butts for its superior endurance when it comes to running. One of many things that makes the human body amazing!