If someone sketched a line vertically starting from the middle of the top of your head to between your feet, the left side and the right side would likely look about the same. And if we look at our skeletons, all the bones in the left side match the bones in the right side. Even our brains are symmetric with right and left hemispheres mirroring each other. But what is so significant about symmetry?
We don’t know the exact reason, but we have a few theories. One theory is that being bilaterally symmetric (meaning we are left-right symmetric) makes it easier for us to travel. Imagine if your left leg was five times bigger than your right leg. It would take more time and more energy to travel the same distance as someone whose legs are the same size.
A second theory is that it is easier for our brains to recognize symmetrical things regardless of what position we are in or what our orientation is.
It has been found that we are attracted to people with symmetrical faces rather than people with asymmetrical faces. In fact, symmetrical faces signify good health (which makes sense because from an evolutionary standpoint, organisms want to mate with healthy organisms to produce healthy offspring). This could be why we appear symmetric.
Another theory is that being symmetrical means there is a smaller amount of instructions needed to build us. The same instructions used to build our right hands could be used to build our left hands (but so that it is mirrored instead of exactly the same). Then, we could use the rest of the instructions for more important things such as our asymmetric internal organs.
Our heart, stomach and pancreas are on the left side of our body, and don’t appear symmetrical at all. Our gallbladder and most of our liver are on the right side and are asymmetric as well. Our intestines are shaped weirdly and our lungs appear symmetrical, but the left lung actually has two lobes whereas the right lung has three lobes. And although our brains look symmetrical, the right hemisphere and left hemisphere have different functions. People whose internal organs are reversed, a condition called situs inversus, are completely fine. But someone whose organs are not fully reversed will likely experience complications.
We do have two eyes that appear to be symmetrical and we could function with just one eye. But, with just one eye, we would lose the ability to understand the depth of objects. And we also have two kidneys and there are many people who have donated their kidney and have been fine with just one kidney. In fact, they seem to do better for 16 years but after 24 years, their renal (relating to kidneys) function may start to decline. (The theory on why some organs come in pairs is that if one organ fails, we can use the other as backup.)
An embryo appears perfectly symmetric. In the pit of the embryo, there is a node lined with hairs called cilia. The hairs tilt from right to left to push the fluids along. This activates genes in the left-side of the embryo to make proteins. A few hours later, the left side of the embryo is chemically different from the right side of the embryo even if the embryo looks symmetric from the outside. This chemical difference is what leads to the development of our asymmetric organs.
Our internal organs are not symmetric because unlike our exterior, they do not have to worry about things such as walking, swimming, being attractive, or the force of gravity pushing down on us. They just have to worry about being functional and making room for the other internal organs.
Even though symmetrical things are usually more attractive, asymmetrical things are just as important for us.
Vaageesha Das is a junior at Morgantown High School.
Today’s information comes from:
- Adams, C. (2018, June 15). Why aren’t internal organs symmetrical? Retrieved January 04, 2021, from https://www.straightdope.com/21344489/why-aren-t-internal-organs-symmetrical;
- Dominguez, T. (2015, July 27). Why Do Some Organs Come In Pairs? Retrieved January 04, 2021, from https://www.seeker.com/why-do-some-organs-come-in-pairs-1792645639.html;
- Roos, D. (2020, December 17). Why Do We Get So Much Pleasure From Symmetry? Retrieved January 04, 2021, from https://science.howstuffworks.com/why-do-get-so-much-pleasure-from-symmetry.htm;
- TEDEducation. “Why Are Human Bodies Asymmetrical? – Leo Q. Wan.” YouTube, TedEd, 25 Jan. 2016, www.youtube.com/watch?v=hLgh1pJP5ng.;
- Than, K. (2005, December 21). Symmetry in Nature: Fundamental Fact or Human Bias? Retrieved January 04, 2021, from https://www.livescience.com/4002-symmetry-nature-fundamental-fact-human-bias.html
