Why do most animals (including humans) have some duplicate organs (lungs,kidney) but only one of our most important organ (hearth).
In: Biology
Most larger animals have what is known as bilateral symmetry. Our left side is basically a mirror image of our right side. This symmetry applies to all of our organs, but sometimes the left and right versions have merged into a single organ. There is a left part and a right part to the brain. There is a left and right part to the heart. There is a left and right part to the intestine, the liver, etc. Now, in the case of internal organs, the line of symmetry is often not in line with the rest of the body. Sometimes one side may be smaller or perform a different function than the right, but they are all there.
Some animals do have multiple heart-like structures for various reasons, but consider this: how will a large animal survive a puncture would directly to the heart long enough to make a secondary heart a useful adaptation?
You bleed out in *seconds* when the heart itself is ruptured, having more hearts isn’t enough – you’d need entire redundant circulatory systems.
Your most important organ would most likely be your brain and central nervous system as it’s the only part that can’t be replaced. For the sake of the argument, the heart is almost a duplicate organ in itself. It has 2 sides that provide blood to different parts of the body. These 2 sides are separated by the septum. Why do we have 2 of some organs and one of others? Evolution, having 2 of some organs has given us an evolutionary survival advantage over having 1. These genes are more likely to survive and get passed down to offspring. Human anatomy today is the anatomy that was most likely to survive throughout our evolution.
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