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There's some down-thread armchair speculation about why humans have two kidneys. I found it interesting, but instead of conniving my own theory did some searchi
by avar 10y ago
There's some down-thread armchair speculation about why humans have two kidneys. I found it interesting, but instead of conniving my own theory did some searching.
The gist of it is that nobody seems to know, but the most simple explanation is that lateral symmetry is common in general because it's more efficiently encoded in the DNA. The organs & structures that don't come in twos are the odd exceptions, not the other way around.
1. https://www.quora.com/Why-is-it-that-humans-(and-many-animals)-have-two-kidneys-but-only-one-liver https://www.quora.com/Why-is-it-that-humans-(and-many-animal...
2. https://www.reddit.com/r/askscience/comments/po4v6/why_did_we_evolve_two_kidneys/ https://www.reddit.com/r/askscience/comments/po4v6/why_did_w...
- AstralStorm 10y agoMost probably the kidneys are vital enough yet inexpensive enough to allow a pair to exist. You do not get two hearts because that muscle is very expensive. Also because a vascular injury to a major artery will also end your life. Similar reason for the liver - too expensive and also easy to regenerate from a partial injury. The brain is well protected and partly redundant. Lungs are fully redundant and protected by the ribcage. Spleen is not critical enough, stomach can heal. The pancreas is probably an odd one.