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Externally, we (humans) look symmetrical. However, internal organs don't show the same patterns of symmetry (heart being on the left side while the liver is on the right side, etc.). It is a bit counter-intuitive to me that the exterior of our body seems to be mainly symmetrical while the interior is asymmetrical.

  1. What is the advantage of having bilateral symmetry in our body?

  2. Why don't all of our organs exhibit bilateral symmetry?


marked as duplicate by MattDMo, AliceD, WYSIWYG Aug 7 '15 at 5:15

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    $\begingroup$ Welcome to Biology.SE. One cannot believe (or not) in evolution, one can only understand (or not) evolutionary biology. $\endgroup$ – Remi.b Aug 6 '15 at 23:49
  • $\begingroup$ The question is interesting +1, I am just afraid that there are two questions in the same post...we'll see if it is an issue. I'd guess that bilateral symmetry was under positive selection for mobility purpose but it is just a guess. $\endgroup$ – Remi.b Aug 6 '15 at 23:50
  • $\begingroup$ I don't wan't to be a bummer but I think you can just skip the I understand/believe evolution part. And the last sentence as well. I edited your question, feel free to roll back if you preferred your version. There are probably a few other edits to improve the question. $\endgroup$ – Remi.b Aug 6 '15 at 23:56
  • $\begingroup$ That's fine, the question gets more clear after the edition. I am thinking that internal asymmetry has something to do with improving biological functions like metabolism and absorption and assimilation, but I have no idea for our external bilaterally symmetry. $\endgroup$ – Rescy_ Aug 7 '15 at 0:13
  • $\begingroup$ also Why are humans and almost every species on earth symmetrical? $\endgroup$ – MattDMo Aug 7 '15 at 2:24