ANSWERS: 2
  • There is probably not a good answer for this question, other than, a common ancestor happened to be bilaterally symmetrical externally. Most living things are not symmetric - take plants and microbes, for instance. We are not completely bilaterally symmetrical, by the way. For instance, we are right or left handed, have one liver, one spleen, one gut/stomach, one heart and our brains have differing functions on either side.
  • Active swimming in a desired direction in water (or even passive overcomming of the drag of a current) requires less energy from bodies with bilateral symmetry. This may be the reason of the evolutionary benefit for the remote common ancestor.

Copyright 2023, Wired Ivy, LLC

Answerbag | Terms of Service | Privacy Policy