The attachment point of the umbilical cord in a baby girl is very close to where her own baby would develop. Is there something in the evolutionary history of mammals that explains this, or some anatomical constraint? Or is it just a coincidence?

  • $\begingroup$ I would say that they are not that close. Yes they are both around the abdomen, but the navel is central to the abdominal cavity and the uterus is quite low in the pelvic cavity, in a non-pregnant woman, (it is even below the pelvic brim, and not even in the peritoneum). $\endgroup$ – jds Dec 24 '12 at 20:35

I would say it is a coincidence because:

  1. the navel is in the same place in males, so if it was there for some evolutionary advantage the charachter would be sexually dymorphic, which clearly is not the case.
  2. I cannot think of any specific function of the navel that is related to pregnancy or delivery (or of a specific function of the navel at all for that matters)
  • 1
    $\begingroup$ Why would it be dimorphic even if it didn't carry an advantage? Usually, sexual dimorphism has to be selected for. Even if the advantage was only to the female, why would the SRY gene code for anyplace else? $\endgroup$ – Chris Wenham Dec 28 '11 at 22:44
  • $\begingroup$ @C. Lawrence Wenham: I'm not sure I follow you... what I meant is that if the position of the navel was selected because it was somehow advantageous for pregnancy I would expect the selection pressure not to exist in males... $\endgroup$ – nico Dec 29 '11 at 0:44
  • $\begingroup$ @nico unless the locus for naval position wasn't sex linked, in which case males would have it in the same place as a side effect of selection for that location in females... $\endgroup$ – Rik Smith-Unna Jul 25 '12 at 7:13

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