You are not currently logged in.
Access JSTOR through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Morning Sickness: Adaptive Cause or Nonadaptive Consequence of Embryo Viability?
Samuel M. Flaxman and Paul W. Sherman
The American Naturalist
Vol. 172, No. 1 (July 2008), pp. 54-62
Stable URL: http://www.jstor.org/stable/10.1086/588081
Page Count: 9
You can always find the topics here!Topics: Embryos, Pregnancy, Financial investments, Signals, Modeling, Viability, Ecological competition, Nausea, Evolution, Vomiting
Were these topics helpful?See something inaccurate? Let us know!
Select the topics that are inaccurate.
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
Abstract: “Morning sickness” is the common term for nausea and vomiting in early human pregnancy (NVP). Recent interest in why NVP occurs—that is, in the evolutionary costs and benefits of NVP—has spurred the development of two alternative hypotheses. The “prophylaxis,” or “maternal and embryonic protection,” hypothesis suggests that NVP serves a beneficial function by expelling foods that may contain harmful toxins and microorganisms and triggering aversions to such foods throughout pregnancy. The alternative “by‐product” hypothesis suggests that NVP is a nonfunctional by‐product of conflict—over resource allocation—between the pregnant woman and the embryo. The critical predictions of the prophylaxis hypothesis have been developed and tested, whereas the by‐product hypothesis has not been subjected to similar scrutiny. To address this gap, we developed a graphical model and used it to derive predictions from the by‐product hypothesis under two different assumptions, namely, that NVP is either (i) a by‐product of current conflict between a pregnant woman and an embryo or (ii) a by‐product of honest signals of viability produced by the embryo. Neither version of the by‐product hypothesis is fully consistent with available data. By contrast, the timing of NVP, its variation among societies, and associated patterns of food cravings and aversions are consistent with the prophylaxis hypothesis.
© 2008 by The University of Chicago.