Creative Destruction

June 16, 2006

Oh, lemon

Filed under: Evolution — Adam Gurri @ 2:28 pm

Taking a look at this chart of the stages of development among different species' embryos has piqued my interest in embryology.

However, I'm having difficulty finding anything which discusses exactly what it is that I'm interested in.

It seems to me that the similarities in the different stages of gestation are less important, ultimately, than the differences. To rephrase: the similarities are fine evidence of an ancestral tie, but the question is, why do the deviations exist?

The real question I'd like to ask is this: is it possible that the only difference between one moment of development and the next was a mutation in the female, which caused a change in how the womb and fertilized egg interacted? Could the primary mutation have been passed down through the females in this manner, since both genders obviously pass through this period of incubation?

Of course, in the case of a bird or fish or reptile, it seems less likely–unless it was some property about the egg itself.

I'm not really sure where to look where these questions are concerned, however.

Cross Posted at: Sophistpundit 



  1. Yes!! Very good Adam. Your theory is interesting and shows brilliant reasoning within the context of evolution. Unfortunately the factors that seem to way heavily in ontogeny are all self contained within the embryo. Our physiology (well not mine, but that of all women out there) seems to deliberately prevent “the womb and fertilized egg” from interacting. Hence the placenta, amniotic fluid, etc. Indeed if any aspect of our resulting physiology was dependent on evolved conditions within the wombs of our mothers, all those test tube babies out there would exhibit some deviant physiology (which to my knowledge they don’t). The factors that seem to influence an embryo’s development are all pre-scripted in the embryo’s genes. They are called transcription factors, and determine which genes are expressed in which cell (thereby having some cells become liver cells while others in the same embryo become muscle cells). Regardless, Developmental Biology is the hot bed of new ideas in evolution. The mystery of how a single fertilized egg with a complete genetic recipe becomes the fully developed organism is wildly complex and surprisingly misunderstood.

    Comment by Peter — September 24, 2006 @ 11:07 pm | Reply

  2. Also the chart you were looking at was drawn by German zoologist Ernst Haeckel. He was trying to further his theory of Recapitulation wherein as a fetus develops it follows it’s full evolutionary lineage exhibiting at each stage in it’s embryonic development various stages in the physiological evolution of it’s species in general. This does not happen as it turns out. Yes early in our embryonic development we develop gill slits, we do not however develop gills. Check out wikipedia: recapitulation theory for some good information on the abandoned theory.

    Comment by Peter — September 24, 2006 @ 11:16 pm | Reply

  3. Indeed if any aspect of our resulting physiology was dependent on evolved conditions within the wombs of our mothers, all those test tube babies out there would exhibit some deviant physiology (which to my knowledge they don’t).

    Are you serious?

    Test tube babies, in the real world, are eggs that are fertilized in a test tube, but then implanted into a womb. There is no such thing as a test tube baby that hasn’t grown to viability within a womb.

    Comment by Ampersand — September 25, 2006 @ 2:37 pm | Reply

  4. I am serious. I was speaking of hereditary traits passed on from parent to child. If a child’s phenotype is at all dependent on the genotype of the surrogate womb in which it developed rather than on its own genotype, then an egg implanted in a foreign womb would exhibit physiological variations deviant from its genetic lineage.
    This is a ridiculous oversimplification, but, say you were a test-tube baby whose genetic parents both had blue eyes (as did everyone in their respective family history). You, however have brown eyes, just like you’re surrogate mother. At this point one might begin to wonder whether eye color is dependent on the individual’s genes or the genes of the woman who carried said individual. Sorry to be vague.

    Comment by Peter — September 26, 2006 @ 2:03 am | Reply

  5. Oh, sorry – I misunderstood what you were arguing.

    Comment by Ampersand — September 26, 2006 @ 9:43 am | Reply

  6. I heard that a the egg that has been fertilized by both parents in a tube that is inserted in the serrogate mom, doesn’t get the traits of the serrogate mom bcuz both dna (genes) are from the woman & man who made the baby. Example “serrogate mom is just renting out her womb for a fetus that was scientifically arranged”. Eh its a way I see it. Lol

    Comment by Sommer — July 1, 2009 @ 6:58 am | Reply

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