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Embryonic Brain Development and the Myth of 40 Days

Hang around anti-choice activists long enough (or let them hang out long enough around you), and you’ll hear one say something like this:

Brain waves have been recorded at 40 days on the Electroencephalogram.

The medium-form version of the claim goes something like this (see Our Lady of Mt. Carmel Parish):

40 days: Brain waves can be measured with an Electronencephalogram
(Today we declare someone to be legally dead when his brain waves cease. So if the end of brainwaves marks the legal end of life, perhaps the start of brainwaves should mark the legal start of life?)

Our commenter and the religious St. Carmel website are both cribbing off of this passage, which you can find cut and pasted with only minor variations on multiple websites and letters to the editors of small-town papers across the country:

Is he aware that the brain waves of a developing baby are recorded at 40 days gestation on the EEG? (H. Hamlin, “Life or Death by EEG.” Journal of the American Medical Association, Oct.12, 1964.) Brain function is reliably present on the EEG at eight weeks gestation. This is six weeks after conception. (J. Goldenring, “Development of the Fetal Brain,” New England Journal of Medicine, Aug. 26, 1982, 564.)

Looks good, doesn’t it? I mean, golly gee whizzikers, the text cites the American Medical Association and the New England Journal of Medicine with academic formatting and everything! The people who wrote the text of this claim depend on that. They depend on you to not look any further.

Unfortunately for the purveyors of this text, Margaret Sykes has done the work to look into the matter, digging not only into the Hamlin and Goldenring publications but also into the citations that Hamlin and Goldenring themselves make. Hamlin made a speech and Goldenring wrote a letter — neither is peer-reviewed and neither is a research paper. Neither Hamlin nor Goldenring cite research demonstrating that “Brain waves have been recorded at 40 days on the Electroencephalogram.”

Even if those “brain waves” were demonstrated to be present, that wouldn’t equal cognition. The current state of knowledge regarding fetal brain development indicates that higher-order cognitive development occurs quite late in gestation, and certainly nowhere near as far back as 40 days. According to the National Institutes of Health, the brain doesn’t even differentiate into as many as five separate areas until 6-7 weeks after conception. At 8 weeks after conception, the fetal brain spans less than a 1/4 inch across (Mayo Clinic). It is not until 30 weeks that the brain begins to develop grooves and indentations that we associate with a fully-cognitive brain.

The claim made by those who cite the Hamlin and Goldenring publications as if they were scientific research is inappropriate. It is unsubstantiated. It is a myth.

4 thoughts on “Embryonic Brain Development and the Myth of 40 Days”

  1. Elle says:

    OMG, you mean, they, Lied!!!!

    How shocking, how unbelievable!!! I mean suggesting that someone as morally superior to us plain old folks as them are would Lie!!!

    What is this world coming to?

  2. matt says:

    All your links are broken or worthless.

    1. Jim Cook says:

      All your letters are belong to us, except the b. The b is worthless.

      Matt, this was written 4 yrs ago. Links change in 4 yrs. The broken links are fixed.

  3. Jennifer Kinder littke says:

    Just so you know, the male brain may not be fully developed until past the age of 20… years old that is. Ok to abort men up until that age?
    You post an assumption of cognition being important though you do not say for what. Is it important because having cognition is the onset of life? Because whose theory are you going by. It becomes important you see Blooms taxonomy of the cognitive domain wouldn’t even allow for an infant to demonstrate cognition of which the basic is knowledge as demonstrated by ability to list, name , state, define. A child might have labeled his mom, bottle, dad but not for several months into life. So we can kill a child until then?
    Brain death is used as a marker for death, for sure, but that means there is losd of even brainstem functions, what is left are possible spinal reflexes. But no part of the brain telling the body to breath. And a heart can go on without neural input– meaning no brain function is necessary. So by those definitions and terms, a person is alive so long as he or she has brain stem function not cognition which takes place in the cerebral hemispheres. So at the very least, if death is brain death ( which medically we measure using things such as nuclear blood flow study), and for death if the brain to have occurred one must have lost brain stem function ( which, remember, participated in autonomic nervous function and allows on to breath on his or her own, but has nothing to do with cognition), then when the fetus has functioning brainstem, we are good to go, right? That’s life? And that is around 6 weeks after conception.

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