Stop me if you think you’ve heard this one before

18 03 2013

Oh that Rand Paul, champion of liberty! Look how he’s standing up for freedom now:

“The Life at Conception Act legislatively declares what most Americans believe and what science has long known – that human life begins at the moment of conception, and therefore is entitled to legal protection from that point forward,” Paul said in a statement. “ The right to life is guaranteed to all Americans in the Declaration of Independence and ensuring this is upheld is the Constitutional duty of all Members of Congress.”

Ahh, conceptional personhood: An idea utterly lacking in biological sense.

Charlie Pierce has the right idea regarding the Paul family: His Five Minute Rule  states that, for five minutes, both the son and the father, Crazy Uncle Liberty (!), make perfect sense on many issues. At the 5:00:01 mark, however, the trolley inevitably departs the tracks.

As Pierce notes, with this we are at the 5:00: 07 mark: The trolley has jumped the tracks, tipped over on its side, and is skidding down the boulevard.

I believe I have covered this before, but let’s go over this again, shall we?

There is no such thing as the “moment of conception”.

As Moore and Persaud note in the 6th edition of The Developing Human: Clinically Oriented Embryology:

Fertilization is a complex series of “coordinated molecular events (see Acosta, 1994 for details) that begins with the contact between the sperm and a oocyte and ends with the intermingling of maternal and paternal chromosomes at metaphase of the first mitotic division of the zygote, a unicellular embryo. Defects at any stage in the sequence of these events might cause the zygote to die (Asch et al, 1995). . . . The fertilization process takes about 24 hours. [p. 34, emph added]

“Process”, Senator Paul, not “moment”. Shall we break it down even further?

  • Passage of sperm through corona radiata surrounding the the zona pellucida of an oocyte.
  • Penetration of the zona pellucida surrounding the oocyte
  • Fusion of plasma membranes of the oocyte and sperm
  • Completion of the second meiotic division of oocyte and formation of female pronucleus
  • Formation of male pronucleus
  • Membranes of pronuclei break down, the chromosomes condense and become arranged for a mitotic cell division—the first cleavage division [pp. 34-36]

There are many more details involved in those stages, but the highlights ought to be enough.

At this point, the zygote is still in the ampulla [middle portion] of the fallopian tube, ambling its way toward the uterus. Beginning around 30 hours post-fertilization, it undergoes a series of mitotic or cleavage divisions, in which the internal cells (blastomeres) divide and become successively smaller. “After the nine-cell stage, the blastomeres change their shape and tightly align themselves against each other to form a compact ball of cells. . . . When there are 12 to 14 blastomeres, the developing human is called a morula (L. morus, mulberry).”  The morula forms about 3 days post-fert, and enters the uterus 3-4 days post-fert. [p. 41]

Okay, 4 days in and the mulberry is still wandering around, unattached, developing away. A fluid filled space called the blastocyst cavity or blastocoel forms, which separates the blastomeres into two parts:

  • a thin outer cell layer called the trophoblast, which gives rise to the embryonic part of the placenta
  • a group of centrally located blastomeres known as the inner cell mass, which gives rise to the embryo [p. 41]

At this point the berry becomes a blastocyst. (FYI: If you are an embryonic stem cell researcher, this is when you’d harvest the inner cell mass in order to cultivate stem cell lines. The blastocyst would, of course, be destroyed in the process.)

The blastocyst continues to float around in “uterine secretions” for a couple of days as “the zona pellucida gradually degenerates and disappears”. [p. 41] With the dissolution of the zona pellucida, the blastocyst is free to bulk up on those tasty secretions, until around day 6 post-fert, when it attaches itself to the endometrial epithelium.

All hell breaks loose now, as the trohoblast differentiates itself and its outer layer, the syncytiotrophoblast, insinuates itself into the endometrial epithelium and into the connective tissue, or stroma. “The highly invasive syncytiotrophoblast expands quickly adjacent to the inner cell mass, the area known as the embryonic pole. The syncytiotrophoblast produces enzymes that erode the maternal tissues, enabling the blastocyst to burrow into the endometrium.” [p. 42]

Although it takes another week for the embryo to implant itself fully into the endometrium and stroma—which further details I will spare you—this is the stage at which one could say a pregnancy begins.

Got it? One day for the process of fertilization, 6 days for sufficient development to begin a pregnancy, for a grand total of 7 days or one week.

Oh, and one more thing: Of all the zygote-morula-blastocysts formed, 25 percent wash out before implantation, and another 35-55 percent miscarry before birth. Only 20-40 percent of those berries results in a baby.

Anyway, if I wanted to be kind to the momentary conceptional folks, I could say that “conception” is achieved after 24 hours; if I wanted to be strict, I could say 7 days, and if I wanted to be a real bitch, I could argue that not until 14 days has the embryo done anything worth considering a “conception”. Even granting a kindness, it’s clear that the moment is, at its shortest, a day.

Why does this matter? After all, for many people who are pro-life, the issue is less the biology than the morality; that the conceptus takes awhile to get itself together does not obviate the fact that the process begins—that human life begins—when the sperm drills itself into the egg. The biology matters only because it is a trigger for something more, not in and of itself.

This, of course, is how you get bullshit proposals like personhood bills and amendments: by treating biology as a chit in the culture war rather than a reality on its own terms.

Human development is an amazing, complicated, and fraught process, one which does not comport itself easily to our moral preconceptions (sorry) about it. By all means, make a moral argument, but don’t pretend that biology tucks up neatly into it.

Senator Paul is free to believe all he wants “that human life begins at the moment of conception, and therefore is entitled to legal protection from that point forward”, but I am also free to point out it is a belief untethered to biological reality.

That trolley done run into nonsense.




4 responses

18 03 2013

heh you and your “science”, hey was it just me or did S-Palin just tell CPAC that natural resources belong to the people of the state and not to multinational coporations, maybe she was briefly possessed by the ghost of hogochavez?

18 03 2013

She can blame it on the sugar in that Big Gulp.

19 03 2013

I think that spirit possession is more down her lane…

10 04 2013

We’ve come all the way from the quickening to this point. Eventually, they’ll pass a law that says conception begins at “Hey, baby, what’s your sign?”

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