[This post contains photographs of infants with serious genetic abnormalities.]
Pro-life people often say:
- Life begins at conception (or fertilization).
- At fertilization there is a new entity genetically distinct from the woman.
- If two humans have sex their offspring will be human (rather than a dog, a frog, or any other species).
This situation demonstrates how messy biology can be. But it doesn’t undermine the basic fact pro-life people are trying to establish: the human zygote is the first developmental stage of a human organism. Every human has his or her own life cycle, and the zygote is the beginning of a human life cycle. HMs don’t change that fact, and in this post I explain why not.
There are two types of HMs: complete and partial.
1. Complete hydatidiform moles (CHM)
A CHM exists when the sperm fertilizes an egg that had no nuclear DNA. While it’s true this mole arises from fertilization, it is not true that the mole is a human organism. The vast majority of human organisms have two sets of DNA: one set of 23 chromosomes from the father and one from the mother. A CHM has only the sperm’s DNA. Here is a relevant excerpt from Larsen’s Human Embryology (Schoenwolf, Bleyl, Brauer, & Francis-West, 5th Edition):
2. Partial hydatidiform mole (PHM)
A PHM arises when two sperm fertilize an egg that does have nuclear DNA. In contrast with other human organisms who generally have two sets of 23 chromosomes, these organisms have three sets of 23 chromosomes. Here is another excerpt from Larsen’s:
Digynic triploid infant surviving for 46 days, Hasegawa et al, American Journal of Medical Genetics, December 1999
|Infant at 4 weeks|
|Click to enlarge.|
To summarize, complete hydatidiform moles are not human organisms. Partial hydatidiform moles are human organisms with severe genetic abnormalities. And neither case changes the fact that a human zygote is the first developmental stage of a human organism’s life.
Human Beings Begin as Zygotes: Refutations to 8 Common Pro-Choice Arguments, Secular Pro-Life Perspectives, August 11, 2017
Do human beings begin at fertilization? Secular Pro-Life Perspectives, November 29, 2012