OMG, Heteropaternity is an Actual Thing!

Contained within an unnessarily complicated article regarding the evolution of the Y Chromosome (which is actually quite fascinating but full of sentences written with Gregor Mendel in mind and not a layperson — it’s all DNA this, X Chromosome that, reinvigoration, chromosomal palindromes, blah blah blah), is this little nugget:

Sperm competition may have been important in the earliest humans, too, for some years after the chimp and human lineages split. Sperm competition could still play a role in human reproduction, some experts think, given the trickle of cases of heteropaternity, the birth of twins with different fathers.

Wait, what?  Turns out there is such a thing as heteropaternity.  In science terms, heteropaternal superfecundation, is “different fathers, multiple babies” through one pregnancy.  It rarely occurrs amongst humans because of 1:1 coupling, but this genetic feat is quite common amongst dogs, cats and even chimpanzes

For this to happen in humans, a women must engage in intercourse with two different partners in close proximity to one another within the same ovulatory period; in the strictest math terms sperm cells can live inside a woman’s fallopian tube for 4–5 days, while her fertility window is usually open for 5-7 days. This phenomena often goes unrecognized unless, for some reason, a DNA test is sought by the identified father.

I feel like a knowledge bomb just got detonated on my face.

Links to individual cases:

MSNBC article about the Stuart twins
Description of the Archer case at Straight Dope
Case of a Croatian woman in 2003 at
Descriptions and references of a set of cases at (references unverified)

General Information:
Press release from a genetics testing firm
Academic study of paternity cases
Wikipedia entry on Twins

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