If youve read ‘health’ news on the internet this week, youve seen this story:
Just put ‘MHC women’ into Google News. Youll get a billion hits for articles talking about this paper:
Ugh. Guys, at this point in time, research connecting MHC genotype with ‘compatible’ mates in humans is good old fashioned woo.
MHC Class I molecules are on the surface of all of your cells. Proteins that your cells make eventually get degraded, and MHC molecules present little bits of these proteins at the cell surface. Its a signal to cytotoxic T-cells that everything is fine.
When your cells are infected with a virus, or have become cancerous, its MHCs start presenting proteins that arent ‘normal’– they become a signal to CTLs that something is wrong, and the cell needs to be killed.
MHC Class II molecules are only on the surface of antigen presenting cells (cells that eat bacteria/viruses/etc). So while MHC I present internal proteins, MHC II present proteins that have been chewed up from the external environment.
While you and I both have MHC I and II, there are lots different genotypes. Different variations of MHCs will present different bits of chewed up proteins. If you and I are both infected with salmonella, you might present Protein Chunk A in your MHC II, and I might present Protein Chunk B.
Theoretically, this means that we would be good ‘partners’. Because our MHCs are different, if we mated, our offspring might be more likely to survive a salmonella plague than either one of us individually.
A bump in the road is the fact we have no idea how I would have any idea what your MHC genotype is. We type people today for transplants/donations through a battery of assays– how the hell could you and I, on a date, know our MHCs are different, and our offspring would be ‘fit’?
The most popular explanation is that we can smell each others MHC type (other mammals might, why not humans too?). Ive read a few of the papers that explore this possibility because I know someone who works for an MHC-match dating service– That we could ‘sense’ another individuals MHC genotype was first publicized in a 1995 study, ‘MHC-Dependent Mate Preferences in Humans‘. Well Ive read that paper, and its garbage. Its just a friggen crap shoot whether a woman picks a ‘similar’ or ‘dissimilar’ MHC type. All of their error bars overlap.
Subsequent papers havent been much better. Some not just saying that we have ways of ‘smelling’ someones MHC, but that we can tell just by looking at someone what their MHC type is.
Now we have this new paper, and ‘science reporters’ are bleating ‘OMG! WOMEN ON THE PILL CHOSE THE WRONG MHC TYPE!!’
… Except in this new paper all the error bars on their graphs overlap between ‘similar’ and ‘dissimilar’ choices, for women on and off The Pill!!
(a) odour pleasantness ratings, (b) odour intensity and (c) odour desirability.
I feel like Im on Wacky Pills! Why the hell is anyone taking this ‘research’ seriously?? I mean, gee, just think of the money and time we could save doing organ transplants:
Transplant Surgeon: “Theres no time to use PCR to determine this motorcycle crash victims MHC type! I can tell by SMELLING HIM hes compatible with my patient! Take his kidneys!”
WTF. Stupid crappy ‘science reporting’ and stupid crappy research. Ugh.