Female Fecundity _ Male Homosexuality

I remade this to slow the text, change the music, and add a couple of images.

Links to related abstracts are here:
http://flagonlyrainbows.blogspot.com/2009/06/male-homosexuality-maternal-fecu...

The statistical finding has been replicated in several studies. Of interest, it only seems to apply to right-handed younger brothers.

The effect has been postulated to operate through a phenomenon described in the maternal immune hypothesis. Since female fecundity is not a universal explanation, other mechanisms must operate.

Begin the Beguine by Cole Porter seemed appropriate. Orchestra: Artie Shaw

Category:

Education

Tags:

• male
• homosexuality
• female
• fecundity
• fertility
• Darwinian
• natural
• selection
• genetics
• X-chromosome
• epigenetics
• family
• tree
• research
• statistics

[Jackies1979]

this explanation is stunning, and to a large extent, I believe, true and valid.... it is the best theory around to explain homosexuality...

however, since it poses the threat of a paradox, i think that the causal links or the causal direction/dynamics of the model should be checked and tested.... this may even more clearly explain how homosexuality evolves...

i discovered the paradox myself.

[flagonlyrainbows]

Padua? A co-author? Mostly, I have seen studies out of Toronto.

It is an interesting theory, particularly the possible mechanism (maternal immune hypothesis). I appear to have been incorrect to suggest that the X-chromosome is implicated. It could be autosomal.

However, aiui, it does not explain all cases of male homosexuality, and it does not explain lesbianism. Presumably, sexual orientation is multi-factorial.

I thought it explained away part of the natural selection paradox. ??

[Jackies1979]

yes, it explained that paradox very well, but there appears another paradox...

andrea camperio ciani already did a study like that in 2004:

Evidence for maternally inherited factors favouring male homosexuality and promoting female fecundity.

Andrea Camperio-Ciani, Francesca Corna, Claudio Capiluppi

Proceedings. Biological sciences / The Royal Society (2004)

Volume: 271 Issue: 1554 Pages: 2217-21

what are you referring to? i'd be very much interested, thanks...

[flagonlyrainbows]

Thanks, I had found that study, but I'm not sure where I placed it on the blog.

"what are you referring to?"

By "natural selection paradox"? I meant the argument that any genetic factor that reduced reproductive transmission could be expected to eliminate itself. However, it is astonishing that people forget that relatives share genes! Thus, a gene that favors reproduction in *other* family members will not eliminate itself.

If the maternal immune hypothesis is correct, then ...

[flagonlyrainbows]

contd

... the younger brother effect is a *side-effect* of the maternal fecundity that manifested by producing older brothers of the proband.

The right-handedness aspect of the effect is hard to explain, though.

By "multi-factorial", I referred to those homosexual males -- and to lesbians --where this mechanism does not provide an explanation.

[flagonlyrainbows]

Ha! I found the article by clicking on the link that I provided.

That was too simple!

;)

[Jackies1979]

...and andrea from the university of padova, author of the 2004 study you mention, thinks about it...