Size Matters—the Story Won’t End

Out of loyalty, I won’t share much of the email exchanges I’ve witnessed over the course of the past two days—both amongst neuroscientists and amongst the “queer folks.” But here’s what happened: Ingalhalikar et al. published an article in late 2013 revealing the allegedly true cause for the cognitive, behavioral, and emotional differences between men and women. At least, that’s how the popular press translated the reported results of sex differences in structural brain connections between female and male brains. I reviewed the study and many voices have been much more critical than mine.

In the meantime, Jürgen Hänggi et al. have published a paper suggesting that the above-mentioned structural brain connections correlate with brain size. This bolsters Neuroskeptic’s and others’ assumption that the measured effects in Ingalhalikar et al. 2013 are themselves a consequence of the bigger average brain size in men, and not any direct cause of stereotypical behavior.

https://www.flickr.com/photos/kk/4727827248/sizes/z/

“H. Sebastian Seung – Science, Living Systems, and the Edge of Change – Poptech Salon” (2010) by kris krüg, CC BY-NC-SA 2.0

A piece in The Scientist, finally, connects1 this finding elaborately to Ingalhalikar et al. 2013. Check it out and pay close attention to the discourse a) on not reported diminished effect sizes after controlling for brain size, and b) on saving the phenomenon of measured sex differences. We are back at the start: the volume difference seems to be enough to distinguish women from men after all! (And let’s not talk about the fact that adolescents were measured in Ingalhalikar et al.’s study.)

An elusive question
Why are we different
And are we?2

  1. Haha, this is the right verb in this connection—and I did it again! []
  2. Anonymous neuroscientist. Quoted from one of the emails I received yesterday. []

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