Thursday, May 1, 2014

Dots on Steroids

I tweeted a couple of times about an olfactory study published today by Wen Zhou et al., in Current Biology. I think it’s pretty weak. Subjects watched a dot-animation of a walking figure and guessed from its gait whether it was male or female. The clips were morphed so that some were obv one sex or the other while others were ambiguous. Subjects inhaled either androstadienone (AND) or estratetraenol (EST) while guessing. With AND, straight women judged the ambiguous samples slightly more masculine; with EST, straight men saw them as slightly more feminine. Homosexual men responded more like straight women, with bi- and homosexual women intermediate.

The effects were tiny and emerged only after some pretty strenuous statistical manipulations. The only control odor was isovaleric acid which the authors mistakenly believe to be a major component of male body odor. Completely lacking were any gender-associated, non-body odor controls, such as floral/rose for feminine. Thus Zhou, et al.’s conclusion that the effects were not due to associative learning is unsupported. As is their claim that the results “provide strong behavioral evidence” that AND and EST communicate gender; unless you think dancing dots are behavior.

Wen Zhou, et al., fail to state an experimental hypothesis and fail to discuss the alleged biological role of AND and EST real life. Is the idea that women need an AND-sensitive olfactory channel to help them sort out ambiguous gender situations? That is, when looking, asking, or groping aren’t possible? And how often does this happen? Frequently enough for there to be selective value in such a response? There is simply no coherent hypothesis here.

However there was enough for the science media to run with. AAAS Science Now headlined its story “Is That a Man or a Woman? Trust Your Nose.” The Daily Mail ran with “You can smell a person’s GENDER: Humans subconsciously identify sex using the subtle odour of pheromones.” Daisy Yuhas at Scientific American went right on over the top: “Human Sexual Responses Boosted by Bodily Scents; Two human steroidal compounds may help scientists make sense of how bodily scents affect sexual arousal.”

Sexual arousal? What paper was Ms. Yuhas reading?

UPDATE May 4, 2014
Rhonda J. Miller, at some site called International Science Times, sees Yuhas and raises her with the ludicrous headline “How A Person's Scent Can Trigger A Powerful Sexual Response, And Say Something About Gender.” As a description of the study this is patently false. What’s going on here? When did science headlines go all Upworthy? I think it’s time to start awarding something like Rotten Tomatoes or The Razzies for contemptible science “journalism.”

The study discussed here is “Chemosensory communication of gender through two human steroids in a sexually dimorphic manner,” by Wen Zhou, Xiaoying Yang, Kepu Chen, Peng Cai, Sheng He, and Yi Jiang, published online in Current Biology, May 1, 2014.

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