From the Department of “Are you absolutely sure about that?”, evolutionary psychology once more is on the march:Love songs may rhapsodise “something in the way she moves”, but a sexy walk is not a sign that a woman is ready to become pregnant. In fact, a new study suggests that the way a woman walks changes during her monthly cycle, and that the most seductive wiggle occurs when she is least fertile.[…]Hmmm. I think the best you can say about this is at least they did the right thing and went ahead and published these desperately unconvincing results rather than sweeping them under a rug.
For the latest study, Dr Provost and her team dressed female volunteers in suits adorned with light markers, as used in Hollywood special effects departments, along the joints and limbs.
This allowed them to film each woman as she walked and then analyse her gait. They also collected saliva samples to find out whether each woman was in the more or less fertile phase of her menstrual cycle.
The women who were ovulating walked with smaller hip movements and with their knees closer together, New Scientist magazine reported. When 40 men were shown the images of the women walking they rated those in the less fertile part of their cycle as having the sexiest walks. […]
That makes evolutionary sense, because it would benefit a woman to advertise her fertility only to those men she believes would make a suitable mate. In contrast, men can pick up on the attractiveness of a woman’s walk from long distance, and it can therefore act as an unwitting signal to less appealing males whom she might not want to choose.
I don't want to be rude but the authors' desperate effort to reconcile the unexpected result with their theory reminds me of economists (I am an economist). A theory which can explain either sign equally well, is a theory which is not ready for prime time. As you tacitly note, the first best of two possibilities would be for men to find women sexier when they are fertile. This would give said men an evolutionary advantage.
"The best you can say" is a bit too good to be said really. If the authors' had swept the result under a rug, they wouldn't have gotten a publication. Similarly, if they had said their result contradicts the natural prediction based on evolutionary psych they would have pissed off an editor and 2 referees.
Finally, I have a less feeble (although still feeble) reconciliation of the observation and the theory (which I just read in a semi old economist article on lap dancers). The article found that fertile lap dancers get larger tips than non fertile lap dancers including those on the pill.
Women have no trouble getting pregnant, they have trouble keeping the fathers of their children loyal to them. Therefore it is in their interest to be sexy all the time (promotes monogamy you should see what Chimpanzees do) while males who can tell which women are fertile gain. The result you mention says that women won the walk round. The result in the economist said that men won the lap dance round. The problem is that any set of results is equally consistent with the theory of natural selection, therefore the whole excercise is a waste of time.
I would have no problem if both arguments appeared in both papers and both concluded that either sign if consistent with the theory. I haven't read the research articles so either or both sets of authors might have done this.
Now evolutionary biology has a problem as most people, in the USA at least, don't believe in it. The intellectual dishonesty of claiming to explain opposite results can't help. The overwhelming evidence in favor of evolution by natural selection has nothing to do with the ex post explanations of interesting phenomenon and much to do with extremely uninteresting things like Whales' hip bones. The unconvincing arguments based on evolutionary biology distract from the evidence and must contribute at least a little to the serious problem of people not accepting the overwhelming evidence on the core question.