Has the Pill shaped Hollywood?

9 October, 2009

The Pill may have “changed women’s taste in men”, according to the Daily Mail, which reports that a new study has found that the hormone-based contraceptive suppresses a woman’s interest in masculine men and makes boyish men more attractive.

The newspaper quotes the study’s authors as saying this may have “long-term implications for society”. The article applies the scientific theory to the popularity of different Hollywood actors, highlighting the shift in tastes from rugged actors such as Steve McQueen to “wimpy, androgynous stars like Johnny Depp”.

The study’s authors argue their case using evolutionary theory, but acknowledge limitations in the evidence and the degree of speculation involved in suggesting that the Pill causes changes in partner choice, relationship satisfaction and reproductive outcomes.

This is flimsy evidence on which to say that the Pill has influenced women’s preferences in men since its introduction. The notion that it affects mate choice and the likelihood of a successful relationship should be seen as speculative at this stage. Equally, there is no need to adjust your movie-viewing habits.

Where did the story come from?

This research was carried out by Alexandra Alvergne and Virpi Lummaa from the Department of Animal and Plant Sciences at the University of Sheffield. The study was funded by the Kone Foundation and the Royal Society of London, and published in the peer-reviewed journal Trends in Ecology and Evolution.

What kind of scientific study was this?

This was a review looking at how the contraceptive pill might influence mating choices. The review was non-systematic, which means it did not describe the criteria used to choose the research it referenced. The study cited 72 research studies that were mostly conducted in humans.

The authors argue that both the female and male choices of mates vary in relation to different stages of the menstrual cycle. They quote studies that show women saying they prefer more masculine, symmetrical and genetically dissimilar men during ovulation than during other phases of their cycle. Other studies suggest that men are more attracted to women who are ovulating.

The researchers quote from studies that support the following statements:

Female fertility increases gradually before ovulation and rapidly decreases afterwards.
Men find women more attractive during this fertile phase.
The oral contraceptive pill contains oestrogen and progesterone, and changes the menstrual cycle by mimicking pregnancy.
Studies looking at women’s mate preferences show that their choice in partner is different at different times of their cycle.

The researchers also summarise some studies in tables and graphs:

They assess female preferences for “extra-pair copulation and paternity” (sexual infidelity and pregnancies where the father is not their main partner). The studies also illustrate at which times of the month these are most likely to occur.
They report the changes in sex hormones and other hormones throughout a typical menstrual cycle.
They show a graph comparing female lapdancer tip earnings across the menstrual cycles of women with normal cycles and women using hormonal contraception.
They discuss the range of preferences expressed by women in small studies and surveys on aspects such as symmetry of facial features and masculinity. The preferences discussed include those for genetically dissimilar men, in terms of having different Major Histocompatability Complexes (MHC) from each other. MHC is a part of the genetic code that contributes to the immune system in mammals. They analyse these preferences in both short-term and long-term relationships.

What were the results of the study?

The authors report that during the past decade more than 75% of studies investigating women’s partner preferences in relation to their menstrual cycles have demonstrated that women seek specific characteristics when their fertility peaks, with ovulating women preferring more masculine and symmetrical male features, and men who are MHC-dissimilar.

The researchers say that women taking the Pill do not appear to show the same preferences as ovulating women, but instead show preferences similar to non-ovulating women, with no preference based on symmetry or masculinity, and favouring MHC-similar men.

What interpretations did the researchers draw from these results?

They concluded that the monthly shifts in mate preference may bring evolutionary benefits in terms of reproductive success.

In relation to mating decisions, they conclude that it is possible that the Pill might also have a “non-negligible” impact, and say they hope that this review will stimulate further research on this question.

What does the NHS Knowledge Service make of this study?

As a non-systematic review, this study did not report how studies were selected for inclusion in the paper, and so it is not possible to say to what extent other perspectives have been included or excluded.

All but one of the studies on preferences quoted were based on comparing users and non-users of the Pill. It was unclear whether these studies controlled for possible pre-existing differences in Pill and non-Pill users, which means that most of the results should be treated with caution.

The researchers acknowledge that their conclusions are speculative when they look at the effect of the contraceptive pill on the choice of partners, relationship satisfaction, durability and reproductive outcomes.

They also say that there may be “crucial social and medical [advantages] of this contraceptive method, which might act in opposite ways from those discussed here”.

This sort of review article is useful for sparking discussion, but at this time should be considered to be speculative.