Humans do some weird stuff during sex. Chocolate fondue, I'm looking at you. These behaviours don't really contribute to reproductive fitness, so surely evolution hasn't influenced any of them.
Actually, a new paper in Medical Hypotheses argues that the seemingly useless practice of stimulating breasts during sex may have evolved. At least according to someone from Cleveland State University.
What drove the evolution of this practice? Well "breast sex" or "sexual breast love" (to use the author's terminology) is hypothesised to promote the health of the breasts!
This benefit drove natural selection spread the behaviour through the population. Soon everyone was fondling breasts during sex.
Healthy functional breast use is characterized by the deeply rooted cultural practice of sexual breast stimulation, which may be instrumental in reducing the risk in women of sexual dysfunction, poor emotional health, cancers of the ovary, uterus, and cervix, and breast cancer.
The logic behind breast sex
The reasoning behind the claim that "sexual breast love" evolved is rather tortured, so please bare with me (haha). Basically:
- Nursing young appears to have some health benefits for the mother, reducing risk of cancer and improving mood.
- Nursing releases oxytocin
- "Breast sex" also releases oxytocin, like nursing
- THEREFORE: "Sexual breast love" also has the same health benefits as nursing.
- This prompted women to force the evolution of this trait in order to gain its benefit.
And yes, it really is that crazy. Women are supposed to have deliberatley manipulated evolution in order to make "sexual breast love" and its health benefits more common. Oh, and it also helped make men and women equal (although since then we broke that system a bit). In case you don't believe someone could utter something so asinine, in the words of our friend from Cleveland:
Women, 150,000 years ago or so, upon discovering the power of sexual breast love, made it a key to the evolution of humanity. Women's discovery and cultural maintenance of sexual breast love, with the cooperation of men, changed human culture and sociality forever. Woman constituted herself as man's social equal when she began to insist on sexual breast love, although equality between the sexes has subsequently been weakened.
Additional evidence for this claim comes from anthropological studies. These identify many hunter-gatherer groups that also practice "sexual breast love". The fact it is present in so many groups confirms - at least to the author of this hypothesis - that they all inherited it from a common ancestor. Thus sexual breast stiumlation has been around for a long time; long enough to have been influenced by evolution.
Although this whole argument is absurd, the anthropological case studies our friend from Cleveland points to are fascinating.
Cora DuBois, in 1944, reported on aspects of culture, including sexuality, on Alor, an Indonesian island. According to DuBois, much erogenous feeling centers on women's breasts and a common euphemism for having intercourse is pulling the breasts, since it is assumed that no woman can help being excited by such a caress
Not the breast idea
As my rather flippant tone suggests this hypothesis is riddled with errors.
- Our friend from Cleveland doesn't demonstrate that its the oxytocin that gives nursing its benefits.
- They fail to show that a women gets a comparable dose of oxytocin during "breast sex".
- They don't show that the health benefits are large enough for evolution to notice (for instance, it evolution is thought to ignore cancer as it occurs so late in life it doesn't influence chances of reproduction much).
And the big one is that organisms can't consciously influence the evolution of traits. Was a cave women sitting around whilst her cavehusband gave her some sexual breast love and thought " Hmm, this feels like its reducing my cancer risk; I'm going to get men to keep doing this for the next 150,000 years". This just shows a fundamental misunderstanding of evolution.
It's completely absurd from start to finish.
Now, to be fair to the author they aren't claiming its a proven idea. It is published as a "hypothesis". An initial idea, perhaps worthy of further study. But given all of these flaws I'm not sure it even qualifies as a cogent thought, let alone a full idea worthy of research. What's worse, it's a "hypothesis" published in a journal that doesn't even understand how evolution works. That's just scary.
Maybe I need to try and get more academics to read my blog. There's at least one out there who desperately needs a crash course in human evolution before they try and fondle someone for science.
Reference
Robinson, V. C. (2015). Support for the hypothesis that sexual breast stimulation is an ancestral practice and a key to understanding women's health. Medical hypotheses.
