Curvy Bottoms Linked To Pregnancy Advantage

Dr. David M.G. Lewis, PhD Assistant Professor Department of Psychology Bilkent Üniversitesi Ankara, Turkey Research Affiliate, Individual Differences and Evolutionary Psychology Area Department of Psychology The University of Texas at Austin
MedicalResearch.com Interview with:

Dr. David M.G. Lewis, PhD
Assistant Professor Department of Psychology
Bilkent Üniversitesi Ankara, Turkey
Research Affiliate,
Individual Differences and Evolutionary Psychology Area
Department of Psychology
The University of Texas at Austin

MedicalResearch: What is the background for this study?

Dr. Lewis: My motivations to conduct this study were a combination of several things. Men would often mention to me the features that they found attractive in women. They would often mention the butt, but not the *size* of the butt…it was something else, but they couldn’t seem to put their finger on exactly what…

I then began reading more deeply into the different muscular, ligamentous, skeletal, etc. structures that could influence the appearance of the buttocks. I moved beyond just buttock tissue and buttock size. What I began to discover is that while the size of the buttocks does indeed influence the buttocks’ appearance, so too does other morphology that is not part of the buttocks themselves. These readings indicated that certain spinal structures can help women shift their center of mass back over the hips during pregnancy and reduce hip torque by roughly 700%. To the extent that women who possess these spinal structures would thereby be better able to carry a pregnancy (or multiple pregnancies) to term without suffering spinal injuries, selection would have favored the evolution of psychological mechanisms in men to prefer women exhibiting cues to these spinal structures. Men could not directly observed women’s vertebrae, but lumbar curvature is an externally visible cue to the relevant spinal structures.

At this point, we had a hypothesis that was both anchored in evolutionary theory and grounded in medical orthopedic literature. It was time we tested our idea that men possess a previously undiscovered, evolved preference for a beneficial intermediate angles of lumbar curvature in women.

MedicalResearch: What are the main findings?

Dr. Lewis: The key findings are that men possess a previously undiscovered preference in women — one that is rooted in spinal structures that influence a woman’s lumbar curvature but also the protrusion of her buttocks. We know that this preference is *not* merely a by-product of a preference for large buttocks. In our critical test, we showed men multiple women whose buttocks stuck out the exact same amount, but for different morphological reasons (e.g., large buttocks vs. spinal curvature). The men showed a strong tendency to prefer women whose buttock protrusion resulted from these spinal structures, not the women with larger buttocks.

MedicalResearch: What should clinicians and patients take away from your report?

Dr. Lewis: I hope that readers take away a new piece of knowledge, one that is distinct from what many people thought they knew (i.e., a male preference for big buttocks as opposed to a male preference for spinal curvature). I also hope they see that an evolutionary approach is one that can inform our understanding of the world around us in new ways. Lastly, I hope that all women who read this study recognize that in no way does this mean that a woman must have a particular angle of lumbar curvature in order to be beautiful. Our research shows that lumbar curvature has an influence on women’s attractiveness, but a closer examination of the data also shows that many women who do not have an ideal angle of lumbar curvature can still seen as very beautiful.

MedicalResearch: What recommendations do you have for future research as a result of this study?

Dr. Lewis: Our research establishes a previously undiscovered standard of attractiveness based on spinal structures, but it does not eliminate the possibility of a true male preference for female buttock size. There are many cultural anecdotes tied to buttock size, and some recent research suggests that fat deposition in this region of the body would have been associated with reproductive benefits. However, there is a relative absence of rigorous scientific investigation of men’s psychology regarding this region of the female body. I hope that we see an increase in good science that provides true tests of what we believe to be true. We may find out that we were right, or wrong — or we may discover something new altogether. Good science can offer all three.

Citation:

Lewis DMG, Russell EM, Al-Shawaf L, Buss DM. Lumbar curvature: a previously undiscovered standard of attractiveness. Evolution and Human Behavior. 2015.

MedicalResearch.com Interview with: Dr. David M.G. Lewis, PhD (2015). Curvy Bottoms Linked To Pregnancy Advantage