A new study has helped researchers figure out that men prefer women with a theoretically optimal angle of lumbar curvature because of an evolutionary reason. The study, conducted by researchers at the University of Texas at Austin, showed that even prehistoric men probably liked women with a curvy backside.

The men involved in the study rated women the highest who had a 45.5-degree curve from back to buttocks. The researchers said that women with this spinal structure were preferred by men even in ancient times because it would have helped pregnant women to balance their weight over the hips. Moreover, these women would have been the best at foraging during pregnancy without suffering spinal injuries.

"In turn, men who preferred these women would have had mates who were better able to provide for fetus and offspring, and who would have been able to carry out multiple pregnancies without injury", said the researchers. This preference of men has evolved for over thousands of years.

The study's co-author David Buss, a UT Austin psychology professor, said the study has provided enough evidence to vindicate that beauty is not entirely arbitrary or in the eye of the beholder, but instead has a coherent adaptive logic.

During the study, the researchers showed men pictures of women and they liked the most the ones having an angle of 45 degrees of lumbar curvature. This means, men prefer women who exhibit specific angles of spinal curvature over buttock mass.

Findings of the study have been published in Evolution and Human Behavior. The study has cited an evolutionary basis over preference of men for women with curvy backside.