Boffins clarify why ladies’s boobs are so large and it isn’t due to milk
Scientists say the large size of women’s breasts aren’t needed for milk and can cause health issues, while previous theories don’t fully explain why they stay permanently enlarged
Breasts have been viewed as an evolutionary way of attracting partners (Image: Getty Images/iStockphoto)
Boffins reckon they’ve finally cracked one of humanity’s most eye-catching mysteries: why women’s boobs are so much larger than those of other animals.
Researchers in a new study argue that the prominent size and shape of female breasts could help protect newborns from hypothermia by acting as built-in heat pads. Essentially, they are less to do with show and more to do with stopping babies from freezing.
“Shared body heat has been the most convenient and reliable heat source since before the invention of fire or protective clothing,” the experts explained in the paper, published in Evolutionary Human Sciences.
They added: “The morphology of the female breast provides a large surface for skin-to-skin contact as the prominent shape and elasticity of the breast multiplies the contact area compared to a planar surface.”
Unlike females of most other mammal species, who only develop temporary swelling when nursing, women retain their size and shape for life. Yet this fullness isn’t actually needed to produce milk and in fact can cause health problems and physical discomfort.
Theories in the past have claimed that breasts evolved as handy fat reserves during tough times, or as a way to attract partners through sexual selection. But neither idea has fully explained why they stay enlarged all year round.
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The researchers continued: “Although there is considerable variation in the breast tissue volume, the prominent shape and size of female breasts is a special trait from an evolutionary perspective. It seemingly does not serve any anatomical or physiological function but instead has clear drawbacks as increased breast size is correlated with several health issues such as back pain.”
To test their theory, the scientists enlisted 27 participants – including breastfeeding women, non-breastfeeding women, and men. Volunteers were exposed to three temperatures – 32°C, 27°C and a brisk 18°C – for 20 minutes, while thermal imaging cameras measured changes in breast temperature.
The results found that breastfeeding women had higher temperatures in their breasts than both non-nursing women and men. They also showed a “distinct resilience” to the cold.
Thermal cameras revealed breastfeeding women lost an average of just 2.5°C of their mammary surface temperature. Men and non-nursing women lost 4.3°C and 4.7°C respectively.
“This could improve a newborn’s chances of survival and provide an evolutionarily grounded explanation for the development of external breasts in humans,” said study author Dr Juho–Antti Junno.
The team added: “Similar studies on other primates, such as breastfeeding and non-breastfeeding female chimpanzees, could shed light on the role of breastfeeding in chest temperatures in general and, consequently, on the origin of perennially enlarged breasts.”
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