Big butts are more attractive on basic instincts level
Science has spoken: men are extremely attracted to the lower spine curvature that women with big butts have. There's a scientific explanation behind this phenomenon. Booty spine curvature ensures a smooth and healthy pregnancy... so it all comes down to basic procreation instincts. Also, girls with big butts are healthier. Having a big butt also means higher leptin and dinopectina levels in the female body. Leptin and dinopectina are hormones responsible for regulating weight and carrying anti-inflammatory, vascular-protective and anti-diabetic attributes.
The shape of a butt is defined by the gluteus maximus, gluteus medius, and gluteus minimus muscles, as well as the fat surrounding these muscles. Women tend to store fat in their hips and lower body thanks to hormones and evolution, preparing females for childbearing. Higher levels of oestrogen make fat storage efficient in preparation for pregnancy, as women carry 6 to 11 percent more body fat than men. Because of these differences in where the sexes store fat, a man is more likely to be overweight with a flat ass and round stomach, while a woman might see it all go to her hips. But even this is dependent on each person's individual genetics.
The anatomical basis for the exceptional size of human butts is due to both a large amount of fat and a large amount of muscle. The latter — the gluteus maximus — adds most of the default bulk, while the layer of fat that sits over it varies a lot more from person to person.
Explaining the size of our butt muscles is reasonably straightforward, at least for evolutionary anthropologists like Associate Professor Darren Curnoe from the University of New South Wales.
“The major differences between humans and other apes are the result of our evolution as bipeds, or two-footed apes,” he says. “The muscles we have in common with apes actually often function quite differently in humans, moving our bodies about on two feet instead of four.”
Large, thick gluteal muscles help us remain stable while walking upright, and our pelvises have been moulded by evolution (wider side-to-side, but also shallower front-to-back) to ease the transition to moving about on two legs, which combine to produce a distinctive curve to our posterior, as well as give us much wider hips.
The abundance of fat on human butts is a little harder to explain. There’s no clear connection between walking upright and needing a thicker layer of fat on the behind, so anthropologists have turned to other hypotheses.
One idea is that “fat around the hips, buttocks and thighs represent a safe storage space to help humans survive episodes of food shortage, which were probably regular for our hunter-gatherer ancestors,” says Curnoe. “But also, because breastfeeding is very demanding in terms of energy consumption, the extra fat is probably a kind of insurance policy for women to ensure both their survival and that of their vulnerable infants during the first few years of life.”
In other words, big butts might be a byproduct of the general fattiness of humans — we’re the some of the fattest primates around, (although mind the fat-tailed dwarf lemur, which stores fat in its tail to get through the winter) even before you consider the world’s current obesity crisis.