Modern day women have slim hips and narrower waists thanks to evolution – not calorie couting.

Scientists made the discovery by comparing fossils from centuries-old remains to the bodies of women today.

Researchers found that more than 200,000 years ago women’s hips would have been several inches wider than the 21st Century woman – likening their not so feminine frames to today’s broad-shouldered men.

Unearthed fossils show how pre-evolution women were saddled with hefty, manly bodies to enable them to give birth to big babies.

However, speaking at Britain’s leading scientific organisation the Royal Society this week, experts highlighted how, during the course of evolution, the pelvis adapted to allow the rotation of the unborn child.

This allows women to have smaller frames while still carrying babies with large heads.

Dr Laura Gruss, of Radford University in Virginia, said the pelvic transformations of early Homo sapiens – modern humans-more than 100,000 years ago, have made today’s women slimmer.

She told how pre-evolution wide hips and thick-set bodies made it easier to produce babies with large heads but harder to walk long distances and stay cool in hot climates therefore pushing the body into change.

Speaking to leading British scientists at the Royal Society, Dr Gruss said: “Their solution was to evolve a birth canal with a twist in it so the baby is rotated through 90 degrees as it is born and comes out facing backwards rather than sideways as in other apes.

“Until this change those women may have been bigger than an average modern man.

“It meant we could produce large brained infants from a slimmer body .

“The twist meant the whole pelvis could be narrower and the hips slimmer.”

Dr Gruss added the changes to the pelvis resulted in women needing less calories to support their new slimmer frame.

Recent studies suggest around the same stage of evolution humans became more reliant on vision rather than smell, began to lose their hair and the the body developed the addition of swear glands.

While the female pelvis developed to carry offspring Homo sapiens were also developing the structure of their teeth, creating the the u-shaped dental structure and the evolution of the chin.

But scientists believe the development of human behaviour came much earlier, with the understanding of culture, language and specialist technology happened around 50,000 years ago.

In 2013 scientists at the Royal Society claimed women have evolved over the years to be ‘indirectly aggressive’ and mean to one another without resorting to violence.

The evolutionary psychology study, which was done to explore the scientific basis for “competition and aggression” between women, found that the constraints of caring for offspring forced women to turn to low-risk aggression.

Researchers stated females compete for resources needed to survive and reproduce, and for preferred mates.