Why pregnant women do not lose their balance despite the additional weight on the front? Scientists explained, pregnant women experience the process of evolution in the lower back and waist joint so that it can adjust the center of gravity. Evolution does not happen in men. Scientists believe, the evolution of lumbar spine and joint women already begun in the early occurrence of the man who walks upright.

Chimpanzee and monkeys did not experience evolution because species are not running with two feet. “We must be grateful to these design changes occur. When pregnant, women experience a significant addition of weight on the front. The weight of this make a woman pregnant does not feel comfortable. However, the inconvenience of the more painful when the design change does not happen,” said University anthropology professor Liza Shapiro of Texas, chairman of the research team. Shapiro is a mother who had experienced pregnancy.

Therefore, Shapiro understand the anguish felt over pregnant women. Shapiro said, pregnant women often experience pain in the back because they have to prop up over-weight on the front. Partners Shapiro, Harvard University anthropology expert Katherine Whitcome, found two physical differences in men and women back. Previously, the difference was not observed at all. First, women have a spine down the shaped more like a triangle. In the men, the bones are shaped more boxes.

Second, women have a waist size of pivot 14 percent more than the men. “Women’s experience of evolution impressive. Berkat evolution, the woman is able to adjust the center of gravity when it contains. This is a wonderful evolution that is very useful for large women,” said Whitcome. Whitcome not only learn the structure of modern human bones, but also ancient human fossil australopithecine called the (living in two million years ago) and the chimpanzee.

Whitcome observed, changes in the design of women has occurred since the beginning of the next generation australopithecine species appear. These changes do not occur in the chimpanzee. Shapiro added, when a woman has, the body of a woman to start leaning back. The process begins when the fetus reaches half of the total mass. Without design changes that occur in the process of evolution, women have to attract the back muscles to compensate for the weight on the front.

“The more muscle hard drawn, we do not necessarily feel more comfortable and spine can be damaged and because of overlapping shifts. design changes, pregnant women do not need to persist back and spine remain safe,” said Shapiro. In the assessment Shapiro, spinal axis woman able to become more perfect when the pregnant woman’s body to play the top of the additional weight. The risk of spinal damage is the man who lurk as a certain kind of belly bulging male bone structure is not designed fortunately bear the additional weight on the front.

“Men certain kind of belly bulging threatened greater risk of spinal damage because men do not have the structure of bone adaptation. To counterbalance weight on the front, men must attract a certain kind of belly bulging muscles back. Therefore, a certain kind of belly bulging men often complain about the pain in the back,” explained Shapiro .

Published in the scientific journal Nature, research, Shapiro and Whitcome involving 19 volunteer pregnant women. During pregnancy, the volunteers always monitored with cameras and motion analysis equipment to map changes in postures and movements.