According to scientists, the consistent use of Caesarean sections greatly affects human evolution. In a study conducted, it shows an increase of mothers needing the surgery to deliver their baby because of constricted pelvis size.
The study discovered that cases of newborn that cannot fit into the birth canal increased from 30 in every 1,000 births in the 1960s. The number of recorded cases rose to 36 in every 1,000 births to date.
In the past, the genes cannot pass on to the succeeding lineage since the child and mother have either died during labor.
Experts in Austria believed the trend will continue, as non-surgical births will remain constant.
The Department of Theoretical affiliate at the University of Vienna, Dr. Philipp Mitteroecker claimed that human evolution is difficult to comprehend.
“Why is the rate of birth problems, in particular, what we call fetopelvic disproportion – basically that the baby doesn’t fit through the maternal birth canal – why is this rate so high?” Dr. Mitteroecker asked.
The doctor also provides the answer to his question. He said, “Without modern medical intervention such problems often were lethal and this is, from an evolutionary perspective, selection. Women with a very narrow pelvis would not have survived birth 100 years ago. They do now and pass on their genes encoding for a narrow pelvis to their daughters.”
Furthermore, scientists often question the size of the human pelvis which stopped growing wider in the past years.
Also, the human head is larger than other primates which indicated that chimps can easily give birth.
Scientists developed a mathematical model based on the World Health Organization data as well as other studies for large births.
Surprisingly, they found contradicting results. Babies born with larger heads proved healthier.
Nevertheless, if the heads grow too big, it will not fit into the mother’s pelvis. The circumstances would serve as catastrophic in the past since the baby cannot inherit the genes.
Dr. Mitteroecker explained that “One side of this selective force – namely the trend towards smaller babies – has vanished due to Caesarean sections. Our intent is not to criticize medical intervention. But it’s had an evolutionary effect”.
The worldwide estimate of case rate of newborns that cannot fit into the pelvis occurs at 30 in every 1,000 birth or 3%.
The number increased in the last 50 to 60 years. It now amounts to 36 in every 1,000 births or 3.3 to 3.6%
The percentage increase of 10-20% from the original data is because of the effects of evolution.
Furthermore, Dr. Mitteroecker stated, “The pressing question is what’s going to happen in the future? I expect that this evolutionary trend will continue but perhaps only slightly and slowly.”
The doctor also claimed, “There are limits to that. So I don’t expect that one day the majority of children will have to be born by Caesarean sections.”
The journal, Processings of the National Academy of Sciences, published the whole study.