Scientists claim caesarean-evolution link

Scientists from Austria have claimed that the regular use of Caesarean sections is having an impact on human evolution. The researchers have estimated that cases where the baby cannot fit down the birth canal have increased from 30 in 1,000 in the 1960s to 36 in 1,000 births today, representing a 10-20 per cent increase of the original rate. They predict that this trend is likely to continue, but not to the extent that non-surgical births will become obsolete. Why the human pelvis has not grown wider over the years is a long standing evolutionary question. The researchers have devised a mathematical model using data from the World Health Organization and other large birth studies, and found opposing evolutionary forces. Dr Philipp Mitteroecker, of the department of theoretical biology at the University of Vienna, said: "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? "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." The research is published in the journal, Proceedings of the National Academy of Sciences.