<p> Regular use of caesarean sections to deliver babies is affecting the human evolution, according to a new study.<br /><br /></p>.<p>An increasing number of mothers now need surgery to deliver a baby due to their narrow pelvis size, researchers said.<br /><br />They estimate 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.<br /><br />Historically, these genes would not have been passed from mother to child as both would have died in labour.<br /><br />According to Dr Philipp Mitteroecker from the University of Vienna in Austria, there is a long standing question in the understanding of human evolution.<br /><br />"Why is the rate of birth problems, in particular what we call fetopelvic disproportion - basically that the baby does not fit through the maternal birth canal - why is this rate so high?" he said.<br /><br />"Without modern medical intervention such problems often were lethal and this is, from an evolutionary perspective, selection.<br /><br />"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," said Mitteroecker.<br /><br />It has been a long standing evolutionary question why the human pelvis has not grown wider over the years.<br /><br />The head of a human baby is large compared with other primates, meaning animals such as chimps can give birth relatively easily, 'BBC News' reported.<br /><br />Researchers devised a mathematical model using data from the World Health Organisation (WHO) and other large birth studies.<br /><br />They found opposing evolutionary forces. One is a trend towards larger newborns, which are more healthy.<br /><br />However, if they grow too large, they get stuck during labour, which historically would have proved disastrous for mother and baby, and their genes would not be passed on.<br /><br />"One side of this selective force - namely the trend towards smaller babies - has vanished due to caesarean sections," said Mitteroecker.</p>
<p> Regular use of caesarean sections to deliver babies is affecting the human evolution, according to a new study.<br /><br /></p>.<p>An increasing number of mothers now need surgery to deliver a baby due to their narrow pelvis size, researchers said.<br /><br />They estimate 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.<br /><br />Historically, these genes would not have been passed from mother to child as both would have died in labour.<br /><br />According to Dr Philipp Mitteroecker from the University of Vienna in Austria, there is a long standing question in the understanding of human evolution.<br /><br />"Why is the rate of birth problems, in particular what we call fetopelvic disproportion - basically that the baby does not fit through the maternal birth canal - why is this rate so high?" he said.<br /><br />"Without modern medical intervention such problems often were lethal and this is, from an evolutionary perspective, selection.<br /><br />"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," said Mitteroecker.<br /><br />It has been a long standing evolutionary question why the human pelvis has not grown wider over the years.<br /><br />The head of a human baby is large compared with other primates, meaning animals such as chimps can give birth relatively easily, 'BBC News' reported.<br /><br />Researchers devised a mathematical model using data from the World Health Organisation (WHO) and other large birth studies.<br /><br />They found opposing evolutionary forces. One is a trend towards larger newborns, which are more healthy.<br /><br />However, if they grow too large, they get stuck during labour, which historically would have proved disastrous for mother and baby, and their genes would not be passed on.<br /><br />"One side of this selective force - namely the trend towards smaller babies - has vanished due to caesarean sections," said Mitteroecker.</p>