Mankind has figured out a way to change its own evolution in a rather unexpected way: through caesarean sections, which are likely to lead to bigger babies in the future, a new study claims. More mothers are using surgery to deliver a baby due to a pelvis size that is too narrow to accommodate the delivery of a baby, increasing from 30 in 1,000 cases in the 1960s to 36 in 1,000 today.

In the past, such a situation would have led to the death of the mother and prevented genes from being passed down, but due to the practice of C-sections we are allowing those babies and mothers to live, and therefore those genes are mixing in with the gene pool, changing our evolutionary future, according to researchers in Austria.

“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?” said Dr. Philipp Mitteroecker of the department of theoretical biology at the University of Vienna according to a BBC report. “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.”

Scientists have scratcher their heads on why the human pelvis isn’t growing wider over the years instead. Humans have a unique problem that monkeys don’t in that the head of a human baby is much larger than any other primate.

Now the question is how much is this going to change the evolution of humans in the future. Over the last 50 to 60 years, there has been a 10-20 percent increase in the rate of C-sections. If that trend continues, the change could be quite rapid in evolutionary terms, although quite slow in our terms, so it’s not like most children will be born via C-sections in our lifetimes. Still, it is a fascinating discovery that sheds light on how we are impacting our own evolution.