How caesareans could affect evolution

BBC: Caesarean births ‘affecting human evolution’ – by Helen Briggs

Recently published research explores the idea that the practice of caesareans over the past 50 years has led to an increase in narrow pelvis size within the population. This is due to the babies born via caesarean, carrying the narrow pelvis gene surviving when before they would not. It leads to a positive cycling effect, where there is an increase in the number of mothers with a narrow pelvis size and thus a further increase in caesareans.

It is an interesting idea. The paper itself, written by Dr. Mitteroecker of the University of Vienna is based on mathematical models shaped from the data of caesarean births since the 1960s.

“The incidence of obstructed labor in humans is strikingly high. Most of these cases result from the disproportion of the newborn’s head or shoulders and the mother’s pelvic dimensions.”

The actual increase in this observed pattern is from 0.030 (in the 1960’s) to 0.036 in recent years. (In effect an increase of 6 babies per 1000 being born by caesarean).

There are of course a whole range of factors that influence whether a caesarean is carried out during birth. Caesareans can be pre-elective or the result of complications during the birth

Through studying Craniosacral Therapy, it is fascinating to discover how compressional patterns to the baby’s head can be stored and influence the shape of the cranial bones as they ossify over the first 2 years of life. It is possible through light-touch of Craniosacral Therapy to feel these compressional patterns both in new-borns and in adults, and help to re-establish a functional balance of cranial movement.

It is from this approach that many conditions such as migraines, fatigue and sleep issues can be lessened and in some cases fully resolved.

Did You Know…
The act of sucking in babies helps re-balance the pressure inside the skull. If a baby hits its head, a primary response is to feed, not only does this comfort the child, it also helps support an internal re-balance.

The ideas proposed in seeing evolutionary changes through shifts in medical practice is an interesting one to observe. To some extent it must make an impact as there is a connection between biological adaptation and the circumstances. However, this comes alongside many other social and cultural factors that influence the number of caesareans made.

Original Paper:
“Cliff-edge model of obstetric selection in humans” – Mitteroecker et al. (2016)
 Proceedings of the National Academy of Sciences of the United States of America