In humans, birth weight is an example of a characteristic affected by stablizing selecetion. What does this me

Question

In humans, birth weight is an example of a characteristic affected by stablizing selecetion. What does this mean to the long-term average birth weight of human babies. How might the increasing number of Caesarean sections be affecting this characteristic?

Answer 1

Hi,  The birth weight of babies is controlled by the need for the baby to emerge from the birth canal and also the need for the child to achieve a certain healthy birth weight for survival.  If the baby is too large then it becomes more traumatic to emerge. Low birth weight is a risk factor for young children.  There is therfore an optimal weight for babies.  Babies that are too small or too large will die.  With Caesarian sections the upper limit becomes less important.  Babies will survive if they are too large.  This will increase the average and move the curve to the right.