Have you ever wondered ..Cont’d Have you ever wondered why human babies are born after 9 months of gestation.. Not 8 or 7 or 10 or 11 ?
Ok, so there are two opposing forces in nature that determine the gestation period (for all mammal species, not just humans) . The first is that the longer the baby is inside the mother the stronger it becomes and has a better chance of survival in the outside world . Remember premature babies are born at 7 months and can also survive with medical care. So technically a baby has a chance of outside survival at 7 months but spends an extra 2 months inside the womb to improve its chances of survival.
The restriction to the length of the gestation period (i.e. beyond 9 months) comes from the size of the birth canal / uterine/ vaginal opening. The baby is continuously growing in the womb. If the baby is too big at the time of birth , there will problems for it to come out.
So 9 months appears to be the optimum. The baby is big enough to survive and the birth will not be dangerous for the mother.
There is another very interesting fact about human birth. As the baby travels down the birth canal, the head twists 90 degrees. So the nose is pointing to the shoulder. This is not seen in any other mammal species. Human babies have very large heads in comparison to other species… because humans also have the largest brain. This twist of the head is necessary for the large head to pass through the birth canal.
Ok, so there are two opposing forces in nature that determine the gestation period (for all mammal species, not just humans) . The first is that the longer the baby is inside the mother the stronger it becomes and has a better chance of survival in the outside world . Remember premature babies are born at 7 months and can also survive with medical care. So technically a baby has a chance of outside survival at 7 months but spends an extra 2 months inside the womb to improve its chances of survival.
The restriction to the length of the gestation period (i.e. beyond 9 months) comes from the size of the birth canal / uterine/ vaginal opening. The baby is continuously growing in the womb. If the baby is too big at the time of birth , there will problems for it to come out.
So 9 months appears to be the optimum. The baby is big enough to survive and the birth will not be dangerous for the mother.
There is another very interesting fact about human birth. As the baby travels down the birth canal, the head twists 90 degrees. So the nose is pointing to the shoulder. This is not seen in any other mammal species. Human babies have very large heads in comparison to other species… because humans also have the largest brain. This twist of the head is necessary for the large head to pass through the birth canal.
No comments:
Post a Comment