As you may already know, I am extremely tired, and just plain done, with being pregnant (currently 39 weeks). So this question popped into my mind, ‘why does it take 9 (very long) months to have a baby?’ and I decided to investigate.
Other mammals, like chimpanzees and horses, have babies that are already able to walk
and, for the most part, take care of themselves. According to Adolf Portmann, zoologist, if we were having babies similar to other mammals, we would need to be pregnant for 18 to 21 months in order for human babies’ brains to reach the same level of development (Adolf Portmann’s book ‘A Zoologist Looks at Humankind’). Are you crazy?! Another 9 to 12 months, HELL NO!
Previous studies have found that this may be due to our physical limits, that our pelvises are not wide enough to birth a baby more developed due to the demands of walking. Anthropologists theorised that evolution made a trade-off between big baby brains and narrow pelvises.
However, current research has proven all of the above is incorrect.
The real reason we are having babies too early is due to our metabolism. Holly Dunsworth, an anthropologist at the University of Rhode Island, mentioned in a Huffington post article
, “There is not a unique pelvic constraint on gestation length and baby size. There is a certain capacity a mother has metabolically, and once that capacity is reached, the baby is born.”So, mothers are actually putting in more energy than our mammal counterparts! Human pregnancies are 37 days longer and are born twice the size of our gorilla friends. According to researchers, our pelvis would only need to widen 1.18 inches (3 centimetres), which is within a normal range of variation for humans. “The extra space wouldn’t add any extra energy burden.” This means we are putting in more energy than we have thousands of years ago and super-sizing our babies. I’ll have a Big Mac please!
So why are babies born after nine months of pregnancy? The real answer: our metabolism. After six months of pregnancy, women exert twice their typical energy, a burden that only gets greater as the fetus gets larger. As we get closer to 9 months, woman just don’t have enough energy to continue with the pregnancy. Explains why I’m so tired all the time!
But isn’t it bad that our babies are not fully developed when they come out of the womb? John Fleagle, an evolutionary biologist at Stony Brook University School of Medicine in New York, said, “it may be a mistake to think of helpless babies as an evolutionary negative. Being born before the brain is set allows human offspring to learn from experience.”
There you have it! We just don’t have enough energy to last another 9 months, and in a way, our babies are learning more on the outside of our womb!
Here is an nifty infographic I found on LiveScience
of Best and Worst places to be a mother: