Bipedalism And Human Birth: The Obstetric Dilemma

Bipedalism & Human Birth: The Obstetric Dilemma
Over hundreds of thousands of years, the human body has evolved in many different ways to help us adapt to our ever changing environment. The obstetric dilemma refers to changes in the female pelvic region as a result of our evolution towards bipedalism, and the resulting difficulties in childbirth. When assessing gestation periods, premature births and maternal & infant health, the question comes up as to why the human body has evolved in such a way as to make childbirth potentially fatal for both mother and child? The advantages of bipedalism can be seen when we throw a ball, carry the shopping bags from the car or collect the mail from the letterbox. But are the advantages we gain
In 1994, the average gestation period was 39.2 weeks, which dropped to 38.8 weeks in 2004 (Australia’s Babies. ABS 2010). Compared with chimpanzees and gorillas, this is a relatively short incubation period. Even though a longer period is desirable for prenatal development, there are many risks involved in child birth today and therefore there are a number of reasons why our species cannot afford the extra time in incubation, nor can we afford for the incubation period to be anything less. Chimpanzees’ offspring are born with 45-50% brain development, while human infants are born with just 25% of their brains fully developed (Discovery Media 2010). Foetal brain development is highly energy costly, and so a prolonged incubation would be detrimental to the health of the mother. This essentially means that a human child will spend close to a year helpless and completely dependent on its
Although they take up a lot of time and effort, in the interest of successful reproduction, the father is more likely to invest more of his time with the infant, providing necessary food and care while the young are growing up. This in turn creates an extended transition period from childhood to adults, meaning that a young child experiencing the world under careful guidance and support has a greater chance of survival. Another evolutionary adaptation is menopause. This is a natural response to aging in women, a process in which the menstrual cycle ceases, preventing women past childbearing age from having any more children. This adaption was made in the interest of reproductive success, because once the mother reaches this point she will now invest her time into her existing children and/or grandchildren. So even though more effort is required from both parents early in life and throughout childhood, it is greatly beneficial in the end as it boosts our chances of reproductive