Obstetrical dilemma

This evolution-related article is a stub. You can help Wikipedia by expanding it.v · human species through a number of biological changes, specifically the shifting of the females' pelvic bones, thereby shortening the fetal incubation period. The dilemma began when human ancestors started to evolve into a bipedal creature. Over this period of transformation, a number of structures in the body changed size, proportion or location in order to accommodate bipedal locomotion. The foramen magnum and the brain stem moved from the back of the skull to the lower side, and the spine formed at a right angle to the jawline. These alterations allow a person to stand upright and face forward without placing undue strain on the neck or back. To help support the upper body, a number of structural changes were made to the spine and pelvis. The ilial pelvic bone shifted forward and broadened, while the ischial pelvic bone shrank, narrowing the pelvic canal. These changes were occurring at the same time as humans were developing larger craniums. Therefore, in order to successfully undergo childbirth, the infant must be born earlier and earlier, thereby making the child increasingly developmentally premature. Today, human infants are born with only 25% of their brains fully developed, compared to chimpanzees, whose offspring are born with 45-50% brain development[citation needed]. Since human infants are born so early, they spend more than a year in a nearly incapacitated state. Therefore, human infants depend on their parents much more and for much longer than other primates. References Bipedalism and human birth: The obstetrical dilemma revisited Wikimedia Foundation. 2010. Игры ⚽ Нужно решить контрольную? Obstetric labor complication Xanthomatous biliary cirrhosis Look at other dictionaries: Obstetrical Dilemma — The Obstetrical Dilemma refers to the evolutionary development of the human species through a number of biological changes, specifically the shifting of the females pelvic bones, thereby shortening the fetal incubation period.The dilemma began… …   Wikipedia Childbirth — Parturition redirects here. For the Voyager episode, see Parturition (Star Trek: Voyager). Childbirth (also called labor, birth, partus or parturition) is the culmination of a human pregnancy or gestation period with the birth of one or more… …   Wikipedia Maternal death — Classification and external resources ICD 10 O95 ICD 9 646.9 …   Wikipedia Human evolution — This article is about the divergence of Homo sapiens from other species. For a complete timeline of human evolution, see Timeline of human evolution. Reconstruction of Homo heidelbergensis which may be the direct ancestor of both Homo… …   Wikipedia Hip — For other uses of the term, see hip (disambiguation). Hip (anatomy) Bones of the hip Latin coxa Gray s …   Wikipedia Circumcision — This article is about male circumcision. For female circumcision, see Female genital mutilation. Circumcision Intervention Circumcision being performed in central Asia, possibly Turkmenistan c. 1865–1872. Restored albumen …   Wikipedia Nursing — For other uses, see Nursing (disambiguation). Nursing is a healthcare profession focused on the care of individuals, families, and communities so they may attain, maintain, or recover optimal health and quality of life from conception to death.… …   Wikipedia 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”