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| Escultura de Fernando Botero |
It should come as no surprise the importance that one bone, just one bone, holds in human genealogy from the perspective of the three Abrahamic religions. According to Genesis (2:23), Eve emerged from Adam's rib:
Then the Lord God caused a deep sleep to fall upon the man, and he slept. And He took one of his ribs, [...] and from the rib that the Lord God had taken from the man, He made a woman.
In addition to creating
woman, this account gave rise to an absurd dogma imposed for centuries: since
Eve was created from a rib taken from Adam, all men had 23 ribs, one less than
women.
Throughout history, the ecclesiastical
hierarchy has made all scientific advancements clandestine. From the movement
of the Earth around the Sun to in vitro fertilization, passing through the
smallpox vaccine, anesthesia, lightning rods, tomatoes, blood transfusions,
painless childbirth, condoms, and stem cell research, those in charge of the
sacred fire have almost always prohibited or condemned any attempt at progress
arising from human intellect. However, despite these efforts to keep us in
darkness, no anathema, excommunication, or bonfire has managed to stop the
human drive that forges a path through the darkness.
This drive to explain the nature of things
scientifically was what led anatomist Vesalius to challenge the Inquisition.
Since the time of the Greek Galen, anatomical dissections had been performed on
animals, but the Catholic Church allowed Vesalius to dissect the bodies of the
executed because, according to theologians, there was no possibility that their
souls would return from hell. Vesalius counted the ribs and debunked the myth
in his Fabrica (1543), organizing a huge debate before inevitably falling, of
course, into the clutches of the Inquisition.
Although some ribs are relatively unimportant
anatomically for human architecture, the same cannot be said for another bone,
the pelvis, and the hip joint, which connects the femur to the pelvis. The
particular configuration of the female hip is the cause of labor pains,
although, in the Old Testament, the origin is attributed to another divine
curse. Indeed, after "knowing" each other in the biblical sense, Adam
and Eve realize their nakedness, and Yahweh condemns the woman: "I will
greatly increase your pains in childbearing; with pain you will give birth to
children" (Genesis 3:16), a prophetic curse that, like many other
prophecies, is made a posteriori, once the prophesied event is known, to
solemnize the obvious and without any chance of failure.
For religion, the rib is fundamental in the
history of humankind, while for the science of evolution, the hip is the key
piece. All the remarkable anatomical and physiological changes that developed,
over millions of years of evolution, the large brain that characterizes Homo
sapiens would have been of no use if, in parallel, a hip capable of supporting
the enormous skull had not evolved.
Unlike other primates, in humans, the bones of
the hip are different in both sexes, which is easily visible in the anatomical
curves and the female way of walking. This structural difference has led all
human cultures to view the hips as a symbol of fertility and a general
expression of sexuality: from the sculptures of classical antiquity to the
full-figured women of Rubens, artistic creations of all kinds have emphasized
the volume of the hips as the most attractive manifestation of femininity.
Women’s hips are wider and deeper than men’s,
with femurs more widely spaced to allow for greater separation during
childbirth. The iliac bone and its associated musculature are shaped in such a
way as to keep the buttocks apart, ensuring that the contraction of the gluteal
muscles does not interfere during delivery.
Despite this, childbirth in humans is extraordinarily complicated. During childbirth, the full-term fetus must pass through the lower part of the pelvis through a bony passage known as the "birth canal." While in large anthropoid apes, delivery is easy, quick, and painless because the birth canal is large relative to the size of the fetal head, human newborns are about the same size as the birth canal, making the passage during delivery incredibly difficult.
The birth canal in
human females has an average maximum diameter of 13 centimeters and a minimum
diameter of 10. Through this space must pass a baby whose head has an
anteroposterior diameter of 10 centimeters and whose shoulders are typically 12
centimeters apart.
To make things even more complicated, the
evolution towards bipedalism (the technical term for walking on two feet, which
characterizes hominids) led to a series of anatomical changes that turned the
already narrow birth canal into a tortuous passage. As in all terrestrial
quadruped mammals, in anthropoid apes, the birth canal is straight, the uterus
is aligned with the vagina, and the fetus is born without flexing, facing its
mother.
In women, due to bipedalism, the bones of the
hip have undergone modifications that have led to the birth canal becoming
angulated, and the vagina forming a right angle with the uterus. As a result,
the mechanism of birth (the series of rotations and twists in the spinal column
that the fetus must perform to emerge through the mother’s tortuous birth
canal) is a peculiarity of humans, absent in vertebrate animals. This
peculiarity is traumatic for the baby and painful for the woman, and it is the
price that seven million years of evolution have forced Homo sapiens to pay as
compensation for its two great evolutionary advantages: upright walking and the
development of a large brain mass.
Since the appearance of the first life forms nearly 3.5 billion years ago, the common mode of movement among living beings has been swimming, crawling, or moving on a fixed number of legs, usually four in terrestrial mammals, among which humans are included. Hominids—bipedal primates—emerged just about seven million years ago.
In issue 106 of the American scientific journal Proceedings of the National Academy of Sciences, anthropologists Weaver and Hublin delve into one of the most accepted paradigms in the complex process of human evolution: the adoption of bipedalism as a vital strategy in the hominid lineage, a key evolutionary step that is responsible, not any biblical curse, for the painful childbirth characteristic of female Homo sapiens, which—as Weaver and Hublin show—was also suffered by Neanderthal females more than 200,000 years ago.
