The brain of a newborn child is only about a quarter the size it will be in a few years. Many parents will remember that an infant’s soft spot is a flexible skull made up of sutures, a fibrous fiber. A newborn skull’s smooth and flexible surface is an evolutionary masterpiece, as it allows the brain to develop and grow unlike that of any other creature.
Zeray Alemseged explains how the human skull has given us an evolutionary edge over other species.
Alemseged, a researcher at Explore, said: “Hominid skulls have changed significantly since we diverged around 7,000,000 years ago from chimpanzees.”
The Human Skull Is Smooth (19459025)
Evolution has altered the appearance of humans over time. To make room for the brain, the brain case (the part of the skull surrounding the brain) has grown. As our desire to chew tough meat diminished, the face shortened and the structures of cranial ridges that attached heavy muscles disappeared.
Over millions of years, the attachments for strong neck muscles that were so important to our primate forefathers have been drastically reduced.
Alemseged said, “In addition, during evolution we lost most of the ridges, crests, and attachments used for chewing heavy food [muscles].” Alemseged adds that today, the main function of the skull is to support the large brain and the previously expanded case.
Protection of our brains (19459025)
The human skull allows our brains grow quickly after birth. The brain’s size is between a quarter and a third of its adult size when we are born.
It doubles in the first year. The brain is 90 percent adult-sized by the time we reach our fifth birthday. Alemseged, a researcher at Discovery told the magazine that a braincase with fewer bumps could help to facilitate brain growth. The skulls of infants have room to grow rapidly because they are born without fused skull bones.
The smoothness is due to the structural integrity of the skull, which provides an uniform shell that protects the brain.
The Cleveland Clinic states that sutures are used to separate the bones of the skull to allow the brain to grow.
The sutures are like quilts that join the bones to create solid bone when they reach their full size. The skull is formed by five major sutures, including the coronal, which runs horizontally between the ears. Lambdoid suture is horizontal and joins a part of the back skull. The metopic suture links the frontal bones to the forehead.
Sagittal suture runs vertically down the top part of the skull. The squamous connects bones over the ears.
Human Skull Development Vs Ape Skull Development (19459025)
The development of the skull in an infant is very different than that of an ape.
At birth, the skull is much larger than it will be in adulthood. The skulls of adult apes, gorillas, and humans have similar numbers.
But that is where most similarities end.
Alemseged stated that “the human skull is similar to a primate’s skull.
The overall structure and bones of the skull are the same as those seen in apes.” The human skull differs from apes because of its large brain, tiny face and gracile teeth. The human skull differs so radically from other primates in this sense.
Great apes, unlike humans, have a face that is heavily built and jutting, Alemseged said, with a ratio of facial size to braincase size. Alemseged said that the human face is hidden beneath the braincase and so small, compared with great apes, it’s “almost faceless”. The difference is mainly in size.
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