A longtime staple of science fiction is the depiction of extraterrestrials having extremely large heads holding almost-as-large brains … think “To Serve Man,” the classic Twilight Zone episode. H.G. Wells may have been the first writer to describe aliens with big heads, and that image eventually became the ‘grey aliens’ many believe are actual extraterrestrials. Many experts paid to ponder what extraterrestrials would look like stick with the ‘big head’ idea. It turns out all of these depictions are rooted in truth … although not because these species evolved into big-brained, smart beings first. A new study of NASA astronauts found that the human brain expands during long-term space fights – a phenomena that space traveler’s skulls may have to evolve quickly to accommodate to avoid damaging their brains. Or will cranial binding return for parents who want their infants to grow up to be Mars explorers?
“When you’re in microgravity, fluid such as your venous blood no longer pools toward your lower extremities but redistributes headward. That movement of fluid toward your head may be one of the mechanisms causing changes we are observing in the eye and intracranial compartment.”
Detailed medical examinations of astronauts post-flight – especially Scott Kelly and his earthbound twin Mark -- found problems with eyesight and cognition long after they returned, raising concerns and prompting more extensive research. In a new study published in the journal Radiology and summarized in Sci-News, Professor Larry Kramer from the University of Texas Health Science Center at Houston led a team which gave MRI scans to 11 astronauts (10 men and one woman) before they departed for extended stays on the International Space Station. The astronauts were then given MRIs the day after they returned from space and periodically throughout their first year back. What they found will definitely affect the future of human space travel.
“What we identified that no one has really identified before is that there is a significant increase of volume in the brain’s white matter from preflight to postflight. White matter expansion in fact is responsible for the largest increase in combined brain and cerebrospinal fluid volumes postflight.”
White matter – the fibers of the central nervous system that act as relays between brain regions – expanded astronauts’ brain and cerebrospinal fluid volumes, causing elevated intracranial pressure to what appear to be dangerous levels. How dangerous?
“We found that the pituitary gland loses height and is smaller postflight than it was preflight. In addition, the dome of the pituitary gland is predominantly convex in astronauts without prior exposure to microgravity but showed evidence of flattening or concavity postflight.”
The pituitary gland is considered to be the body’s master gland because it controls the thyroid and adrenals, the ovaries and testicles, and others, affecting the body’s hormone levels. The MRI scans found that this elevated cranial pressure lasted the entire year and can cause normal pressure hydrocephalus, whose symptoms include difficulty walking, bladder control problems and dementia.
Will future human space travelers need to develop larger skulls – either evolutionarily or artificially? As usual, more research is needed. However, it wouldn’t be the first time that H.G. Wells saw the future and depicted it accurately. Let’s hope Rod Serling and “To Serve Man” isn’t the same.