Star Larvae Hypothesis
(WARNING! Digression: The binge-purge strategy characterizes not only the development of brains, but also the evolution of planetary life generally. Episodes of mass speciation have alternated with episodes of mass extinction. During the past several hundred thousand years, cycles of glaciation have intensified evolutionary competition, and the cycles have driven evolution—while preserving Gaia's climatological support systems—toward a pinnacle of planetary adaptedness in the form of Homo sapiens. Humankind spans all climates; we are the most geographically dispersed species on Earth, having adapted to all climates by engineering locally hospitable mini-climates. This is the process of urbanization, and its extensions now include the weightless International Space Station.
Glaciation cycles function as genetic filters—stress tests—that drive the Earth's gene pool toward climatological adaptability—an adaptability that ultimately takes the form of humankind’s ability to construct niches that enable it to occupy climates as hostile as that of outer space. A readable book that places this genomic plasticity in the larger context of Earth's ontogeny is Peter Ward and Donald Brownlee, The Life and Death of Planet Earth. See also Gould and Eldredge's theory of Punctuated Equilibrium.)
Evidence from prenatal research corroborates the emphasis on movement as the primary factor in producing enrichment effects. Fetuses cavort in their amniotic capsules like astronauts, and their gyrations apparently pay off neurologically. In The infant Mind, Richard Restak notes that ultrasound imaging reveals two predictable patterns of intrauterine movement:
"In the first movement pattern, the head is flexed backward and turned to one side. This is accompanied by rotation of the trunk and the rest of the body to the same side. In the second movement pattern, leg movements occur, almost as if the fetus were pedaling a stationary bicycle, resulting in a somersault as the legs contact the uterine wall. . . . These movements serve the purpose of stimulating brain development, especially those structures having to do with balance, coordination, and coping with the forces of gravity."
How spinning in three-dimensions in an environment of simulated weightlessness would prepare an organism for the relative flatness of a gravity-bound world is unclear. Newborn brains might be better adapted to a weightless environment, given their prenatal experience. In any case, the womb bears the hallmarks of an enriching environment. It exercises (kinesthetic and tactile, vestibular and proprioceptive) sensorimotor feedback loops.
Brains that develop in weightlessness will be wired more complexly than their planetbound counterparts.
Psychologist Timothy Leary proposed a model of exo-psychology in which the psychedelic state foreshadows the psychology of native extraterrestrials.
But once its bearer towels off, a fetal brain's prospects plummet. Birth is a crisis for a developing brain. It demotes the gymnastic fetus to the lowly status of sidelined newborn. No matter how intense its sensory experience, a newborn can’t respond with much movement. No more brain-stimulating gymnastics for the kid in the crib. Infants are essentially beached marine mammals. Outside the watery environment of the womb, they are unable to respond in any gross muscular way to their sensory inputs. They are "observers" in the clinical sense of the rat experiments.
— I. P. Couliano
Out of This World
Healthy newborns eventually overcome their immobility by sequentially mastering specialized skills. They squirm and in a few months learn to roll over and crawl. Infants will pull themselves up by clutching onto furniture at ten months or so and take a step somewhere around their first birthday. They go on to walk, run, climb, jump, pedal bicycles, and in other ways establish working relationships with gravity.
This programmed sequence segues later in life into rote habits of adulthood. In its mature state in a workplace, a typical middle-class American brain will spend much less time moving in complex ways than it did on the playground in its formative youth. It may be subjected to long hours immobilized at a desk engaging a computer through keystrokes and mouse clicks, in a bucket seat engaging a drivetrain through slight arm and foot movements, and reclining in an overstuffed chair engaging TV fare through buttons on a remote control.
The paralysis of the newborn, the skills acquired in sequence during childhood, and the relative sloth of adulthood collectively must engage and maintain a relatively meager set of sensorimotor feedback loops. Synapse-rich toddlers become brain-damaged adults as they schlep into their senior years the few synapses that survive "the trimming of exuberant collaterals," as some researchers have labeled the synaptic selection process. And in this relatively impoverished state modern urbanites function normally, for the most part, being by adulthood well adapted to the vestibular and proprioceptive impoverishments of terrestrial urbanity.
In contrast to the strictures just described, an enriching curriculum awaits brains that develop in weightlessness. Not having to spend their first postnatal months beached on the gravitational shore and instead enjoying the freedom to fly, is a prospect that a brain’s "exuberant collaterals" could only welcome.
Moreover, the neural enrichment that weightlessness promises stands to be augmented by the addition of new neurons throughout life. In contrast to the traditional view that no new neurons form after birth, research conducted in the 1990s revealed that brains develop new cells throughout their lives and that bodily movement stimulates the development of these cells. Space brains might become pumped up not only in terms of synaptic density per neuron, but also in terms of the sheer numbers of neurons that they possess.
New cells in adult brains don't arise from the same process as do most other cells in a body, which arise when a mature cell divides into two cells. The brain cells that arise after birth develop instead from layers of immature stem cells that are retained deep in the brain from its embryonic days. The cells mature as they migrate out of the immature layers.
The new research is summarized by neurobiologists Gerd Kempermann and Fred H. Gage in the May 1999 Scientific American. The authors conducted their own enriched/impoverished experiments using a variation of the standard methodology. Two groups of mice were raised in standard cages, one with running wheels and one without. "The mice having unlimited access to the wheels made heavy use of the opportunity and ended up with twice as many new nerve cells as their sedentary counterparts did, a figure comparable to that found in mice placed in an enriched environment," the researchers report, confirming the preeminence of bodily exercise in promoting enrichment effects.
The cover story of the March 26, 2007, Newsweek goes further and reports on the link between exercise and brain growth in human subjects.
"After working out for three months, all the subjects appeared to sprout new neurons; those who gained the most in cardiovascular fitness also grew the most nerve cells. [. . . .] So far, though, for reasons no one really understands, the few studies that have examined stretching, toning, and weight lifting have found little to no effect on cognition."
This observation underscores the connection between complexity of sensorimotor feedback (cardiovascular exercise vs stretching, toning and lifting) and enrichment effects.
Research that Gage and colleagues continue to conduct in this field keep turning up results that support the contention that varieties of bodily movement promote neurological enrichment and thereby, by implication, that weightlessness is a neurologically enriching environment, because it promotes the greatest variety of bodily movements. A feature article in the October 2015 issue of The Scientist magazine (“Brain Gain”, by Jef Akst), summarizes the ongoing work:
“What we found was that there was surprisingly much neurogenesis in adult humans,” [Jose] Frisén says—a level comparable to that of a middle-aged mouse, the species in which the vast majority of adult neurogenesis research is done. “There is hippocampal neurogenesis throughout life in humans.”
As the article later acknowledges, “Epidemiological studies have shown that people who lead an active life—known from animal models to increase neurogenesis—are at a reduced risk of developing dementia, and several studies have found reduced hippocampal neurogenesis in mouse models of Alzheimer’s.”
The theme of exercise merges into that of youthfulness, or juvenilization: “For a period of about four or five weeks, while [the newborn neurons] are maturing, they’re hyperexcitable,” says researcher Gage. “They’ll fire at anything, because they’re young, they’re uninhibited, and they’re integrating into the circuit.”
The story of life. But the characterization grabs the attention of the star larvae hypothesis, because it supports the hypothesis’ contention that bodily movement drives neurological enrichment and that, therefore, weightlessness is the ultimate neurological enricher.
So, what’s an enriched brain supposed to do with all that extra gray matter? The Newsweek article suggests the direction in which enrichment carries a brain: "[T]he hippocampus is especially responsive to BDNF's effects, and exercise seems to restore it to a healthier, 'younger' state. 'It's not just a matter of slowing down the aging process,' says Arthur Kramer, a psychologist at the University of Illinois. 'It's a matter of reversing it.'" (BDNF is brain-derived neurotrophic factor, a brain chemical described in the article as "Miracle-Gro for the brain".)
Weightless, enriched, neurology would seem to aim its corresponding subjectivity—the qualities of experience that it mediates—at youthfulness, at juvenilization.
Although this page focuses on neurological effects of weightlessness, genetic effects also have been observed, as referenced below.
"Recent cell culture experiments by Timothy Hammond at Tulane University suggest that the activity of more than 15 percent of the human genome changes during microgravity exposure. This is not just a simple statistic; it's a profound demonstration that gravity alters gene expression of cells, which must affect our basic structure and composition. We've barely begun to explore what these changes mean."
-- From testimony of Dr. James Pawelczyk, Associate Professor of Physiology and Kinesiology, Pennsylvania State University, to the Senate Commerce, Science, and Transportation Committee meeting on the International Space Station, October 29, 2003.
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Identical twins, Scott and Mark Kelly, serving as test subjects--Scott, who spent a year on the International Space Station between 2016 and 2017, and his brother Mark, who spent that year on Earth--revealed dramatic effects of weightlessness on genes. Preliminary results of the twins experiment were made public in early 2017 and included observations pertaining to the effects of weightlessness on telomeres, chromosomal structures that seem to function as age markers--they shrink as a person ages. Scott's telomeres grew longer in space, then reverted to normal length once he returned to Earth. How conventional evolution theory would account for such a genetic sensitivity to weightlessness is unclear. A more complete report of the research results is scheduled to be released later in the year.
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In February 2017, the natureresearch journal Scientific Reports published the results of experiments carried out on the International Space Station that demonstrated a peculiar reaction of living mammalian cells to weightlessness. The results showed that microgravity inhibits the oxidative burst reaction, a behavior characteristic of rat macrophages, a type of white blood cell that plays an important role in the rat immune system. The experimental observations are peculiar in that exposure to weightlessness inhibited this response, but only for a few seconds. Then the response resumed, indicating an initial reaction to weightlessness and then a rapid adaptation to that environment.
A University of Zurich (UZH) news release reports,
“Mammalian cells fully adapt to zero gravity in less than a minute. Real-time readings on the International Space Station (ISS) reveal that cells compensate ultra-rapidly for changes in gravitational conditions. [. . . .] Based on real-time readings on the ISS, UZH scientists can now reveal that cells are able to respond to changes in gravitational conditions extremely quickly and keep on functioning. Therefore, the study also provides direct evidence that certain cell functions are linked to gravity. [ . . . .] The research team used the so-called oxidative burst – an old evolutionary mechanism to kill off bacteria via defense cells – to study how rat cells responded to changes in gravity. With the aid of centrifuges, [astronaut Samantha] Cristoforetti altered the gravitational conditions on the ISS, which enabled the team in the control center to track how the cells reacted. “Ultra-rapidly,” explains Oliver Ullrich, a professor from the Institute of Anatomy at the University of Zurich. 'Although the immune defense collapsed as soon as zero gravity hit, to our surprise the defense cells made a full recovery within 42 seconds.'”
The Scientific Reports paper further explains, “We measured the oxidative burst reaction in mammalian macrophages (NR8383 rat alveolar macrophages) exposed to a centrifuge regime of internal 0 g and 1 g controls and step-wise increase or decrease of the gravitational force in four independent experiments. Surprisingly, we found that these macrophages adapted to microgravity in an ultra-fast manner within seconds, after an immediate inhibitory effect on the oxidative burst reaction. For the first time, we provided direct evidence of cellular sensitivity to gravity, through real-time on orbit measurements and by using an experimental system, in which all factors except gravity were constant. The surprisingly ultra-fast adaptation to microgravity indicates that mammalian macrophages are equipped with a highly efficient adaptation potential to a low gravity environment.”
“The gravitational force has been constant throughout the 4 billion years of Earth’s evolutionary history and probably played a crucial role in the evolutionary explosion of organisms. All terrestrial life, including man, has adapted to this fundamental force by developing a number of important features in their composition and functions, whereas changes of the gravitational environment induce strong alterations of human physiological systems, which respond and adapt to the new gravitational environment within hours or weeks. Importantly, microgravity has been demonstrated to have profound effects at the cellular and molecular level, including changes in cell morphology, proliferation, growth, differentiation, signal transduction and gene expression. In spite of the witnessed serious and often disastrous effects on cells, many astronauts have now completed long term stays in space without suffering from any severe health problem associated with the effect of microgravity. Regarding the innate component of the immune response, the magnitude of the change during spaceflight is not great or the pattern of change across various functions is not consistent.”
"This leads to the hypothesis that the cells of the body must have an enormous capacity to adapt to microgravity, be capable of reacting to altered environmental conditions and of restoring cellular functions to a considerable degree. [. . . .] In our study, we demonstrated for the first time and through real-time measurements on board of the International Space Station (ISS) that mammalian cells have the capacity to adapt to microgravity within seconds.”
"The molecular mechanisms with which oxidative burst reacts and adapts to a new gravitational environment are yet unknown. Discussions of whether an in vitro single cell or a cell population can sense changes in the gravitational field are very controversial and theoretical considerations suggest that the forces involved are too small to trigger any cellular response to the changed environment. In spite of these theories, experimental data indicate that several types of cultured cells are sensitive to gravity, pointing to the cytoskeleton as a potential initial gravity sensor. In our study we demonstrated direct evidence of a cellular response to microgravity.”
"Our results imply that mammalian cells are equipped with a surprisingly ultra-fast and efficient adaptation potential to low gravity and that therefore key cellular functions of multicellular life could adapt to and exist in a low gravity environment. [. . . .] These adaptations appear to include very complex changes of cellular and molecular parameters. Due to the fact that gravity has been constant throughout the history of Earth and evolution of life, no pre-set adaptation program or genetic memory of life responding to gravitational force changes can be expected. Cellular response to altered gravity may be less organized than other adaptation processes, yet many of the so far investigated terrestrial organisms are able to perceive gravitational forces in the range of 10−3g. This happens in spite of the Earth’s acceleration of 1 g, which has been constantly present over millions of years, an enigma named the ‘gravi-paradox’”
What do Darwinism, Neo-Darwinism, the modern synthesis, or even the recently coined “Extended Evolutionary Synthesis” have to say by way of explaining DNA’s responsiveness to variations in gravity? How would any purely terrestrial, non-teleological model of evolution account for it? It could be accounted for, seemingly, only by explaining it away as a fluke.
But the star larvae hypothesis welcomes this new data. In the star larvae model, DNA is very much at home in an environment of variable gravity, because, in this model of the stellar life cycle, DNA spends time not only on planets, but also in space. Once terrestrial phenotypes extend themselves through sufficiently advanced technology, life returns to the familiar environment of weightlessness, from which it arrived on planets in the first place. DNA is equally at home with and without gravity.
The new data serve not only as evidence in favor of the star larvae hypothesis, but also as good news for space-faring humans. Concerns about detrimental effects of weightlessness on human tissues might be overblown. Further research will discover the robustness of biology’s capacity to adapt to weightlessness.
NEXT > Neuroplasticity and Neurological Neoteny
The Star Larvae Hypothesis:
Stars constitute a genus of organism. The stellar life cycle includes a larval phase. Biological life constitutes the larval phase of the stellar life cycle.Elaboration: The hypothesis presents a teleological model of nature, in which
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