Abstract
The idea that scientists could take the one and only example of a biological control system that developed on planet Earth, which we call a “nervous system”, and compare it with similar or analogous systems that we do not yet know even exist on other worlds would seem to be a totally impossible task. Yet, those of us who call ourselves astrobiologists are now finding that our new science is quickly approaching a critical point when we will need to have this information, or at least have developed a sound strategy for obtaining it when we get the opportunity which, hopefully, will not be too far in the future. With the recent finding that life on our planet is far older, far more diverse, and far more resistant to destruction than previously believed (i.e., the discovery of extremophile forms of life everywhere), along with the sudden and rapid surge of discoveries of possible homes (exoplanets or their moons) for alien life everywhere in space, many of our space and life scientists are now beginning to feel the urgent need to begin making preparations for investigating what may be the next big breakthrough in astrobiology related to determining not only what life “is or is not” but also how it functions and interacts with its own surrounding environments. Our astrobiologists need to now start thinking about how ETs, if they exist, might interact not only with their own environments but perhaps also with us humans who might be about to become “their” new fellow inhabitants of “our” universe.
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Notes
- 1.
However, before going any further in this bizarre attempt on my part to describe how I (even as the lifelong professional neuroscientist that I am) think nervous systems might be able to evolve on other worlds, I must unequivocally and very strongly emphasize that while I know a considerable amount about how brains developed on Earth, I, like the reader and everybody else on Earth, know absolutely nothing about how, or even whether, nervous systems exist elsewhere or could even develop elsewhere in our obviously vast and hostile universe. However, I strongly believe that with all the incredible discoveries of extremophiles and exoplanets that our scientists have made in the past few years, the possibility that we are not alone in the universe is now definitely growing. It is now time for some astronomy student out there to team up with someone with knowledge of how brains develop and work on Earth, and take the lead in trying to merge our rapidly exploding fields of both astrobiology and brain science. Perhaps it Is time to develop doctoral level training programs (or at least coursework) in “astrobiological neurosystems”, “astroneurobiology ” or “astroneuroscience ”, or some such “moniker” that we could impress our colleagues with.
- 2.
The author would like to state totally upfront that he believes the single greatest impediment to our neuroscientists discovering exactly what kinds of functions different animal species are capable of is that our social history, due to our being predatory and emotional beings has totally ingrained many of us with the idea that, as a species, man ranks directly below God and the angels in terms of our mental capabilities. Mankind’s pervasive anthropocentric concept (the idea that man is unique in being “god-like” in having large varieties of complex mental capabilities, while “lower” animals have very few such higher level mental capabilities) has plagued the brain science literature for centuries and caused many of us to believe that consciousness, problem solving skills, language, and many other complex mental activities are quite common in man but totally (or near totally) absent in most lower animal species. Man “thinks” and “solves problems” while lower animals rely on inherited or ingrained built in or prewired instinctive mechanisms. When our astrobiologists, in the next few centuries, begin finding complex living creatures on other worlds, our neuroscientists must dump this anthropocentric constraint to their professional thinking, or they will fail miserably in their work.
- 3.
In order to avoid boggling the reader’s brain any more than is necessary, the author has deliberately chosen not to attempt to describe the complex process by which nerve impulses or action potentials are actually created and transmitted. The process involves the transfer of positively and negatively charged potassium and sodium ions across the coverings (outer layers or “skin”) of the cell membranes of nerve cells, axons , and dendrites and the chemically induced “all-or-none” triggering (or inhibition) of new nerve impulses in other neurons . If the reader desires to learn more about this quite complex process, I would suggest consulting almost any recent introductory level textbook on neuroanatomy or neurophysiology. I have referenced three such introductory level books (Amthor 2012; Dubin 2002; Liebman 1986) in my Further Suggested Readings section at the end of the present book.
- 4.
In reality, rather than neurons “ordering” the cell nucleus to build new neural transmitters and ship them to the synapse to trigger a new nerve impulse, the nerve cell nucleus contains small organelles (factories) that are constantly manufacturing neural transmitters and placing them into small packets to be delivered down the axon to the synapse so that they will be readily available whenever a new action potential needs to be triggered (or inhibited).
- 5.
More recent studies have started to dispute this 10 to 1 glial cell to brain cell ratio. Some studies now suggest the ratio might be closer to 1 to 1. The ratio could, however, vary widely among different animal species, or between different parts of the brain. Counting numbers of glial cells in different brains does not appear to be one of neuroscience’s burning questions! We neuroscience professors have never been able to interest a doctoral student into taking on this project for his/her doctoral dissertation (thesis).
- 6.
How fast do nerve impulses travel, you ask. The speed at which action potentials travel along typical axons or dendrites varies greatly, depending on the specific kind of nerve involved (i.e., whether the axons and dendrites have fatty myelin sheaths wrapped around them which speeds up neural conduction or do not have myelin sheaths which slows down their conduction), or the particular species involved, i.e., primitive or advanced (e.g., cockroach or man, etc.). The typical range of speed varies from a typical “snail’s pace” of 2 miles/h (in snails or other kinds of insects, of course) to 250 miles/h in some animal brains (cats, birds of prey, jack rabbits, etc).
- 7.
In 1950, the Nobel prize winning atomic physicist Enrico Fermi was having lunch with a small group of his science colleagues. The group was having an informal discussion related to the possibility that large numbers of habitable planetary systems might exist in the universe, and some could be home to advanced technological civilizations. At the end of this discussion, Dr. Fermi reportedly turned to the person seated next to him at the table and said something to the effect of “So, where is everyone?” While a very simple question at the time, Dr. Fermi’s question has, in subsequent years, become the famous Fermi Paradox that is at the center of the SETI research effort. If there are so many potentially habitable worlds out there, why has science so far not found some evidence of the existence of intelligent extraterrestrial civilizations?
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Cranford, J.L. (2015). If Other Kinds of Nervous Systems Exist in the Universe, How Do We Locate and Identify Them?. In: Astrobiological Neurosystems. Astronomers' Universe. Springer, Cham. https://doi.org/10.1007/978-3-319-10419-5_3
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