Artist’s Depiction of Oumuamua [6]
Oumuamua is the first confirmed interstellar object. It was spotted on October 19, 2017, by the University of Hawaii’s PAN-STARRS1 telescope. The telescope was designed to find and catalog near-Earth objects. This discovery is a fluke. Various telescopes tracked it as it slingshots past the sun and it was out of range by the time it passed Mars orbit on its way out of the solar system. [6] Since then, one other interstellar object has been found, comet 2I/Borisov on August 30, 2019. [7] Now that we are looking we will no doubt find more in the future and perhaps in existing data. Oumuamua means “a messenger from afar arriving first” in Hawaiian and it has turned out to be a unique object. It is not a comet but it did speed up as it left the solar system as comets tend to do. It is not like any known asteroid, having an extremely high ratio of length to width. It is 10 times longer than it is wide. One side of the object is 10 times brighter than the other, something that has never been seen before. [6] This has raised many questions and the limited time we’ve had to study the object has not helped. We now know that large chunks of matter can travel between the stars. We also know that this matter can take on at least two shapes, one familiar and the other unfamiliar. Work to turn Oumaumau into a special comet is ongoing and a paper just recently released conjectures that it is made of nitrogen ice. [9] Another question is how do these objects start on interstellar voyages to begin with. The main candidates are explosions or massive collisions. Oumuamuais such a unique object that it has started another line of inquiry, mainly proposed by the Harvard astronomer, Avi Loeb, who has written a book [10] on the subject and has given several long-format interviews. [11][12] His view is that we can’t reject the idea that Oumuamua might be an alien-made object.
Let’s play a bit with this idea. First, I’d like to say that I see nothing wrong with Dr. Loew’s conjectures as a legitimate scientific study and any push back from his school or the astronomy community other than disagreement is a sad state of affairs. What I do see is a fundamental question that is missing here. Could any of these objects harbor or harbor evidence of a non-Earthbiology? Is Oumuamua just a random chunk of stuff that may or may not have been shaped by its journey or is it the interstellar equivalent of a spore or a seed, or, as Dr. Loew postulates, a production of a sentient civilization?
I’m going to make some assumptions about what interstellar biology might be like. Underlining these assumptions are some ideas from modern biology, contingency, convergent evolution, and island biogeography, first postulated by Robert MacArthur and E. O. Wilson in 1967. [1]
According to recent cosmology, the Universe will expand forever and as the expansion reaches the speed of light, fade out like a dying ember. This current iteration of the fate of the Universe has always dissatisfied me. Life reverses entropy at a local level, living systems are open rather than closed. Maybe the purpose of life is to reverse the heat death and maybe even the expansion of the Universe? To speak of purpose puts me on dangerous ground and will enrage many a biologist. Even to speak of emergent properties of complexity will make some nervous. Biological thought has gone from life being designed by some supernatural agency to a Scale of Nature or a Great Chain of Being, a ladder of life climbing from lowest forms to human supremacy,
Aristotle’s Ladder [4]
to the current view of humans as just one lone species in a vast web of complexity.
Current Tree of Life [5]
Humans do have unique features like language and technology that have allowed us to colonize or visit most of the planet including near orbit and to extend our senses by many orders of magnitude. Rather than progress or purpose, biologists talk about major transitions in evolution [14] like to multi-celled animals or to social behavior or again, to human language. Maybe the next transition in evolution is for life to leave the planet? Could this have happened elsewhere? Does this require human-like sentience?
Steven Jay Gould in Wonderful Life [3] famously stated that human uniqueness is perhaps just a random event and if the “tape of life” was rewound and played back again, there was no guarantee that humans would exist or that we’d look anything the same. This he called “contingency,” the fact that life has a history of having to deal with billions of small random events and many large ones. He notes first, the great extinctions, many caused by asteroid impacts, and that during the Cambrian explosion there were several basic body plans for animals that did not survive. For this and other ideas he was and still is castigated as a dangerous commie. [13]
Contingency is hard to prove and current thought is that it may have mattered more at evolution’s beginnings than it does now [2]. One early transition that may be contingent is the chirality (handedness) of amino acids. All life’s amino acids are left-handed. There is no real reason why they shouldn’t be right-handed or a mixture of both. I have seen no evidence that left-handed amino acids are in any way superior to right-handed. Chirality may be due to chance. Would a right-handed life form pose a danger or would it be driven extinct?
Homology is when a similar biological character (pathway, structure, behavior) exists in two different species but a direct line of descent can be found between the two species. For example, the three tiny bones in our inner ear are homologous to three bones in the jaws of lizards. The use and shape of the bones have changed but they are directly related. Convergent evolution is when two characters are similar but not related. Javelina in Arizona and Mexico look like pigs but are related to hippos. They look similar because they inhabit a similar environment. Another example is winged flight which has arisen independently in insects, birds, and bats. Convergent evolution has been postulated as a counterexample to the idea of contingency but I think the two are not incompatible, just with genomics, convergent evolution has been easier to prove. Life is the most complex process we know of and complex systems are sensitive to initial parameters. An Earth-like planet would have life-forms for similar solutions but not the same and from animals with a different evolutionary history than Earth’s animals. For non-Earth-like planets, all bets are off. Humans are the first species to leave the planet but on other worlds there is no guarantee that technological sentience is the only solution for life leaving the planet. Contingency and convergent evolution are both important concepts if we are to think about life on and between planets.
Another biological concept to consider is island biogeography. Biogeography is the study of where life forms originated and how they got to their current location. How did life get to remote locations like sea islands which can contain many unique species (endemics)? Did life spontaneously evolve there or did it somehow come from somewhere else? The answer is the latter. Life arose just once. The Earth is a dynamics system and, due to plate tectonics, landmasses combine and pull apart over millions of years. Birds can carry seeds and insects thousands of miles, major storms can blow living beings across the ocean, and currents can carry life-rafts of many species. In addition, these survivors rapidly diversify to fill the various ecological niches on their new home. An example of this is picture-wing flies in Hawaii.
Picture Wing Flies [15]
Panspermia [8] is an idea that comes out of island biogeography. Life evolved originally on only one planet and has spread out from there due to random processes. Our planet was seeded by interstellar life that is now endemic to earth. This is a compelling idea but I think a bit fragile. Distances are just too great for a single genesis. I favor both processes. Life evolving independently and spreading off-planet. This would be most pronounced in dense star clusters. A problem with island biogeography is that sometimes when a new species is introduced it can out-compete and drive to extinction an endemic species. Rats in Hawaii arrived off the ships of the first Europeans and are a terrible problem. Maybe we missed a bullet with Oumuamua?
Dr. Sarah Inari Walker is an astrobiologist and theoretical physicist interested in the origin of life on Earth and elsewhere. She is currently at Arizona State University. It was listening to two podcasts of hers that inspired me to write this article. [17][18] Life in terms of physics has always frustrated theorists and Walker has taken on this challenge by questioning how physics thinks of information. Living things do two things, they replicate and they metabolize. Thus they are information structures that cause matter to change and can build copies of themselves. These are called constructors and are arranged in hierarchies of causal control. One interesting note is that humans with computation and technology may have created a universal constructor. These are ideas that kind of break my mind and I intend to come back to them in the future. Oumuamua is still a vast mystery and even if it is just a frozen rock, it is still very important as our first discovered cosmic visitor.
“It is important to note that while information is abstract, in the sense that it involves one entity symbolically representing another, it is nonetheless physical and only exists when physically instantiated (it, therefore, holds similar ontological status to energy). There is thus no conflict with information playing a causal role in the dynamics of living systems.” [15]
MacArthur, Robert Helmer, and Edward Osborne Wilson. The Theory of Island Biogeography. Princeton University Press, 1967.
Çabej, Nelson. Epigenetic Principles of Evolution. Elsevier, 2012.
Gould, Stephen Jay. Wonderful Life: The Burgess Shale and the Nature of History. W. W. Norton & Company, 1990. https://www.amazon.com/Wonderful-Life-Burgess-Nature-History/dp/039330700X.
Genevaganda. “Theories on Evolution.. Scale of Nature..” Accessed November 1, 2021. http://biology-g10p.blogspot.com/2006/12/theories-on-evolution-aristotles-ladder.html.
Olson, Randal S. “Current Research,” May 11, 2012. http://www.randalolson.com/about/research/.
NASA, Science. “Oumuamua.” NASA Solar System Exploration. Accessed September 19, 2021. https://solarsystem.nasa.gov/asteroids-comets-and-meteors/comets/oumuamua/in-depth.
NASA, Science. “Comet 2I/Borisov.” NASA Solar System Exploration. Accessed September 19, 2021. https://solarsystem.nasa.gov/asteroids-comets-and-meteors/comets/2I-Borisov/in-depth.
Wesson, Paul S. “Panspermia, Past and Present: Astrophysical and Biophysical Conditions for the Dissemination of Life in Space.” Space Science Reviews, Springer, 2010.
Phan, Vo Hong Minh, Thiem Hoang, and Abraham Loeb. “Erosion of Icy Interstellar Objects by Cosmic Rays and Implications for `Oumuamua.” ArXiv:2109.04494 [Astro-Ph], October 28, 2021. http://arxiv.org/abs/2109.04494.
Loeb, Abraham. Extraterrestrial: The First Sign of Intelligent Life Beyond Earth: Mariner Books, 2021. https://www.amazon.com/Extraterrestrial-First-Intelligent-Beyond-Earth/dp/0358278147.
Lex Fridman. Avi Loeb: Aliens, Black Holes, and the Mystery of the Oumuamua | Lex Fridman Podcast #154, 2021. https://www.youtube.com/watch?v=plcc6E-E1uU.
Carroll, Sean. “131 | Avi Loeb on Taking Aliens Seriously - Sean Carroll’s Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas (Podcast).” Listen Notes. Accessed November 5, 2021. https://www.listennotes.com/podcasts/sean-carrolls/131-avi-loeb-on-taking-7WF0k6Hgpm4/.
Queller, David C. “The Spaniels of St. Marx and the Panglossian Paradox: A Critique of a Rhetorical Programme.” The Quarterly Review of Biology 70, no. 4 (December 1995): 485–89. https://doi.org/10.1086/419174.
Maynard Smith, John, and Eörs Szathmáry. The Major Transitions in Evolution. Reprinted. Oxford: Oxford Univ. Press, 2010.
National Academy of Sciences. Evolution in Hawaii: Accessed November 5, 2021. https://doi.org/10.17226/10865.
Walker, Sara. “Top-Down Causation and the Rise of Information in the Emergence of Life.” Information 5, no. 3 (July 21, 2014): 424–39. https://doi.org/10.3390/info5030424.
Lex Fridman. Sara Walker: The Origin of Life on Earth and Alien Worlds | Lex Fridman Podcast #198, 2021. https://www.youtube.com/watch?v=-tDQ74I3Ovs.
Carroll, Sean. “79 | Sara Imari Walker on Information and the Origin of Life – Sean Carroll’s Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas – Podcast.” Podtail. Accessed November 5, 2021. https://podtail.com/podcast/sean-carroll-s-mindscape/79-sara-imari-walker-on-information-and-the-origin/.
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