We keep trying to extend our reach into the heavens, but the idea of panspermia is that the heavens are actually responsible for us. Which is to say, that at least the precursor materials that allow life to emerge came from elsewhere, and did not originate on Earth. Over a hundred years ago Swedish scientist Svante Arrhenius suggested that the pressure of starlight could push bacterial spores between planets and we can extend the notion to interstellar journeys of hardy microbes as well, blasted out of planetary surfaces by such things as meteor impacts and flung into outbound trajectories.
Panspermia notions inevitably get into the question of deep time given the distances involved. The German physician Hermann Richter (1808-1876) had something interesting to say about this, evidently motivated by his irritation with Charles Darwin, who had made no speculations on the origin of the life he studied. Richter believed in a universe that was eternal, and indeed thought that life itself shared this characteristic:
“We therefore also regard the existence of organic life in the universe as eternal; it has always existed and has propagated itself in uninterrupted succession. Omne vivum ab aeternitate e cellula!” [All life comes from cells throughout eternity].
Thus Richter supplied what Darwin did not, while accepting the notion of the evolution of life in the circumstances in which it found itself. By 1908 Arrhenius could write:
“Man used to speculate on the origin of matter, but gave that up when experience taught him that matter is indestructible and can only be transformed. For similar reasons we never inquire into the origin of the energy of motion. And we may become accustomed to the idea that life is eternal, and hence that it is useless to inquire into its origin.”
The origins of panspermia thinking go all the way back to the Greeks, and the literature is surprisingly full as we get into the 19th and early 20th Century, but I won’t linger any further on that because the paper I want to discuss today deals with a notion that came about only within the last 60 years or so. As described by Carl Sagan and Iosif Shklovskii in 1966 (in Intelligent Life in the Universe, it’s that panspermia is not only possible but might be something that humans might one day attempt.
Indeed, Michael Mautner and Greg Matloff proposed this in the 1970s (citation below), while digging into the potential risks and ethical problems associated with such a project. The idea remains controversial, to judge from the continuing flow of papers on various aspects of panspermia. We now have a study from Asher Soryl (University of Otago, NZ) and Anders Sandberg (MIMIR Centre for Long Term Futures Research, Stockholm) again sizing up guided panspermia ethics and potential pitfalls. What is new here is the exploration of the philosophy of the directed panspermia idea.
Image: Can life be spread by comets? Comet 2I/Borisov is only the second interstellar object known to have passed through our Solar System, but presumably there are vast numbers of such objects moving between the stars. In this image taken by the NASA/ESA Hubble Space Telescope, the comet appears in front of a distant background spiral galaxy (2MASX J10500165-0152029, also known as PGC 32442). The galaxy’s bright central core is smeared in the image because Hubble was tracking the comet. Borisov was approximately 326 million kilometres from Earth in this exposure. Its tail of ejected dust streaks off to the upper right. Credit: ESA/Hubble.
Spreading life is perhaps more feasible than we might imagine at first glance. We have achieved interstellar capabilities already, with the two Voyagers, Pioneers 10 and 11 and New Horizons on hyperbolic trajectories that will never return to the Solar System. Remember, time is flexible here because a directed panspermia effort would be long-term, seeding numerous stars over periods of tens of thousands of years. The payload need not be large, and Soryl and Sandberg consider a 1 kg container sufficient, one containing freeze-dried bacterial spores inside water-dissoluble UV protective sheaths. Such spores could survive millions of years in transit:
…desiccation and freezing makes D. radiodurans able to survive radiation doses of 140 kGy, equivalent to hundreds of millions of years of background radiation on Earth. A simple opening mechanism such as thermal expansion could release them randomly in a habitable zone without requiring the use of electronic components. Moreover, normal bacteria can be artificially evolved for extreme radiation tolerance, in addition to other traits that would increase their chances of surviving the journey intact. Further genetic modifications are also possible so that upon landing on suitable exoplanets, evolutionary processes could be accelerated by a factor of ∼1000 to facilitate terraforming, eventually resulting in Earth-like ecological diversity.
If the notion seems science fictional, remember that it’s also relatively inexpensive compared to instrumented payload packages or certainly manned interstellar missions. Right now when talking about getting instrumentation of any kind to another star, we’re looking at gram-scale payloads capable of being boosted to a substantial portion of lightspeed, but directed panspermia could even employ comet nuclei inoculated with life, all moving at far slower speeds. And we know of some microorganisms fully capable of surviving hypervelocity impacts, thus enabling natural panspermia.
So should we attempt such a thing, and if so, what would be our motivation? The idea of biocentrism is that life has intrinsic merit. I’ve seen it suggested that if we discover that life is not ubiquitous, we should take that as meaning we have an obligation to seed the galaxy. Another consideration, though, is whether life invariably produces sentience over time. It’s one thing to maximize life itself, but if our actions produce it on locations outside Earth, do we then have a responsibility for the potential suffering of sentient beings given we have no control over the conditions they will inhabit?
That latter point seems abstract in the extreme to me, but the authors note that ‘welfarism,’ which assesses the intrinsic value of well-being, is an ethical position that illuminates the all but God-like perspective of some directed panspermia thinking. We are, after all, talking about the creation of living systems that, over billions of years of evolution, could produce fully aware, intelligent beings, and thus we have to become philosophers, some would argue, as well as scientists, and moral philosophers at that:
While in some cases it might be worthwhile to bring sentient beings into existence, this cannot be assumed a priori in the same way that the creation of additional life is necessarily positive for proponents of life-maximising views; the desirability of a sentient being’s existence is instead contingent upon their living a good life.
Good grief… Now ponder the even more speculative cost of waiting to do directed panspermia. Every minute we wait to develop systems for directed panspermia, we lose prospective planets. After all, the universe, the authors point out, is expanding in an accelerated way (at least for now, as some recent studies have pointed out), and for every year in which we fail to attempt directed panspermia, three galaxies slip beyond our capability of ever reaching them. By the authors’ calculations, we lose on the order of one billion potentially habitable planets each year as a result of this expansion.
These are long-term thoughts indeed. What the authors are saying is reminiscent in some ways of the SETI/METI debate. Should we do something we have the capability of doing when we have no consensus on risk? In this case, we have only begun to explore what ‘risk’ even means. Is it risk of creating “astronomical levels of suffering” in created biospheres down the road? Soryl and Sandberg use the term, thinking directed panspermia should not be attempted until we have a better understanding of the issue of sentient welfare as well as technologies that can be fine-tuned to the task:
Until then, we propose a moratorium on the development of panspermia technologies – at least, until we have a clear strategy for their implementation without risking the creation of astronomical suffering. A moratorium should be seen as an opportunity for engaging in more dialogue about the ethical permissibility of directed panspermia so that it can’t happen without widespread agreement between people interested in the long-term future value of space. By accelerating discourse about it, we hope that existing normative and empirical uncertainties surrounding its implementation (at different timescales) can be resolved. Moreover, we hope to increase awareness about the possibility of S-risks resulting from space missions – not only limited to panspermia.
By S-risks, the authors refer to those risks of astronomical suffering. They assume we need to explore further what they call ‘the ethics of organised complexity.’ These are philosophical questions that are remote from ongoing space exploration, but building up a body of thought on the implications of new technologies cannot be a bad thing.
That said, is the idea of astronomical suffering viable? Life of any kind produces suffering, does it not, yet we choose it for ourselves as opposed to the alternative. I’m reminded of an online forum I once participated in when the question of existential risks to Earth by an errant asteroid came up. In the midst of asteroid mitigation questions, someone asked whether we should attempt to save Earth from a life-killer impact in the first place. Was our species worth saving given its history?
But of course it is, because we choose to live rather than die. Extending that, if we knew that we could create life that would evolve into intelligent beings, would we be responsible for their experience of life in the remote future? It’s hard to see this staying the hand of anyone seriously attempting directed panspermia. What would definitely put the brakes on it would be the discovery that life occurs widely around other stars, in which case we should leave these ecosystems to their own destiny. My suspicion is that this is exactly what our next generation telescopes and probes will discover.
The paper is Soryl & Sandberg, “To Seed or Not to Seed: Estimating the Ethical Value of Directed Panspermia,” Acta Astronautice 22 March 2025 (full text). The Mautner and Matloff paper is “Directed Panspermia: A Technical and Ethical Evaluation of Seeding the Universe,” JBIS, Vol. 32, pp. 419-423, 1979.
At least it can’t hurt to think about aliens…
The ‘panzoic effect’: the benefits of thinking about alien life
By Graham Lau
https://psyche.co/ideas/the-panzoic-effect-the-benefits-of-thinking-about-alien-life
Reflecting on the potential for extraterrestrial life can inspire awe and have a profound effect on your worldview
In 1985, the author Frank White coined the term ‘overview effect’ to describe something striking that happens to people who have been to space. The term would become the title of White’s 1987 book that popularised the concept: after gazing down at Earth, he observed, some astronauts report a change in their worldview. They describe feeling a oneness with humanity and our biosphere, and an awareness of the precarious nature of our existence.
Anousheh Ansari, the first female private space explorer, recounted that after returning from space she was never again bothered by rush-hour traffic or being late to a meeting. And after William Shatner, who played Star Trek’s Captain Kirk, returned from his own suborbital space trip in 2021, he wrote in Variety magazine that: ‘It reinforced tenfold my own view on the power of our beautiful, mysterious collective human entanglement, and eventually, it returned a feeling of hope to my heart.’ [Shatner also said after that same jaunt that the blackness of the void terrified him; so much for Captain Kirk.]
The overview effect ties into something that is much larger about humanity: we can be roused through experiences of wonder and awe to think in bigger ways about ourselves, and to be more compassionate and understanding.
I have never looked down at the Earth from space myself, but I believe it’s possible to experience a similarly profound perspective shift by looking outward from our planet, too. As an astrobiologist and science communicator, I spend my days thinking about the possibility of alien life, considering what – or who – is out there among the stars. The idea that our seemingly barren Universe might contain an abundance of living creatures fills me with a sense of awe, and it has transformed how I see the world. I call this grand shift in perspective the ‘panzoic effect’.
Looking at the night sky and wondering what those celestial lights might be is something humans have done since before written history. Thousands of years ago, people from Babylonia to China and from the Americas to Aboriginal Australia saw part of themselves reflected in the heavens.
In ancient Greece, Anaximander proposed that Earth was a body floating in an infinite void, and Epicurus wrote that: ‘There is an unlimited number of cosmoi [worlds], and some are similar to this one and some are dissimilar.’ Much later, thinkers such as Giordano Bruno would argue not only for a multitude of worlds but also for the potential for multitudes of intelligent beings beyond Earth.
If there are aliens out there, we could be very near to finding some of them
The scientific study of astrobiology, though, is a more recent effort. By investigating the origins, evolution and distribution of life in the Universe, it asks: ‘Where does life come from?’, ‘How does a living world change over time?’ and ‘Might there be other life out there?’ I’ve been fascinated by these questions for much of my own life: at first through science fiction, and then later in my research and science communication. But along the way, I’ve seen significant changes in how we go about seeking answers.
Astrobiology was once a speculative discipline – viewed sceptically by many scientists in the 20th century – but it is now mainstream. Today, it is no longer about whether looking for aliens is worthwhile, rather now our focus is on what methods, technologies and space missions will best increase the likelihood of finding them – we’ve gone from ‘So what?’ to ‘Now what?’
Moreover, in recent years the possibility of success has drawn tantalisingly close. Since 2000, we’ve confirmed the existence of more than 5,000 exoplanets – before that, the count was around 30 – with seemingly countless more awaiting discovery. Here in our own solar system, we now know that ancient Mars had liquid surface water and a much different climate, and that ancient Venus may also have been habitable. And icy moons with potential subsurface oceans like Europa and Enceladus – orbiting Jupiter and Saturn, respectively – have tantalised us with the possibility of deep ocean biospheres. Even if there is no other life here around our Sun, the exoplanets we’ve found have intimated a great many worlds that could possibly be home to other biospheres.
All this is culminating in a profound idea – if there are aliens out there, we could be very near to finding some of them. Of course, there is a possibility that life may have arisen only once, here on Earth. Until we find definitive evidence – be it a Martian microbe, signs of life on an icy moon or in an exoplanet’s atmosphere, or some signal of alien technology – we cannot claim any certainty. However, in light of recent discoveries, I’ve met many astrobiologists who will adamantly state that alien life has to be out there.
A visit to an astrobiology conference these days will reveal a number of optimistic scholars who think it’s not a matter of ‘if’ but a matter of ‘when’ at this point. (White, incidentally, shares this view. ‘Given what we know, it seems really likely that some form of life has arisen elsewhere,’ he told me recently.)
What if alien life is not just present, but abundant? What if there are myriad worlds afar where life has happened, perhaps even with some similarities to our own? There may even be other civilisations out there that have developed their own art, philosophy and science. Convergent evolution suggests that some alien forms may resemble Earth life in some ways while others could be utterly unrecognisable.
Thinking about alien life is not just a scientific endeavour; it’s a call to be better stewards of our world
It’s by reflecting on these ideas that you can take the first steps to experiencing what I call the panzoic effect. Like the overview effect, thinking about a possible abundance of life in the Universe can lead you to look with fresh eyes at humanity and life on Earth.
For example, the search for alien life drives us to consider the range of possible settings for life to emerge and to evolve, and to consider how different the story could have been for our own world. We know that Earth life has faced many threats through the past – impacts from space, largescale volcanism, rapid changes in climate, and so on. And yet, as the character Ian Malcolm states in Jurassic Park (1990), life truly has found a way. Extinctions for some have led to opening of ecosystems for others. Life has had a long, complex history on our planet.
And when we contemplate the vastness of space and the possibilities for extraterrestrial life, we’re often reminded of our shared humanity and responsibilities to life on our planet. In this way, thinking about alien life is not just a scientific endeavour or a means to frame our considerations of the future; it’s a call to be better stewards of our world and more compassionate members of the cosmos.
Most of all, though, when I reflect on the possible abundance of alien life, it fills me with wonder and awe. In recent years, psychologists have shown that these are powerful, perspective-changing emotions. Wonderment at the nature of the world – from being curious about the workings of everyday things to wandering in the world around us – inspires us and helps us to develop new ideas and perspectives. Awe, meanwhile, is the feeling of being in the presence of something that transcends your current understanding of yourself and your place in the cosmos.
When I feel the panzoic effect, it encourages me to envision a hopeful future
The psychologist Dacher Keltner writes in his book Awe: The New Science of Everyday Wonder and How It Can Transform Your Life (2023) that:
From our first breath to our last, awe moves us to deepen our relations with the wonders of life and to marvel at the vast mysteries that are part of our fleeting time here, guided by this most human of emotions.
As Keltner suggests, there are many forms through which awe can come into our lives: from experiencing depth in music and art to feeling the grandness of nature or seeing people act in morally impactful ways.
Indeed, this is what may be going on when astronauts change their perspective following spaceflight. In the journal article ‘The Overview Effect: Awe and Self-Transcendent Experience in Space Flight’ (2016), David B Yaden and his colleagues conclude: ‘Awe and self-transcendence are among the deepest and most powerful aspects of the human experience; it should come as no surprise that they emerge as we gaze upon our home planet and our whole world comes into view.’
When I feel the panzoic effect, it encourages me to envision a hopeful future, one where our explorations inspire unity, and our shared wonder leads to greater care for one another and the planet we call home. Whether we ever encounter extraterrestrial life or not, I believe that the journey of seeking it can help us rediscover and improve ourselves. Much like the overview effect, the panzoic effect suggests that the wonder and awe we experience in this cosmic mirror – by looking out and, in turn, looking back in – has the potential to alter how we view ourselves and our place in the cosmos. And as White himself told me: ‘I think that’s the big question.’
Are we alone? We don’t yet know, but asking the question forces us to appreciate our existence here on Earth, while offering us a glimpse into our possible cosmic futures. Considering alien life is a means for considering ourselves.
What might be the relevance in an octillion-year time frame?
Equally, considering that there may not be any other intelligent life, at least not within relevant distance and time, generates in me the same awe, and the fear that we humans are precariously situated and may not survive in deep time…
We had best learn to keep and protect what we have already got.
That sounds like the same argument as whether the human race should continue to procreate and is just as silly. An intelligence that evolves billions of years from now would be suited to its habitat, at least as well as we are.
I often wonder how rare life in the universe might be, and it sometimes makes me cringe to do weeding or even clear moss from the walkway. But if we are the first or very rare, then it makes little difference what we do unless we sterilize our own world. Impacts on Earth will likely spread life to other stars over time if we leave well enough alone. A cell is a von Neumann probe.
If we decide to try to plant life on worlds that may already have it we should strongly resist the idea of sending aggressive, strong species; we should send things that a resident ecosystem can easily defend itself against. Granted we probably don’t have the knowledge to be sure we’d succeed.
On another hand, if there’s any chance of an existing technological species being there, we might want to avoid revealing the source of our package by changing course partway there.
What a wonderful and disruptive question. Of course human beings reproduce themselves continually on this planet within the same moral dilemma. How does the nature of this question really change when scaling life to new worlds, new systems, new galaxies? If suffering is inherent in life, what else is inherent? And what does it mean to a living universe, where for some it is short, nasty and brutish while elsewhere cultured and transcendent?
Well said.
AI Overview
+1
The idea of “rewinding and replaying evolution,” or the “tape of life,” explores whether evolution is repeatable and predictable, or if it’s contingent on unique historical events. While some evolutionary outcomes might be predictable, others depend on the specific details of a lineage’s history, making evolution both deterministic and contingent.
Here’s a more detailed explanation:
The “Tape of Life” Metaphor:
Stephen Jay Gould famously used the “tape of life” metaphor to illustrate the idea that if we could rewind time and replay the evolutionary process, the outcome might not be the same, emphasizing the role of contingency.
Determinism vs. Contingency:
Determinism: Natural selection, in principle, could lead to predictable outcomes, as it favors traits that increase fitness in a given environment.
Contingency: However, the specific sequence of random mutations, rare environmental events, and other historical factors can lead to unique evolutionary paths, making outcomes unpredictable.
Experimental Evidence:
Replay Experiments: Biologists are conducting experiments, both in the lab and in nature, to test the repeatability of evolution.
Parallel Replay Experiments: These experiments involve replicating populations under identical conditions to see if they evolve similarly.
Historical Difference Experiments: These experiments explore how past evolutionary history influences later evolution.
Examples of Repeatability and Contingency:
Convergent Evolution: Sometimes, different lineages evolve similar traits in response to similar environmental pressures, suggesting that evolution can find the same solutions repeatedly.
Idiosyncratic Outcomes: However, even under similar conditions, lineages can take different evolutionary paths, highlighting the role of contingency.
Implications:
Understanding the interplay between determinism and contingency is crucial for understanding the evolutionary process.
It also has implications for how we think about the future of evolution and the potential for new life forms to emerge.
rewinding and replaying evolution as discussed
Exactly. By my count at least 5 intelligent hominem species have arisen on this planet and 4 of them have gone extinct. If there were more than 5 then we can restate the case, all but one has gone extinct, so far.
Contingent indeed!
Diaspora
Unlike the Americans, Chinese and Russians, not all space explorers save their waste for the return to base. Instead, some of them dumped their vehicle latrines into the cold of space expecting they would all fall into the local star. Indeed almost all of them did. However, 38,000 years later, one gob of this frozen goo landed on an eco-planet.
Immediately when first ejected, and given a push away from the vehicle for safety reasons, its surface became frozen and dessicated in deep space. The rest of the gob was encapsulated in water-laden material that effectively provided a radiation shield, and the whole kilogram, which had been seething with the flora and fauna carried in living bowels, was deeply frozen.
This particular gob, propelled by its accidental trajectory, boomaranged around a gas giant planet, gaining speed, and headed out of its star’s reach. Given the density of objects in the galaxy, it was inevitable that the gob was pointed directly at a far system, which it eventually reached.
In a second accident of its trajectory the gob encountered a planet before it reached the central star. It was slowed considerably by the gravity of the largest gas giant in that system, then crashed into the watery suface of a warm, rocky planet. As luck would have it, out of the thousands of flushes over many thousands of years this particular gob landed on an M-class planet circling a G-class star.
The rest of it is human history..