The difference between astronomers and biologists

The debate about intelligent, extra-terrestrial aliens goes on, with the usual divide: astronomers insisting that the galaxy must be swarming with alien intelligences, which is popular with the media, and the biologists saying no, it's not likely, there are probably swarms of single-celled organisms, but big multicellular intelligences like ours are probably rare. And the media ignores us, because that answer simply is not sufficiently sensational.

But we will fight back! Here's an interesting review of the alien argument. There is actually a historical and conceptual reason why astronomers think the way they do.

In response [to a paper arguing that SETI was a waste of time], Sagan co-wrote a paper with William Newman “The Solipsist Approach to Extraterrestrial Intelligence” which right from the title attacks Tipler for believing Earth to be unique. Sagan is of course citing the Copernican Principle, which roughly states the Earth is NOT the center of the heavens. The Copernican Principle is the modern foundation for Astronomy, Cosmology and Relativistic Physics. Sagan thought anyone claiming the Earth to be special must be doing bad science. Here’s a typical quote: Despite the utter mediocrity of our position in space and time, it is occasionally asserted, with no sense of irony, that our intelligence and technology are unparalleled in the history of the cosmos. It seems to us more likely that this is merely the latest in the long series of anthropocentric and self-congratulatory pronouncements on scientific issues that dates back to well before the time of Claudius Ptolemy.

It's all about our perception of the rules. Astronomers see a universe with uniform laws that set up similar patterns everywhere: stars, rocks, gas. Life is lumped in with rocks as a phenomenon that just pops up everywhere, and with their limited idea of biology, just see all life as life like ours. Biologists also see universal laws, but we know from our experience that those laws generate endless diversity -- there are millions of species on this planet, and each one is unique.

Now unlike Astronomy, the discipline of Biology takes a highly favorable view of uniqueness. Evolution constantly discovers quirky and highly contingent historical paths. Biology takes it for granted that everybody is a special snowflake. In fact the third sentence of Tipler’s 1980 paper calls this out:

The contemporary advocates for the existence of such [extraterrestrial intelligent] beings seem to be primarily astronomers and physicists, such as Sagan (2), Drake (3), and Morrison (4), while most leading experts in evolutionary biology, such as Dobzhansky (5), Simpson (6) Francois (7), Ayala et al. (8) and Mayr (9) contend that the Earth is probably unique in harbouring intelligence, at least amongst the planets of our Galaxy.

And as quoted in Mark A. Sheirdan’s book, we have eminent Evolutionary Biologist Theodosius Dobzhansky (“Nothing in Biology Makes Sense Except in the Light of Evolution“) joining the fray:

In his article Dobzhanksy turned Sagan’s argument on its head. Dobzhansky cited the fact that of the more than two million species living on Earth only one had evolved language, extragenetically transmitted culture, and awareness of self and death, as proof that it is “fatuous” to hold “the opinion that if life exists anywhere else it must eventually give rise to rational beings.”

And here's a nice, short table to summarize the differences.


I have to add that it is probably another of those universal laws that Darwinian replicators will expand to fill an empty ecosystem, but that there are many ways to do that. It's also a rule that the replicators are exploiting short term advantages to supplant competitors -- there is no teleological imperative that says Strategy X is a good one, because while it slows our species down for the next billion years, there's a chance we might build spaceships two billion years from now. Spaceship building is never going to be a selectively advantageous feature -- it's only going to emerge as a spandrel, which might lead to a species that can occupy a novel niche. And that means that spaceship builders are only going to arise as a product of chance, which will mean they're going to be very rare.

On the other hand, a species that does successfully exploit space as an ecosystem is going to have a phenomenally fascinating future history of radiating forms. Think of the first space colonizers as equivalent to the first cells that evolved a metabolism that allowed them to exist outside the coddled, energy-rich environment of a deep-sea vent. It's only the first step in a long evolutionary process that's going to produce endless forms most beautiful…and also unexpected variations. It's silly to expect that the successful, thriving interstellar life forms will be bipeds adapted to life on a planetary surface, living in large metal shells as autonomous agents crewing a spaceship. The real thing would be alien, and probably terrifyingly incomprehensible.


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Interesting! I have some issues with astronomers. On this I guess I'm agnostic. Maybe y'all should have a contest: Put your maths where your mouths are and see who can come up with the strongest formula for estimating the probabilities of life, distribution, complexity, and so on...

By Obstreperous A… (not verified) on 28 Jun 2014 #permalink

Interesting point of view form the both sides.
If you include philosophers then it would be chaos.As for me I am believer,so it is dead end.

This non-biologist agrees with you, probably because of Stephen Jay Gould's Wonderful Life. I suppose that, with trillions of stars, it's likely that intelligent life has appeared at one time or another in the last 10 billion years, but the universe is hardly teeming with advanced civilization. Simon Conway Morris wrote a book about convergence to show that homo sapiens sapiens were inevitable, even though we are unique! I just found out he supports intelligent design, so I guess I'm not surprised.

I am an astronomer working on instruments to directly image planets around nearby young stars and have a variety of colleagues working in a variety of astrobiology topics all the way up to SETI. This is a horrible characterization of astronomers and focuses on only the most optimistic views of some astronomers from 40 years ago. All astronomers working in these fields are well aware of the possible rarity of life, especially advanced life. In fact there have been conferences trying to come up with answers to the Fermi paradox since the 1960's and a recurring theme is that life may be quite rare. Yes, the popular media loves picking up the optimistic view of aliens everywhere, and there are astronomers like Sagan and Drake who were once very optimistic. But even Frank Drake has commented recently that all the failed SETI searches imply that there at least are not lots of civilizations out there communicating with radio waves. Astronomers are discovering many planets that are getting closer and closer to Earth-like conditions suggesting that Earth is not particularly special in terms of temperature and size. But we all realize that it may be quite a rare event for life to sustain itself for billions of years on a planet and evolve into intelligence. I see no reason to focus on the optimistic (and often old) popular views and slam a field that is very sober to the realities of a relatively sterile universe.

By James Larkin (not verified) on 28 Jun 2014 #permalink

This is a poor and unnecessary straw man of biologists and astronomers. There are plenty of discussions both overly optimistic and overly pessimistic regarding the issue regardless of scientific expertise. No need to make it a simplistic duel between professions. Also as an astronomer, I say biologists are stinky. :p

By Science Bulldog (not verified) on 28 Jun 2014 #permalink

I can think of a couple of complications. Looking at humans, maximum reproductive success doesn't seem to be at the forefront of our minds when we can successfully have sex without a high risk of pregnancy, live longer lives (including after the end of our peak life-span areas of having children), and don't have incentives to do so like the need for many children for farming/taking care of us in old age/living to adulthood since a big chunk of them are dying in early childhood. If we get immortality or near-immortality, that's going to be drawn out even further - the annual birth rate may drop down to near-zero even if people are having more children in the long run by spreading them out over centuries.

I also think the "self-replicating probes" people are really underestimating the difficulty of building them and even traveling at a reasonable pace over interstellar distances. You need probes that can not only fly and observe, but also do all the monitoring done by ground crews and the maintenance a long mission might require. You need really fast rocket engines that don't exist except on paper yet, which might have a whole ton of unforeseen engineering issues that you don't know about in advance until you try building them. And you need your "self-replicating probes" to take a host of resource gatherers, resource refining equipment, and fabrication equipment just to start building the infrastructure you'll need in a new solar system to build more interstellar probes.

That's hard stuff, and it makes me wish we could get an aerospace engineer's thoughts on it to go with the biologists and astronomers.

Humans aren't the only intelligent species on this planet. I share my yard with an assortment of dinosaurs, some of whom are conspicuously vocal. They have language and perhaps culture.

Modern human technology is based on fossil fuels, the first of which to be exploited was coal, an improbable product of abrupt climate change. It's unlikely that we would have drilled for oil and gas without that first taste of free energy.

We're broadcasting less and less information in easily interpreted analog form; TV signals are now compressed digital streams, scarcely distinguishable from noise. SETI couldn't detect us unless we constructed a beacon.

Spacefaring is really, really hard. The distances between solid objects even within the thin disk of our solar system confounds our expectations. We can imagine terraforming alien planets, yet maintaining our own seems to be beyond our means.

The Drake equation has a term for the lifetime of an advanced civilization, and it's perhaps the one we can best estimate. It's not looking good.

Another complication, a (Unlikely) civilization living off of Oort cloud resources would have no need to touch dirt again and might lose the ability to do so, we don't have the tech, yet, to see much out there. Too soon to expect meaningful answers about the neighbors, unless they're unusually conspicuous.

From the only data point we have, us, it seems that the evolution of intelligent life takes billions of years from planet formation. How long after that does it take for intelligent life to travel through the galaxy, either in person or by proxy probes? Thousands of years? Millions of years? How long can a civilisation survive on only one planet? That we haven't found anyone else might mean either that we are the first or that no-one lasts long enough to do it.

Or the ETs could simply be hiding. Many authors, including Douglas Adams made a point of characterizing Earth as a backward, violent planet of no interest to anybody.

By Politicalguineapig (not verified) on 30 Jun 2014 #permalink

Also I wanted to add that ball lightning were only recently accepted by pseudo-skeptic and their fellow psychologists as real phenome ny. Before that only "very bad" parapsychologists and paranormal investigators studied ball lightning.
Many times paranormal won against pseudo-skeptics, for exemple ESP and sixth sense magnetoreception is proven (considered as myth by pseudo-skeptics), human echolocation is proven, placebo effect of the mind is proven, tummo is proven, effects of meditation are proven, weak psychokinesis too (with biofeedback and neruofeedback you can learn to control your bioelectromagnetic field and electromagnetic waves of the brain and by doing so you can manipulate the surrounding electromagnetic field). I am sure soon dermo-optical perception, telepathy, remote viewing, psychokinesis, homeopathy and cold fusion will be accepted too.

By Josephson (not verified) on 01 Jul 2014 #permalink

Even if SETI found evidence of extraterrestrial life the information would be useless to us. Undoubtedly the extraterrestrials would be too far away (say, 100 light-years) for us to study. If the extraterrestrials were sentient we could send a message. At the speed of light we could hope for a reply in 200 years. If they understood the message. If they answered right away.

How can any scientist seriously hazard a "probability" for extra-terrestrial life? We have a sample size of one instance of life arising in the universe, and we're uncertain about the mechanism by which that happened. We can't make responsibly make probabilistic guesses with a sample size of one and a lack of knowledge of the mechanics underlying the event we're trying to understand.

Every time a theist tries to tell me the probability of life arising on its own without divine guidance, I always laugh. There's no way a theist can give me such a probability, because we don't have numerous instances of when life arose, when it did not, when it did on its own versus when it did with divine guidance, etc. We don't have that data, so we can't make guesses on probability.

Atheists and scientists should be more responsible about throwing phrases around like, "I think it's probable that life abounds in the universe." We don't have enough information even to hazard a reasonable guess on the odds.

Stanton Friedman, nuclear physicist and otherwise smart man who claims to have worked on engines for interstellar travel, argues 'SETI is a stupid way to search', rather than 'searching is stupid'. He makes some good arguments. He certainly has convinced me of his opinion for SETI.

In my opinion biology and astronomy as everything else in our universe comes under the same umbrella and that is NATURE.
life will evolve anywhere it can, be it in a cave without light, a tree in the Amazon or on your garden wall.
If the rest of the Universe has the some organic compounds as we have then the rest of the Universe must be teaming with life.

Rab B: life will evolve anywhere it can.

Yup. Given what we know about extremophiles now, astronomers and biologists alike should rethink the idea that only 'goldilocks' planets can harbor life. The real question is whether there are other sentients out there.

By Politicalguineapig (not verified) on 07 Jul 2014 #permalink

wow what a nice post given i like it a lot its very amazing there is interesting point of view both the sides.

By Tabish khan (not verified) on 10 Jul 2014 #permalink

"There ist nothing inevitable about evolving intelligence"

As a biologist I must take the astronomer's side here. Have you thought about convergent evolution. The anatomy of fish, dolphins and penguins is remarkably similar - well adapted to hydrodynamics. As New Zealand does not house a hedgehog type mammal, the with the kiwi it was a bird that slipped into that ecological niche.

So I would expect live on other planets to adapt to their physical conditions quite the same way: Evolving cells, multicellularity, finns in water, legs on land, brains to compute signals from eyes and transform it into movement of muscles. Big brains could well be necessary to survive in big groups anywhere.

Flofi: Big brains could well be necessary to survive in big groups anywhere.

Yes. Alternatively, you could end up with something like a sentient hive-mind, or a silicon intelligence that's spread out across a planet.

By Politicalguineapig (not verified) on 11 Jul 2014 #permalink