Breakthrough Listen will monitor the 1 million closest stars to Earth over a ten year period. Credit: Breakthrough Initiatives
In July of 2015, Breakthrough Initiatives – a non-profit dedicated to the search for extra-terrestrial intelligence, founded by Yuri Milner – announced the creation of Breakthrough Listen. A ten-year initiative costing $100 million, this program was aimed at using the latest in instrumentation and software to conduct the largest survey to date for extraterrestrial communications, encompassing the 1,000,000 closest stars and 100 closest galaxies.
On Thursday, April. 20th, at the Breakthrough Discuss conference, the organization shared their analysis of the first year of Listen data. Gathered by the Green Bank Radio Telescope, this data included an analysis of 692 stars, as well as 11 events that have been ranked for having the highest significance. The results have been published on the project’s website, and will soon be published in the Astrophysical Journal.
The Green Bank Telescope (GBT), a radio telescope located at the Green Bank Observatory in West Virginia. Credit: greenbankobservatory.org
While the results were not exactly definitive, this is just the first step in a program that will span a decade. As Dr. Andrew Siemion, the Director of the BSRC, explained in a BI press release:
“With the submission of this paper, the first scientific results from Breakthrough Listen are now available for the world to review. Although the search has not yet detected a convincing signal from extraterrestrial intelligence, these are early days. The work that has been completed so far provides a launch pad for deeper and more comprehensive analysis to come.”
The Green Bank Telescope searched for these signals using its “L-band” receiver, which gathers data in frequencies ranging from 1.1 to 1.9 GHz. At these frequencies, artificial signals can be distinguished from natural sources, which includes pulsars, quasars, radio galaxies and even the Cosmic Microwave Background (CMB). Within these parameters, the BSRC team examined 692 stars from its primary target list.
For each star, they conducting three five-minutes observation periods, while also conducting five-minute observations on a set of secondary targets. Combined with a Doppler drift search – a perceived difference in frequency caused by the motion of the source or receiver (i.e. the star and/or Earth) – the Listen science team identified channels where radio emission were seen for each target (aka. “hits”).
The Parkes radio telescope, one of the telescopes comprising CSIRO’s Australia Telescope National Facility. Credit: CSIRO/David McClenaghan
This led to a combined 400 hours and 8 petabytes worth of observational data. All together, the team found millions of hits from the sample data as a whole, and eleven events that rose above the threshold for significance. These events (which are listed here) took place around eleven distant stars and ranged from to 25.4 to 3376.9 SNR (Signal-to-Noise Ratio).
However, the vast majority of the overall hits were determined to be the result of radio frequency interference from local sources. What’s more, further analysis of the 11 events indicated that it was unlikely that any of the signals were artificial in nature. While these stars all exhibited their own unique radio “fingerprints”, this is not necessarily an indication that they are being broadcast by intelligent species.
But of course, finding localized and unusual radio signals is an excellent way to select targets for follow-up examination. And if there is evidence to be found out there of intelligent species using radio signals to communicate, Breakthrough Listen is likely to be the one that finds them. Of all the SETI programs mounted to date, Listen is by far the most sophisticated.
Not only do its radio surveys cover 10 times more sky than previous programs, but its instruments are 50 times more sensitive than telescopes that are currently engaged in the search for extra-terrestrial life. They also cover 5 times more of the radio spectrum, and at speeds that are 100 times as fast. Between now and when it concludes in the coming decade, the BSRC team plans to release updated Listen data once every six months.
Aerial view of the Automated Planet Finder at the Lick Observatory. Credit: Lick Observatory/Laurie Hatch
In the meantime, they are actively engaging with signal processing and machine learning experts to develop more sophisticated algorithms to analyze the data they collect. And while they continue to listen for extra-solar sources of life, Breakthrough Starshot continues to develop the first concept for a laser-driven lightsail, which they hope will make the first interstellar voyage in the coming years.
And of course, we here in the Solar System are looking forward to missions in the coming decade that will search for life right here, in our own backyard. These include missions to Europa, Enceladus, Titan, and other “ocean worlds” where life is believed to exist in some exotic form!
Breakthrough Listen‘s data analysis can be found here. Director Andrew Siemion also took to Facebook Live on Thursday, April 20th, to presents the results of Listen’s first year of study.And be sure to check out this video that marked the launch of Breakthrough Initiatives:
This artist's concept shows what each of the TRAPPIST-1 planets may look like, based on available data about their sizes, masses and orbital distances.
Credits: NASA/JPL-Caltech
The Trappist-1 system has been featured in the news quite a bit lately. In May of 2016, it appeared in the headlines after researchers announced the discovery of three exoplanets orbiting around the red dwarf star. And then there was the news earlier this week of how follow-up examinations from ground-based telescopes and the Spitzer Space Telescope revealed that there were actually seven planets in this system.
And now it seems that there is more news to be had from this star system. As it turns out, the Search for Extraterrestrial Intelligence (SETI) Institute was already monitoring this system with their Allen Telescope Array (ATA), looking for signs of life even before the multi-planet system was announced. And while the survey did not detect any telltale signs of radio traffic, further surveys are expected.
Given its proximity to our own Solar System, and the fact that this system contains seven planets that are similar in size and mass to Earth, it is both tempting and plausible to think that life could be flourishing in the TRAPPIST-1 system. As Seth Shostak, a Senior Astronomer at SETI, explained:
“[T]he opportunities for life in the Trappist 1 system make our own solar system look fourth-rate. And if even a single planet eventually produced technically competent beings, that species could quickly disperse its kind to all the rest… Typical travel time between worlds in the Trappist 1 system, even assuming rockets no speedier than those built by NASA, would be pleasantly short. Our best spacecraft could take you to Mars in 6 months. To shuttle between neighboring Trappist planets would be a weekend junket.”
Illustration showing the possible surface of TRAPPIST-1f, one of the newly discovered planets in the TRAPPIST-1 system. Credits: NASA/JPL-Caltech
Little wonder then why SETI has been using their Allen Telescope Array to monitor the system ever since exoplanets were first announced there. Located at the Hat Creek Radio Observatory in northern California (northeast of San Francisco), the ATA is what is known as a “Large Number of Small Dishes” (LNSD) array – which is a new trend in radio astronomy.
Like other LNSD arrays – such as the proposed Square Kilometer Array currently being built in Australia and South Africa – the concept calls for the deployment of many smaller dishes over a large surface area, rather than a single large dish. Plans for the array began back in 1997, when the SETI Institute convened a workshop to discuss the future of the Institute and its search strategies.
The final report of the workshop, titled “SETI 2020“, laid out a plan for the creation of a new telescope array. This array was referred to as the One Hectare Telescope at the time, since the plan called for a LNSD encompassing an area measuring 10,000 m² (one hectare). The SETI Institute began developing the project in conjunction with the Radio Astronomy Laboratory (RAL) at the UC Berkeley.
In 2001, they secured a $11.5 million donation from the Paul G. Allen Family Foundation, which was established by Microsoft co-founder Paul Allen. In 2007, the first phase of construction was completed and the ATA finally became operational on October 11th, 2007, with 42 antennas (ATA-42). Since that time, Allen has committed to an additional $13.5 million in funding for a second phase of expansion (hence why it bears his name).
A portion of the Allen Telescope Array. (Credit: Seth Shostak/The SETI Institute. Used with permission)
Compared to large, single dish-arrays, smaller dish-arrays are more cost-effective because they can be upgraded simply by adding more dishes. The ATA is also less expensive since it relies on commercial technology originally developed for the television market, as well as receiver and cryogenic technologies developed for radio communication and cell phones.
It also uses programmable chips and software for signal processing, which allows for rapid integration whenever new technology becomes available. As such, the array is well suited to running simultaneous surveys at centimeter wavelengths. As of 2016, the SETI Institute has performed observations with the ATA for 12 hour periods (from 6 pm and 6 am), seven days a week.
And last year, the array was aimed towards TRAPPIST-1, where it conducted a survey scanning ten billion radio channels in search of signals. Naturally, the idea that a radio signal would be emanating from this system, and one which the ATA could pick up, might seem like a bit of a longshot. But in fact, both the infrastructure and energy requirements would not be beyond a species who’s technical advancement is commensurate with our own.
“Assuming that the putative inhabitants of this solar system can use a transmitting antenna as large as the 500 meter FAST radio telescope in China to beam their messages our way, then the Allen Array could have found a signal if the aliens use a transmitter with 100 kilowatts of power or more,” said Shostak. “This is only about ten times as energetic as the radar down at your local airport.”
A plot of diameter versus the amount of sunlight hitting the planets in the TRAPPIST-1 system, scaled by the size of the Earth and the amount of sunlight hitting the Earth. Credit: F. Marchis/H. Marchis
So far, nothing has been picked up from this crowded system. But the SETI Institute is not finished and future surveys are already in the works. If there is a thriving, technologically-advanced civilization in this system (and they know their way around a radio antenna), surely there will be signs soon enough.
And regardless, the discovery of seven planets in the TRAPPIST-1 system is very exciting because it demonstrates just how plentiful systems that could support life are in our Universe. Not only does this system have three planets orbiting within its habitable zone (all of which are similar in size and mass to Earth), but the fact that they orbit a red dwarf star is very encouraging.
These stars are the most common in our Universe, making up 70% of stars in our galaxy, and up to 90% in elliptical galaxies. They are also very stable, remaining in their Main Sequence phase for up to 10 trillion years. Last, but not least, astronomers believe that 20 out of 30 nearest stars to our Solar System are red dwarfs. Lots of opportunities to find life within a few dozen light years!
“[W]hether or not Trappist 1 has inhabitants, its discovery has underlined the growing conviction that the Universe is replete with real estate on which biology could both arise and flourish,’ says Shostak. “If you still think the rest of the universe is sterile, you are surely singular, and probably wrong.”
We’ve covered the Fermi Paradox many times over several articles on Universe Today. This is the idea that the Universe is huge, and old, and the ingredients of life are everywhere. Life could and should have have appeared many times across the galaxy, but it’s really strange that we haven’t found any evidence for them yet.
The Sloan Digital Sky Survey telescope stands out against the breaktaking backdrop of the Sacramento Mountains. 234 stars out of the Sloan's catalogue of over 2.5 million stars are producing an unexplained pulsed signal. Image: SDSS, Fermilab Visual Media Services
We all want there to be aliens. Green ones, pink ones, brown ones, Greys. Or maybe Vulcans, Klingons, even a being of pure energy. Any type will do.
That’s why whenever a mysterious signal or energetic fluctuation arrives from somewhere in the cosmos and hits one of our many telescopes, headlines erupt across the media: “Have We Finally Detected An Alien Signal?” or “Have Astronomers Discovered An Alien Megastructure?” But science-minded people know that we’re probably getting ahead of ourselves.
Skepticism still rules the day when it comes to these headlines, and the events that spawn them. That’s the way it should be, because we’ve always found a more prosaic reason for whatever signal from space we’re talking about. But, being skeptical is a balancing act; it doesn’t mean being dismissive.
What we’re talking about here is a new study from E.F. Borra and E. Trottier, two astronomers at Laval University in Canada. Their study, titled “Discovery of peculiar periodic spectral modulations in a small fraction of solar type stars” was just published at arXiv.org. ArXiv.org is a pre-print website, so the paper itself hasn’t been peer reviewed yet. But it is generating interest.
The two astronomers used data from the Sloan Digital Sky Survey, and analyzed the spectra of 2.5 million stars. Of all those stars, they found 234 stars that are producing a puzzling signal. That’s only a tiny percentage. And, they say, these signals “have exactly the shape of an ETI signal” that was predicted in a previous study by Borra.
A portion of the 234 stars that are sources of the pulsed ETI-like signal. Note that all the stars are in the narrow spectral range F2 to K1, very similar to our own Sun. Image: Ermanno F. Borra and Eric Trottier
Prediction is a key part of the scientific method. If you develop a theory, your theory looks better and better the more you can use it to correctly predict some future events based on it. Look how many times Einstein’s predictions based on Relativity have been proven correct.
The 234 stars in Borra and Trottier’s study aren’t random. They’re “overwhelmingly in the F2 to K1 spectral range” according to the abstract. That’s significant because this is a small range centred around the spectrum of our own Sun. And our own Sun is the only one we know of that has an intelligent species living near it. If ours does, maybe others do too?
The authors acknowledge five potential causes of their findings: instrumental and data reduction effects, rotational transitions in molecules, the Fourier transform of spectral lines, rapid pulsations, and finally the ETI signal predicted by Borra (2012). They dismiss molecules or pulsations as causes, and they deem it highly unlikely that the signals are caused by the Fourier analysis itself. This leaves two possible sources for the detected signals. Either they’re a result of the Sloan instrument itself and the data reduction, or they are in fact a signal from extra-terrestrial intelligences.
This graph shows the number of detected signals by Spectral Type of star. Image: Ermanno F. Borra and Eric Trottier
The detected signals are pulses of light separated by a constant time interval. These types of signals were predicted by Borra in his 2012 paper, and they are what he and Trottier set out to find in the Sloan data. It may be a bit of a red flag when scientist’s find the very thing they predicted they would find. But Trottier and Borra are circumspect about their own results.
As the authors say in their paper, “Although unlikely, there is also a possibility that the signals are due to highly peculiar chemical compositions in a small fraction of galactic halo stars.” It may be unlikely, but lots of discoveries seem unlikely at first. Maybe there is a tiny subset of stars with chemical peculiarities that make them act in this way.
To sum it all up, the two astronomers have found a tiny number of stars, very similar to our own Sun, that seem to be the source of pulsed signals. These signals are the same as predicted if a technological society was using powerful lasers to communicate with distant stars.
We all want there to be aliens, and maybe the first sign of them will be pulsed light signals from stars like our own Sun. But it’s all still very preliminary, and as the authors acknowledge, “…at this stage, this hypothesis needs to be confirmed with further work.”
The Breakthrough team don’t seem that excited about Borra’s findings. They’ve already poured cold water on it, trotting out the old axiom that “Extraordinary claims require extraordinary evidence” in a statement on Borra’s paper. They also give Borra’s findings a score of 0 to 1 on the Rio Scale. The Rio Scale is something used by the international SETI community to rank detections of phenomena that could indicate advanced life beyond Earth. A rating of 0 to 1 means its insignificant.
“This supports our initial assumption that the signal was made by human intelligence, not extraterrestrial intelligence,” said Doug Vakoch, President of METI International (Messaging Extraterrestrial Intelligence), a group doing follow-up observations of the star system HD 164595, where the signal was thought to maybe, perhaps originate.
When the news broke of the possible alien signal, SETI scientists were quick to temper the excitement with measured skepticism, saying more often than not, these signals end up being “natural radio transients” (stellar flare, active galactic nucleus, microlensing of a background source, etc.) or interference of a terrestrial nature (a passing satellite or a microwave oven, for example.)
But still, people were excited and the news went viral. Crazy viral.
“Being no stranger to how the media can hype SETI stories, I can sympathize with those at the center of the latest dustup,” said astronomer and SETI researcher Jason Wright from Penn State University. “It’s understandable that many content outlets, seeking ‘clickbait’ headlines, would spin this particular story in the most intriguing, exciting way, and once that happens a ‘bidding war’ of hype can make the story spin out of control.”
But is it all about clickbait? Since I’m part of the media (and admittedly was initially very excited about this story,) I’d like to think that the excitement and viral-tendencies of news about possible alien signals say more about humanity’s fervent hope that we aren’t alone in the cosmos, rather than who can get the most pageviews.
And I do know that researchers who dedicate their careers to the search for alien signals and Earth-like planets aren’t doing so just so they can keep telling us to not get excited. They, too, are hoping for that chance, that very remote possibility, that we’ve got company in our big and magnificent Universe.
“You can’t always be cynical,” said SETI senior astronomer Seth Shostak. “If a signal is looking promising, we are going to check it out.”
And that’s the thing, say the researchers. They get signals like this all the time.
“This is the sort of thing SETI researchers do all the time, because by the nature of the search, radio SETI experiments come across strong signals all the time,” Vakoch said via email. “At the end of the day, these need to be confirmed as coming from distant locations in space, and if we can’t, we need to consider them spurious. The unusual feature of HD 164595 is that this process of checking is being followed by the media.”
And while scientists were surprised (and maybe annoyed) at the amount of attention the ‘alien signal’ news got this week, there is an upside.
“The silver living here is that those who read the more responsible stories carefully will learn a lot about how SETI works,” Wright told Universe Today, “that communication SETI researchers see “one-off” signals all the time from both astronomical and terrestrial sources, in addition to perhaps the occasional instrumental glitch. Searches using arrays (like the ATA) have an automatic check against many of these, but in any event no one will be popping the champaign until a signal repeats enough for an independent telescope and instrument to detect it, and its intelligent origin is clear.”
“The public is getting an inside view of the usual process of following up interesting SETI candidates,” said Vakoch. “This helps the public understand the standard process of doing SETI: we find interesting signals, and then we see if we can verify them. If not, we move on.”
Vakoch and Wright said that the confirmation process, however, involves a lot of steps, and it’s not always easy or quick to follow-up. So, most of the time, determining the source of the signal takes time.
“Unlike Hollywood movies, where you get a quick “yes or no” about a possible signal from aliens,” Vakoch explained, “the real SETI confirmation process takes some time. It’s easy to think that all we need to do is get on the phone with an astronomer at another location, and we’re all set. But even when colleagues at other facilities are willing to observe, they may face technical limitations.”
The Allen Telescope Array (ATA). Credit: Seth Shostak / SETI Institute
Typical radio SETI searches look for narrowband signals, and most observatories aren’t set up to detect such signals on short notice. And even though radio observatories can make observations even when it’s cloudy, there can be other types of local interference at certain radio frequencies.
“If you need to do a real-time follow-up of a promising SETI signal, you might face significant roadblocks to a ready confirmation – even if the signal is really there,” Vakoch said.
Another upside of the recent media attention is that SETI researchers can let everyone know they aren’t getting much funding for this type of research, and the search could really use a lot more eyes and ears on the Universe, as Jill Tartar tweeted:
Re: HD 164595 – who knows? One telescope is not enough and an array is better.
“It’s all the more evident that we need to replicate these innovative optical SETI systems over and over,”Vakoch said, “so we can have a global network of modest-sized observatories ready for follow-up of promising SETI signals. Developing such a network is one of METI International’s top priorities as an organization.”
Wright said while the public interest in SETI is great, sometimes the media (or the tin foil hat crowd or conspiracy theorists) can blow things out of proportion.
“This can make it hard for anyone doing SETI to talk about their work, because any mention of ‘strange’ or ‘candidate’ signals has the potential to enter that echo chamber,” he said.
Which can go viral.
But if anyone is worried that SETI researchers are keeping secrets or not telling the whole story, I can personally vouch that during this week, absolutely every SETI researcher I contacted answered all my questions in an extremely timely manner (and provided even more information than I was expecting) plus, other researchers contacted me, asking to be able to explain the signal and the process of how SETI works.
“Nothing would make us more excited than to verify it,” said Bill Diamond, president and CEO of SETI, “But we have to observe it and look at the data.”
RATAN-600 radio telescope located in Northern Caucasus in the Karachaevo-Circassian Republic of Russian Federation. . Credit: SAO RAS.
We’re not saying its aliens, but this could be the most enticing SETI-related signal from space since the famous “Wow! Signal” in 1977.
Over the weekend, interstellar expert Paul Gilster broke the news that “a strong signal” was detected by Russian radio astronomers from the region around the star HD 164595. This signal has attracted enough attention that two prominent SETI observatories are quickly making follow-up observations. Alan Boyle reports in Geekwire that the Allen Telescope Array in California has already been observing the star system and the Boquete Optical SETI Observatory in Panama will make an attempt this evening, if the weather is clear.
Doug Vakoch, the President of METI International (Messaging Extraterrestrial Intelligence) told Universe Today via email that the Allen Telescope Array has already completed its initial reconnaissance of HD 164595, “with no indications of alien technologies at radio frequencies.”
“The first step in following up a putative SETI signal is to look at the same frequency where it was first detected,” Vakoch said, and with the nil detection from the ATA, “now it’s time to search other parts of the electromagnetic spectrum.”
Vakoch said METI International will be observing HD 164595 for brief laser pulses from the Boquete Optical SETI Observatory in Panama as soon as weather permits.
“It looks like the Boquete Observatory will be hit by heavy thundershowers late this afternoon and into this evening,” he said, “so we’ll likely need to wait to observe until another night. Once the evening sky is clear in Boquete, we’ll have about an hour to observe in the direction of the constellation Hercules shortly after sunset.”
The signal from HD 164595 was originally detected on May 15, 2015, by the Russian Academy of Science-operated RATAN-600 radio telescope in Zelenchukskaya, Russia. It is located about 95 light years from Earth in the constellation Hercules. The signal had a wavelength of 2.7 cm, with an estimated amplitude of 750 mJy.
Gilster wrote on his Centauri Dreams website that the researchers have worked out the strength of the signal and that if “it came from an isotropic beacon, it would be of a power possible only for a Kardashev Type II civilization,” which means a civilization capable of harnessing the energy of the entire star, and developing something like a Dyson sphere surrounding the star, and transfer all the energy to the planet.
Freeman Dyson theorized that eventually, a civilization would be able to build a megastructure around its star to capture all its energy. Credit: SentientDevelopments.com
If the beam was narrow and sent directly to our Solar System, the researchers say it would be of a power available to a Kardashev Type I civilization, a type of civilization more advanced than us that is able to harness the full amount of solar power it receives from its star.
Of course, like any other signal, such as the recent study of the dimming light curve of KIC 8462852 (Tabby’s Star) that is still being researched, it is possible the signal comes from other “natural” events such microlensing of a background source or even comets as been proposed for both Tabby’s Star or the “Wow! Signal.”
The SETI website explains that narrow-band signals – ones that are only a few Hertz wide or less – are the mark of a purposely built transmitter. “Natural cosmic noisemakers, such as pulsars, quasars, and the turbulent, thin interstellar gas of our own Milky Way, do not make radio signals that are this narrow. The static from these objects is spread all across the dial.”
Update: A member of the SETI@Home team posted a note online that they were “unimpressed” with the paper from the Russian radio astronomers. “Because the receivers used were making broad band measurements, there’s really nothing about this “signal” that would distinguish it from a natural radio transient (stellar flare, active galactic nucleus, microlensing of a background source, etc.) There’s also nothing that could distinguish it from a satellite passing through the telescope field of view. All in all, it’s relatively uninteresting from a SETI standpoint.”
So, this detection might not be as exciting as originally reported. Also SETI senior astronomer Seth Shostak has now weighed in on the topic, also with measured skepticism on the excitement, with a post about this event on the SETI website.
What has probably fueled interest in this signal is the striking similarities between the star and our Sun. HD 164595 is a star just a tad smaller than our Sun (0.99 solar masses), with the exact same metallicity. The age of the star has been estimated at 6.3 billion years it is already known to have at least one planet, HD 164595 b, a Neptune-sized world that orbits the star every 40 days. And as we’ve seen with data from the Kepler spacecraft, with the detection of one planet comes the very high probability that more planets could orbit this star.
Why the Russian team has only made this detection public now is unclear and it may have only come out now because the team wrote a paper to be discussed at an upcoming SETI committee meeting during the 67th International Astronautical Congress in Guadalajara, Mexico, on Tuesday, September 27.
As Gilster wrote, “No one is claiming that this is the work of an extraterrestrial civilization, but it is certainly worth further study.”
The Search for ExtraTerrestrial Intelligence could be a waste of time according to a recent statistical analysis of the likelihood of life arising spontaneously on habitable-zone exoplanets out there in the wider universe (and let's face it - when have predictive statistics ever got it wrong?) Credit: SETI Institute.
Many years ago, Carl Sagan predicted there could be as many as 10,000 advanced extraterrestrial civilizations in our galaxy.
After nearly 60 years of searching without success, a growing list of scientists believe life on Earth only came about because of a lucky series of evolutionary accidents, a long list of improbable events that just happened to come together at the right time and will never be repeated.
Is it possible they are right and we are all there is?
Highly unlikely.
Earth is a typical rocky planet, in an average solar system, nestled in the spiral arm of an ordinary galaxy. All the events and elements that came together to build our world could happen almost everywhere throughout the galaxy and there should be nothing unusual about the evolution of life on this planet or any others.
In a galaxy of hundreds of billions of stars, the law of averages dictates that intelligent life must exist somewhere.
So, why haven’t we found it yet?
There could be many reasons.
Planets everywhere. So where are the aliens? Credit: ESO/M. Kornmesser
Looking for a radio signal in a galaxy of over 400 billion worlds across 100,000 light years and billions of radio frequencies makes the proverbial needle in a haystack sound easy. Imagine you are driving home, your spouse in one car and you in the other. There’s a thick fog making visual confirmation impossible and no cell phone reception. Luckily, a week ago you had a 250 channel CB installed in both cars. Unfortunately, you forgot to agree on a broadcast channel. To chat, the two CBs would have to be on at the same time and you’d need to independently search every channel, listen, broadcast, then move to the next, hoping to get lucky enough to land on the same channel.
What are the odds that would happen? Not very good. Multiply this scenario one hundred billion times and you have some idea of the challenges facing SETI. To add to that, advanced civilizations probably only stay radio active for a relatively short time in their development as they develop more sophisticated technology. Searching the radio spectrum would require looking at one frequency 24/7 for years to be sure you weren’t missing something and telescope time is far too expensive for that. While you were sitting on that single frequency, 20 extraterrestrial signals could have come in on other channels and you’d never know it.
The Fermi Paradox is used by many skeptics as the holy grail when trying to prove there is nobody out there. Fermi theorized that a galaxy with so much potential for life must be full of extraterrestrials. He noted that since the majority of stars are considerably older than our sun, extraterrestrials could be millions of years more advanced than us. Fermi calculated that even at sub light speed one of those civilizations should have colonized the galaxy by now and we would have seen evidence of it.
There is however a problem with that logic.
In 50,000 years, humans will probably look a little different than people do now. In 10 million years, considerably different. Imagine a civilization completely different from us from the start and 10 million years more advanced. We might not even be able to recognize them as life forms, let alone see any evidence of their existence.
Arthur C. Clarke once said advanced extraterrestrials would probably be indistinguishable to us from magic. Their communications would be like listening for an answer to drumbeats and getting only silence while the ether around you is filled with more information in a second than one could utter in a lifetime. There could be the alien equivalent of the super bowl going on a few light years away and we would probably not even have a clue.
The distances in our galaxy are incredibly vast. Current spacecraft travel about 20 times faster than the speed of a bullet. While that sounds fast, at that speed it would take a spacecraft 75,000 years to travel to our nearest star only 4 light years away. Light years are a measure of distance so if we could speed that ship up to 186,000 miles per second (300,000 km/second), it would take 4 years to reach that same star.
The Arecibo Radio Telescope in Puerto Rico was the site of NASA’s High Resolution Microwave Survey, a search for extraterrestrial radio messages. Credit: Unites States National Science Foundation
Looking at a star 1,000 light years away is like being in a time machine. You are not seeing it as it is now, but one thousand years ago. Our galaxy is about 100,000 light years across with over 200 billion stars. Current theory suggests there may be as many as one billion earth-like planets in our galaxy. If just one tenth of those had some kind of life, that would leave us with about 100 million worlds harboring one celled creatures or better.
If just the tiniest fraction of them, (one one hundred thousandth) managed to spawn an advanced race of beings, there could be as many as 1,000 extraterrestrial civilizations in our galaxy. Regardless of whether you consider that a lot or a little, that would mean one technically advanced alien society exists for every hundred million stars. Our nearest extraterrestrial neighbor might be very, very far away. In the movies, the speculative fiction of warp speed, hyper drive and worm holes enable spaceships to travel faster than the speed of light and breach those distances fairly easily. But if the physics of this turn out to be impossible, then even the nearest alien civilizations may find interstellar travel very difficult and quite undesirable.
Another reason extraterrestrials may have made themselves scarce could be that the galaxy is jam packed with all sorts of weird beings and wondrous destinations. In this scenario why would advanced forms of life want to come here? There are probably so many more interesting places to visit. It would be like hunting for an exotic bird and not even giving the ant hill below your feet a second look.
Stephen Hawking has said, “I believe extraterrestrial life is quite common in the universe, although intelligent life less so. Some say it has yet to appear on Earth.”
Many think once a civilization achieves radio, it has a short window of but a few hundred years before it starts to integrate artificial intelligence into its own biology. Machines do everything so much easier, with far less risk and are immortal. It is entirely possible any aliens we hear from will have morphed into something more machine like than biological.
The Allen Telescope Array (ATA) is a “Large Number of Small Dishes” (LNSD) array designed to be highly effective for simultaneous surveys undertaken for SETI projects (Search for Extraterrestrial Intelligence) at centimeter wavelengths. Credit: Seth Shostak / SETI Institute
There has been a push lately for SETI to expand its operations from just passively listening, to actively broadcasting messages into the cosmos. One of the smartest men on the planet, Stephen Hawking, doesn’t think that’s a good idea. He believes that our messages might attract unwanted attention from unsavory creatures looking to blast us back into the stone age. He uses what happened to the Native Americans when they first encountered Columbus as an example. Alien races may have had to endure the same aggressive survival of the fittest culture. If they are at least as smart as Stephen Hawking, then everyone out there could be listening and nobody is broadcasting for fear of attracting the equivalent of Darth Vader and the Evil Empire to their shores.
Or, maybe there is a signal on its way right now, having traveled thousand of years, arriving next week, month or year.
Many scientists like Paul Davies, think SETI needs to start thinking more out of the box in its search methods. He advocates analyzing places in our own solar system like the moon, planets, asteroids and the Earth for evidence that aliens have passed this way. We should also be open to the possibility that we have already received a message from the stars and don’t recognize it because it arrived by something other than radio. Physist Vladimir Charbak thinks that life may have been spread throughout the galaxy by intelligent design and there may actually be evidence of this within our own DNA just waiting to be discovered.
Another reason we have yet to detect alien life could be there is nothing out there to find. Or to put it another way, we are the only game in town. To best answer that question, ask yourself, does this seem logical? There is a very good chance that one or more worlds just in our own solar system harbor some form of life. In a galaxy with as many as one billion or more potentially habitable planets, one could almost guarantee many of them will host life. There may potentially be hundreds of millions of worlds with living things on them. Does it make sense that in all that habitable real estate we are the only race to evolve into an intelligent species?
Extraterrestrials in the 1979 movie “Close Encounters of the Third King.” Credit: Columbia Pictures / Alien Wiki
We humans tend to think of things with a distinctly anthropomorphic spin. Notions like, life needs water, oxygen and is based on carbon. Or, an advanced alien race would use radio and their signals should repeat. In popular culture, extraterrestrials portrayed in movies look remotely like us. This is done so we can recognize emotions and that fills movie theaters. I can remember aliens portrayed in the classic science fiction television show, “The Outer Limits” as energy balls, dust motes and tumbleweeds. They weren’t the most popular episodes, but the reality is that those portrayals are probably closer to the truth than ET and his heart lamp. Extraterrestrials will probably be as different from us as we are from a blade of grass and their motivations a complete mystery. It is very possible that the reason we haven’t found them yet is one that completely eludes our understanding at this point.
So where does that leave us?
Time and patience.
If you compare the 4.5 billion year old earth to a 24 hour clock, mankind doesn’t appear until a little over a minute before midnight. Take the almost sixty years we have been looking for extraterrestrials and project that on the same clock, it probably represents only about 20 or 30 seconds worth of searching for intelligent beings who may have been around millions and perhaps billions of years longer than we have. Our passage through time is just a tiny almost imperceptible blip when compared to the evolution of our galaxy.
Lasers like this one, at the VLT in Paranal, help counteract the blurring effect of the atmosphere. Powerful arrays of much larger lasers could hide our presence from aliens. (ESO/Y. Beletsky)
New, very powerful listening devices will be coming into operation soon as well as sophisticated instruments that will be able to analyze exoplanets atmospheres to look for hints of life. SETI will expand into new areas and scientists will be able to devote a lot more telescope time to the search as the newly funded (100MM) Project Breakthough Listen kicks into high gear. It will cover 10 times more of the sky and the entire 1-10GHz radio spectrum. There will be more powerful optical and infrared searches and it is estimated the project will generate in a day as much data as SETI produced in an entire year. Recently, Project Breakthrough Starshot was announced as well. Seeded by another 100MM by Russian Billionaire, Yuri Milner, this ambitious project seeks to send a tiny light propelled robotic spacecraft to our nearest star system, Alpha Centauri. Stephen Hawking thinks this can be accomplished within the next generation and that new technology would allow a journey of only 20 years.
SETI scientist Nathalie Cabrol thinks its also time for a new approach to SETI’s search, a reboot if you will. She feels that “SETI’s vision has been constrained by whether ET has technology that resembles or thinks like us. She feels that the search, so far, has in essence been a search for ourselves. Electromagnetic fingerprints of radio transmitions carry a strong like us assumption”. She proposes involving a lot more disciplines in a redesign of the search. Astrobiology, life sciences, geoscience, cognitive science and mathematics among others. Her plan is to invite the research community to help craft a new scientific roadmap for SETI that very well may redefine the meaning of life and the cosmic search for new forms of it.
Some experts say we won’t see evidence of extraterrestrials for another 1500 years. That’s the time it will take for our TV and radio signals to have reached enough stars and have the best chance to be discovered.
In my opinion, I think highly advanced extraterrestrial societies already know we’re here and in about 10-15 years we’ll start getting some of the answers we’ve been looking for.
The logo of the METI International Puerto Rico workshop. At the center is Charles Darwin, the nineteenth century British naturalist whose theory of evolution is central to assessing the likelihood and nature of extraterrestrial intelligence. To the left is the octopus, a creature that evolved sophisticated cognition and perception along an evolutionary path quite different from that of humans. To the right is the peacock, whose elaborate tail feathers evolved by sexual selection, a process that may also have been of central importance to the evolution of human intelligence. METI International, used with permisson.
In our galaxy, there may be, at least, tens of billions of habitable planets, with conditions suitable for liquid water on their surfaces. There may be habitable moons as well. On an unknown number of those worlds, life may have arisen. On an unknown fraction of life-bearing worlds, life may have evolved into complex multicellular, sexually reproducing forms.
The purposes of the newly created METI (Messaging to ExtraTerrestrial Intelligence) International include fostering multidisciplinary research in the design and transmission of interstellar messages, and building a global community of scholars from the natural sciences, social sciences, humanities, and arts concerned with the origin, distribution, and future of life in the universe.
On May 18 the organization sponsored a workshop which included presentations by biologists, psychologists, cognitive scientists, and linguists. This is the third and final installment of a series of articles about the workshop.
In previous installments, we’ve discussed some ideas about the evolution of intelligence that were featured at the workshop. Here we’ll see whether our Earthly experience can provide us with any clues about how we might communicate with aliens.
Many of the animals that we are most familiar with from daily life, like humans, cats, dogs, birds, fishes, and frogs are vertebrates, or animals with backbones. They are all descended from a common ancestor and share a nervous system organized according to the same basic plan.
Molluscs are another major group of animals that have been evolving separately from vertebrates for more than 600 million years. Although most molluscs, like slugs, snails, and shellfish, have fairly simple nervous systems, one group; the cephalopods, have evolved a much more sophisticated one. The common octopus, Octopus vulgaris, Is a cephalopod mollusc, has evolved sophisticated cognition and perception along a very different evolutionary path than have human beings and our relatives. The brain is located between the eyes. The large bulbous structure below the eyes is the mantle, a muscular organ involved in swimming. Public domain.
Cephalopods include octopuses, squids, and cuttlefishes. They show cognitive and perceptual abilities rivaling those of our close vertebrate kin. Since this nervous system has a different evolutionary history than of the vertebrates, it is organized in a way completely different from our own. It can give us a glimpse of the similarities and differences we might expect between aliens and ourselves.
David Gire, an associate professor of psychology at the University of Washington, and researcher Dominic Sivitilli gave a presentation on cephalopods at the Puerto Rico workshop. Although these animals have a sophisticated brain, their nervous systems are much more decentralized than that of familiar animals. In the octopus, sensing and moving are controlled locally in the arms, which together contain as many nerve cells, or neurons, as the brain. Dr. David Gire is an Assistant Professor in the Department of Psychology at the University of Washington and a behavioral neuroscientist. He presented at the Puerto Rico workshop on cephalopod intelligence.
The animal’s eight arms are extraordinarily sensitive. Each containing hundreds of suckers, with thousands of sensory receptors on each one. By comparison, the human finger has only 241 sensory receptors per square centimeter. Many of these receptors sense chemicals, corresponding roughly to our senses of taste and smell. Much of this sensory information is processed locally in the arms. When an arm is severed from an octopus’s body, it continues to show simple behaviors on its own, and can even avoid threats. The octopus’s brain simply acts to coordinate the behaviors of its arms.
Cephalopods have acute vision. Although their eyes evolved separately from those of vertebrates, they nonetheless bear an eerie resemblance. They have a unique ability to change the pattern and color of their skin using pigment cells that are under direct control of their nervous systems. This provides them with the most sophisticated camouflage system of any animal on Earth, and is also used for social signaling.
Despite the sophisticated cognitive abilities it exhibits in the lab, the octopus is largely solitary.
Cephalopod groups exchange useful information by observing one another, but otherwise exhibit only limited social cooperation. Many current theories of the evolution of sophisticated intelligence, like Miller’s sapiosexual hypothesis, which was featured in the second installment, assume that social cooperation and competition play a central role in the evolution of complicated brains. Since cephalopods have evolved much more impressive cognitive abilities than other molluscs, their limited social behavior is surprising.
Dominic Sivitilli is a post-baccalaureate researcher in the laboratory of David Gire, studying responses to chemical signals by the octopus. He is the co-presenter of a talk on cephalopod cogntition at the METI International Puerto Rico conference. METI International used with permission.
Maybe the limited social behavior of cephalopods really does set limits on their intelligence. However, Gire and Sivitilli speculate that perhaps “an intelligence capable of technological development could exist with minimum social acuity”, and the cephalopod ability to socially share information is enough. The individuals of such an alien collective, they suppose, might possess no sense of self or other.
Besides Gire and Sivitilli, Anna Dornhaus, whose ideas were featured in the first installment, also thinks that alien creatures might function together as a collective mind. Social insects, in some respects, actually do. She doubts, though, that such an entities could evolve human-like technological intelligence without something like Miller’s sapiosexuality to trigger a runaway explosion of intelligence.
But if non-sapiosexual alien technological civilizations do exist, we might find them impossible to comprehend. Given this possible gulf of incomprehension about social structure, Gire and Stivitilli suppose that the most we might aspire to accomplish in terms of interstellar communication is an exchange of mutually useful and comprehensible astronomical information.
Workshop presenter Alfred Kracher, a retired staff scientist at the Ames Laboratory of the University of Iowa, supposes that “the mental giants of the Milky Way are probably artificially intelligent machines… It would be interesting to find evidence of them, if they exist”, he writes, “but then what?” Kracher supposes that if they have emancipated themselves and evolved away from their makers, “they will have nothing in common with organic life forms, human or extraterrestrial. There is no chance of mutual understanding”. We will be able to understand aliens, he maintains, only if “it turns out that the evolution of extraterrestrial life forms is highly convergent with our own”.
Peter Todd, a professor of psychology from Indiana University, holds out hope that such convergence may actually occur. Earthly animals must solve a variety of basic problems that are presented by the physical and biological world that they inhabit.
They must effectively navigate through a world of surfaces, barriers and objects, finding food and shelter, and avoiding predators, parasites, toxins. Extraterrestrial organisms, if they evolve in an Earth-like environment, would face a generally similar set of problems. They may well arrive at similar solutions, just as the octopus evolved eyes similar to ours.
In evolution here on Earth, Todd notes, brain systems originally evolved to solve these basic physical and biological problems appear to have been re-purposed to solve new and more difficult problems, as some animals evolved to solve the problems of living and finding mates as members of societies, and then as one particular ape species went on to evolve conceptual reasoning and language. For example, disgust at bad food, useful for avoiding disease, may have been become the foundation for sexual disgust to avoid bad mates, moral disgust to avoid bad clan mates, and intellectual disgust to avoid dubious ideas.
If alien brains evolved solutions similar to the ones our brains did for negotiating the physical and biological world, they they might also have been re-purposed in similar ways. Alien minds might not be wholly different from ours, and thus hope exists for a degree of mutual understanding.
In the early 1970’s the Pioneer 10 and 11 spacecraft were launched on the first exploratory missions to the planet Jupiter and beyond. When their missions were completed, these two probes became the first objects made by humans to escape the sun’s gravitational pull and hurtle into interstellar space.
Because of the remote possibility that the spacecraft might someday be found by extraterrestrials, a team of scientists and scholars lead by Carl Sagan emplaced a message on the vehicle, etched on a metal plaque. The message consisted, in part, of a line drawing of a man and a woman. Later, the Voyager 1 and 2 spacecraft carried a message that consisted, in part, of a series of 116 digital images encoded on a phonographic record. The use of images in interstellar communication. In 1977, NASA launched the Voyager 1 and 2 spacecraft on a mission to explore the outer solar system. Destined to wander interstellar space forever following the completion of their mission, each spacecraft carried an interstellar message encoded on a phonographic record. The message, designed by SETI pioneers Carl Sagan and Frank Drake and their collaborators, included 116 digital images. This image is intended to show extraterrestrials how human beings eat and drink. Will extraterrestrials understand such images? The limited quality of the image reflects the state of digital imaging technology in the 70’s National Astronomy and Ionosphere Center, public domain.
The assumption that aliens would see and understand images seems reasonable, since the octopus evolved an eye so similar to our own. And that’s not all. The evolutionary biologists Luitfried Von Salvini-Plawen and Ernst Mayr showed that eyes, of various sorts, have evolved forty separate times on Earth, and vision is typically a dominant sense for large, land dwelling animals. Still, there are animals that function without it, and our earliest mammalian ancestors were nocturnal. Could it be that there are aliens that lack vision, and could not understand a message based on images?
In his short story, The Country of the Blind, the great science fiction writer H. G. Wells imagined an isolated mountain village whose inhabitants had been blind for fifteen generations after a disease destroyed their vision.
A lost mountain climber, finding the village, imagines that with his power of vision, he can easily become their king. But the villagers have adapted thoroughly to a life based on touch, hearing, and smell. Instead of being impressed by their visitor’s claim that he can ‘see’, they find it incomprehensible. They begin to believe he is insane. And when they seek to ‘cure’ him by removing two strange globular growths from the front of his head, he flees. The Mexican blind cavefish (Astyanax mexicanus) has lived in the total darkness of a cave system in central Mexico for more than a million years, and has evolved the loss of its eyes. Astyanax possess a sense that land dwelling animals lack. The lateral line sense, which is present in all fishes, allows these animals to sense their near surroundings based on pressure differences in fields of water flow around their bodies. They also have an acute sense of taste, with taste receptors on their bodies as well as in their mouths. The evolution of cave dwelling intelligent life is probably unlikely, since large brains are metabolically expensive, and food is scarce in caves. On the surface, plants capture energy from sunlight and form the base of the food chain. State Museum of Natural History, Karlsruhe.
Could their really be an alien country of the blind whose inhabitants function without vision? Workshop presenter Dr. Sheri Wells-Jensen, an associate professor of Linguistics at Bowling Green State University, doesn’t need to imagine the country of the blind, because, in a sense, she lives there. She is blind, and believes that creatures without vision could achieve a level of technology sufficient to send interstellar messages. “Sighted people”, she writes, “tend to overestimate the amount and quality of information gathered by vision alone”. Dr. Sheri Wells-Jensen is an associate professor of linguistics at Bowling Green State University. She presented at talk at the Puerto Rico workshop on alternative perceptual systems and interstellar communications. METI International, used with permission.
Bats and dolphins image their dimly lit environments with a kind of naturally occurring sonar called echolocation. Blind human beings can also learn to echolocate, using tongue clicks or claps as emitted signals and analyzing the returning echoes by hearing. Some can do so well enough to ride a bicycle at a moderate pace through an unfamiliar neighborhood. A human can develop the touch sensitivity needed to read braille in four months. A blind marine biologist can proficiently distinguish the species of mollusc shells by touch.
Wells-Jensen posits a hypothetical civilization which she calls the Krikkits, who lack vision but possess sensory abilities otherwise similar to those of human beings. Could such beings build a technological society? Drawing on her knowledge of the blind community and a series of experiments, she thinks they could.
Finding food would present few special difficulties, since blind naturalists can identify many plant species by touch. Agriculture could be conducted as modern blind gardeners do it, by marking crops using stakes and piles of rock, and harvesting by feel. The combination of a stick used as a cane to probe the path ahead and echolocation make traveling by foot effective and safe. A loadstone compass would further aid navigational abilities. The Krikkits might use snares rather than spears or arrows to trap animals, making tools by touch.
Mathematics is vital to building a technological society. For most human beings, with our limited memory, a paper and pencil or a blackboard are essential for doing math. Krikkits would need to find other such aids, such as tactual symbols on clay tablets, abacus-like devices, or patterns sewn on hides or fabric.
Successful blind mathematicians often have prodigious memories, and can perform complex calculations in their heads. One of history’s greatest mathematicians, Leonard Euler, was blind for the last 17 years of his life, but remained mathematically productive through the use of his memory.
The obstacles to a blind society developing technology may not be insurmountable. Blind people are capable of handling fire and even working with molten glass. Krikkits might therefore use fire for cooking, warmth, to bake clay vessels, and smelt metal ores. Initially there only astronomical knowledge would be of the sun as a source of heat. Experiments with loadstones and metals would lead to a knowledge of electricity.
Eventually, the Krikkits might imitate their sonar with radio waves, inventing radar. If their planet possessed a moon or moons, radar reflections from them might provide their first knowledge of astronomical objects other than their sun. Radar would also enable them to learn for the first time that their planet is round.
The Krikkits might learn to detect other forms of radiation like X-rays and ‘light’. The ability to detect this second mysterious form of radiation might allow them to discover the existence of the stars and develop an interest in interstellar communication.
What sorts of messages might they send or understand? Well-Jensen believes that line drawings, like the drawing of the man and the woman on the Pioneer plaque, and other such pictorial representations might be an impenetrable mystery to them. On the other hand, she speculates that Krikkits might represent large data sets through sound, and that their counterpart to charts and graphs might be equally incomprehensible to us.
Images might pose a challenge for the Krikkits, but perhaps, Wells-Jensen concedes, not an impossible one. There is evidence that bats image their world using echolocation. Kikkits might be likely to evolve similar abilities, though Wells-Jensen believes they would not be essential for making tools or handling objects.
Perhaps humans and Krikkits could find common ground by transmitting instructions for three dimensional printed objects that could be explored tactually. Wells-Jensen thinks they might also understand mathematical or logical languages proposed for interstellar communication.
The diversity of cognition and perception that we find here on Earth teaches us that if extraterrestrial intelligence exists, it is likely to be much more alien than much of science fiction has prepared us to expect. In our attempt to communicate with aliens, the gulf of mutual incomprehension may yawn as wide as the gulf of interstellar space. Yet this is a gulf we must somehow cross, if we wish ever to become citizens of the galaxy.
The peahen (at left) and the peacock (at right). The peacock’s elaborate plumage and many other similar animal ornaments posed a troubling difficulty for Charles Darwin in his development of the theory of evolution, since they seemed to have no value for survival. The peacocks that were everywhere present in English gardens were a frustrating and ever-present reminder of the difficulty. “The sight of a feather in a peacock’s tail”, Darwin wrote, “whenever I gaze at it, makes me sick!”. Darwin solved the problem with his theory of sexual selection, which posits that such ornaments evolved because they help animals to woo mates, and thereby pass the trait into the next generation. Since mating in peafowl is by female choice, elaborate tail feathers are vital to the peacock, but unnecessary to the peahen. Sexual selection is increasingly recognized as a central evolutionary process by modern biologists. Evolutionary psychologist Dr. Geoffrey Miller posits that the enormous human brain evolved by sexual selection through the choices of both genders. Understanding how human intelligence evolved here on Earth is critical to understanding whether or not alien civilizations are likely to exist. Picture is from the Miho Museum, Shiga, Japan, 1781, public domain.
In the first instalment of this series, we saw that intelligence, of various sorts, is widespread across the animal kingdom. Workshop presenter Anna Dornhaus, who studies collective decision-making in insects as an associate professor at the University of Arizona, showed that even insects, with their diminutive brains, exhibit a surprising cognitive sophistication. Intelligence, of various sorts, is a likely and probable evolutionary product.
Animals evolve the cognitive abilities that they need to meet the demands of their own particular environments and lifestyles. Sophisticated brains and cognition have evolved many times on Earth, in many separate evolutionary lineages. But, of the millions of evolutionary lineages that have arisen on Earth in the 600 million years since complex life appeared, only one, that which led to human beings, produced the peculiar combination of cognitive traits that led to a technological civilization. What this tells us is that technological civilization is not the inevitable product of a long term evolutionary trend, it is rather the quirky and contingent product of particular circumstances. But what might those circumstances have been, and just how special and improbable were they?
Dr. Geoffery Miller is an associate professor of psychology at the University of New Mexico, and is the author of a 2001 book, The Mating Mind, where he explains his theory that human intelligence evolved by sexual selection to a general audience. He presented at the METI Institute conference in Puerto Rico, in May 2016. Picture used with permission.
Workshop presenter Geoffrey Miller is an associate professor of psychology at the University of New Mexico. Miller thinks he has an answer to the question of what the special circumstances that produced human evolution were. Our protohuman ancestors inhabited the African savanna. But so do many other mammals that don’t need enormous brains to survive there. The evolutionary forces driving the production of our large brains, Miller surmises, can’t be due to the challenges of survival. He thinks instead that human evolution was guided by an intelligence. But Miller is no creationist, nor does he have the alien monolith from the 1960’s science fiction classic 2001: A Space Odyssey in mind. Miller’s guiding intelligence is the intelligence that our ancestors themselves used when they selected their mates.
Miller’s theory harkens back to the ideas of the founder of modern evolutionary theory, the nineteenth century British naturalist Charles Darwin. Darwin proposed that evolution works through a process of natural selection. Animal offspring vary one from another, and are produced in too great of numbers for all of them to survive. Some starve, some are eaten by predators, others fall prey to the numerous other hazards of the natural world. A few survive to produce offspring, thereby passing on the traits that allowed them to survive. Down the generations, traits that aided survival become more elaborate and useful and traits that did not, vanished. Charles Darwin published his theory of evolution, in his book, The Origin of Species, in 1859. The theory was inspired, in part, by observations he made during his five year voyage as a naturalist on board the HMS Beagle and has become the central principle of much of modern biology. Picture by George Richmond (1830’s) public domain.
But Darwin was troubled by a serious problem with his theory. He knew that many animals have prominent traits that don’t seem to contribute to their survival, and are even counterproductive to it. The bright colors of many insects, the colors, elaborate plumage, and songs of birds, the huge antlers of elk, were all prominent and costly traits that couldn’t be explained by his theory of natural selection. Peacocks, with their elaborate tail feathers were everywhere in English gardens, and came to torment him.
At last, Darwin found the solution. To produce offspring, an animal must do more than just survive, it must find a partner to mate with. All the traits which worried Darwin could be explained if they served to make their bearers sexier and more beautiful to prospective mates than other competing members of their own gender. If peahens like elaborate plumage, then in each generation, they will choose to mate with the males with the most elaborate tail feathers, and reject the rest. Through the competition for mates, peacock tails will become more and more elaborate down the generations. Darwin called his new theory sexual selection.
Many subsequent evolutionary biologists regarded sexual selection as of limited importance, and lumped it in with natural selection, which was said to favor traits conducive to survival and reproductive success. However, in recent decades evolutionary biologists have come to view sexual selection in a much more favorable light. Geoffrey Miller proposed that the human brain evolved through sexual selection. Human beings, he supposes, are sapiosexual; that is, they are sexually attracted by intelligence and its products. The preference for selecting intelligent mates produced greater intelligence, which in turn allowed our ancestors to become more discerning in selecting more intelligent mates, producing a kind of amplifying feedback loop, and an explosion of intelligence.
On this account, language, music, dancing, humor, art, literature, and perhaps even morality and ethics exist because those who were good at them were deemed sexier, or more trustworthy and reliable, and were thus more successful in securing mates than those who weren’t. The elaborate human brain is like the elaborate peacock’s tail. It exists for wooing mates and not for survival. There are some important ways in which protohumans were different from peafowl. Both males and females are choosy and both have large brains. Protohumans, unlike peafowl, probably formed monogamous pair bonds. Miller’s theory has complexities that space won’t permit us to explore here. To show that his theory can work, Miller needed to develop a computer model.
The evolution of protohuman intelligence through geography and time. Homo egaster lived in the early Pleistocene between 1.9 and 1.4 million years ago and had a brain about half the size of modern Homo sapiens. It developed advanced stone tools, and may have domesticated fire. It was closely related to Homo erectus. Homo antecessor lived from 1.2 million to 800,000 years ago and spread from Africa into Europe. It’s brain was also about half as large as that of ours. Homo rhodesiensis lived about 120,000 to 300,000 years ago. Our species, Homo sapiens, arose in Africa about 200,000 years ago and spread throughout much of the world. Homo neanderthalensis had a brain capacity somewhat larger than that of modern humans, and its larger eye sockets suggest keener vision. They disappeared about 30,000 years ago, and may have died out, in part, through competition with Homo sapiens and cooling of the climate. Public Library of Science 2003.
If Miller is right, then just how probable is the evolution of a technological civilization, and how likely is it that we will find them elsewhere in the galaxy? Miller thinks that if complex life exists on other planets or moons, it is likely to evolve reproduction through sex, just as has happened here on Earth. For complex organisms that depend on a large and complicated body of genetic information, most mutations will be neutral or harmful. In sexual reproduction half the genes of one’s offspring come from each parent. Without this mixing of genes from other individuals, asexual lineages are likely to falter and go extinct due to an accumulation of harmful mutations. Unless sexually reproducing creatures choose their mates purely at random, sexual selection is an inevitability. So, the basic conditions for runaway sexual selection to produce a brain suited to language and technology probably exists on other worlds with complex life.
One problem, though, that Anna Dornhaus pointed out, is that in sexual selection, the trait that gets exaggerated is essentially arbitrary. There are many bird species with elaborate plumage, but none exactly like the peacock. There are many species where brains and cognitive traits matter for mating success, like the singing ability of nightingales and many other birds, or gibbons, or whales. Male bower birds build complicated structures, called bowers, out of found items, like sticks and leaves and stones and shells, to attract a female. Chimpanzees engage in complex power struggles that involve negotiation, grooming, and fighting their way to the top.
But despite the selective success of cognition and braininess in many species, our specific human sort of intelligence, with language and technology, has happened only once on Earth, and therefore might be rare in the universe. If our ancestors had found big noses rather than big brains sexy, then we might now have enormous noses rather than enormous radio telescopes capable of signaling to other worlds.
Miller is more optimistic. “It’s a rare accident” he writes, in the sense that mate preferences only rarely turn ‘sapiosexual’, focused so heavily on conspicuous displays of general intelligence… On the other hand, I think it’s likely that in any biosphere, sexual selection would eventually stumble into sapiosexual mate preferences, and then you’d get human-level intelligence and language of some sort. It might only arise in 1 out of every 100 million species though,…I suspect that in any biosphere with sexually reproducing complex organisms and a wide variety of species, you’d quite likely get at least one lineage stumbling into the sapiosexual niche within a billion years”.
A planet or moon is currently deemed potentially habitable if it orbits its parent star within the right distance range for liquid water to exist on its surface. This distance range is called the habitable zone. Since stars evolve with time, the duration of habitability is limited. Such matters can be explored through climate modeling, informed by what we know of the climates of Earth and other worlds within our solar system, and about the evolution of stars.
Current thinking is that Earth’s total duration of habitability is 6.3 to 7.8 billion years, and that our world may remain habitable for another 1.75 billion years. Since complex life has already existed on Earth for 600 million years, this seems a generous amount of time for complex life on a similar planet to stumble upon Miller’s sapiosexual niche. Stars of smaller mass than the sun are stable on longer timescales, some perhaps capable of sustaining worlds with liquid water for a hundred billion years. If Miller’s estimates are reasonable, then there may be worlds enough and time for an abundance of sapiosexual alien civilizations in our galaxy.
A central message of the METI Institute workshop is that, animals evolve whatever sort of intelligence is necessary for them to survive and reproduce under the circumstances in which they find themselves. Human-style intelligence, with language and technology, is a peculiar quirk of particular and improbable evolutionary circumstances. But we don’t know just how improbable. Given the vastness of time and number of worlds potentially available for the roll of the evolutionary dice, alien civilizations might be reasonably abundant, or they might be once-in-a-billion galaxies rare. We just don’t know. Better knowledge of the evolution of life and intelligence here on Earth might allow us to improve our estimates.
If alien civilizations do exist, what can life on Earth tell us about what their minds and senses are likely to be like? Are they, like us, visually oriented creatures, or might they rely on other senses? Can we expect that their minds might be similar enough to ours to make meaningful communication possible? These intriguing questions will be the subject of the third and final installment of this series.
Special Guest:
Dr. Seth Shostak is the Senior Astronomer at the SETI Institute. He also heads up the International Academy of Astronautics’ SETI Permanent Committee. In addition, Seth is keen on outreach activities: interesting the public – and especially young people – in science in general, and astrobiology in particular. He’s co-authored a college textbook on astrobiology, and has written three trade books on SETI. In addition, he’s published more than 400 popular articles on science — including regular contributions to both the Huffington Post and Discover Magazine blogs — gives many dozens of talks annually, and is the host of the SETI Institute’s weekly science radio show, “Big Picture Science.”
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