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The Astrobiological Cat

Predrag Slijepcevic questions standard views of intelligence by thinking on an evolutionary scale.

In one of its 1995 issues a little-known newsletter, Bioastronomy News, published a memorable debate between two famous scientists. The echos of that debate still reverberate, in places from the New York Times to modern scientific journals and books. On one side of the argument was celebrated astrophysicist Carl Sagan (1934-1996); on the other, respected biologist Ernst Mayr (1904-2005). The topic of the debate was the validity of the research programme known as the Search for Extraterrestrial Intelligence, or SETI.

According to Sagan, nature rewards smartness. He eloquently argued that the unimaginable vastness of the Milky Way and the huge number of stars with potentially habitable planets in it means it must contain other civilisations that, like ours, have discovered electromagnetic waves. By using radio telescopes, and with a bit of luck, we might be able to detect the radio wave traces of distant civilisations with which we share the convergent quality known as intelligence. The long-anticipated rendezvous with our cosmic neighbours may come to fruition one day.

Mayr, on the other hand, expressed deep doubts about the chances of SETI finding anything. His basic argument was that intelligence of the human type must be extremely rare; so rare, indeed, that the probability of two human-level civilisations sharing coordinates of space and time from which they could communicate with or even reach each other is negligible. From the evolutionary perspective, in which success is measured by the survival of the gene line, it is more advantageous to be stupid than smart, Mayr argued. Bacteria – which we generally see as rather stupid organisms – survive all sorts of planetary catastrophes, while smartness of the human type is actually an obstacle to evolutionary longevity. Bigger brains means more sophisticated tools and technologies; and sophisticated technologies generate existential risks such as nuclear war, genocidal plague, or environmental self-destruction.

The theme of this article is not SETI but intelligence on the evolutionary scale. The debate between Sagan and Mayr is a good introduction to this topic because it captures nicely two approaches to the problem of intelligence, Sagan’s anthropocentric approach, and Mayr’s more general approach. Either approach, on its own, is incomplete. Only when combined can they be useful in the interpretation of intelligence as an evolutionary phenomenon. The product of this complementarity is a metaphor I have called the astrobiological cat, from the proverb, When the cat’s away, the mice will play. Let’s find out who’s the cosmic cat, and who are the mice.

Anthropocentric & Artificial Intelligence

Definitions of human intelligence will always be contentious. Perhaps the least controversial way of defining intelligence is through analysis and measurement of the components that make it up: learning, reasoning, and the ability to manipulate symbols. Learning is a process of acquiring knowledge. Reasoning is the ability to draw valid conclusions from acquired knowledge. The ability to learn and reason is possible because we have the ability to manipulate symbols, which is the heart of both language and mathematics.

Another way of defining intelligence is related to its purpose. What’s the purpose of our ability to manipulate symbols? A simple answer, according to the leading futurist Ray Kurzweil, is that intelligence allows its owner to develop strategies for achieving and improving her goals (The Age of Intelligent Machines, 1992). In biology, goals are defined in relation to the ability of individual organisms or species to survive. It is not yet possible to know with certainty whether intelligence serves to increase evolutionary fitness, but we may conclude that our intelligence helps us achieve such goals as economic, social, or scientific success.

Kurzweil goes on to suggest that the peak of human intelligence is the ability to create intelligent machines. As we know from modern AI research, machine intelligence constantly advances. By contrast, human intelligence remains the same. From this we can conclude that machine intelligence will overcome human intelligence in the near future, and become a superior form of life. In AI circles this is known as the technological singularity or intelligence explosion.

While evolution took 3.8 billion years to create humanity, the most intelligent species our planet has so far known, we have needed incomparably less time to create intelligent machines – who will in all likelihood soon surpass us in many ways. In this trajectory of intelligence-based creativity, we beat evolution, and intelligent machines will equally beat us, argued the Oxford philosopher Nick Bostrom in his book Superintelligence. Bostrom’s colleague Huw Price dubbed the anticipated future dominance of the machine intelligence the ‘Machinocene’ era, as opposed to the Anthropocene, the current era of the human transformation of the planet. Kurzweil goes further, and predicts that machines will turn the Earth into a gigantic computer by the year 2099, and that this will open the door for the computerization of the cosmos.

Biocentric Intelligence

Modern biology is under the heavy influence of neo-Darwinism, a combination of Darwin’s theory of evolution by natural selection with genetics. For neo-Darwinian biology, evolution is a blind and mindless process. Any hint of ‘intelligence’ in this process looks suspiciously purpose-oriented, almost Aristotelian.

The neo-Darwinian narrative set out by Richard Dawkins and others goes like this. Assemblies of genes called genotypes (as embodied in DNA) produce particular traits or phenotypes in living organisms such as bacteria, plants, giraffes, humans. Competition then ensures the selection of the organic traits best adapted to the environment. Adaptability is judged by fitness, which is measured by the number of descendants produced by possessors of an organic trait. The mechanism behind adaptability is gene mutation, which fine-tunes the phenotypes, the forms of organisms, and in this way gives both the genotypes and the phenotypes evolutionary longevity. Evolution is thus a blind game played between genes and the natural environment. Organisms are passive, dumb puppets (or in the words of Richard Dawkins, ‘lumbering robots’) controlled by these two powerful evolutionary forces.

However, the neo-Darwinian picture is not universally accepted. Biological innovation does not have to be the result of gene mutations, and survival is not only the result of competition. The first biologist who successfully rebelled against the neo-Darwinian view was Lynn Margulis (1938-2011). She was famous for popularising the concept of symbiogenesis. According to this, innovation can also happen by the merging of two or more microbes into one – the very process from which all plants and animals descended. The merging of organisms is known as symbiosis, meaning ‘living together’.

Margulis’s critique of neo-Darwinism (celebrated in a recent documentary film, Symbiotic Earth: How Lynn Margulis Rocked the Boat and Started a Scientific Revolution), encouraged a growing number of biologists and philosophers of biology to think outside the neo-Darwinian box, and also to analyse intelligence on the evolutionary scale.

Contrary to standard neo-Darwinian views, intelligence seems a biological universal. Organisms, from bacteria to elephants, are not passive ‘lumbering robots’, but instead are active learners, who actively construct their environments. Recent scientific papers are replete with terminology which suggests that (i) Organisms are agents, and (ii) Evolution is a cognitive process. Here are some relevant terms: ‘bacterial IQ’; ‘bacterial cognitive tool-kit’; ‘plant intelligence’; ‘bacterial linguistics’; ‘language of the bees’; ‘plant language’; ‘bacterial internet’; ‘zoo-pharmacognosis’; ‘honeybee democracy’; ‘ant agriculture’; and so on. The increasingly intelligence-based view of evolution is often referred to as ‘evolutionary epistemology’. It reminds me of the famous remark by Karl Popper that there is little difference between Einstein and an amoeba in terms of their restless quest for knowledge. Another philosopher, W.V.O. Quine (1908-2000), put forward the idea of ‘naturalised epistemology’. And backing up the view that biological intelligence is at the very centre of evolution, Cambridge University Press has recently published the first dedicated natural epistemology book, The Systems View of Life, by Fritjof Capra and Pier Luigi Luisi (2014).

Life: A Synthesis of Energy & Matter

The systems view of life interprets intelligence as an integral part of the process of life. This emerging branch of biology opens up a new possibility that I call biocivilisations.

The concept of biocivilisations is simple. Each species intelligently recreates its own surroundings – the equivalent of a species-specific civilisation – by actively constructing its environment. For example, in the beginning, bacteria turned the dead planet Earth into a living world fit for diverse organisms. This amazing transformation required natural skills such as communication (bacterial language), construction (for example, the oxygenation of the atmosphere) and computation (for example, ‘natural calculation’ behind the carbon cycle, controlled by bacteria). The primordial bacterial ‘civilisation’ became the basis for the entire biosphere, which was gradually enriched by millions of new species and their own ‘civilisations’, all emerging from the bacterial world.

This said, the concept of biocivilisations is a great challenge to Sagan’s and Mayr’s visions of intelligence. We can see this by considering the origins and development of biocivilisations.

One ordinary cosmic energy factory – a star we call the Sun – found its first biological partner, photosynthetic bacteria or cyanobacteria, on the microcosmos of a minor planet we call Earth, roughly three billion years ago. The result was photosynthesis, a process that to this day fuels life on Earth. The light-energy radiated by the Sun travels 150 million km until a small portion of it reaches the Earth. At the end of the journey a photon from that great flow of energy finds a partner structure inside the wall of a cyanobacterium, from which it dislodges one electron. In a convoluted chemical process that takes place in the membranous structure of the bacterial wall, this electron creates a chemical gradient known as a proton pump. This pump harvests the useful energy, and converts it into the universal energy currency of the biosphere, a molecule called adenosine triphosphate or ATP, which enables many biological reactions to happen, including the operation of muscles in human bodies.

Over time this Sun-cyanobacteria partnership became the complex biological system we call the biosphere, producing all the plants and animals, including us. The biosphere is an open thermodynamic system, meaning that it constantly exchanges matter, energy, and information with its cosmic surroundings. Life was born within the Earth’s dead matter on the waves of the Sun’s thermodynamic storm. We are temporary and fragile surfers on the thermodynamic storm of life, like the riders on the storm from the Doors song. And bacteria are the basis of the biosphere. Lynn Margulis understood this better than anyone else when she helped James Lovelock explain how bacteria maintain Earth’s biosphere.

A New Understanding Of Intelligence

This narrative reveals several new qualities that can be associated with biological intelligence. First, bacteria are an intelligent cosmic ‘player’ in the sense that they detect and respond to cosmic electromagnetic waves. It’s as if they’re doing their own SETI! Bacteria detect that part of the electromagnetic spectrum we call visible light, within a wavelength range of about 400-700 nm. They then transform the light energy into useful work, which in the long evolutionary process created the biosphere.

The biosphere can be thought of as a giant bacterial superorganism that envelops the planet, even going deep into its surface. We can perhaps best imagine it as a sort of planetary biological cloud. The microbiologist Sorin Sonea (1920-2017) suggested that this bacterial planetary cloud is intelligent because it possesses an information-exchange network, in the form of a planetary ‘free market’ for bacterial genes. If there is a bacterial lineage anywhere on Earth in search of a specific gene, it will find it and acquire it in a complex process of genetic exchange. This was thought of by Sonea as a sort of ‘natural mind’ at work. Eshel Ben-Jacob (1962-2015), a physicist and microbiologist, not only thought that the bacterial planetary superorganism possesses a natural mind, but also that it carries out acts of natural computation which are at the core of the biosphere’s self-regulation – the biogeochemical cycles of organic elements. A leading microbiologist, James Shapiro, further believes that bacteria are more sophisticated than humans ‘in controlling complex operations’.

A second important novelty is the strangeness of the bacterial universe. In our universe, we are the most significant species. But when we see things from the perspective of the bacterial world, we become insignificant. To some philosophers of biology, in the bacterial world all large organisms, such as plants and animals, are ‘macrobes’ within the microbial (that is, bacterial) network. Macrobes are bacterial chimeras. For example, on this view, photosynthesis is still carried out by bacteria, which are now parts of the macrobes we call plants. All macrobes have microbiomes, bacterial ecosystems, without which they cannot survive. And all macrobes, including us, are bacterial vectors: organisms to transport bacteria. When a bird is flying, its microbiome is in the sky too. When we fly into the cosmos, our bacteria travel with us. Scientists have shown that the International Space Station is contaminated with bacteria from our microbiome. Attempts to decontaminate the Station will surely remain unsuccessful. If we create human settlements on distant planets, bacteria will be there as well. If such colonies fail, the bacteria they brought will continue the mission of the survival of life – for bacteria can survive any new environment, unlike us. The good news is that the two universes, human and bacterial, are not mutually exclusive. Our biosphere is a kind of collage of biological worlds that depend on one another.

The third novelty is the poverty of neo-Darwinism when it comes to interpreting intelligence. Ernst Mayr’s claim that on the evolutionary scale it is better to be stupid than smart is false. The claim betrays the rigidly neo-Darwinian treatment of microbes: bacteria are lower organisms than plants and animals, and the most primitive forms of life. As we have seen, however, many biologists who do not follow the neo-Darwinian narrative consider bacteria intelligent: they just have a different definition of ‘intelligence’ – as meaning, say, ‘integrated problem solving’. These biologists clearly disagree with Mayr. To them, if there is stupidity on planet Earth, it’s certainly not associated with bacteria.

The fourth novelty is the fallacy of the views that Homo sapiens is at the top of biological intelligence, and that it has surpassed evolution. Kurzweil’s prediction that the Earth will become a gigantic computer by the year 2099 is eclipsed by the fact that natural computation on a planetary scale has existed for billions of years, in the form of the bacterial regulation of cycles of carbon, nitrogen, and other organic elements.

Any doubt of bacterial dominance on the planetary scale is dispelled by scientists from California and Japan in a recent study in Nature Microbiology 1, ‘A New View of the Tree of Life’ (Laura A. Hug et al., 2016: see nature.com/articles/nmicrobiol201648). They used modern genomics and mainframes to reconstruct the ‘tree of life’ by analysing DNA samples from numerous locations scattered around the planet. The result was unequivocal. By far, the most dominant group of organisms on the contemporary tree of life are bacteria.

Bacteria’s next step in the conquest of the universe: The International Space Station.
The International Space Station from Discovery © NASA 2011

Cosmic Zoology

We can finally focus on the astrobiological cat metaphor. Bacteria, or more precisely the planetary superorganism of bacteria, are/is the dominant biogenic factor on the cosmic scale, being a biological structure that looms over the planet. Moreover, bacteria have existed for 3.8 billion years, which is for most of the existence of the Earth itself, and over a quarter of the duration of the entire cosmos. Sagan’s idea of intelligence glorifies the human version of it regardless of its relative insignificance on the temporal scale, and regardless also of the fact that bacteria can ‘read’ a portion of the electromagnetic spectrum just as well as we can. Mayr’s idea also denies any hint of intelligence to bacteria, and reserves it exclusively for Homo sapiens.

Although it has been in control of planetary life since its inception 3.8 billion years ago, the bacterial superorganism is invisible to us. This invisibility gives rise to the false notion that humans are the masters. However to a biologist like me, influenced by a systems view of life, this situation is reminiscent of the old proverb When the cat’s away, the mice will play – with one important difference: the cat is not absent, but invisible. Hence, the astrobiological cat – by which I mean the ‘invisible’ planetary cloud of bacteria that has been controlling planetary life for billions of years with its natural mind. The control is benign enough to allow all sorts of proverbial mice.

Why is this astrobiological cat so unnoticeable that its apparent absence allows us mice a disproportionate sense of our own importance? I strongly believe that the neo-Darwinian paradigm, which focuses on macrobes (in particular animals) and almost completely ignores microbes, is to blame for this blindness of the mice. Neo-Darwinian biology needs deep reforms in order to deal with new challenges, such as a wider biological definition of intelligence. The reforms have already begun through research programmes such as biosemiotics, evolutionary epistemology and the like, all gathered within the emerging discipline of the systems view of life.

The astrobiological cat metaphor also has some practical applications. I see two research avenues originating from it. The first is related to the bacterial superorganism, the microbial cloud that contains its own mind I call the bacterial internet (see theconversation.com/microbes-have-their-own-version-of-the-internet-75642). Estimates show that the total number of bacteria that form the cloud of life is about 10³⁰. However, bacteria are not the most abundant microbes on Earth. The most numerous biogenic structures on Earth are viruses. For each bacterium, there are at least ten viruses. What’s the role of viruses in the planetary microbial network? The only useful clue, for now, is the idea of a planetary free market of genes, which enables the bacterial superorganism to perform all the necessary processes involved in biogeochemistry. Viruses are pieces of inert genetic information protected by a biological membrane. Each is like a message in a bottle floating through the bacterial sea until it finds the appropriate bacterium, and helps it in the search for biological innovation.

The other potential avenue is related to SETI. My suggestion is that a new way of thinking should be incorporated into SETI, overcoming any anthropocentric bias, to see how life as an intelligent biogenic process can spread into cosmos. As bacterial vectors, we macrobes undoubtedly play an important role in this process. The two universes, microbial and macrobial, are not mutually exclusive. Together, they form a multiverse useful for both groups of species. SETI should accept this biological reality.

As Margulis argued in her book Symbiotic Planet (1999), bacteria will almost certainly outlive the human species. Macrobes like us are relatively transient biological forms – temporary structures gone with the evolutionary wind like dust. Contrary to our anthropocentric bias, only bacteria live forever. The best evidence for this claim is the fact that bacteria are as old as life itself.

Predrag Slijepcevic is a Senior Lecturer in Biology at Brunel University, London. He’d like to dedicate this article to admirers of bacterial civilisation Lynn Margulis and Sorin Sonea, who believed that bacteria and archaea are one species.