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Life and Language beyond Earth

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     Introduction       Overview Presentation       Astronomy      

     Evolutionary Biology       Palaeoanthropology       Neuroscience

     Language & Linguistics       News     

     Link to Book       Contact     

The central question for this book is: ‘Do beings exist on planets beyond our Solar System with whom we could engage in meaningful exchange?’ To approach this issue we can break it down as follows:

Four basic questions about life and language beyond Earth

   1)   Is there any life beyond Earth?
   2)   Is there intelligent life beyond Earth?
   3)   Does such life have a communication system we would recognise as language?
   4)   Is this life technologically advanced enough to communicate with us across interstellar distances?

The following sections offer a brief outline of the main sections in the book. If you are curious about any or all of these matters then you will find in-depth discussions in Life and Language beyond Earth along with a detailed final chapter which assesses the likelihood of conditions similar to those with humans on Earth arising on an exoplanet and which weighs up the possibility of our ever coming in contact with intelligent beings from another world and how we might communicate with them.



A common question asked these days is ‘Are we alone in the universe?’. It looks like a simple question with a ‘yes’ or ‘no’ answer. But far from it, the question involves a whole raft of issues which need to identified and discussed. Let’s begin by deconstructing the question.
     First ‘universe’, that's relatively easy. For all practical purposes, now and for the foreseeable future, by ‘universe’ we can only mean a radius of some tens of light years around us, maybe a hundred light years at most. That is only a tiny fraction of our galaxy, the Milk Way. Our galaxy is, however, only one of several hundred billions in the observable universe and possibly only one of trillions and trillions of galaxies in the actual universe. So the patch of space which ‘universe’ in the initial question can refer to is an infinitesimally small area in a universe of inconceivable vastness. Nonetheless, since the advent of modern exoplanetology we know that nearly all stars have planetary systems and that some planets would have conditions similar to those on Earth. There are probably something in the order of 50-100 billion Earth-like planets orbiting stars just in our galaxy alone.
     Next comes the plural personal pronoun ‘we’. I think it is fair to say that when the question is asked, people mean by ‘we’ forms of life which are in principle comparable to us: at least equal in level of intelligence and recognizable in appearance and behaviour and at least as technologically advanced as we humans, though there is much speculation about how far beyond us they might be. And then there is the issue of communication: could we have sensible exchanges with them? To do this, they would have to have a system which is comparable to human language and one which we could decipher and then use for communication. In my book, forms of life for which all that would hold are called ‘exobeings’, i.e. human being analogues on exoplanets.
     Recall that complex life forms, on any planet, can only arise from much simpler life forms through Darwinian evolution by natural selection with random mutations, genetic drift and flow in the mix as well. I stress that is the only way exobeings could arise on exoplanets: ultimately from simple cells over at least hundreds of millions of years. To get a handle on how that might happen elsewhere it is necessary to take a closer look at how it happened on Earth and consider key events and developments which led from the simplest of cells to ourselves, Homo sapiens.
     The key questions in this connection are (i) how did life arise on Earth, (ii) how did the Homo species come to be, (iii) how did Homo sapiens develop such large brains and, finally, (iv) how did we come to speak, i.e. to have language. The fields of science centrally concerned with these four questions are:

   1)   evolutionary biology
   2)   palaeoanthropology
   3)   neuroscience
   4)   linguistics

The book is organised into six major sections with each devoted to specific issues in the relevant areas of science treated in the book (see table below). Certain readers may not need to read sections closely which they are au fait with from their professional background.

Part Section Intended readership
II The universe we live in general readers, not necessarily for astronomers/astrophysicists
III Our story on Earth general readers, not necessarily for evolutionary biologists and paleoanthropologists
IV The runaway brain general readers, not necessarily for neuroscientists
V Language, our greatest gift general readers, not necessarily for linguists
VI Life and language, here and beyond all readers

When searching for exoplanets with life the time factor must be borne in mind. Consider the following possibilities:

1)   There may have been exocivilisations with advanced technology which are long since gone.
2)   There may be planets with forms of life which, in their future, may evolve into intelligent beings with science and technology capable of interstellar communication.
3)   There may be planets with civilisations which are already well into their digital age, even by millions of years.

What we know about exoplanets, general

1)   Rocky exoplanets in the habitable zones of their stars exist in abundance.
2)   Such exoplanets can contain (i) molecular oxygen and (ii) liquid water.
3)   Complex organic (carbon-based) molecules have been found outside Earth and are known to exist in the great clouds of dust (proto-planetary disks) from which stars and their planets form.

What we know about exoplanets, details

1)   Any elements found on exoplanets would be the same as those we know from Earth (about 90 occurring naturally). Their properties would lead to the same classification, as gases, metals, etc.
2)   The fundamental laws of physics and the constants of nature would apply on exoplanets exactly as on Earth.
3)   The aggregation of atoms to molecules to macromolecules would apply just as on Earth.
4)   The principles and organisation of chemistry, for example, the types of molecules, such as acids, bases, salts, sugars, fats as well as classes of processes, such as redox reactions (involving the gain or loss of electrons), would obtain on an exoplanet just as on Earth.
5)   Intermolecular (electrostatic) forces, holding huge numbers of molecules together, e.g. as objects we can observe on our human size scale, would apply just as on Earth.
6)   Each exoplanet would likely avail of light and heat from its parent star as sources of energy, though internal sources could also be exploited.
7)   Life on an exoplanet would be subject to the gravity of the planet and would adapt accordingly.
8)   Life on an exoplanet would require a continuous source of energy to fuel its metabolism. Oxygen is a prime candidate for such a source, though not the only option.
9)   Life on an exoplanet would, in its advanced forms, most likely be heterotrophic. This means that they would gain energy from nutrients which they would take in through a process analogous to eating as for animals on Earth.


Overview Presentation

   Could we Communicate with Exobeings?



The following images form a progression from the observable universe, a small section of the probably much, much larger actual universe, down to the small region in our Milky Way which contains our Solar System. The search for life beyond Earth is for the present restricted to this very modest region of space.

The observable universe is approximately 93 billion light years in diameter. Nowadays astronomers assume that this is only a tiny fraction of the actual universe. However, we can never see this as light beyond the observable universe can and will never reach us. In fact, the observable universe is decreasing in content (for us) as the expansion rate of the universe is actually increasing and distant galaxies are receding from us at rates which are faster than the speed of light meaning they will pass the horizon of visibility for us in the future.

The Virgo Cluster is part of the Virgo Supercluster (the dot in the middle of the previous image) and contains something in the range of 1,500 to 2,000 galaxies.

The Local Group is also contained in the Virgo Supercluster and consists of the two large galaxies, Andromeda and our own Milky Way, along with tens of further dwarf galaxies. Among the latter are the Large and the Small Magellanic Clouds which are dwarf satellites to the Milky Way.

Our Solar System is located in an arm of our galaxy about 26,000 light years from the centre (the above image is an artist's impression; we cannot view our galaxy from the outside but see it tilted on its side as a band of stars across the night sky). The Milky Way is about 100,000 light years across and contains several hundreds billion stars, nearly all of which host planets, many of which are presumed to be in the habitable zone of their parent stars and thus, in theory, capable of sustaining life if the composition of the planets, their atmospheres and conditions on the surface are suitable.

The inset here shows a region about 5,000 light years across. Our Solar System, with the Sun and its eight planets, is located roughly where the arrow is pointing.

Earth is the third planet out from the Sun, after Mercury and Venus, and before Mars, the Asteroid Belt, Jupiter, Saturn, Uranus and Neptune. There are millions of trans-Neptunian objects in the distant Kuiper Belt and the even more distant Oort Cloud. Note that in the above image the distances are not shown to scale as this would not be possible given the widths of even very large computer screens. Earth is 150 million kilometres from the Sun which is why the latter appears so small in the sky. All planets, except Mercury and Venus, have moons and their number varies greatly, from one for Earth and to over 90 for Jupiter.


Evolutionary Biology

The first matter here is that of abiogenesis. This is the process, as yet unknown how it is triggered, by which life itself begins. There have been many attempts to replicate cell formation and reduplication under laboratory conditions but none of these led to life forms being created.

On any exoplanet with life abiogenesis must have occurred. Something, sometime, somewhere on the planet must have triggered cell reduplication and thus initiated the long, complex process of biological evolution. Or life-forms may have been delivered to the planets by comets, asteroids or meteorites – the panspermia hypothesis – which some scientists believe could also have been the source of life on Earth. The panspermia hypothesis is not an explanation for abiogenesis, it just pushed the question further back: where did the externally originating lifeforms themselves come from?

Basic questions for biological evolution

1)   Do cells form spontaneously by organic membranes creating enclosures to contain relevant functional parts and establishing energy gradients across these membranes to drive various metabolic processes?
2)   Do DNA molecules (or their functional equivalents), the carriers of genetic information, form spontaneously under favourable conditions (perhaps via simpler molecules as with RNA on Earth)?
3)   Do cells maintain themselves and replicate spontaneously, leading over time to rise of a large biosphere?
4)   Do cells naturally increase in internal complexity (possibly by incorporating other cells and co-opting them into cooperation as happened on Earth) leading over time to the evolution of increasingly more complex life forms?
5)   Do the principles of natural selection and random mutation apply to biological systems on exoplanets?

Bear in mind that any exobeings on an exoplanet, no matter how far they may be in their digital, post-human, post-biological era will nonetheless have arisen from simple cells to more complex biological organisms through the process of Darwinian evolution involving natural selection and random mutations along with some genetic drift and gene flow. There is no other possible path for lifeforms in our universe.

Shared features between possible exobeings and humans

1)   Bodies which would allow them free and flexible movement in the three-dimensional space of their planets.
2)   Limbs with analogues to our hands showing a power and a precision grip. Otherwise they could not construct anything.
3)   The ability to receive and process sensory input from their surroundings, at least visual and auditory data, though probably tactile data and possibly olfactory and gustatory data as well. These abilities would have arisen during their evolution.
4)   Complex physical structures capable of the sophisticated computation which human brains achieve.
5)   Conscious awareness of themselves and their surroundings with memory of their past and the ability to plan for their future. Exobeings would have the potential for learning and at least some of them would be curious to discover more about their environment and advance science on their planet.
6)   A system for organising their thoughts and communicating with others which would be functionally equivalent to human language. This would be based on an evolved internal faculty which would be expressed as perhaps one of many exolanguages. There are cogent reasons for assuming that these would avail of sound, but other modalities are also possible.

Differences between possible exobeings and humans

1)   Darwinian evolution on their exoplanet may have resulted in beings which are physically organised very differently from us, with brains which we would not immediately recognise as such, maybe with a more distributed nervous system, like an octopus.
2)   The continuing evolution of exobeings, including technological advances, might have resulted in changes to their lifeforms into realms which we cannot imagine, for example, digital extensions to biology, which we have no inkling of.



Likelihood of life beyond Earth, in decreasing order

Category Occurrence Some preconditions
1) microbial life common cell development, maintenance and reduplication
2) animal life fairly common complex cell forms
3) human-like exobeings,
i.e. 'intelligent life'
extremely rare a 'runaway' brain and manual dexterity

Salient features of anatomically modern humans

1)   Large pre-frontal cortex with a brain size of about 1200-1400 cc.
2)   A round head without a bulge at the back.
3)   Small mouth, teeth and jaw muscles, suggesting the consumption of cooked food.
4)   Long legs, somewhat shorter arms, with wide-range joints on the torso; longer neck.
5)   Manual dexterity with a power grip, via the fist, and a precision grip, via the opposable thumb and index finger.
6)   Flexible tongue muscle capable of realising different configurations of the oral cavity. Lowered larynx with hyoid bone positioned for precise muscular movements to produce sounds. Agile vocal folds for generating voice, essential for vowels and many consonants.

And what about language?

Not all linguists agree on just how old human language is or how it arose. Some are of the opinion that the ability to have open-ended grammar, which is not bound to the hear and now, is a fairly recent development arising via a sudden mutation, perhaps about 70,000 years ago, with a single individual (or maybe just a few such persons). However, the majority of linguists working in the field of language evolution hold the view that language developed slowly over a period of some hundreds of thousands of years from an original simple means of basic communication consisting of just some words which gradually evolved into a grammatical system allowing for complex sentences providing nuanceand flexibility to both the internal management of thought and the external communication with other members in social groups. The evidence that our nearest Homo relatives, the Neanderthals (and by extension the Denisovans), had a communication system comparable in principle to our language is compelling.



Consciousness is the seamless inner subjective state which accompanies you in every moment of your wakeful life and which no-one else is privy to. It is a non-physical experience which cannot be observed by examining the brain.

Proposed explanations for consciousness

Type A:   Hard-line materialism. There are only physical brain states. Consciousness is an illusion, it has no real existence, but is accounted for by the behaviour and dynamics of the brain (the philosopher Daniel Dennett).
Type B.   There is consciousness and there is a gap between what we observe physically and what we experience subjectively. But it is a matter of perspective: from the outside we see the physical brain, from the inside we experience consciousness. So we have two ways of thinking about the same underlying reality. This view maintains that consciousness and the brain are one thing in nature.
Type C:   The gap is only one of knowledge and will be resolved sooner or later, scientists have just not arrived at the solution to this difficulty yet.

Any exobeings attempting communication outside their solar system would be conscious in a way in principle similar to ours. Exobeings building technological artefacts would have minds which were the product of whatever structures their bodies possess and which would be analogous to our brains. There is no way an organism can be conscious without a physical substrate which enables this. On Earth this is a brain consisting of billions of interconnected neurons, above in the frontal area of the head (with humans). Some functionally similar biological structure would have to exist with exobeings to allow consciousness in these life-forms. However, there would probably be a gradient for degrees of consciousness across their animal kingdom much as there is on Earth.

Consciousness with exobeings would likely manifest itself as a subjective awareness of their surroundings, an ability to reflect on themselves, remember their past and plan their future. With consciousness similar to ours they would have the capacity for abstract thought with which they could solve scientific problems and attain high levels of technological achievement. Consciousness would also be a necessary precondition for any communication system even remotely comparable to human language.


Language & Linguistics

The following are the broadest generalisations which one can make about language on Earth:

1)   Language is a system of communication and thought organisation
2)   It involves sounds with arbitrary symbolic value (with signing as a further modality)
3)   It is used solely by humans
4)   It is a rule-governed system which is open-ended

Five steps to view and analyse language

1)   How language is structured and how it can be analysed by linguists
2)   How language is related to our brains and cognitive abilities
3)   How we produce language given our anatomy
4)   How we acquire language in our childhood
5)   How language probably evolved on Earth

The open-ended flexible nature of human language would apply to any exolanguage, otherwise it would not be adequate for the development of complex societies with advanced technologies. Human language is divided into various interlaced levels as shown in the following diagram.

There is a progression of levels from the left to the right with each level providing the building blocks for the next level as indicated in the following schema.

Furthermore, the relationship of sounds to words is not fixed by some external contingency, but is arbitrary, though fixed by social conventions. Words in a language refer to concepts and do not denote objects in the world directly. This characterstic of human language makes it very flexible and capable of abstract thought, storing information for later retrieval and planning for the future.



Carbon dioxide on Europa

The James Webb telescope, which has been in operation at a considerable distance from the Earth for the past year or so, is coming up with new and interesting findings. The one which perhaps made general headlines in the media the most was the discovery of very large galaxies just a few hundred million years old, i.e. after the Big Bang. Normally, astronomers have assumed that galaxies require a few billion years to grow to a large size given that they do so by incorporating many smaller galaxies they collide with.

Just very recently (late summer 2023) the James Webb telescope found traces of carbon dioxide (by spectroscopic analysis) on Jupiter's water world moon, Europa. This is significant because, on Earth, one of the major sources of carbon dioxide is respiration by living organisms (animals and humans breathe it out) and the decay of dead organisms. So it could be an indication that some form of life in the sub-glacial oceans of Europa could be producing the carbon dioxide which then escapes through vents on the surface. Just that, it *could* be an indication of possible life forms. More information will doubtlessly come from the Jupiter Icy Moons Explorer (Juice) launched by the European Space Agency (ESA) in April 2023 and from Nasa's Europa Clipper spacecraft, planned for launch in 2024. The journey to Jupiter takes about eight years (using the gravity-assist function by which a spacecraft flies by a planet and is flung away from it at increasing speed) so that the first results should be available in the early 2030s.

OSIRIS-Rex capsule returned safely to Earth

A small sample of the near-Earth asteroid Bennu was returned to Earth on 24 September 2023. The sample was collected when the OSIRIS-Rex probe, which had been examining Bennu for some time, landed on the asteroid and collected dust and grains churned up from its surface. On its return journey the probe released the capsule with the sample before continuing beyond Earth to complete the second half of its mission, to explore the asteroid Apophis. The capsule landed safely in the Utah desert and has been taken to the Johnson Space Center in Houston, Texas for a careful examination of its contents. The reason the Bennu sample is so important is that the asteroid stems from the formation phase of our Solar System over 4.6 billion years ago. If the sample contains organic compounds, or even amino acids (complex molecules consisting of carbon, oxygen, hydrogen and nitrogen, some with sulfur or selenium), then this would mean that the building blocks for life on Earth were already available in the disk of gas and dust out of which the Earth later formed.

New books on questions surrounding possible exolife

The literature on exoplanets, possible life beyond earth and all the issues surrounding these matters, is growing continuously. A few new books appeared in 2023, too late to have in the references of my book, so I am including them here just in case readers might wish to see what other authors have to say.

Impey, Chris 2023. Worlds Without End: Exoplanets, Habitability, and the Future of Humanity. Cambridge, MA: The MIT Press.
Frank, Adam 2023. The Little Book of Aliens. New York: Harper.


Fermentation technology as a driver of human brain expansion

A new study has appeared addressing the question of why the increase in brain size with early Homo erectus began approximately a million years before the control of fire and the advent of cooking with this species. The time gap has long since been known as an issue requiring a satisfactory account. The following study offers a novel explanation – the External Fermentation Hypothesis – by postulating that early Homo erectus consumed food that was fermented, this providing an external phase during which tough, fibrous material could be broken down into a denser energy-richer form before its intake as food. It is postulated that fermentation sites were the caches used to store food over a period of time and that the fermentation rates increased through re-use of these sites. The pre-digestion effect of fermented food promoted the evolution of the large intestine with hominins: it reduced the colon in size, and hence used less energy, and with that came a corresponding – metabolically expensive – increase in brain size due to a more rapid processing of the nutrients in the food consumed by early hominins. The authors of the study thus claim that the consumption of externally fermented foods provided the initial metabolic trigger for brain expansion.

Bryant, Katherine L., Christi Hansen and Erin E. Hecht 2023. Fermentation technology as a driver of human brain expansion. Communications Biology 6 (1190).

Unfortunately, this study appeared too late to be included in my book. However, there is a discussion of the issue of brain size and food intake, see pp. 216-200.

The following article, quoted by Bryant, Hansen and Hecht is also relevant in this context:

Robert R. Dunn, Katherine R. Amato, Elizabeth A. Archie, Mimi Arandjelovic, Alyssa N. Crittenden and Lauren M. Nichols  2020. The Internal, External and Extended Microbiomes of Hominins. Frontiers in Ecology and Evolution. Section: Social Evolution, Vol. 8.


Link to Book

   Cambridge University Press website



The above email address is that of the university where I worked up to recently. I have kept this email address because it is that which colleagues, students and others have used over the years and to avoid confusion I still use this and will do so (as long as the university in Essen allows me to).