The Rare Earth Hypothesis: Part One

If the Search for ExtraTerrestrial Intelligence (SETI) is a viable experiment and not a waste of time; if UFOs and ancient astronauts are facets that help document the existence of extraterrestrial intelligence, then the very existence of an advanced extraterrestrial intelligence with technology has to be plausible in the first place. Unfortunately, it’s a long hard road to get from inorganic chemistry through to E.T. and there are many possible bottleneck hurdles that have to be overcome before the one evolves into the other. Goldilocks factors – not too this, not too that, but just right – have to be with you every step of the way. IMHO the major bottlenecks are the transition from unicellular to multicellular life and the evolutionary development and use of technology.

It’s been pointed out by others, and based on my readings I tend to have to agree, that astronomers (physical scientists) tend to be much more optimistic and supportive of the notion that advanced life forms in the Universe (extraterrestrial intelligence) are a dime-a-dozen relative to biologists (life scientists), who hedge their bets and who it must be said are presumably better qualified to pass judgments. So, taking things from a more biological perspective, what’s what?

For starters, our Universe is a Goldilocks Universe in that the fundamental laws, relations and principles of physics unite in such a way as to be ultimately bio-friendly. If the Universe wasn’t bio-friendly, we wouldn’t be here to comment on that. That’s not to say however, in relative contrast, that many (most) parts of the Universe aren’t overly bio-friendly. You’d be hard-pressed to survive and thrive in the depths of a stellar core, heading down a Black Hole, vacationing on the surface of a White Dwarf or in the hard vacuum of space itself.  So, overall the physics of the Universe displays the physics of a Goldilocks Universe, but actually very few addresses within an overall Goldilocks Universe are really, by our definition, Goldilocks. However, starting with bio-friendly physics, where do we go from that point? Well, physics begat inorganic chemistry. That’s step number one, and clearly that’s easy because there’s an awful lot of inorganic chemistry in our Universe.

Going from inorganic chemistry to organic chemistry isn’t difficult either. Interstellar space is full of dust and gases made up of organic chemicals; ditto many of the planets and moons within our solar system (i.e. – Titan, a moon of Saturn) have organics being part and parcel of their composition, and comets, asteroids and meteors too can contain organic compounds.

Judging by how quickly organic chemistry turned into biochemistry (the origin of life) on the early Planet Earth, it’s not difficult to generate simple proto-cellular to unicellular life forms if the conditions (adequate energy, temperatures, environments) are Goldilocks conditions.

Yet life, even microbial life, is still very, very complex (try making a microbe from scratch if you doubt it). The fact that life arose from scratch on Earth within a very, very short span of geological time after the planet formed is a bit suspect IMHO. But what if Earth were seeded by microbial life forms already in existence from space (or deliberately seeded by extraterrestrials as the Nobel Prize winner Francis Crick has proposed)? Now I realize that just puts off the origin of life question to another time(s) and place(s). However, given the vastness of the cosmos is far greater than that of our finite globe, and given that the cosmos existed for vastly longer periods of time before our sun, solar system and home planet came into existence, such additional time and space easily turns the improbable into a near certainty. And once established somewhere, then life could spread throughout that time and space, until it reached our young planet.

Earth arose billions of years after the universe and our galaxy had evolved, ample time for life to have arisen elsewhere, and seed the early Earth. This is the concept of panspermia. We know that comets, meteors, and the cosmic dust of outer space are chock-o-block full of complex organic molecules. We know that simple terrestrial life can survive the outer space environment if suitably shielded – and it doesn’t take much to do the shielding. We know that surface bits from planets/moons can be ejected into space, carry a cargo of microbes, and land on another planet, even eons later with the microbes still viable. Of course 99.999% of all such microbial life will be doomed to forever wander in space or crash onto a cold, surface of a planet with no atmosphere or water, or plunge into a star, etc. But, sheer numbers will insure that now and again some microbes will land on a hospitable abode and be fruitful and multiple and evolve. The interesting bit is that if then, then now. And thus panspermia will be happening today. Certainly some meteorites which have impacted Earth have inside them ‘organized elements’ suggestive of microbial structures – the Murchison Meteorite from Australia is one such stone. The problem is terrestrial contamination as there are often lengthy time periods between their fall and subsequent discovery. As an aside, if Fred Hoyle & Chandra Wickramasinghe are correct (and I believe they are), microbes (bacteria and viruses) impacting Earth today are largely responsible for some select or various disease epidemics and pandemics, past present, and no doubt future.

On Earth, microbes rule, OK? The biomass of all the bacteria, etc. put together easily equals the biomass of every other multicellular plant and animal added together. And microbes can live in environments where multicellular critters fear to tread and often can’t: from the coldest terrestrial environments, up to the near boiling temperatures, from deep underground to the heights of the atmosphere, from inside water-cooled nuclear reactors and the interior of rocks, to intensely saline, acidic and alkaline environments, to ecosystems where the sun never shines, like the abyssal depths.

They can even survive outer space. Bacteria survived on the surface of the Moon – on Surveyor Three. This was possibly the most significant discovery of the entire Apollo Moon program and it hardly even rated a mention. Astronauts from the Apollo 12 mission brought back to Earth parts of the unmanned Surveyor Three Lunar Lander. Terrestrial bacteria on those parts survived the lunar vacuum, solar radiations (UV, etc.), the massive temperature extremes, and lack of water and nutrients. Experiments since then in low earth orbit have confirmed that given just minimal shielding, bacteria can boldly go!

You’d be aware of how difficult it is to totally sterilize something, be it hospital equipment or a spacecraft bound for a Martian landing. They’re tough – have you ever read about a mass extinction event where a bacterial species, unlike say the multicellular dinosaurs, went poof? Microbes are easy to transport. They can be blasted off the surface of the Earth, shielded from radiation by the debris, and survive to land on another world and be fruitful and multiply. There’s little doubt that somewhere way out there, terrestrial bacteria have hitched a ride to the stars, bolding going where lots of microbes have gone before! Translated, I firmly expect that the universe is teaming with life in all sorts of places. The less than glamorous catch is that LGM is not going to stand for Little Green Men, but Little Green Microbes.

But now we come to our first and major bottleneck.

It took 0.5 billion years for the unicellular origin of life on Earth, or for microbes from space to take root on Earth, but then it then took nearly another 3.5 billion years between the appearance of that ‘simple’ single proto-cell life form and the eventual evolution and the resultant Cambrian explosion of multicellular (complex) life forms. For some reason(s), it appears to be biologically difficult to go from the simple single cell to a complex multicellular organism based on the only example we have to judge such things. Probably the overall obstacle to the early quick-smart establishment of multicellular (complex) life is that heretofore microbes (single cells) were 100% self-sufficient generalists. Complex organisms require the evolution of single cells to give up being generalists, become specialists, and work as part of a team. That degree of organization apparently takes lots of time, especially to the stage of where it can leave a large fossil presence, if it takes place at all.

Once you get to the multicellular stage, and in order to evolve further, well the trick is to survive, for the Universe is a dangerous place.

Planetary environments tend to be dangerous and rarely stable, and thus you need a lot of factors in place to ensure that even simple life even survives the long term and get the chance to evolve into multicellular life. Or, if you have evolved multicellular life, the odds are pretty good it’s going to get the Big “E” – Extinction.  I mean complex life is very vulnerable to environmental forces. A tornado probably isn’t going to bother bacteria, but it sure could tear you apart. That’s not to say bacteria can survive everything the cosmos can throw at them, but when nasties come, you stand a better chance of survival if you’re a microbe. So, in order to get to the first proto multicellular critter, and from that to us, you need a lot of Goldilocks factors operating in your favour.

To be continued…

Are We the Proverbial “It”? Part One

Every one and their great grandmother has apparently had a go at, and calculated a value for the Drake Equation (named after radio astronomer and SETI scientist Frank D. Drake). The Drake Equation estimates (guesstimates is actually more accurate) the number of extraterrestrial civilizations in our galaxy that could in theory say “Hi” to us and receive our “Hello” in return by examining all the factors that are part and parcel of that scenario. Seeing as how the Universe is some 13.7 billion years old, and seeing as how the current human species has been around for only some 200,000 years (give or take), then I have to ask, is it logical to assume that we’re the proverbial “It”? Here’s my two cents worth.

Are we alone in the Universe? That’s a question that’s been asked by millions over the eons, without, to date resolution. Of course the word ‘alone’ implies alone in the sense of whether or not there exists elsewhere our rough equals, more likely as not betters. We want to get to know our neighbours across the street, not their pets, or their plants. The standard gut-feeling answer to the question usually revolves around how vast the Universe is, and surely, given the billions of stars in our galaxy and the existence of billions of galaxies each with billions of stars, etc. and the vastness of time, surely we can’t be the proverbial “It”. There’s unfortunately one slight flaw in that statistical approach. There’s a rather long chain of events that have to happen, hurdles to be jumped, in order to get from the elements of star-stuff to biological cosmic neighbours. Depending on whom you talk to, that chain can be extremely long indeed. The point is, if any one factor in that chain of causality has a very low probability of coming to pass, it matters not one jot whether or not all the other factors are extremely probable, the overall result is going to be low. If any one factor is as close to zero as makes no odds, then the overall answer will also be a close to zero as makes no odds. Certainty multiplied by certainty multiplied by certainty multiplied by certainty multiplied by zero multiplied by certainty multiplied by certainty multiplied by certainty ultimately equals zero!

Rather than give an exhaustive list of all those factors required to give us cosmic neighbours, I’ll focus on six essentials.

Firstly, one has to have the right kinds of matter and energy that can produce beings like us, and a solid surface to stand on. That’s no problem. The Universe has lots of kinds of energy on tap; stars can manufacture and disperse the required kinds of matter, like carbon, nitrogen, oxygen, silicon, etc. There’s lots of solid bodies (planets) out there. That’s one vote for certainty. 

Secondly, one has to have a solid planetary body turn into a habitable world; a suitable environment for physics, chemistry, biochemistry and biology to do their evolutionary thing. Fortunately, that shouldn’t be a problem. There’s a lot of real estate out there and it comes in all sizes and flavours. While there’s only ever going to be one Planet Earth (I’ll avoid discussions of the Many Worlds Interpretation of quantum physics, the notion of parallel worlds, and the Multiverse here which could argue the contrary), there has been, is, and will be, lots and lots of earth-like abodes, just letter perfect for life-as-we-know-it to survive, even thrive. If one wants to throw in life-not-as-we-know-it, there will be lots of worlds suitable for those possibilities as well. So, that’s another vote for certainty.

Thirdly, physics has to become chemistry, and chemistry has to become biology. We need biology to have had origins, or an origin, an origin(s) of life that’s an inevitable outcome of the everyday ordinary interactions between physics and chemistry. Well, many will argue that the origin of life is as nearly predictable as death and taxes, given a suitable habitat. Many will also argue that the origin of life is a fluke! In my point of view, the origin of life need only happen once, and that clearly has been a certainty – we exist and we are life. Once there’s one origin of life, the rest is just distribution. Panspermia provides the ways and means of distributing (microbial) life throughout the cosmos. So, I’ll have to cast another vote for certainty again!

Fourthly – well, now we hit the proverbial brick wall.  You and your neighbours aren’t microbes – you’re a colony of microbes. In short, you’re a multicellular life form. We seek, in the cosmos, other multicellular life forms, on the grounds that the odds that a microbe or unicellular life form isn’t going to prove to be much of a companion or drinking buddy is a near given. So, we need to get from unicellular to multicellular, and therein lays the rub. And it’s here that we have to rely for guidance on a sample of one – Earth. Note: It’s dangerous to extrapolate from a sample of one, but what choice do we have? 

There’s no ecological niche on Earth occupied by multicellular critters that’s not also occupied by unicellular critters (microbes). The reverse isn’t true. You may think the world is totally dominated by multicellular critters – you, your partner, your family, your pets, your garden, your food, all the life you see around you is multicellular. There’s millions of species of insects – all multicellular. What’s more common than bugs? Yet, if you did a biological census, even in your home and your garden, you’d find that apparently common multicellular life forms are out-common-ed, vastly outnumbered, by unicellular life forms by a ratio of trillions to one. What you don’t see does matter!

So, are multicellular critters an evolutionary certainty? Is there anything a ‘colony’ of 2 or 20 or 200 or 2000 cells can accomplish or fill a previously unfilled ecological niche that one cell can’t? And by the way, that 2 or 20 or 200 or 2000 stage has got to be selected for before one can get to the two million and two billion colony stage. Well, clearly the transition happened here, albeit it took some three billion years to seriously kick-start the process, so it’s hardly some inevitable ‘law of nature’. I mean taking some three billion years to get to a colony of cells from a single cell doesn’t inspire confidence that the process is easy, necessary or inevitable. Anyway, it did happen here, so it’s obviously possible. I just don’t see it as a super-evolutionary development that confers immediate survival-of-the-fittest advantage. Of course a colony of two cells might be harder to eat than one cell, but at that level, ‘food’ tends to be absorbed at the molecular level. In any event, microbes can easily attack and ‘eat’ multicellular critters, causing sickness, death and decay. We’re ultimately food for the microbes and the proof of that pudding is how we spend small fortunes keeping them at bay. But, eventually, though you might win the battles against the microbes, you’ll lose the last one, and thus the war.

Another factor that argues against multicellular organisms being a universally common feature of the Universe is that it is also a lot harder to transport around the Universe by natural means – that concept of panspermia – multicellular critters. I mean getting a microbe from Earth to Mars is one thing. Getting a cockroach there is a whole different scenario.   

Multicellular development; its probability, can’t be zero since we’re multicellular, but, on balance, I can’t assign a high probability to the transition between unicellular and multicellular life on every habitable planet, every time. This one is nearing zero!

Fifthly, as noted earlier, you don’t want to interact with your neighbour’s multicellular pets or multicellular garden plants, but your neighbours. What do you have in common with your neighbours that you don’t have in common with your neighbour’s pet or garden plants? Intelligence (even if you probably think your neighbours are a few cents short of a dollar!).

The issue now is whether, having evolved to a multicellular stage, will one develop some higher brain function? Is there any further evolutionary advantage towards increasing one’s intelligence? By going back to our sample of one, if Earth is any guide, the answer is roughly ‘not likely’. There are millions of multicellular species that have existed, and do exist, on Planet Earth. There are apparently only a very few species that have evolved something beyond the minimum level of brain power required for their day-to-day survival. That doesn’t inspire confidence that intelligence has inevitable value as a means of survival.

By far and away, most multicellular critters just operate on pure instinct and don’t (can’t) stop to figure things out (far less stop to smell and appreciate the roses) - but, there are an admittedly few exceptions.  Many wild birds would put our everyday companion animals to shame in the IQ department. I mean I love my cats, but little Einstein’s they’re not. Whales and dolphins have also been credited with being in the higher IQ bracket; ditto our close primate cousins. In the invertebrate kingdom, the octopus is pretty smart – by invertebrate standards (and then some if one is honest). However, on balance, most multicellular critters put their evolutionary strategies into something other than higher brain function. Take my cats. Is it to their survival advantage to ‘figure things out’ or to be just a bit faster afoot, hear just a bit better, see ever more clearly? Nearly all organisms put their survival abilities into something other than pure brain-power. Clearly brain-power has survival-of-the-fittest attributes. But, it’s not the only game in town, and therefore doesn’t have what I’d call evolutionary ‘certainty’.  However, it would be illogical to say that developing intelligence, the ability to figure things out, isn’t valuable and doesn’t have survival value, it’s just that if you were to list all the multicellular animal species on Planet Earth, very few would have an IQ of even one (the human average is 100). So, let’s say intelligence is somewhere between certainty and highly improbable.

Next, let’s assume your intelligent neighbours are fairly far away and the usual means of keeping in touch is by phone (or email). That introduces one additional complication; it’s not enough to just be intelligent. You need to have technology. Then, and only then, will the ‘are we alone?’ question be answered to our absolute satisfaction. We need technology if we are to find extraterrestrial intelligence(s); and/or extraterrestrial intelligence(s) will need technology to find us. One or both of us has to have invented engineering to a somewhat sophisticated level - maybe rocket ships, maybe radio telescopes, but something technological is required. There’s also a hidden assumption here – you actually want to seek out new civilizations. It matters not if you have all the required technology but care not to use it for the purpose of answering that question – ‘are you alone in the Universe?’ I’ll assume here that if you have intelligence, and it’s been able to construct technology, then part of your intelligence is devoted to be a curious critter who wants to know and find out things – so that’s a certainty of one. But what’s the level of certainty of developing technology in the first place? Rather poor judging from those terrestrial species that have some reasonable smarts to their credit. There’s the human species of course, and though while we’re not quite a sample of one, it’s pretty close. There are documentary observations of some animals (primates mainly) not so much making, but making use of existing ‘tools’ to assist in their survival. Alas, most intelligent species lack the anatomy and/or the right environment to manipulate objects. In the case of dolphins and whales, their ocean environment stymies any way and means of constructing things and making use of fire, for example. So, developing technology has to be rated, judging from our terrestrial sampling, as rather low. 

Technology is also a double-edged sword. The use of technology has had obvious survival value for the human species. You wouldn’t be hard-pressed to come up with dozens of technological inventions that have enabled us to survive longer and thrive better. But, out technological genie is out of the bottle, and unless you’re a hermit, you will have noted by now that technology can also reduce our quality of life, and no doubt you wouldn’t be equally hard-pressed to cite dozens of examples. Which leads nicely into the last consideration. 

To be continued…

Germs from Space

In the original “War of the Worlds” novel, our Martian invaders where thwarted not by us high and mighty humans, but by humble terrestrial bacteria who just ate them up! The question therefore is would extraterrestrial ‘bacteria’ find us (terrestrial life) a nice snack? The answers could be both ‘yes’ and ‘no’.

The War of the Worlds Scenario:

No, I don’t mean by this that there is any analogy between the UFO extraterrestrial hypothesis (ETH) and alien invasion, a typical example being the “War of the Worlds” (be it the original novel, the movies, the TV series, the musical, etc.). I refer here to the ultimate resolution of that alien war scenario – that ultimately what defeated the Martians were terrestrial microbes – bacteria to which the alien invaders had no resistance. That was a really excellent plot device – it was also lousy science! If there is one truism in biology, it is that cross-species infection is rare. There are of course a few exceptions to the cross-species infection rule, but they remain by far a minor, minor, minority. Micro-organisms tend to be species specific in terms of their nastiness. Thus, if I sneeze, my cats aren’t in any danger of catching my cold – and vice versa. I’m not about to infect any of my garden plants by touching them with my dirty soiled hands – I’m not likely to become infected with a deadly disease from a maple tree. If a wild bird has beak and feather disease and my cats should happen to catch and eat it – well, the bird was doomed anyway, and I’m not going to have to rush the feline predator off to the vet for shots! So, if it is relatively unlikely for one terrestrial species to be a contagion towards another terrestrial species (unless they are very closely related – evolutionary speaking), then what odds a terrestrial species will be deadly to an extraterrestrial species – and vice versa.

What’s the point of all this? Well, if UFOs can be explained by the ETH, then it is unlikely in the extreme that the ETH exists in a species vacuum. That is, ‘ufonauts’ (for lack of a better term), more commonly known as ‘the greys’, will be associated with their extraterrestrial micro-organisms (maybe ever their extraterrestrial equivalents of head lice, mites, bedbugs, cockroaches and rats depending on how hygienic they are). We do not exist in a bacteria free environment, nor could we even if we wanted to. ‘Ufonaut’ bodies and their UFOs will be as ‘bacteria-ridden’ as our bodies, our homes, automobiles, and in fact any and all other bits and pieces of our environment. We haven’t endured or experienced any pandemic or epidemic due to micro-organisms associated with ‘ufonauts’, and presumably ‘ufonauts’ haven’t caught cold or smallpox or the measles from microbes associated with us, our cats, birds, or any other terrestrial life forms.

So, UFO sceptics can’t invoke the “War of the Worlds” resolution as an argument that the UFO ETH is an invalid one. So, by all means, shake hands with an extraterrestrial (ET - if you meet him/her/it) and don’t worry about any resulting medical bill – it ain’t gonna happen.

However, this does open up an interesting research area – one I’ve never, ever, seen mentioned in the UFO literature. That is, extraterrestrial microbiology. If UFOs are piloted by alien beings, biological beings that must be associated with extraterrestrial micro-organisms, then presumably said ET microbes have entered into our terrestrial biosphere. Presumably, said ET microbes would be so biochemically distinct or unique that any microbiologist examining same would immediately note that something was afoot! Of course, if you’re not looking out for it, you’re unlikely to find it or get that ‘eureka’ moment even if you do find it. Perhaps UFO abductees or UFO landing sites should be examined for the presence of extraterrestrial microbes.

So what then to make of the late Sir Fred Hoyle’s et al. claims or ideas that some of our terrestrial disease outbreaks originated from outer space? It’s a variation on the panspermia idea – life on Earth originated from extraterrestrial microbiological life forms seeding our planet.

The Fred Hoyle Scenario:

It’s well established that interstellar space is full of gas and dust. What came as a surprise was the unexpected discovery that many of those interstellar regions are also rich in organic molecules. Organic means that the compounds contain carbon, one of the elemental building blocks central to biology – along with hydrogen, oxygen and nitrogen, also well represented in interstellar gas and dust clouds. Many dozens of organic compounds have now been verified in the reaches of outer space, more than a few highly complex organic molecules, many associated in one way or another with life and biological processes.

Also verified has been the discovery that actual life forms, albeit simple microbial ones like bacteria, can, if not thrive, at least survive the rigors of outer space with minor shielding (say dust particles) to protect again harmful radiation. Terrestrial bacteria have survived three years on the Moon as demonstrated when the Apollo 12 astronauts brought back from the Moon pieces of the Surveyor III Lunar Lander, which had landed on the lunar surface three years prior. Experiments in Earth orbit have confirmed that some terrestrial microbes can boldly go in the cold and vacuum of space. 

Not so verified, but highly plausible, is the idea that simple life forms can be transported throughout the galaxy, hitching rides on dust particles, even larger objects like small hunks of rock that were ejected from their home planet. Recall the Martian meteorite (ALH84001) found in Antarctica which showed various lines of evidence that it was home to ancient fossilized Martian microbes. The controversy over that still hasn’t been resolved to the satisfaction of all.

Comets are known to be rich in organics, ditto some asteroids, and some have claimed that debris, say chips of an asteroid that have impacted and landed on Earth as a meteorite have ‘organised elements’ inside them suggestive of unicellular life forms. The possibility of course exists that those ‘organised elements’ were terrestrial contamination, since it can often be a long time between the fall of a meteor, and the discovery and analysis of the meteorite it became.   

The late Sir Fred Hoyle, along with several colleagues, most notable of which was Chandra Wickramasinghe, went a few steps further. Not only were there simple life forms in the depths of outer space, not only could they have seeded suitable planets with life – like Earth – but they to this very day rain down upon us. Further, they provide a far more logical explanation for various epidemics, maybe pandemics, experienced here on Earth. Why should some of these extraterrestrial bacteria be potentially infectious to us?  Well, if these microbes are the same sorts of microbes as seeded Earth ‘in the beginning’, that is were responsible for kick-starting life on Earth; providing the origin or life on Earth, then we share a common ancestry with them. We evolved from them over all those billions of years. Looking at it another way, we, in fact all life on Earth, really isn’t terrestrial life, but extraterrestrial life. We are the aliens!

Anyway, how does it happen? Specifically that is, or at least one mechanism, Earth’s orbit intersects now and again a stream of bacteria-laden cometary dust and debris – germs from outer space – that impact Earth’s atmosphere and ultimately filter down (perhaps incorporated in rain drops) to ground level and do their infectious thing.

However, to be fair, to state that their ideas are controversial is very definitely an understatement. For their side of the story, you’ll need to examine the evidence they present in there books (see further readings).

So, is there a conflict with extraterrestrial bacteria escaping out of a UFO and having no impact on the terrestrial biosphere and extraterrestrial bacteria arriving from interstellar gas and dust clouds, or cometary and/or asteroid debris? Well, there’s no conflict IMHO. The two sources of alien microbes are just that – two independent extraterrestrial sources that have no connection with each other. Of course relatively few experts in infectious diseases give any credibility to Hoyle’s theory so that might eliminate that. Then too many scientists don’t give any credibility to the UFO extraterrestrial hypothesis (ETH), hence to alien microbes originating from that source. However, whether none, one or both ideas have or lack credibility doesn’t result in any ultimate contradictions.

Further readings:

Hoyle, Fred; Evolution from Space: The Omni Lecture Delivered at the Royal Institution, London on 12 January 1982; University College Cardiff Press, Cardiff; 1982:

Hoyle, Fred & Wickramasinghe, Chandra; Cosmic Life-Force; J.M. Dent & Sons Ltd, London; 1988:  

Hoyle, Fred & Wickramasinghe, Chandra; Diseases from Space; J.M. Dent & Sons Ltd, London; 1979:

Hoyle, Fred & Wickramasinghe, Chandra; Evolution from Space; J.M. Dent & Sons Ltd, London; 1981:

Hoyle, Fred & Wickramasinghe, Chandra; From Grains to Bacteria; University College Cardiff Press, Cardiff; 1984:

Hoyle, Fred & Wickramasinghe, Chandra; Life on Mars? The Case for A Cosmic Heritage; Clinical Press Limited, Bristol; 1997: [Note: This title is very misleading. It has nearly bugger-all to do with Mars but everything to do with panspermia.]

Hoyle, Fred & Wickramasinghe, Chandra; Lifecloud: The Origin of Life in the Universe; J.M. Dent & Sons Ltd, London; 1978:

Hoyle, Fred & Wickramasinghe, Chandra; Living Comets; University College Cardiff Press, Cardiff; 1985:

Hoyle, Fred & Wickramasinghe, Chandra; Our Place in the Cosmos: The Unfinished Revolution; J.M. Dent & Sons Ltd, London; 1993:

Hoyle, Fred & Wickramasinghe, Chandra; Proofs That Life Is Cosmic; Memoirs of the Institute of Fundamental Studies, Sri Lanka; December 1982:

Hoyle, Fred & Wickramasinghe, Chandra; Space Travellers: The Bringers of Life; University College Cardiff Press, Cardiff; 1981:

Hoyle, Fred, Wickramasinghe, Chandra & Watkins, John; Viruses from Space; University College Cardiff Press, Cardiff; 1986:

Ponnamperuma, Cyril (Editor); Comets and the Origin of Life; D. Reidel Publishing Company, Dordrecht, Holland; 1981:

Seargent, David A.J.; Genesis Stone? The Murchison Meteorite and the Beginnings of Life; Karagi Publications, The Entrance, NSW: 1991: