Without nitrogen PAHs tend to be hostile to the biochemistry of life. On Earth they are largely the result of the breakdown of organic material, for example the burning of fossil fuels, making them pollutants and in some cases carcinogenic. But with nitrogen it’s a different story. Without nitrogen-containing PAHs, amino acids, DNA and RNA, as well as a host of other vital molecules (for example haemoglobin, chlorophyll – and even essentials such as chocolate) could not exist. Indeed, one of the theories of how life originated on Earth puts nitrogen-rich PAHs right at the centre. But the big question is how they developed in the first place.
The discovery that nitrogen-bearing PAHs are present in space provides a major piece of the puzzle. The current understanding, based on the NASA Ames team’s work, is that they are formed and ejected into space by the death of stars. As Douglas Hudgins puts it:
There was a time that the assumption was that the origin of life, everything from building simple compounds up to complex life had to happen here on Earth …
This stuff contains the building blocks of life, and now we can say they’re abundant in space.7
Hudgins points out that discovering nitrogen-containing PAHs in interstellar space does not prove that life on Earth came from the stars but that as it is the simplest theory, according to Occam’s Razor, this is the one that science should prefer.
ON THE TAIL OF COMETS
Another way that building blocks can be seeded on planets is via comets. Not through scoring a direct hit on Earth – which would incinerate any ‘seeds’ – but by drifting down with the ‘rain’ that floats into the atmosphere as the planet passes through the debris from the tail of comets.
Most comets are believed to be left over material from the gas and dust clouds that coalesced at the birth of the solar system, now roaming its highways and byways under the influence of the gravity of the heavenly bodies, generally orbiting the sun. The endless process of heating and freezing as the comet approaches and recedes from the sun causes reactions in its basic chemicals, which creates new compounds.
The idea that seeding occurs via comets has received strong support from the study of meteorites, especially fragments from the famous specimen believed to be from the nucleus of a comet that exploded over the small Australian town of Murchison, Victoria, in 1969. Analysis of the Murchison meteorite has continued ever since – the latest batch of test results, after examination with cutting-edge techniques, was released in February 2010. One of the first things to be discovered was that it was made up of organic carbon chemicals – it even smelt of petrol. It contains 70 different amino acids, including two, glycine and alanine, which are fundamental to life on earth – the very same, in fact, as those that emerged from the Urey-Miller experiments with the primordial soup that so excited scientists back in 1953.
There is an even more direct connection between comets and glycine, which is chemically the simplest amino acid. In 1999 NASA launched the probe Stardust to collect material from the comet Wild-2, which orbits the sun once every six years. In January 2004 Stardust swept up dust from the comet’s coma – the cloudy halo around the nucleus – returning it to Earth in a sealed container nearly two years later. Analysis revealed the presence of glycine. As Dr Carl Pilcher, head of NASA’s Astrobiology Institute announced:
The discovery of glycine in a comet supports the idea that the fundamental building blocks of life are prevalent in space, and strengthens the argument that life in the universe may be common rather than rare.8
LIFE IN THE LAB
Some of the greatest revelations have come from attempts to reproduce interstellar conditions in the laboratory, in what is effectively a cosmic version of the Urey-Miller experiments. At the forefront of this quest is the NASA Ames Research Center in the 1990s with a team led by Louis Allamandola.
Allamandola set out to study how dust grains in gas clouds interact with the gases by replicating the conditions. He and his team placed methane, water vapour, ammonia, carbon monoxide and so on in extremely thin densities and very, very cold temperatures and bathed them in ultraviolet radiation. Under these conditions, chemical reactions occur that would be impossible under normal earthly conditions. The radiation breaks apart the molecules, and the icy cold puts them back together in very unusual and complex ways. But although many of these structures had never been seen before, some were eerily familiar to biochemists …
The first surprises related to the PAHs. Interstellar conditions, particularly exposure to ultraviolet, transform the PAHs’ carbon into useful forms for life such as alkaloids – ‘ubiquitous in the plant world’9 – and quinones, essential for photosynthesis and the functioning of muscle and brain cells. These vital substances simply wouldn’t exist without the gas and dust clouds in deep space. But there were even more ground breaking discoveries.
Back in 1985, American biologist David Deamer had discovered something very odd in the Murchison meteorite: small ‘bubbles’ closely resembling biological structures known as vesicles – basically membrane sacs containing liquid biochemicals that constitute part of cells. But were they really vesicles? It was only in the late 1990s that Deamer realized the potential of Allamandola’s work: Could it be that similar bubbles had appeared in his simulated interstellar environment? Indeed they had. They found identical vesicles, about the size of red blood cells. They called in biochemist Jason Dworkin – a former collaborator with Stanley Miller – who identified them as lipids, a class of macromolecule that includes fats and waxes.
Lipids perform several vital functions, but most tantalizingly they make up the membranes of cell walls, which may be small but are in fact big operators. They separate biochemicals into packets – capsules, basically. Without them many of the processes and reactions vital to the development of life could never happen because the biochemicals would be too dilute. As geneticist Pascale Ehrenfreund, specifically commenting on the Ames discovery, pointed out, ‘membrane formation is a crucial step to the first forms of life.’10
Researchers trying to replicate the origins of life had never previously had any success in replicating lipids under terrestrial conditions. But here, in interstellar gas clouds, they appeared utterly spontaneously – in fact, the Ames team never noticed they had made lipids until David Deamer asked them to look. The similarity with the vesicles found in the Murchison meteorite shows that this process really does happen in space. It isn’t just the Frankenstein child of jiggery pokery in a lab.
In other experiments, Allamandola’s team demonstrated that not merely cell membranes, but some of their internal biogenic chemicals – ammonia, formaldehyde and even amino acids – can also be made in the interstellar clouds. Allamanodola speculates that the first cells could have come from inside comets – all the ingredients are there, and so is the membrane to neatly wrap them up – although he admits that this theory is untestable.11 At least at the moment.
In fact, Allamanodola wasn’t the first to make such a suggestion. With so many of life’s building blocks being found in space, Fred Hoyle and Chandra Wickramasinghe had suggested back in the 1970s that they could be developed into what they termed ‘protocells’ that could then be seeded onto planets by comets. The Ames discovery shows this is almost certainly correct.
To us the important thing, though, was the implications of creating lipids in the lab. As Louis Allamandola pointed out:
The most amazing thing is that we start with something really simple. And then suddenly we’re making this enormous range of complex molecules. When I see this kind of complexity forming under these extreme conditions, I begin to really believe that life is a cosmic imperative.12
THE LIVING, BREATHING EARTH
The universe – not just planets, but space itself – is bursting with the potential and materials for life, created and transported around like ocean currents carrying seeds between remote islands. However, it is still only on planets that these can develop into something more complex than bacteria at best, which brings us to another even
more controversial idea that fits very neatly into the ‘universe designed for life’ vision.
The Gaia hypothesis was proposed in the 1970s by British scientist James Lovelock, who is even more of a maverick or independent thinker, depending on your point of view, than Sir Fred. Similarly, Lovelock’s brilliance is acknowledged even by his critics (even if they believe his imagination sometimes gets the better of him), as are his very real contributions to science.
Lovelock describes himself as an ‘independent scientist’, neatly encompassing both his attitude to the freedom of thought he believes is essential for a scientist and his avoidance throughout his long career of being tempted by commercial or even academic institutions – although he has occasionally been successfully headhunted as a consultant. With his broad knowledge of all the sciences, and contempt for the increasing specialization that blinkers scientific thinking, he would have been at home in the Renaissance.
Lovelock is that rare being, someone whose brilliance has actually changed the face of the world. Most significantly, this occurred in the early 1970s through his discovery that human-made chlorofluorocarbons (CFCs) had penetrated the environment to such a degree they were present in places as remote from human industry as Antarctica. It was because of Lovelock that today’s world is CFC-free.
The concept behind Gaia was a spin-off of Lovelock’s work for NASA in the 1960s, when he was devising ways to detect life on Mars. He reckoned analysis of the Martian atmosphere might reveal the characteristic changes caused by the presence of living organisms. Looking further into this question and the impact life has on the Earth’s atmosphere led him to certain striking observations. It isn’t just that the presence of plants and animals – the biosphere – changes the atmosphere, but they appear to be regulating it, actively keeping the Earth habitable. Life itself keeps the planet in a condition suitable for life.
From such phenomena Lovelock developed the idea that the Earth is a ‘self-regulating entity’, where living things are not passive guests but ensemble players with integral parts in shaping conditions on the planet.
A prime example of this self-regulation, besides a host of others, relates to the Earth’s response to changes in the sun’s output. Living organisms can only survive within a narrow range of temperatures, about 10 to 20 degrees centigrade. However, although astrophysicists agree that since life first appeared on Earth at least 3.5 billion years ago the sun’s heat has increased by about 30 per cent, the Earth has obviously remained at a temperature suitable for life. Somehow the increasing heat has been balanced to keep the average global temperature steady.
As a 2 per cent drop in the heat reaching Earth from the sun is enough to trigger an ice age, imagine what the Earth would be like with 30 per cent less heat. When life originated, something – probably a high level of greenhouse gases in the atmosphere – made the Earth significantly warmer than it would have been otherwise. But as the sun grew hotter, some other factor must have altered conditions – the mix of gases in the atmosphere, for example – as compensation. And that unknown factor had to keep step with the steady increase in solar heat.
As Lovelock pointed out, any of the processes that have been proposed to explain this compensation would have had to be staggeringly precise. Even small variations in, say, the mix of atmospheric gases would result in runaway reactions that would either seriously overheat the Earth (the oceans would literally boil away), or reduce it to a frozen ball. Yet that clearly didn’t happen; the process seems somehow to have been controlled.
… the Earth’s living matter, air, oceans, and land surface form a complex system which can be seen as a single organism and which has the capacity to keep our planet a fit place for life.13
Following the suggestion of his neighbour, the novelist William Golding, Lovelock called this the ‘Gaia hypothesis’, after the ancient Greek Earth goddess. In 1979 he produced Gaia: A New Look at Life on Earth.
When Gaia was first published there were howls of outrage from the scientific world, led predictably by Richard Dawkins. (Lovelock declared that he ‘hated Gaia as much as he hates God’.)14 Dawkins condemned Lovelock’s system because to him it could never have evolved by natural selection, while Lovelock maintains that it fits natural selection perfectly. However, as a 2010 BBC documentary on Lovelock’s work showed, much of the thinking behind the once-controversial Gaia hypothesis has now become mainstream, while some still regard Lovelock’s idea as oddball and over-imaginative, others, including the philosopher John Gray, consider the idea as revolutionary as Charles Darwin’s.15
Despite widespread belief to the contrary, what the Gaia hypothesis does not proclaim is that the world is alive in the same way that an animal is alive, or that it is somehow self-aware, with some higher planetary consciousness controlling and ordering the individual parts to benefit the whole. In fact, Lovelock is scathing about the New Age, which took (or most probably, hugged) his book to its heart, believing in some way that it was scientific proof of the reality of the Mother Goddess. To Lovelock such concepts exist outside the realm of science, since they can’t be tested by scientific methods.16 Lovelock uses the term ‘alive’ metaphorically, taking pains to explain - with superb chutzpah, but pinpoint precision – ‘the planet is alive in the same way that a gene is selfish’.17 To him the Earth fits the definition of a ‘superorganism’: ‘bounded systems made up partly from living organisms and partly from non-living structural material’18 – as, for example, a beehive. Literal interpretations of the word ‘alive’ also seems to be behind Dawkins’ hostility, which implies a certain lack of sophistication in his understanding or perhaps an unwillingness to confront the theory properly.
The Gaia theory is what one would expect, indeed predict, from the designer universe hypothesis. If the universe is fine-tuned to support life, and life is a cosmic imperative arising wherever conditions are conducive, then one would expect that once complex life did take hold on a planet, some kind of mechanism would be in place to ensure its survival. We should recall here the concept of the anima mundi, the ‘world soul’, which animates and also controls the world so dear to the Hermeticists’ hearts.
But however exciting the Gaia hypothesis might seem, we should remember it has yet to be conclusively proven. Nor does it prove the designer universe theory correct. But, as with the existence of biochemical evidence in support of the cosmic imperative, it nevertheless fits and supports the concept of a designer universe.
THE COSMIC IMPERATIVE
It no longer seems a question of whether panspermia happens – it does, quite clearly – but rather of how far the building blocks of life can be fused in space before they need a planet to really get going. Christian de Duve sums up the current state of our knowledge:
There is … ample evidence that a number of biogenic compounds can form spontaneously under primitive Earth conditions, in interstellar space, and on comets and meteorites. Most likely, such compounds provided the first seeds of life. How much was made locally, how much was brought in from outer space, is still widely debated.19
The latest scientific thinking about the origin of life in the universe is very compatible with the concept of a designer universe. Rather than life being a billion-to-one fluke, it seems to be a common – even a universal – phenomenon. And the different parts of the universe play vital roles in the creation and dissemination of life.
We must be careful, however, not to put words into the mouths of the likes of Louis Allamandola and Christian de Duve. When they use the expression ‘life is a cosmic imperative’, they are saying that conditions in the universe mean that wherever life can evolve, it inevitably will. This is emphatically not the same as saying that the ‘purpose’ of the universe is to produce living organisms. Scientific objectivity and a strict adherence to current evidence could never allow them to draw such a conclusion. But if the universe is designed for life, would we be able to tell the difference between that more Hermetic kind of cosmic imperative and de Duve and Allama
ndola’s version?
It is unlikely. If the universe is fine-tuned to produce the chemical elements and right physical conditions for intelligent life, then that same delicate balancing act would have to also include the imperative that biochemistry is now beginning to recognize. It would be pretty pointless otherwise.
Unlike many in the biological sciences, de Duve does give houseroom to the more metaphysical interpretations of the cosmic imperative. In Vital Dust he discusses the ideas of Pierre Teilhard de Chardin, the French Jesuit priest and palaeontologist who put forward a theory of cosmic evolution very similar to the designer universe, albeit with a Christian gloss. To Teilhard, creation evolves from simple matter, to life and on to consciousness as part of a divine plan, which de Duve considers a valid possibility.20
As biochemistry has become increasingly sophisticated, it has found nothing to contradict the idea of intelligent design. Quite the reverse. However – and to many this will be a very big caveat indeed – the evidence for life as a cosmic imperative is, like that for the fine-tuning of the big bang, hard to square with the image of the biblical God. This is far too limiting for that kind of personal entity, with his alleged omniscience but all-too-human emotions.
An alternative to scientific atheism, which also fits this evidence, is the Hermetic interpretation, in which the cosmos was specifically built for life. Some of de Duve’s statements even read like an expression of Hermetic cosmology – a belief in the living universe – albeit in biochemical terms:
The universe is not the inert cosmos of the physicists, with a little life added for good measure. The universe is life, with the necessary infrastructure around; it consists foremost of trillions of biospheres generated and sustained by the rest of the universe …
The Forbidden Universe: The Origins of Science and the Search for the Mind of God Page 24