Thursday, January 20, 2011

Goodbye Little Green Men

They’re here, apparently. They’re visiting our world on a regular basis. Some – the mysterious ‘Men In Black’ – may have infiltrated prominent positions within our society to act as fifth columnists. Others are leaving indecipherable messages for us in corn fields. Sinister ‘greys’ steal cattle and mutilate horses and even abduct humans in order to do experiments on them, often with a particular focus on harvesting our eggs and sperm or putting machines up our bottoms.

They travel to our world in cigar-shaped motherships and land in saucer-like scout craft. The US government has known about them for years – certainly ever since the well-publicised Roswell incident of 1951 - and may even be collaborating with them to get their hands on new technologies like stealth bombers and Pop Tarts. Some say that the Illuminati - the secret rulers of the world – are a reptiloid species that includes among its number the British royal family and a succession of Republican US presidents. Others say that the visitors are here to guide us, to shepherd us towards the next stage in our evolution as a species. A third, more worrying claim, is that they’re using our stolen gametes to create a race of part-alien part-human hybrids with which to launch an invasion. Watch the skies …

If any part of that paragraph is true, it is the most astounding thing to have happened to humanity since we climbed down from the trees and walked upright – assuming that’s what happened and aliens didn’t bio-engineer us. Aliens from other worlds are visiting us? They walk among us? Can it really be true? An awful lot of people seem to think so.

In a recent (April 2010) Reuters/ Ipsos poll of 23,000 adults in 22 countries, more than 20% of those polled said that they believe in aliens. 40% of people from India and China believe that aliens disguised as humans are all around us. Meanwhile, according to a 2002 SKY News poll of people in the UK, 65% of people think that UFOs are alien spaceships. A similar Gallup poll taken in the USA in 1997 put that figure at 45%. The poll also revealed that 71% of Americans are positive that the US government knows more than it’s letting on. In the same year a poll by CNN and Time magazine showed that 80% of citizens believed in a cover-up, 50% believed in abductions, 64% that aliens have contacted us and 74% that aliens would look humanoid. A staggering 3% - that’s a potential nine million people – claimed to have been abducted. That’s around the population of London.

While we’re talking about polls, it’s interesting to note that at the time of the first recorded modern UFO sighting in 1947, 90% of Americans taking part in a Gallup poll had heard of flying saucers but 29% put them down to optical illusions and only 9% said that UFOs were anything other than hoaxes, US or Russian secret weapons or weather balloons. By 1957, a Trendex poll showed that belief in saucers as alien craft had grown to 25.3%. It could be that aliens had started to visit the Earth with greater frequency after Kenneth Arnold’s famous 1947 sighting. But it’s also possible that increased media awareness, plus the Golden Age of Hollywood sci-fi, helped public opinion along. Classic films like The Thing from another world (1951), Invaders from Mars (1953), It came from outer space (1953), Earth vs the flying saucers (1956) and Invasion of the Saucer Men (1957) mostly portrayed flying saucers and their occupants as dangerous threats to humanity. No one ever made a film called Fluffy green bunnies from Mars want cuddles. There were exceptions of course, such as the excellent The day the Earth stood still (1951) and This island Earth (1955), which said more about human fear and irrationality than about alien aggression. But these kinds of films were in the minority. By 1971, polls showed that 54% of people believed in UFOs and 76% suspected a government cover-up (National Enquirer). And the percentages have stayed pretty constant ever since.

It’s also notable that arguably the most famous and most often-quoted alien abduction story – that of Betty and Barney Hill in 1961 – occurred just days after an episode of The Outer Limits was aired that contained aliens very similar to that remembered by Betty in her dreams. Their abduction seems to have become the template for just about every alien abduction since and it’s notable just how few stories of ‘Greys with wraparound eyes’ exist before the Hill’s story broke. Of course, history is full of stories of abductions by fairies, goblins, demons and devils. It’s remarkable how similar many of these historical accounts are to modern UFO abduction stories. According to Robert Bigelow, who part-funded a Roper survey of abductees in July-September 1991, more than four million Americans or some 100 million humans worldwide have been abducted by aliens. As Carl Sagan wryly commented at the time: ‘It’s surprising more of the neighbours haven’t noticed.’

However, The topic under discussion here isn’t whether UFOs are alien spaceships or even whether aliens are visiting the planet. It’s the aliens themselves I want to discuss. In particular, I want to look at the likelihood of them being humanoid.

Next time you get a chance, take a close look at a creepy crawly. It may be a snail or an ant, a spider or a woodlouse, or something more exotic found in the sea or the rainforest. Look it over from head to tail (if it has either) and ask yourself this question: ‘How different am I from this creature?’

If the creature you’re looking at is a starfish, there are some interesting differences between it and you. You are bilaterally symmetrical; the left side of your body is pretty much a mirror image of the right. You have two arms and two legs and two eyes. A starfish, however, has pentaradial symmetry and usually between five and 15 arms (it is nearly always a multiple of five) radiating from the central ‘hub’. Some species have 50 or more but, however many arms the starfish has, each has a simple eye at the tip. What’s more, if a limb is severed, it can be regrown. In fact, providing some of the central hub is attached, a severed leg can also regenerate a whole new starfish. The starfish’s ‘blood’ is water, pumped around the body by way of a vascular system that replaces the need for muscles, sinews and tendons. Starfish move by way of hundreds, sometimes thousands, of hydraulic tubular ‘feet’. Its skeleton – a series of interlocking calcified plates or ossicles – is on the outside. Their mouth is at the centre of the lower surface of their bodies and their anus directly above on the top surface. Some species can ‘throw’ their stomach over their prey and drag it back inside the body to be absorbed. Others push their inverted stomachs inside shellfish and start to dissolve them from the inside out. Some of the digestive system is found inside the legs. A starfish has a complex nervous system that allows it to register touch, temperature, light, orientation and odour. However, it has no central brain; the nervous system acts as a simple ‘distributed’ brain. Starfish commonly reproduce by releasing eggs and sperm into the sea and letting them find each other. The fertilised eggs can turn into miniature starfish but the larvae of many species are bilaterally symmetrical free-swimming plankton that look a bit like spiders made of jelly.

If the creature crawling up your arm is a common house spider, it also differs from you in a number of important ways. Firstly, it has an external skeleton made of chitin – the stuff your fingernails are made of – covered in sensory hairs, or setae, that perform different functions. Many are concerned with touch, as you’d imagine, but some are chemical receptors. A spider can, in general terms, smell and taste with its hair. Inside the spider’s suit of armour, you’ll find a bunch of organs floating in a fluid called haemolymph. This is pushed into the hollow legs by hydraulic pressure enabling the spider to walk, which is why when a spider dries out or loses its blood, its legs curl inwards. Spiders have eight legs and modified pairs of limbs near their anus called spinnerets that extrude silk; a protein fibre that hardens on contact with air and which has a tensile strength greater than steel or kevlar. Despite this, it can be stretched to 140% of its original length without snapping and is incredibly light. A strand of spider silk long enough to encircle the Earth would weigh less than 1lb (500 grams). Spiders don’t have jaws and cannot swallow solid food. Instead, they inject a liquefying agent into the victim’s body by way of stabbing fangs and then drink the resultant ‘soup’. Most spiders breathe by way of a ‘book lung’; a respiratory organ that looks like a bellows. The moist ‘pages’ absorb oxygen directly from the air. Spiders have four pairs of eyes. Some species, such as the jumping spiders, have extraordinarily good eyesight; ten times better than the best insect eyesight (dragonflies) and one fifth as acute as a human’s.

When we turn to more exotic creatures, things get even stranger. Osedax mucofloris—otherwise known as the bone-eating snot-flower worm – lives on the seabed and eats the bones of deceased whales. Symbion Pandora lives only on the ‘lips’ of Norwegian lobsters and has a sex life that involves at least three distinct body forms and two penises. There are frogs that break their own bones to create claws (Trichobatrachus robustus), and solar-powered sea slugs that ingest algae and then benefit from being able to photosynthesise food. There’s a tongue-eating louse (Cymothoa exigua) that attaches itself to a fishes’ tongue, feeds off the blood supply causing it to atrophy, then lives in the mouth thereafter performing the role of the now dead tongue.
Herring communicate by farting, butterflies taste with their feet and there is a simple jellyfish-like creature called Turritopsis nutricula that is effectively immortal. Once it gets old, it reverses the ageing process until it becomes a sexually immature polyp and then has its life all over again. It can do this indefinitely. Then there are the tardigrades, or water bears, or moss piglets (aww …), a group of tiny, cute soft-bodied micro-creatures that can live at temperatures below –273°c and above 150°c. They can also go without water for a decade, withstand pressures of up to 6000 atmospheres – that’s six times deeper than the deepest part of the ocean – and can take 1000 times the dose of radiation that it would take to kill you. They can even survive in a vacuum as space scientists learned when they popped a few into low-Earth orbit for 10 days on the Biopan 6 Experimental Platform.

No matter how oddly bizarre a creature may be, they all share something in common with us; their DNA. DNA is the complex nucleic acid that decides the differences between a horse and a seahorse and a seaweed. And, indeed, the defining features of every distinct living organism on this planet. Everything from a vampire finch to a winkle, a diplodocus to Johnny Depp, has the same DNA inside its cells. It is the particular arrangement of the components of the DNA strand in each that dictates who sucks blood, who weighs 14 tons and who collects an Oscar.

Imagine four switches, each of which has two positions – Off and On. By choosing which to switch off and which to switch on, we can create 16 different permutations:


Now imagine a bank of several hundred thousand switches and the possible number of permutations becomes astronomically large. That’s basically what DNA is. Every change of switch position results in a small dviation. It means that even our closest genetic relatives, our siblings and parents who have just a few different switches, look slightly different to us. Chimpanzees, who share around 98% of the same DNA sequence as us look significantly different. We share 50% of our DNA with bananas and 51% with pineapples. So, if all of the life forms on Earth in all of their extreme diversity are products of a single nucleic acid arranged in a myriad different ways … just how different could life look on a world that has evolved in a completely different way?

The late, great biologist and essayist Stephen Jay Gould once created a thought experiment he called 'replaying life's tape.' ‘You press the rewind button and, making sure you thoroughly erase everything that actually happened, go back to any time and place in the past’, he said. ‘Then let the tape run again and see if the repetition looks at all like the original. I suggest any replay of the tape would lead evolution down a pathway radically different from the road actually taken. […] Alter any early event, ever so slightly and without apparent importance at the time, and evolution cascades into a radically different channel.’ Our very existence is based upon a million, billion, trillion, quadrillion tiny chance events and advantageous mutations. So, already the chances of us meeting like this are highly unlikely. But if that were not extraordinary enough, consider this …

You are only able to read this book because all of your ancestors survived; every single one of them, going right back to our humble squidgy origins. Life is believed to have begun around four billion years ago – that’s 4,000,000,000 years – and yet, from those earliest, primitive, single-celled proto-life forms right up to the present day, there is an unbroken chain of progenitors leading to you. Every one of your ancestors – the upright apeman, the tree-dwelling primate, the primitive mammal, the synapsid, the amphibian, the fish, the agnathan, the primitive notochordate, the pool of organic goop – every single one of them managed to stay healthy long enough to mature, find a mate and get laid. What are the chances of that happening again if we replayed life’s tape? Would there necessarily be otters or elephants or bedbugs if we did the same? The chance event that means that one animal dies while another, slightly different, lives is what decides whose genes make it to the next generation. It really is all very random. And things could have been very different indeed.

In 1909, a paleontologist called Charles Doolittle Walcott discovered some interesting fossils in a black shale bed in Yoho National Park, high up in the Canadian Rockies. It became known as the Burgess Shale (as it is near the Burgess Pass) and, over several expeditions, Walcott collected many fossils from the shale that he identified as new species of arthropods. However, later examination of Walcott’s fossils in the 1980s revealed a startling truth – what Walcott had discovered were not new species but wholly new types of organisms. Work by Harry Whittington, Derek Briggs and Simon Conway Morris showed that many of the Burgess Shale creatures in fact constituted whole new phyla

A phylum is a large family group. The phylum to which we belong is Chordata. We are chordates. The Chordata includes all mammals, reptiles, amphibians, fish, birds and extinct creatures like dinosaurs, pterosaurs and mammal-like reptiles (pelycosaurs and therapsids); everything, in fact, with a spinal chord. Insects belong to the phylum Arthropoda, which also includes other jointed-legged animals like spiders, scorpions, woodlice, lobsters, isopods and the extinct trilobites. All of the animals on Earth consist of just 30-odd phyla; 95% of all species exist within just nine. Therefore the discovery of any new phylum is an extraordinary find. The Burgess Shale, and discoveries of similar species in the Maotianshan Shales of Yunnan Province in China and Emu Bay, Australia, have added at least six new phyla to the story of life. Many of the species still defy classification today.

The creatures of the Burgess Shale lived in the Middle Cambrian Era, around 500 million years ago when there was a sudden ‘explosion’ of diversity in animal types and body-plans. This is sometimes referred to as the Big Bang of Evolution. It was a time when nature experimented with many different designs for life, most of which proved ultimately to be unsuccessful. Among the fossils so beautifully preserved in the finely textured shale were creatures like opabinia, which had five eyes on stalks and a snout like a vacuum cleaner hose tipped with a grasping claw. There was the huge (at three feet long it was one of the largest animals on the planet at that time) predatory anomalocaris with its grasping arms and waste disposal-type grinding mouth, and the wonderfully named hallucigenia; scientists still don’t know which end of the animal was the head and which was the tail but one side has silicon spikes and the other a set of grasping mobile tentacles. Everything we now call a chordate may have evolved from a flat, blade-shaped worm creature called pikaea.

Sadly, the opabinia didn’t make it (although there is some evidence that the tardigrades are their descendants). But what if they had? What if, like pikaea, they’d evolved into millions of different species as different from each other as bullfrogs and blue whales? What if one of those branches on the evolutionary tree evolved into an intelligent species? What would we look like if we’d evolved from a creature with five eyes and a claw-tipped trunk? You can be pretty sure it wouldn’t be terribly humanoid.

Now consider this; part of the reason we look the way we do and live the way we do is the planet we’re on. Our gravity (dictated by the mass of our world), our distance from the Sun, the stability provided by a large moon, the speed with which we rotate and travel in our solar orbit … all of these factors allow life of a certain kind to have evolved. But what some or all of those factors were different? What if we’d evolved on a low gravity world? Or a world where gravity exerts the same pressures that we find at the bottom of the deepest oceans? What if it were so hot that liquid water couldn’t exist? What if there were no oxygen? The fact that so-called extremophiles exist on this planet that can live in environments that would kill humans instantly shows that life will find a way. There are forms of bacteria that can live in excessively acid or alkali environments that would dissolve flesh. There are microbes that live in molten asphalt and boiling thermal springs. There are hagfish, crabs and tube worms that cluster around thermal vents on the ocean floor that derive all of their nutrition from chemical energy – they get nothing from the Sun. And, just recently, a creature called a loriciferan was discovered that doesn’t need oxygen; something that was previously believed to be essential for all life. Three species of the creature, which are only a millimetre long and resemble jellyfish encased in shells, were found 2.2 miles (3.5km) underwater on the ocean floor, 124 miles (200km) off the coast of Crete. One by one, the conditions we consider to be necessary for life to exist are being stripped away. If creatures can exist without oxygen, without sunlight and even in the vacuum of space, then the universe may be teeming with life that doesn’t necessarily need a clone of the Earth to live on.

To my layman’s eyes, scientists looking for life elsewhere seem to fall into three distinct camps. There is the CETI or SETI brigade who are training radio telescopes at areas of space in the hoping of hearing someone say ‘Ahoy there!’ Then there are the astrobiologists and the xenobiologists. The main difference, it seems to me, is that astrobiologists tend to focus upon finding 'Goldilocks' worlds where conditions are 'just right' for life like that on Earth to have evolved. They have scored a success recently by finding the planet Gliese 681g which appears to be much like Earth. Xenobiology, meanwhile, is more adventurous. Dr Jack Cohen, currently at the University of Warwick and a noted and popular xenobiologist, puts it like this: ‘Instead of looking for carbon copies of Earth, we ought to be theorising about and looking for the different kinds of planets, and other potential habitats for life, that exist out there in the wide universe. ‘Exotic’ habitats should be seen not as obstacles, but as opportunities; instead of dismissing them with an airy wave of the hand and saying, ‘Obviously life couldn’t exist there’, we ought to be asking, ‘What would it have to be like if it did?’’

What, for instance, would life look like if it were based on silicon rather than carbon? It's been a staple of science fiction for years; think of Terry Pratchett's rock-eating trolls, the planet-wide life form in Arthur C Clarke's Crusade, the alien in the Alien Trilogy, and the crystalline entity and the Horta of Star Trek's Silicon Avatar and The Devil in the Dark episodes. Silicon-based aliens are everywhere. But why do sci-fi writers pick on silicon as opposed to other elements like helium or mercury or calcium? It's basically because silicon is the closest thing to carbon in terms of structure.

It's interesting to speculate what a silicon-based life form would be like. It's more interesting to ask why there are none on Earth (as far as we know) as silicon is far more abundant than carbon here. At first glance, silicon looks like a good basis for an alternative biology. Carbon and silicon both have something that chemists and physicists call a ‘valence of four’. That means that individual silicon atoms can make four bonds with other elements to form chemical compounds; like a jigsaw puzzle piece that has four sides and can therefore connect with four other pieces. Carbon can form over 10 million different compounds with other elements, among them many that are essential for life as we know it, such as sugars, celluloses, chitins, alcohols, fats, antibiotics, amino acids and proteins. Silicon can form almost as many, although different, compounds.

Secondly, both silicon and carbon can bond with oxygen. Not all elements can. And, as far as we know at this time, nearly all living organisms need to process oxygen.

Thirdly, by using oxygen as a kind of 'glue', both silicon and carbon atoms can form long chains called polymers. Two examples of this are the carbon-based poly-acetal, a kind of plastic, and silicon-based polymeric silicones, which we use for waterproofing and lubrication. It is carbon's ability to form long complex chains that led to the formation of DNA ... and it is entirely conceivable that silicon could evolve something similar. However, while there are marked similarities between the two elements (which is why they appear so close together on the Periodic Table), there are some major differences too.

You'll have seen that an atom is often represented in books and articles as looking something like a mini planetary system with a central nucleus surrounded by circling electrons (although in newer reference works the orbiting electrons are sometimes represented as more of a cloud). Well, with the carbon atom there are six electrons whizzing around a nucleus made of six protons and six neutrons (hence carbon's Atomic Number of 6). Silicon has 14 electrons circling a nucleus made of 14 protons and 14 neutrons (Atomic Number 14). What this means is that the 'cloud' of electrons around the silicon nucleus is bigger and, therefore, the forces that bind it all together are weaker. Consequently, the silicon atom does not form as strong bonds with other atoms as carbon does (which is why even the hardest silicon-based rock is not as hard as carbon-based diamond). This alone makes it difficult to imagine a silicon-based molecule the length of DNA forming and remaining stable.

The chemistry of life is difficult (although not impossible) to visualise for a silicon-based life form. When carbon unites with oxygen (oxidisation) during breathing, it forms carbon dioxide, a gas. We breathe it out and plants breathe it in. However, when silicon oxidises, it forms a solid called silicon dioxide. It's hard to imagine a creature that breathes in oxygen and breathes out something that is essentially sand. There would also be some 'disposal' issues for a silicon-based life form as it would excrete similar silica-based substances. It adds a whole new dimension to the expression 'Shitting a brick'.

And where would a silicon-based life form draw its energy from? All living things need a way to collect, store and utilise energy. Once absorbed or ingested, the energy must be released exactly where and when it is needed within the body. Otherwise, all of the energy might liberate its heat at once, incinerating the life-form. In a carbon-based life-form, storage takes the form of carbohydrates (the curse of us fatties). A carbon-based life-form 'burns' this fuel in controlled steps using speed regulators called enzymes. Carbohydrates (the clue is in the name) are carbon-based compounds that oxidise to form water and carbon dioxide, which are then exchanged with the air. Silicon doesn't form many compounds that will duplicate the function of enzymes so it's hard to imagine how a silicon-based living organism could function. But that doesn’t make it impossible. One speculative study of the possibility of silicon-based life by ATS paints a fascinating possibility: ‘A major component of glass is silicon. It might be possible that an organism based on glass exists. An organism like that may get its energy from solar-cell like cells.'

Then, of course, there's life based on nitrogen, phosphorous, arsenic, ammonia ...

Dr Jack Cohen believes that the possible shapes and habits of life are not only stranger than we imagine, but stranger than we can imagine. ‘Asking what humans would look like if they'd evolved on Mars is like asking what fish would look like if they'd evolved on the Moon,’ he says. He does point out, however, that there would be some points of commonality with Earth life. He calls these calls Universals. ‘During evolution, some things have happened independently many times’, he explains. ‘The most common are what I jokingly call The Four Fs: Fur, flight, photosynthesis and sex. Mice, bumble bees and some plants have all independently evolved fur. Insects, bats, birds, pterosaurs, even fish and snakes have evolved flight. There are still four different kinds of photosynthesis and many more have gone extinct. As for sex … everything is at it in one form or another. But these aren’t the only universals. Convergent evolution has given animals that swim through liquid water similar shapes - sharks, icthyosaurs, dolphins and penguins for example. Eyes are everywhere from the complex to the simple. Rhinos, lizards and beetles have horns. There’s a lot of bilateral symmetry. Running evolution again would give universals like these so it’s possible that they’d also appear on other worlds.’ In contrast, he points to what he calls Parochials; features that have evolved specifically and often only in one group of lifeforms such as feathers, pentadactyl (five fingers or toes) limbs, even the human trait of looking after the ‘cute’ baby animals of other species. Our closest relatives, the Chimpanzees will eat their young during tribal wars - there is nothing 'sacred' about the young to them.

On the subject of Gould’s ‘rewinding life’s tape’ concept, Cohen says: ‘A different fish leaving the sea would have given a different result. The particular fish that did come out of the ocean had its airway crossing its foodway. If a different fish species had come out, we wouldn't choke. Also, it had its reproductive and excretory systems mixed up. If it hadn't, we wouldn't have 'dirty' books - we'd have different kinds of hang-ups altogether. For credible aliens, we want to know what could plausibly happen if we ran evolution again. There are lots of possibilities. Construct the plot from the ecology. Have the ecology and ‘adventure into it’.’

Cohen believes that, when and if we do meet aliens, they won't be biological. They’ll be robots, just like the robots we send out into deep space on missions too long for them to be manned. Voyager 1 was launched in 1977 and, despite travelling at 10 miles per second, will not leave our own solar system until 2015. At that speed, it will take more than 74,400 years to reach the nearest star. Even travelling at the speed of light – 186,000 miles per second – the journey would take four years. It seems a very long way to come to Earth just to identify a few solitary souls that (a) no one will ever believe and (b) who are incapable of operating even a simple point and shoot digital camera with which to capture some decent evidential shots, and then fly all the way home again.

There is also the unlikely fact that they found us at all to consider. Would they really come all the way here without knowing for certain that life exists? Yes, we’ve been streaming radio and TV broadcasts off into space for more than a century but if we can’t hear alien civilisations, why do we expect them to hear us? The likelihood that an inhabited planet lies in the path of our signals is like expecting to shoot the antennae off an ant with a crossbow while blindfolded.

Of course, we can imagine beings for whom an average life span is thousands of years. We can visualise creatures that can survive happily at near-light speeds and maybe even survive in the vacuum of the raw universe. But doesn’t that make it even more unlikely that they’d be humanoid and, for some reason, intent on sexually assaulting us? The analogy would be our astronauts arriving on an alien planet and snogging some moss.
And if evolution of life in Earth - quite possibly the only inhabited planet is the universe - has shown us anything it's that variety is King. Unless we have a common origin, it's next to impossible for life to evolved elsewhere that looks like us, with all of our Parochial features.

Greys? Little Green Men? I don’t think so. Do you?

No comments: