The Oldie
Profitable Wonders
August 2009
The Earthworm
The seventeenth century metaphysical poet Thomas Traherne in the introduction to his major work Centuries of Meditation’had a mind to fill it with Profitable Wonders’. Not, obviously, the profit of income over expenditure but rather the profit that is advantageous to those who recognise what it means to live in an enchanted world. “You never enjoy the world aright till the sea itself flows in your veins, till you are clothed with the heavens and crowned with the stars,” he wrote, “till you so love the beauty of enjoying it, you are earnest to persuade others to enjoy it too.”
For Thomas Traherne there was nothing too commonplace that did not command his attention. Here the obvious of our everyday lives becomes, on reflection, distinctly non-obvious. “What diamonds are equal to my eyes, what gates of ivory to the double portal of my lips and teeth. Is not sight a jewel, is not hearing a treasure, is not speech a glory."
And there is nothing so full of profitable wonder as the natural miracle of self renewing life marching down through the ages in such an abundance of shape, form, attributes and propensity as to encompass the full range, and more, of what might be possible. Why should the ten thousand species of birds yet be so readily distinguishable one from the other by their pattern of flight, or the shape of their wings, the colour of their plumage or the notes of their song? “By their melodious accents they gratify our ears,” observed John Ray, the original ‘twitcher’, founder of the scientific discipline of ornithology and direct contemporary of Thomas Traherne. “By their beautiful shapes and colours they delight our eyes, without them the hedges and woods would be lonely and melancholy."
Four hundred years on we should, by rights, be vastly more appreciative of such profitable wonders for we now know so much more about the natural world and the deep complexities that underpin it. Yet one could search a shelf’s worth of biology textbooks in vain for the slightest hint of the extraordinary in their detailed exposition of the fact of zoology and botany, anatomy, physiology or embryology. Science no longer does ‘wonder’ for it is in thrall to the belief that there is nothing in principle it cannot account for, where the unknown is merely waiting-to-be-known. This presupposition of understanding that would reduce that near infinite diversity of life to the nuts and bolts, proteins and enzymes of which all living things are made, disenchants the world by propagating the illusion we know so much more than we do, or can.
It was not always thus for biologists of preceding generations were inspired by the grander vision that ‘the truth’ lay rather in the intricate interdependency of the living world. Thus, the survival and prosperity of our species is, as the one time Professor of Natural History at Aberdeen University J Arthur Thomson points out, utterly dependent on the labours of the humble earthworm—without whose exertions in aerating the dense, inhospitable soil there would never have been a single field of corn.
"When we pause to think of the part earthworms have played in the history of the earth, they are clearly the most useful of animals. By their burrowing they loosen the earth, making way for the plant rootlets and the raindrops; by bruising the soil in their gizzards they reduce the mineral particles to more useful forms. They were ploughers before the plough, five hundred thousand to an acre passing ten tons of soil every year through their bodies."
December 2009
The Heart
For the Reverend William Paley of ‘Natural Theology’ fame, the mechanics of the living world exhibited ‘every indication of contrivance, every manifestation of design’—which when compared to man’s much humbler efforts (and here Paley cited the complex interdependent components of a watch)’is greater and more to a degree that exceeds all computation’.
At the time it seemed a knock down argument, and indeed there was something exhilarating about living in a world where every aspect of nature spoke of God’s ‘wonder and providence’. But the more that science progressed in describing in ever greater detail the physiological and anatomical aspects of (for example) the eye, the less convincing became Paley’s suggestion that it ‘alone would be sufficient to support the conclusion … as to the necessity of an intelligence creator’. It seemed an absurdity, demeaning indeed, to suppose that He had nothing better to do than concern himself with the minutiae of designing the nuts and bolts of tens of thousands of species,both living and long since extinct. And anyhow who was to tell what the technical advances of the future might bring—and Paley could scarcely have anticipated microelectronics and the silicon chip—that might permit man to equal, or indeed surpass, the Grand Designer’s best efforts?
This latter proposition has recently, and interestingly, been put to the test with the research programme to develop an artificial heart whose (relatively) simple pumping mechanism is no different in principle from the ubiquitous electric pump that powers the household shower.
To be sure, the human heart is a lot more powerful. No bigger than an orange and weighing little more than a pound it generates enough force to propel the body’s five litres of blood through the pipeline of arteries and veins that stretched end to end would stretch from Paris to Moscow—fifteen hundred miles in all. The human heart is also ‘highly efficient’ in the technical sense of performing twice as much ‘work’ in relation to the amount of fuel utilised as any conventional man-made pump. This is due in part to the unique arrangement of the overlying spirals of its muscle fibres which become progressively shorter as they taper down to the tip (in the same way that a number of bricks in each row of a cathedral spire gradually diminished as it tapers upwards), thus squeezing every last drop of blood out of the cavity of the ventricles at each heart beat. And for good measure this masterpiece of engineering efficiency should, with luck, run for the two and a half thousand million cycles of a lifetime without maintenance or lubrication, or the need to replace its four sets of valves which open and close four thousand times every hour.
Starting in the 1960s, the early pioneers of the artificial heart anticipated some difficulty in matching these specifications, but it still took twenty years to come up with the first workable device. This was implanted into a retired American dentist who went on to develop respiratory and kidney failure and blood poisoning before dying four months later. Over the next few years a similar fate befell a further two hundred patients before the American Food and Drug Authority intervened and called a halt.
By now it was clear the task was hopeless—but perhaps it was suggested it might be possible to achieve a compromise with an artificial heart that could act as a stopgap measure. And after forty years and billions of dollars that, it seems, is as far as we are likely to get. The current model weighs twice as much and is a fraction as efficient as nature’s version, its energy supply transmitted through a couple of tubes connected to a console the size of a chest of drawers which can only be moved around on rollers. This clumsy device can sustain the patient for up to two months in hospital until a transplant of nature’s much better version becomes available—that can keep its recipient fit and healthy, climbing mountains or deep sea diving, for twenty years or more.
The pump-like mechanism of the heart is much the simplest of physiological systems, simpler by far than the complexities of brain or kidney or the sense organs such as the eye—that so excited the Reverend Paley’s admiration. So when, as here, the purposeful efforts of today’s bioengineers, employing the most sophisticated medical technology, falls so far short of nature’s model, one can only profitably wonder at what prodigious biological phenomenon—as yet unknown to science— ensures the nuts and bolts of life are indeed constructed to the very highest specifications of automated efficiency.
December 2010
Skin Deep
We are, for the most part, so comfortable in our skins as to rarely reflect how this seamless stocking, flexing around the contours of the body, should combine so many variations on a single theme:delicate and callused, radiant and wrinkled, smooth and hairy, lax over the joints yet tight over the shins. Nor indeed how it reconciles in a single structure the two contradictory properties of resilience and sensitivity—both a robust barrier against the physical assault of heat, cold and pollutants of all kind, yet also exquisitely sensitive to the subtlest of changes in the external world.
Charles Darwin in a famous passage from The Voyage of the Beagle captures this paradox in a memorable image, describing how when anchored off Tierra del Fuego, “A canoe with six quite naked Fuegians came alongside and remained all day out of curiosity". He was particularly struck by seeing a woman “suckling a recently born child whilst sleet fell and melted on her naked bosom, and on the skin of her naked baby".
The same year, far away in the Czech (at the time) city of Breslau, the recently appointed Professor of physiology, translator of Shakespeare and general polymath Jan Purkinje was refining the techniques for visualising down the microscope the then hidden microstructure of the body’s tissues. “Every day brings new discoveries!” he wrote excitedly in his diary—including the profundities of that seamless stocking.
First, its resilience poses the obvious question how the fragile delicate cells from which it is fashioned can nonetheless form that inviolable protective barrier. Here Professor Purkinje noted how the layer of living cells just beneath the surface of the skin grew outwards to form a single flattened layer of dead cells—the stratum corneum. This is then discarded at the rate of hundreds of millions of cells a day to be replaced by those moving up behind—just like successive waves of infantrymen marching into battle.
So, the whole of life, our existence and that of all living creatures, is utterly dependent on this layer of dead cells, no thicker than a sheet of tissue paper—that has the further vital property of being doubly waterproof, both preventing water getting in (or otherwise we will become water logged every time we took a bath), while ensuring the sustaining internal fluids do not leak outwards.
And as for the skin’s antithetical virtue of sensitivity, it can be difficult to grasp its staggering acuity in being able to discriminate between an ethereal puff of wind and a single molecule of water on the skin. Here professor Purkinje and his colleagues scrutinising their slides down the microscope discovered an abundance of different shaped nerve endings, round, thin, oval and many others that mediate those diverse sensations of touch, pain, pressure, heat and cold.
And if that were not enough the microscope also revealed another wonder of a different kind of direct relevance to those naked Fuegians—how it is that though the temperature that day must have been hovering around freezing, their body temperature would remain constant at 37 degrees centigrade—thus melting, as Darwin noted, those flakes of sleet on that naked bosom.
The explanation lies in the network of capillaries just below the surface of the skin that is far too extensive than would be required were it just supplying oxygen and nutrients to the surrounding tissues. Rather the network’s purpose is to ensure the constancy of that core temperature –dilating on a hot summer’s day to dissipate the body’s heat outwards and, on that bitterly cold day in Tierra del Fuego, constricting to conserve it. The most optimistic of bioengineers could never aspire to create a covering with such extraordinary specifications—and, pace Charles Darwin, one might profitably wonder why.
March 2011
Regeneration
The salamander is a most intriguing creature, its poetic sounding name being derived from the Persian for ‘the fire within’—as, according to the 12th century Latin text The Book of Beasts,’it prevails against fire … the only creature that can live in a blaze without being hurt’. This charming notion, it is suggested, derives from the effect of adding its favoured habitat of damp logs to a fire—from which it must be presumed it was sometimes observed to escape unscathed.
There are around 500 species of this splendid amphibian ranging in size from the minute at just over an inch long to the six foot Chinese Giant Salamander. The most familiar, and a popular family pet, is the handsome (if redundantly named) Fire Salamander whose shiny black skin is splashed with what looks like splodges of bright yellow paint.
They are for the most part carnivorous feeding on insects, snails and slugs. The Palm Salamander from Central America possesses reputedly the fastest moving tongue in the animal kingdom whose explosive thrust and elasticated recoil captures its prey on its sticky padded tip in less than a thousandth of a second—far too rapid to be seen by the human eye.
But the most impressive attribute of the salamander, for which it is justly famous, is its extraordinary ability to regenerate injured or amputated limbs as first described in 1769 by the Italian biologist (and catholic priest) Lazzaro Spallanzani.
Within a few hours cells start to migrate from the cut surface of the limb stump to cover the wound beneath which a ‘blasteme’ of tissue is transformed into the bone, nerves, muscle and blood vessels that’pushes out’ to form a perfect replica of the missing appendage.
This process is similar to the formation of the limb bud during early embryonic development but with the remarkable feature that the new limb exactly replicates the missing part. Thus, an amputation at the level of the ankle will result in regeneration of foot and toes, whereas at the hip the leg will regrow in its entirety. Remarkably too, the blasteme is also autonomous containing within itself all the necessary instructions for the regenerative process independent of any influence from the amputated stump—so will regrow the limb even if transplanted to some other site, such as the eye.
Spallanzani’s observations prompted biologists to seek out similar more or less extraordinary instances of regeneration: insects such as the locust and cockroach can also, like the salamander, regrow lost limbs, as can the crab and lobster; cut the eye bearing stalk of a snail and it will grow another, and repeatedly so if the experiment is repeated; the star fish exhibits ‘bidirectional regeneration’, replacing an arm if lost while the ‘lost arm’ in turn will give rise to a new star fish; lizards will regrow a tail surrendered to a predator, and the stork and chicken can regenerate a damaged beak.
The planarian worm most impressively of all will, if chopped into 250 pieces, regrow a head and tail for each. They will, in the interim, feed off their own tissues to provide the energy necessary to survive before regrowing a new mouth and gut.
We might rightly admire such exuberant examples of the normal processes of healing and repair that, observes Alejandro Alvarado of the Carnegie Institution in Washington,’has withstood the probing of scientific inquiry for 250 years and still awaits a satisfactory mechanistic explanation’. Perhaps the more instructive aspect of the phenomenon of regeneration is its insight into how organisms possess a wholeness of form that transcends the materiality of their constituent parts. Those parts can be destroyed yet the salamander and star fish, crab and planarian worm can still reconstitute that wholeness—as if guided by some metaphysical intuition of what is entailed in existing in their entirety.
May 2011
The Ant and the Butterfly
The Large Blue butterfly is in truth not very large at all, its two inch wing span being only slightly greater than that of the Common Blue. It does, however, occupy a special place in the affections of all lepidopterists by virtue of its unusual life history which ranks amongst the strangest of any creature. In the last week of June and early July the female deposits her miniscule pearl like eggs on the petals of wild thyme flowers from which the caterpillar form emerges to feed on their downy blossom. Then the caterpillar, after its third skin-casting, becomes restless, drops to the ground and begins to walk,’as though’, comments naturalist E L Grant Watson,’ it wants something but is not quite sure what’.
The caterpillar walks and walks until it meets and is recognised by a red ant of the species myrmica sabuleti who starts to caress and stroke it with feet and antennae to which it responds by secreting from a pore on its tenth segment a sweet honey-like dew much to the ant’s liking. After a time,’prompted by some unexplained and mystic sympathy’, the caterpillar rears up—a signal it wants to be carried off. The ant seizes it gently in its jaws and heads for its underground home placing it in one of the chambers where its own progeny, the young ant eggs and larvae are being nurtured—and on which the caterpillar will feed, while continuing to produce its honey dew secretions as payment for its hosts’ generous food and lodging.
They hibernate together for the winter, and come the spring, the caterpillar pupates forming the chrysalis from which it will emerge as a butterfly, its wings at first unexpanded, like limp and shrivelled leaves drooping on each side of its body. How unlikely a place—the dark underground of an ant’s nest—for a butterfly to find itself.
And then the hosts, in a final act of inexplicable altruism, escorts this one time devourer of their children through the dark passages of their home up towards the light , encircling it to ward off any predators as the butterfly fills the veins of its wings with its pale yellowish green blood. And off the Large Blue flies for the few short weeks of its adult existence, just time enough to seek a mate and produce its eggs, before the life cycle starts over again.
That transition from egg to adult depends on so many bizarre and fortuitous events, its seems astonishing that the Large Blue exists at all—and indeed just over thirty years ago it became extinct in Britain. But that is not the end of the matter, for when Jeremy Thomas, Professor of Ecology at Oxford University sought to reintroduce it back into this country, he discovered its survival is predicated on several other factors—not just colonies of red ants in close proximity, but as they are heat dependent, that the grass is kept short by grazing animals so as to warm the soil. Nor can the summer be too hot, as rain encourages the ants to forage—thus increasing the likelihood of that chance encounter with the caterpillar.
It has taken Professor Thomas the best part of a decade of intense effort to recreate the right ecological balance for butterfly and ant to renew their surprising relationship—and now once again the Large Blue can be seen fluttering across the meadows of Devon and Somerset. “The extravagant idiosyncrasies of its life,” suggests Grant Watson should cause all’to pause and wonder’.
August 2011
The Potato
We may like to imagine our distant ancestors helping themselves to Nature’s bounty, plucking ripe grapes from the vines overhead, lifting splendid sized turnips and carrots from the soil—but as the famed naturalist Jean-Henri Fabre points out it was never like that. While she supplies, through the food chain, abundant provision from the highest to the lowest of the animal kingdom, for humans she has always been’a harsh step-mother’, requiring us to labour mightily, the sweat forming on our brows, cultivating the original wild varieties of grasses and vegetables so as to transform them into life-sustaining, hunger-assuaging foods.
Wheat would be a pale shadow of its present self were it not for two fortuitous genetic accidents ten thousand years ago creating the fertile hybrids with other grasses that would turn it into ‘the staff of life’. But the plump ‘ears’ of grain that resulted, tightly enclosed in their protective sheath of chaff could not propagate themselves. It required rather human labour to reap the harvest, winnow it, grind the grain into flour and then scatter the seeds for next year’s crop.
And so too the potato which in its original state in the inhospitable mountains of Chile and Peru was, as Fabre records,’a meagre inedible tubercle, the size of a walnut’. “Man plants this sorry weed, tends it and makes it fruitful. The potato thrives growing in size and nourishing properties to finally becoming a farinaceous tuber the size of a fist."
And that farinaceous tuber—so easy to grow it can be cultivated, if necessary, with bare hands—sustained the great 400 year civilization of the Incas whose empire stretched from present day Argentina to Colombia. And then famously it arrived in Europe to become the cheap staple diet of the labouring masses making possible that explosion in population that underpinned the Industrial Revolution.In Ireland between 1760 and 1840—where just half an acre of potatoes could sustain a (large) family for a year—the population soared from 1.5 million to 9 million, an increase of 600% in just 80 years.
It would be difficult to underestimate the influence of the potato on human affairs for reasons that verge on the metaphysical. It is, to start with, no mean achievement to be a’staple food’ requiring the potato not just to provide sufficient energy generating calories to fuel the cycle of life, but all those essential vitamins—thiamine, riboflavin, folic acid and niacin-, and minerals—magnesium, phosphorous, iron and zinc—without which humans are vulnerable to such devastating deficiency diseases as scurvy, beriberi, anaemia and the like.
Nor does it stop there, for this commonplace undistinguished tuber provides more joyous gastronomic variety than any other food. Jane Grigson devotes nearly 20 pages of her famous vegetable book to the possibilities whose names alone are sufficient to evoke a thousand memorable meals—roast, boiled, mashed and baked potatoes, potato salad, soup, gnocchi and gratin. Nigel Slater elaborates, reflecting on what it is about eating potatoes that make him ‘feel so good’. “Could it be the way its flesh soaks up cream and garlic in a gratin, or mashes so beautifully with butter? Might it be the way its outside crisps and shines when roasted while its inside stays moist and gooey? Perhaps it is the pleasure I get from squashing a steamed potato into the gravy of a lamb casserole. Maybe it is hearing the salty rustle of the thinnest frites around a sizzling steak. Or could it be that moment when I smash open a baked potato and its solid white flesh turns to hot white snow?"
Growing concealed from view beneath several inches of earth it is perhaps too easy to take for granted the source of so much goodness and pleasure. Certainly the subterranean alchemy by which the potato plant absorbs nutrients from air and soil defies any ready explanation—as does its converting them into those bulging edible protuberances on its roots. “When we eat a potato, we eat the earth and we eat the sky", writes the ecologist John Stewart Collis. This, he suggests, exemplifies that law of nature, “Much from little, even something out of nothing. Whenever anyone takes a good look at a potato, faith is reborn."
October 2011
Life’s Big Bang: Part 1
Science’s ability to penetrate deep into the unimaginably distant past never ceases to amaze. It is impressive enough that we can trace our human lineage all the way back to our earliest ancestors on the plains of the African Savannah three million years ago. But traversing the aeons of preceding time, palaeontologists can now provide a comprehensive account of the whole range of complex life forms that emerged during the Cambrian period 530 million years ago—so long ago that in the interim, as it were, the glacial movement of the tectonic plates beneath the earth’s surface have had time enough to elevate the depths of the oceans to the soaring peaks of the Rocky Mountains.
This notion of the Cambrian ‘explosion’ of life is scarcely novel. Victorian geologists tapping away at ancient rocks with their hammers were forcibly impressed by the dramatic transition between those strata empty and devoid of life only to be filled, from apparently nowhere, by the sudden influx of billions upon billions of fossilised remains.
Still it was not till the first decade of the twentieth century that the opportunity arose to examine those fossils in the detail necessary to recognise their unique and striking characteristics. In 1909 Charles Walcott of the Smithsonian Institute in Washington was returning from an expedition in the Rocky Mountains when his (pregnant) wife’s horse stumbled on a rock—prompting him to split the offending boulder with his hammer, revealing a profusion of the most perfectly preserved fossils ever encountered. Since then palaeontologists have dug out, scrutinised and categorised 70,000 specimens from the Burgess Shale, as it is known, (and similar more recently discovered sites in Siberia and China)—the highlights of which Professor Simon Conway Morris describes in his book The Crucible of Creation.
We start with the’mud dwellers’ in the ocean floor featuring the ‘efficient and dangerous’ worm-like predator Ottoia whose retractable proboscis sucks its prey towards its mouth where a formidable array of sharp teeth, pointing inwards and downwards extends astonishingly into the upper line of the digestive tract —ensuring there can be no escape. Then we encounter the remarkable variety of sponge-like ‘mud-stickers’ fixed to the ocean floor such as Dimonischus that resembles a daisy with a long stalk topped by a goblet-shaped body formed from a palisade of plates each covered by numerous miniscule hair-like cilia that strain the sea water from food. Next we meet this extraordinary bestiary of ‘strollers walkers and crawlers’ including the famed trilobite with its armoured carapace and Hallucigenia, so called because of its ‘bizarre and dream-like appearance’ propelling itself on seven sets of stilts echoed by seven tentacles protruding from its back. And finally there are the ‘swimmers and floaters’ such as the darting lancet-like Pikaia that moves by flicking its body in a series of rapid side to side undulations.
This exhilarating exuberance of the these fossils would seem to contradict the common perception of the Tree of Life starting off simply enough before diversifying into ever more sophisticated and complex forms. And indeed it does—but its true significance is much profounder still.
The main virtue of the scientific method is its ability to reveal the hidden and unifying reality behind appearances—and no more so perhaps than in recognising that the millions of species with which we share the planet, and the vastly greater number long since extinct, can all be categorised as belonging to just one or other of a limited number of basic ‘body plans’. Thus while the diverse forms of insects (butterflies, beetles, flies, ants and so on), crustaceans (crabs, lobsters, shrimps) and the arachnids (notably spiders) could scarcely be more distinct, they are all arthropods built on the same plan with segmented bodies consisting of a head, thorax and abdomen, six or more legs, held in place by an external exoskeleton. This is in marked contrast to, for example, the very different body plan of the legless worms with their long cylindrical tube-like bodies, or the echinoderms such as the star fish or sea urchin defined by the radial symmetry of their five or more similar parts. And then there are the chordates with a backbone and spinal cord and complex circulatory and nervous systems that encompasses the millions of species of fish, reptiles, birds and mammals (including ourselves).
The most astonishing of all the extraordinary observations—which has only recently become apparent—to emerge from categorising these fossilised forms of life that arrive ‘from apparently nowhere’ during the Cambrian explosion is that (bar one) each of these basic ‘body plans’ is represented. “Let us seek to fathom those things that are fathomable", observed the great poet and naturalist Johann Goethe, “and reserve those things that are unfathomable for reverence and quietude".
November 2011
Life’s Big Bang: Part 2
The world, and our understanding of it, is happily full of surprises—though few quite as surprising as the recent scientific revelations of the distant past. The notion of a’Cambrian explosion’ is certainly familiar enough as suggested by the sudden appearance of the fossilized remains of diverse forms of life in ancient rocks laid down 540 million years ago. But who could have imagined that when palaeontologists had finished categorising those first simple (though in fact very complex) creatures they would encompass the distinctive body plans on which all subsequent forms of life are modelled—insects, crabs and spiders, legless worms, segmented starfish and the ‘chordates’, the millions of species of fish, reptiles, birds and mammals with which we share our planet.
There have been surprises too of a rather different, but similarly challenging, sort from studying the life and history of the most successful of those early creatures—the famed trilobite. The joy of the trilobite is that its armoured carapace fossilizes so well, as indeed do the several intermediates it must discard as it increases in size to adulthood.
This near limitless supply of fossilized remains found in successive strata of rock provides the unique opportunity to observe the entire evolutionary history of a single organism from its first appearance to its final extinction 250 million years later.
First their general structure provides an opportunity to reflect briefly on what is entailed in the sudden emergence of a novel form of life where ,as paleontologist Richard Fortey describes, “There is not a sniff of a trilobite as you work your way up from one (geological) bed to another till quite suddenly one as big as a crab will pop into your waiting hand as you split a rock".
The trilobite’s carapace consists of three segments, the head together with a pair of antennae and two prominent eyes (the trilobite was amongst the first creatures to see), a segmented body and tail. The paired legs are arranged beneath together with its mouth, anus and digestive tract, a simple circulatory system and a brain to coordinate its activities and perceive the external world. It is not necessary to be a creationist to be deeply puzzled as to how these many specialised parts and functions ‘came together’ seemingly from nowhere to form the immensely successful creature the trilobite will become.
Then, reverting to the geological search for this fossilized remains Robert Fortey describes how in the rocks a foot or so higher up ,that first trilobite is joined by others “half a dozen or so different species all individually quite distinctive’. A bit further up and there are more still and it becomes clear that the cardinal feature of the trilobite is its creative exuberance: its 17,000 (or more) species each a readily recognisable variation on the same simple theme, “As odd a parade as any carnival could offer—giants and dwarves, pop eyed popinjays, blind grovellers, flat as pancakes or puffy as profiteroles.”
Some bristle with dangerous,fantastically shaped spikes while others are covered with ridges ‘as complex as a fingerprint’. And that variation extends beyond the merely anatomical to whole scale specialised adaptations as trilobites diversified to become variously predators tearing their prey apart with their legs and spines, peaceful grazers on beds of algae ,or (like whales) particle feeders with filter chambers to extract the nutrients from the sea.
All this however is no more than a triviality when trying to conceive the processes behind that evolutionary leap to becoming a sighted creature requiring the simultaneous development of an eye composed of thousands of perfectly angled lenses with a photosensitive cell at the base of each and the neural networks in its brain to construct a visual image of the external world.
And how they endured! Each of those thousands of species persisting virtually unchanged for tens of millions of years. Then towards the end of their 250 million year reign, the trilobites life force seems to have exhausted itself , its numbers dropping precipitously till finally vanishing as suddenly as it had arrived—leaving behind a stunning affirmation, immortalised forever, of the creativity of life.
Recent Comments