by Simon Barnes
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I. “The Windhover” by Gerard Manley Hopkins, subtitled “To Christ our Lord”. Windhover is an old name for kestrel; another, perhaps wisely not used by Hopkins, is wind-fucker.
II. Woody Allen, being a professional pessimist, entitled a collection of his writing Without Feathers.
III. This point is taken up in the blasphemous song “The Ballad of Joking Jesus”, sung by Malachi Mulligan in the first chapter of Ulysses. It is adapted from a poem written by Mulligan’s prototype, Oliver St John Gogarty.
“I’m the queerest young fellow that ever you heard.
My mother’s a Jew, my father’s a bird.”
No sex please, we’re bdelloids
Some species of bdelloid rotifers haven’t had sex for several million years, but we’ll get to them in a moment. Let us first consider the miraculous appearance of the classic rotifers: the ones that gave the phylum its name, which means wheel-bearers. They look as if they are carrying a rapidly turning wheel on their heads (insofar as it can be termed a head). This is a bigger shock to the perceptions than it sounds: it is not possible for organic life to contrive a mechanism that spins like a wheel, independent of the rest of the structure. The sight of it makes you feel slightly dizzy, faintly seasick. It looks like a piece of clockwork: perhaps the kind used to power Dali’s watches. The first instinct is to say that no, they simply can’t be animals; they can’t be part of organic life as we know it. They look like science-fiction hybrids: part animal, part mechanism: a soft machine.I
A wheel that spins independently of the rest of the structure is a human invention. It required immense imagination to leap away from the forms found in nature: that’s why its invention was such a radical step.
The rotifer wheel is an illusion. It is not a wheel but a mouth surrounded by a corona of cilia: tiny beating hairs that move in a coordinated and rhythmic fashion. This coordination is what makes it look as if the thing is going round and round, much as warning lights on a level crossing look like one light jumping from side to side, rather than two lights going on and off rhythmically. The corona is used for feeding, and in some species it also drives the animal along. This is another example of something that evolved for one purpose successfully used for a second purpose; like feathers in the previous chapter.
Most of us feel as if we may have heard of rotifers. They crop up in pond-dipping experiences and in aquariums. They are microscopic, or near microscopic – there are one or two real monsters measuring 2 mm, .08 inches. They are mostly freshwater creatures, though there are a few that live in salt water, and some that can operate in moist soil and on mosses and algae. Some are free-swimming, some anchor themselves, some crawl along the bottom. There are 25 colonial species. All in all there are (estimates as usual vary) between 1,800 and 2,200 species. They form an important part of freshwater life. Many of them are part of freshwater plankton and are an essential part of the food chain; most are consumers of organic detritus, and so play a big role in keeping fresh water habitable and life-sustaining. It is this talent as cleaner-uppers that makes them useful in aquariums.
We have known about them since 1696. They possess both a mouth and an anus, which makes them incontestably animals. They even have a small brain. And they’re odd about sex. Many of the bdelloid group reproduce by means of parthenogenesis, or virgin birth. A bdelloid rotifer can make more, genetically identical bdelloid rotifers, apparently just by thinking about it. And as said above, it is believed they’ve done so for many millions years: finding no need for genetic diversity as they spin their wheels and live out their aqueous lives.
Not all rotifers take this austere view of sex. Other species are pretty keen on it. Usually, the female is bigger; in some cases as much as ten times bigger. Some species produce degenerateII males that don’t even possess a digestive system. They are, quite literally, only interested in one thing, and are equipped with a penis to fulfil the one function they have been born for.
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I. The Soft Machine is a novel by William Burroughs, and as such, a description of the human body.
II. The word is used here in its scientific sense to mean something that has passed from a complex to a more simple state.
The nausea of Charles Darwin
Birds are beautiful. There’s no ducking it. They’re not incidentally beautiful: they’re beautiful for no reason other than to gladden the senses – and that’s a tough nut for a Darwinian to crack. The hard-eyed functionalism and bracing reductiveness of Darwinian thought seems to come a cropper when you look at birds whose beauty apparently possesses no other function than its own loveliness. Birds really are bright and beautiful. “The sight of a feather in a peacock’s tail, whenever I gaze at it, makes me feel sick,” said Darwin.
There is beauty to be found among us mammals, that’s not in dispute. But the beauty of mammals tends to be incidental. I have never seen anything quite as beautiful as a night-hunting leopard, strolling as if every joint had been bathed in a gallon of oil and glowing as if lit from within. But this beauty is functional: the glorious feline gait tells us about the speed and skill of the hunter; the immaculately maculated coat enables him to hide, both from his prey and from those (che brutto!) that might do him harm. A leopard is beautiful in the manner of an athlete in competition at a track and field meet. Many birds are beautiful in the manner of a female athlete scrubbed up, made up and wearing her posh frock. A female athlete in competition is beautiful quite inadvertently; a female athlete togged up for some big occasion is beautiful on purpose. A female athlete in such circumstances is beautiful like a bird.
You can start with the orange bill and sleek black plumage of the male blackbird in your garden (the female is much less conspicuous) and go on to the plumes of the birds of paradise, the ridiculous elongated tails of the paradise flycatcher, and then to the ultimate swaggering debating point of the peacock, erecting his tail and shivering all over so that the many eyes in the great fan fluoresce and strobe in the sunlight.
There is no reason for a peacock’s tail other than its beauty and splendour. It certainly doesn’t help the bird to live longer: au contraire, it’s a serious handicap, one it sheds rapidly when it’s no longer required. I once startled a peacock that was hiding in a single isolated large bush. I heard something inside the bush and walked around it half a dozen times trying to catch sight of whatever it was, expecting a small bird, thrush-size at best. A peacock with a full tail suddenly lost his nerve at my incessant circling and exploded out of the bush with a great scattering of twigs, alarming the hell out of me as he did so: it was like a hundred pheasants getting up at your feet all at the same time (male pheasants being another example of gratuitous beauty). It was a revelation (epiphany) of the cumbersome nature of the tail: it seemed to take about ten minutes to go past. It needs a huge output of energy to get the whole damn thing up in the air; which is no doubt why the peacock first trusted to concealment rather than escape. The shocking suddenness is part of its withdrawal tactics; if you can make a predator jump, you’ve won yourself a crucial half-second advantage. Life with a tail is hard for a peacock; but it’s no fun at all without one.
Darwin cracked the conundrum eventually: that was his way. He took every problem and ground it relentlessly in the rollers of his mind until he had turned it into powder. He came up with the breakthrough notion of sexual selection: something that “depends not on a struggle for existence but a struggle between the males for possession of the females; the result is not death to the unsuccessful competitor but few or no offspring”. That’s the end of the line for his genes, as we now understand the situation. In other words, males compete for females, and those who please the females most (and who also succeed in repelling male rivals most effectively) are those who get to pass on their genes. So if females like, say, a red breast, then the bird with the reddest breast will find favour while a bird with a duller breast won’t. It makes sense, then, to flaunt that breast, both at females and at riv
al males: which is of course exactly what the robin in your garden does.I Competition is at the heart of Darwinism. Different species compete with each other as to which is most suitable – most fit – to exploit a certain ecological niche; individuals of the same species also compete. And competing for the finest female available is one aspect of this competition.
And here’s a snag that made the idea of sexual selection very unpopular when Darwin first introduced it: the implication of sexual selection is that the casting vote on the future of a species lies with the females. Males come up with suggestions; females make the decisions. The traditional Victorian world-view didn’t find it easy to accept that sexual selection – that female choice – was an important force in shaping the world we live in, and was perhaps a factor in determining who and what we humans are today.
Sexual selection says how: and that’s how a peacock’s tail came about. It doesn’t say why. Why have peafowls chosen, over the centuries, these extravagances of blue and green? What aesthetic preferences guided them to these choices that led to this maddest of avian affectations? How come that again and again in the class of birds, very clear but very different aesthetic standards were established?II Why do birds desire beauty?
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I. The great ornithologist Chris Mead claimed to have observed a robin displaying at his own glorious red beard.
II. A question explored in David Rothenberg’s remarkable The Survival of the Beautiful.
Evolution in reverse?
Life starts simple and gets more and more complex. That’s the idea; that’s the whole bloody point, isn’t it? You start off with slime mould and end up with the blue whale. And us, of course. The whole idea of evolution is to make ever-more complex creatures: a great unfolding saga of improvement. With us as the crown of creation.
And then you get to the Acanthocephala, or thorny-headed worms. They have taken the reverse direction. They have simplified. They have lost the gut, and most other organ systems have been drastically reduced – apart from those to do with sex. They don’t even have a mouth. They were originally considered a phylum of their own; now they are more frequently regarded as greatly modified rotifers. Greatly simplified rotifers: they have discarded complexities, all the better to live the life of a parasite. Once established in the gut of some vertebrate, they just hang there absorbing nutrients. And that’s where the thorny head comes in handy: all the better to attach themselves to the gut wall. The proboscis has a collection of spines or hooks and the whole thing can be withdrawn into the body cavity. Once established in the gut, there the thorny-heads dangle: I have seen a picture of the gut of an eider duck that is lined, positively furred, with these pendant worms. There is a record of 750 worms in a single duck. The loss of nutrients to these parasites is a problem for the host, of course, but the greater problem is the ulceration of the gut lining caused by the thorny-heads and their uncompromising trick of attachment.
They have abandoned complexity in body plan, but they have certainly acquired complexity in life cycle. Their basic plan is to exploit two hosts: as a juvenile, this is usually a crustacean or an insect, typically a beetle or grasshopper. But they need this host to be eaten by a vertebrate if they are to become adults. One species tends to parasitise a crab that lives in darkness and obscurity, but once infected by the thorny-head in question, it abandons the ways of its kind and becomes an urgent seeker after light, sometimes climbing clear of the water onto exposed rocks or emergent plants: more or less begging to be devoured. It’s a pattern not unlike the Hamlet worm in the chapter on nematomorphs, but it gets even cleverer.
Once the first host has been devoured the worm can become an adult and set up residence in the gut of the devouring vertebrate. These hosts are usually fish, though all classes of vertebrate are options. Inside the host they meet, have sex and produce eggs: and the eggs are passed out of the host with the faeces… which is in turn devoured by some scavenging crustacean or insect, which then becomes host number one for the newly hatched juvenile. There are more than 1,000 species described, most of them less than 20 cm or 8 inches long, though some measure up to 60 cm or a couple of feet.
So it’s not survival of the cleverest, the most beautiful, the most complex: it’s survival of the fittest. The most suitable. And the great simplifications of the thorny-heads make them superbly suited to the task of parasitising the guts of vertebrates. This is not evolution working backwards, for with evolution there is no forwards and no backwards. Only survival. Here is a good word: teleology. It is about purposeful direction: in Ulysses, Mr Deasy says: “All history moves towards one great goal, the manifestation of God.” Teleology is about being goal-orientated: but evolution is not teleological. Evolution is not driven towards a great goal of complexity. Evolution is just about getting through the day.
How many ways of catching a fish?
It looked so exactly, so perfectly as it was supposed to that I could hardly believe it was real. This was my first sight of a toco toucan: the oneI with the orange and black bill and the black and white plumage: the classic toucan from the Guinness advert. It was as if I had been taken back to the Garden of Eden, the one you can read about in the book of Guinnesses.II How gloriously absurd: is this the beak of beaks? I wondered that the bird didn’t tip nose down and crash out of the trees into the Paraguay River. You can’t believe, watching with mammalian eyes, that such a thing could be airworthy.
But the forces of evolution can do almost anything with beaks. Archaeopteryx, the proto-bird, had a bony head and teeth, being a half-and-halfer. But modern birds have beaks made from keratin, the same stuff that feathers (and for that matter fingernails) are made from. This is weirdly strong and fantastically light, and it has allowed birds to come up with the most extraordinary variety of shapes and sizes and ways of making a living.
So sit with me on the banks of the Luangwa River on a bright morning and count the number of beaks: count the different ways in which a bird can catch a fish. A grey heron, the same species as found in Britain, holds still and stares at the water, waiting for a chance to lunge with a spear-shaped beak and grab. This technique works so well that there is a great radiation of herons across the world, and many of them are found in the Luangwa: the tiny green-back heron clambering in overhanging branches, the rightly named Goliath heron, the little and the great white egrets,III the black egret that adds a refinement to the wait-and-grab technique by making a shade over the water with its wings, and the black-crowned night heron that has the river mostly to itself when the daytime fishers are in bed.
Then there are kingfishers: the tiny malachite kingfisher that fishes from a perch, the chunky pied kingfisher that hovers, and so is freed from the ties of the bank, and the football-sized giant kingfisher. They have beaks of different sizes, each one adept at taking fish of different sizes. The yellow-billed stork adopts a wait-and-see tactic, standing in the water with big yellow bill agape, locating fish by touch. Behind them, immensely busy, looking like a husband showing his wife how the hoovering should really be done, is the African spoonbill, sieving up small scraps of life with its damn great ladle of a bill. The African fish eagle prefers to swoop on a fish from a riverside tree, sweeping it up in a killing clasp and taking it to a perch to butcher it with its great hooked bill. I have seen a fish eagle catch a fish too heavy to fly with: it just about got it to the bank, but couldn’t take off, and eventually lost the prize to a croc. In the night, the same fishing tactic is pursued by the massive tangerine-coloured Pel’s fishing owl, which generally works from the banks. Pelicans are not often seen on the river, but can be found on the lagoons when the dry season ends, where they use their preposterous bills a bit like purse-seiners. They are particularly fond of the time at the end of the dry season when the lagoons shrink drastically and the fish are exposed. The lagoons become muddy puddles boiling with fish, and taking them out really is like spearing fish in a barrel.
And then along the river, uncommonly graceful, comes a pair of
African skimmers. They look like enlarged terns – until they start to fish. Then they drop the lower mandible of the bill – noticeably longer than the upper – and plough a furrow across the water, leaving a beautiful, long, straight, ever-vanishing line, as if they were drawing across the surface of the water with a Chinese calligrapher’s brush. But it’s not art, not from the skimmers’ point of view: their senses are fully engaged and they are ready to snap up anything they come across. And if you make a trip across Zambia to the Bangweulu Swamp, you might be lucky enough to find a shoebill: a heron with a beak like a Dutch clog that it uses to catch lungfish.
So many fish: so many ways of catching them. So many birds: so many beaks. The Luangwa riverside is a virtuoso display of evolution: an almost showing-off demonstration of how many variations can be worked on a theme. Evolution takes keratin and moulds it into beak after beak after beak, as a child makes endless shapes with a chunk of Plasticine. The feather is the soul of the bird and is common to all birds. The beak is a more individual thing, something that often defines a species. A feather is a symbol of the great class of Aves. The beak is a badge of individuality, sported by each separate species.
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I. The toucan family, the Ramphastidae, comprises 40 species in five genera.
II. A joke stolen from Finnegans Wake.
III. Why are egrets white? It makes them stand out from the surrounding countryside with uncomfortable clarity. But if you look at them from the water upwards, as a fish does, then you see only the egret’s pallor against the pallor of the sunlit sky. A fishing egret is close to invisible to its prey.