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Accidents of life

Darwinian theory was the best idea of all time, but why did it take so long to evolve? And what if w

If you have overdosed on Darwin this anniversary year, the great man himself is partly to blame: he was inconsiderate enough to publish On the Origin of Species when he was exactly 50. The resulting coincidence of sesquicen­tennial with bicentennial was bound to excite the anniversary-tuned antennae of journalists and publishers. Anniversaries are arbitrary, of course, dependent on the accident of our having ten fingers. If we had evolved with eight instead, we would have to suffer centenaries after only 64 (decimal) years, and style gurus would prate about the changing fashions of octaves instead of decades.

Incidentally, it is not far-fetched that we might have evolved a different number of fingers. The pentadactyl limb (five digits on each) has become a shibboleth of vertebrate zoology, and even animals such as horses (which walk on their middle fingers and toes) or cows (two digits per limb) have lost the extra digits from a five-fingered ancestor. But the lungfish-like group of Devonian fishes from which all land vertebrates are descended included species with seven (Ichthyostega) or eight (Acanthos­tega) digits per limb. If we were descended from Acanthostega, instead of from an unsung five-fingered cousin of the same fish, who knows what feats of virtuosity pianists might now perform with 16 fingers? And would computers have been invented earlier, because hexadecimal arithmetic translates more readily than decimal into binary?

Historical accidents of this sort are rife, contrasting with the illusion of good design to provide some of our most convincing evidence that evolution happened. Sometimes the legacy of history goes beyond arbitrary accidents, and spills over into downright poor design. The vertebrate retina is installed backwards, facing away from the light, which perforce has to pass through a carpet of nerves on their way to the "blind spot" where they dive through the retina, bound for the brain. In spite of this we see tolerably well, because natural selection is good at cleaning up after its bodges. But an engineer who produced such a travesty of design would be fired instantly. The retina is a legacy of remote history.

For whatever reason lost in some Devonian swamp, our ancestors evolved with ten fingers. And that is why Darwin was exactly half a century old when he published the book that set us on the path to understanding the whole of life - its diversity, complexity, beauty, compelling illusion of design, and every detail such as why we have the eyes, fingers and toes that we do.

Mysterious gap

But why did Darwin wait until he was 50 before publishing his great idea (the best idea anyone has ever had, according to the distinguished philosopher Daniel Dennett)? The idea of natural selection came to Darwin more than two decades earlier, in 1838. He wrote out a pencil sketch of it in 1842, then a fuller version in 1844, which he asked his wife Emma to publish if he should die. Then nothing: the mysterious gap. If you were a young man of 30, in possession of the best idea anyone had ever had, would you sit on it until you were 50?

When Darwin eventually did write On the Origin of Species, he was jolted into it by another travelling naturalist, Alfred Wallace, who had the same brilliant idea in 1858. Again in an accident of history, Wallace, who was recovering from a malarial fever on the Indonesian island of Ternate, chose to send his manuscript to - of all people - Charles Darwin.

A potential priority dispute was averted by the gentlemanly behaviour of both protagonists and the smooth diplomacy of Charles Lyell and Joseph Hooker. These elder statesmen of science arranged for Wallace's and Darwin's papers to be read, in their absence, at the Linnean Society in London in 1858, where the great idea fell completely flat and was ignored by all. We remember Darwin more than Wallace because he wrote the book, published in 1859, which fell anything but flat and revolutionised our world for ever.

Hypotheses to explain Darwin's delay range from "He didn't want to upset his pious wife" to "He wanted to get all his ducks in a row before the shooting began", and there may be truth in both. But I remain mystified by the larger question of why humanity as a whole waited until the 19th century. On the face of it, any one of Newton's achievements - optics, gravity, the laws of motion, the differential and integral calculus - seem more difficult, yet Newton's annus mirabilis pre-dated Darwin by nearly two centuries. The proof of Pythagoras's Theorem, and others of Euclid's elegant compendium, pre-date Darwin by more than two millennia.

Once again, Darwin's achievement doesn't seem all that difficult. Why did it elude Aristotle? And everybody else - great philosophers, mathematicians, anatomists, thinkers and achievers of all kinds down the centuries? Why did this simple but staggeringly powerful idea have to wait until the middle of the 19th century before bursting into our consciousness through the medium of two Victorian naturalists? And why, even today, do so many people have difficulty grasping it?

So, what is this best of all ideas, the idea of evolution by natural selection? It is really the principle of the sieve, multiplied a billionfold and applied cumulatively over billions of years. Every generation is a gene sieve (Darwin didn't put it this way, because he didn't know about genes). The genes that fall through the sieve are the minority that drop through from the current generation to the next. In order to do so, the individuals possessing them have to reproduce. And in order to reproduce, they have to survive. Surviving is difficult. There are predators waiting to pounce, diseases waiting to strike. Incompetence takes its toll in missed footfalls or unheeded signals of danger.

Reproduction, too, is an obstacle course. The individual has to find a mate, woo her with alluring feathers or smells, fight off rivals with talons or antlers, feed the young and protect them from marauders. In any generation, only a minority of individuals will become long-term ancestors. The vast majority of animals that ever lived have no surviving descendants. And the genes that jostle and jockey for position in every generation are the genes that, without a single, solitary exception, have passed through the bodies of an ancestral elite, the tiny minority who managed to become ancestors.

The genes that exist are the genes that made it through a million sieves in cumulative cascade. And what was it that made them do so well? They co-operated, through the intricate processes of embryology, with other successful genes to build an unbroken succession of elite individuals, equipped by them to become ancestors. That is why the qualities of the elite are the qualities inherited by every animal and plant: because existence is tough, and competition sorted out the ancestors from the failures

An arms race

The exact equipment for survival varies from species to species, for there are many ways to survive: streamlined wings, in the case of swallows; powerful flukes in whales and spades in moles; bewildering camouflage and mimicry in insects; shimmering tail feathers in birds of paradise. All these are the outward and visible levers that propel the genes that made them through the sieves of the generations. And, to complicate matters, the survival techniques of each species open windows of opportunity for others to exploit, as Darwin recognised.

Wherever you see elaborate and complicated machinery in a living body, it is usually the end product of an arms race, run in evolutionary time, each side accumulating improved equipment to outdo the other - an arms race between predators and prey, between parasites and hosts, even between males and females of the same species.

The modern theory of evolution by natural selection can be expressed mathematically, in a calculus of changing gene frequencies. Darwin was no mathematician and he knew nothing of genetics, but he had the essence of this great and simple idea, and he expressed it with the luminous clarity of one of the greatest minds ever to emerge from the process of evolution that he discovered.

Richard Dawkins FRS was the first Charles Simonyi Professor for the Public Understanding of Science at Oxford. His latest book is “The Greatest Show on Earth: the Evidence for Evolution" (Bantam Press, £20)

This article first appeared in the 21 December 2009 issue of the New Statesman, Christmas Special

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Puffins in peril

Britain’s best-loved seabird is vulnerable to global extinction.

The boatmen helped us scramble ashore and soon there were 50 people wandering on an uninhab­ited slab of sea-battered dolerite called Staple Island. It is one of the National Trust-owned Farne Islands in Northumberland and among England’s most spectacular wildlife locations. There are 100,000 pairs of breeding seabirds here and they were everywhere: at our feet, overhead, across every rock face. The stench of guano was overwhelming.

While the birds seemed to be boundless, the human beings converged on the grassy knoll where the local star attraction resides. It’s the creature that adorns the boat company’s publicity and is emblazoned on the National Trust’s website for the island, the bird that possesses what the poet Norman MacCaig called the “mad, clever clown’s beak”: the pint-sized, parrot-faced puffin.

The British love for this creature is so intense that it is, in essence, the robin redbreast of the sea. Nearly all of its breeding colonies around our coast are tourist attractions. Just across the water, along the shore from Staple Island, is the town of Amble, which holds an annual festival devoted to the puffin. From Lundy in Devon and Skomer in Pembrokeshire to the Isle of May off the Fife coast, or Fair Isle in the Shetlands, trips to puffin colonies are frequent, sometimes daily, events.

“Every tourist shop on these islands sells puffin merchandise – knitwear patterns, tumblers, carvings, coasters, cuddly toys, clothes and, of course, puffin hats,” Helen Moncrieff, the area manager in Shetland for the Royal Society for the Protection of Birds (RSPB), told me.

While the love affair is unquestionable, what seems in doubt is our ability to help the bird now that it is in trouble. Fair Isle once supported a puffin colony of 20,000 birds. In less than three decades, that number has halved. Similar declines have been reported at Britain’s most important puffin site on St Kilda, Scotland, where millions are said to have bred. Now there are fewer than 130,000 pairs, half the total recorded as recently as the 1970s.

The national picture is alarming but the news from elsewhere is even worse. Continental Europe holds more than 90 per cent – five million pairs – of the global total of Atlantic puffins but they are shared primarily between three countries: Denmark (the Faroe Islands), Iceland and Norway. Across this subarctic region, losses have been estimated at 33 per cent since 1979, when monitoring began. But the most striking figure comes from a colony on Røst, Norway, where there has been a fall over this period from nearly 1.5 million pairs to 285,000.

The Westman Islands off the south coast of Iceland hold a substantial proportion of the country’s puffins. Since 2005, breeding success there has been almost nil, and a similar failure has recurred on the Faroe Islands for more than a decade. In both places, where hunting puffins was once a staple of cultural life, catchers today have initiated a self-imposed moratorium.

Puffins are long-lived species and a life­span of between 20 and 30 years is not unusual, yet Euan Dunn, principal marine adviser to the RSPB, explains the implications of persistent breeding failure. “Puffins on Shetland or the Westmans may go on attempting to breed for years, even decades, but eventually all those old adult birds will die off and, if they haven’t reproduced, then the numbers will start to plunge.”

BirdLife International, a conservation network that classifies the status of birds worldwide, has reached the same conclusion. It judges that the Atlantic puffin is likely to decline by between 50 and 79 per cent by 2065. The nation’s most beloved seabird has been declared a species that is vulnerable to global extinction.

To unpick the story of puffin losses, marine ecologists have examined the bird’s oceanic ecosystem and looked particularly at changes in the status of a cold-water zooplankton called Calanus finmarchicus. This seemingly insignificant, shrimp-like organism plays a crucial role in North Atlantic biodiversity and has experienced a huge decline as sea temperatures have risen steadily since the 1980s. While the decline of the finmarchicus coincided with swelling numbers of a close relative, this other zooplankton species is less abundant and nutritious.

As the finmarchicus has suffered, so, too, has one of its main predators, the lesser sand eel. And it is this formerly superabundant fish that is the staple food of puffins in many areas of the Atlantic. At the root of the disruption to marine life are the hydra-headed effects of climate change.

Though no one disputes that an important shift is under way in the sea areas of northern Britain and beyond, not everyone agrees that the present puffin situation is a crisis. A leading British expert, Mike Harris, thinks it is premature to designate the bird an endangered species. There are still millions of puffins and, he says, “We need numbers to plummet before we even start to assume that things are terminal.”

Similarly, Bergur Olsen, one of the foremost biologists studying puffins in the Faroe Islands, believes that the talk of extinction is over the top. “The food situation may change and puffins may well adapt to new prey, and then their numbers will stabilise and perhaps increase,” he says.

***

On Staple Island, the extinction designation does appear bizarre. The Farne Island puffin population has increased by 8 per cent since 2008 and there are now 40,000 pairs. This success mirrors a wider stability among puffin colonies of the North and Irish Seas. The distinction in feeding ecology which may explain the birds’ varying fortunes is that, in the southern parts of the range, puffins can prey on sprats when sand eels are scarce. Sprats appear to have suffered none of the disruption that assails the other fish.

But Dunn says it is important to look at the whole picture. “It’s fantastic that puffins are doing well in places like the Farnes, but remember: Britain holds less than 10 per cent of the world total. Also, the declines that have beset puffins in Shetland and St Kilda are even worse for other seabirds.”

The numbers of a silver-winged gull called the kittiwake have fallen by 90 per cent in Shetland and St Kilda since 2000 and by 80 per cent in the Orkneys in just ten years. Shetland’s guillemot numbers have also halved, and the shag, a relative of the cormorant, has experienced falls of over 80 per cent on many islands since the 1970s – 98 per cent, on Foula. Most troubling is the fate of the Arctic skua, which feeds mainly on fish it steals from other seabirds and is reliant on their successes. Its declines are so severe that Dunn fears its eventual loss as a breeding species in Britain.

While there is disagreement about what to call the puffin predicament, there is unanimity on one issue: much of the data that informs the discussion in Britain is out of date. All of these seabirds, which are of global importance, have been monitored decade by decade since the 1970s. Yet the most recent big audit of our cliffs and offshore islands was concluded in 2000. The full census data is now 16 years old. The organisation that underwrites this work is the Joint Nature Conservation Committee; it is sponsored by the Department for Environment, Food and Rural Affairs, which has suffered deep budget cuts since the 2008 financial crisis. There is no certainty that another comprehensive census will be mounted any time soon.

“Much is made on wildlife television of how special these islands are for wildlife and how much we care about it,” Dunn says. “In the case of our seabirds, one of those claims is indisputably true. Britain holds populations of some species that are of worldwide significance. But if we lack even basic information on those birds and how they’re faring, especially at a time when our seas are in such flux, what message does that send about how much this country cares? And how can we ever act effectively?”

The plight of the puffin is shedding light on the fortunes of our marine wildlife generally and the shifting condition of our oceans as a result of rising carbon-dioxide levels. Now, puffin politics is also starting to show
this government’s indifference to nature.

This article first appeared in the 28 July 2016 issue of the New Statesman, Summer Double Issue