Whales’ Legs, Flies’ Eyes and Human Tails

German scientist Ernst Haeckel made many contributions to the sum of human knowledge. He described thousands of species, coined scientific terms such as ecology and stem cell and made one of the first serious attempts to construct a tree of life based on evolutionary principles. He was also a talented artist, his book of illustrations, Kunstformen der Natur, having a major influence on early twentieth century art.

Haeckel summarised his most controversial theory with the phrase ‘ontology recapitulates phylogeny‘ meaning that the development of an organism (ontology) mirrors its evolutionary past (phylogeny). For example, he believed that in early stages of development the human embryo possessed fish-like features. It then progressed to a reptilian state followed by an early mammal form before becoming recognisably human.

This idea combined with Haeckel’s stridently anti-religious outlook made him a target of public campaigns to discredit him. He was accused of modifying his illustrations of embryological forms to support his theory, which to some extent he probably did. Haeckal no doubt believed in recapitulation but in his earnestness he interpreted the superficial similarities between embryos and other animals as concrete evidence, not unlike the pareidolia suffered by Japanese paleontologist Chonosuke Okamura.

The theory of recapitulation has long been discredited but the idea that we retain some imprint of our distant evolutionary predecessors may not be so far-fetched.

Atavism, from the Latin atavus meaning great-great-great grandfather, is the phenomenon of an organism reverting to an ancestral form. Many examples of whales with hind legs have been recorded, occasionally with feet and toes, an atavistic throwback to their land-dwelling deer-like ancestors. There are also sporadic reports of horses with ulnas and fibulas, one of the pair of bones found in the fore and hindlimbs of many animals but which is normally absent in horses.

One of the most striking atavisms in humans is the occurrence of tails. True human tails are rare. They contain vertebrae, muscles and nerves and can be voluntarily moved.

In 2010, a report surfaced regarding a man in Texas who presented himself to hospital suffering from chest pains. Imaging showed that the structure of his heart resembled that of reptile, having only three chambers instead of the normal four.

So, why do atavisms occur? The genetic systems controlling embryological development are extremely complex and not fully understood. They are byzantine networks of switches, balances and final effects. A subtle change at a critical point can mean the difference between an arm and a leg or three toes instead of four. Perturbations to these networks in fruit flies can have bizarre results such as growing legs instead of antennae or forming eyes on wings.

An organism’s genome, like its body, contains vestiges of its evolutionary past – genes that are suppressed or genetic pathways that are blocked. Atavisms may be these vestiges re-emerging and interfering with the genetic controls that govern embryogenesis.

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The Immunology of Bats

A few years ago I suffered a needle-stick injury at work. The needle was attached to a syringe containing Nipah virus. I spent the next two weeks alone in a quarantine unit, watching DVDs and checking my temperature regularly. My food was left at the door and I was not allowed within ten metres of another person. My enforced holiday ended without incident which is fortunate as there’s no effective treatment for Nipah virus encephalitis.

Nipah virus is a relatively new discovery. It was discovered during an outbreak in Malaysian pig farms in 1999. A mysterious illness began killing the pigs and soon spread to the farm workers. By the time the epidemic was over, 257 people had been infected, 105 were dead and a million pigs had been slaughtered to control the spread. Further outbreaks have occurred sporadically since then, mostly in Bangladesh, with fatality rates of up to 90%.

A related pathogen called Hendra virus is present in Australia. Since its discovery in 1994, numerous cases in horses and humans have occurred along the east coast of Australia. So far, infection of humans has only occurred after exposure to infected horses.

Hendra and Nipah virus both come from the same source: bats. Fruit bats in Asia and Australia act as reservoirs for the virus. Spillover into other species occurs when food or water is contaminated with bat urine or saliva. A number of the outbreaks in Bangladesh have been linked to uncooked fruit or date palm juice. Date palm juice is the sap of the date palm and is collected overnight in pots. Fuit bats feeding in the trees at night can contaminate the juice which is drunk fresh the following morning before it begins to ferment.

It’s not known how bats are able to harbour and circulate these viruses without falling victim themselves. And the henipaviruses are not unique. Bats are reservoirs for a large number of pathogenic viruses including SARS coronavirus, Ebola virus, Marburg virus and rabies virus as well as a host of lesser known viruses such as Mokola virus and Duvenhage virus that emerge from time to time, claim a small number of victims and disappear again.

The mobility of bats combined with their habit of roosting in very large, closely packed groups may have contributed to their resistance to viruses. A long evolutionary history in such virus-friendly conditions may have selected for an immune system that is uniquely capable of harbouring pathogens without succumbing to them.

As human populations encroach further into bat habitats, virus spillover events are likely to become more frequent and demands for culling of bats louder. By protecting themselves from the effects of viruses, bats may have inadvertently  made themselves the target of an even bigger threat.

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Tree Lobsters and Other Lazarus Species

In 1918, the S.S. Makambo ran aground on Lord Howe Island in the Tasman Sea. It took nine days to repair and refloat the ship and when it sailed away, it left behind some of its non-paying passengers. Black rats had taken the opportunity to disembark.

With abundant food and a lack of predators, the rats flourished. Over the following decades, many of Lord Howe Island’s native birds, reptiles and invertebrates were wiped out by predation and competition from the rats. One of the most vulnerable was Dryococelus australis, better know as the tree lobster, a type of stick insect reaching up to 15 cm in length. Within two years of the Makambo’s arrival, tree lobsters could no longer be found on the island.

For eighty years, they were assumed to be extinct. In 2001, acting on unconfirmed reports from the 1960s, a team of entomologists arrived on Ball’s Pyramid, an islet 20 km southeast of Lord Howe Island. The world’s tallest volcanic stack, Ball’s Pyramid is a narrow, 560 m tall blade of rock. Around 100 m up, water seeping from a crevice feeds a small melaleuca bush. It was here that the world’s last tree lobsters were found.

A breeding pair were relocated to Melbourne zoo and a large population has been established there. Ultimately, reintroduction to Lord Howe Island is planned but has been hampered by the remaining rat problem.

Tree lobsters are an example of a Lazarus species, an organism that appears to be extinct but is later rediscovered, having figuratively arisen from the dead.

The combination of Australia’s size, its large number of islands and remote areas as well as an unenviable record of driving species to the edge of extinction and beyond has resulted in a number of Lazarus species. Gilbert’s Potoroo, the Mahogany Glider and the New Holland Mouse were all unsighted for up to 120 years before rediscovery in the mid to late twentieth century. The tiny Mountain Pygmy possum was known only from fossil records until found alive and well at a ski resort on Mount Hotham in 1966. However, the Australian record (so far) for longest gap between presumed extinction and rediscovery belongs to a tree.

In 1994, David Noble was exploring part of the Wollemi National Park, 150 km north-west of Sydney. In a narrow canyon he found some unusual-looking trees and took samples back with him for analysis. The tree, named the Wollemi Pine, turned out to belong to a genus that was thought to have vanished two million years ago.

The Wollemi Pine has since been propagated for sale in nurseries. In the meantime, the few hundred trees in the wild are under threat from a pathogenic water mould, possibly introduced by visitors to the canyon whose location has never been publicly released.

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The War Magician

Susanna Clarke’s 2004 novel Jonathon Strange and Mr Norrell is set in an alternate Georgian-era Britain at a time when magic has fallen into disuse. The two eponymous characters resurrect the art, becoming the first practising magicians in centuries, and find themselves duty-bound to use their powers in furthering Britain’s war efforts against Napoleon. They conjure up phantom ships, move entire towns and resurrect dead soldiers for interrogation (putting them to rest again proves more difficult).

Of course, none of those things really happened during the Napoleonic wars. However, the autobiography of one of the most remarkable figures of the Second World War claims many of them occurred during that conflict.

Jasper Maskelyne was born into a long line of stage magicians. His father, Nevil Maskelyne, was a magician and an early proponent of wireless telegraphy. He once interrupted one of Marconi’s early demonstrations by transmitting his own message to the receivers in London. The message was a poem ridiculing Marconi’s claims that his technology was immune to eavesdropping.

Some of John Maskelyne's acts (Zoe was an automaton).

Jasper’s grandfather John, a contemporary of Houdini, was one of the greatest stage magicians of his age. He created many famous illusions that are still popular today. Strangely, he also invented the pay toilet, inadvertently giving birth to the euphemism to spend a penny.

Jasper himself achieved fame when he published his autobiography, Magic: Top Secret. The book details an amazing series of events during the Second World War in which Maskelyne used his skills of illusion to outwit the German forces. He began by convincing the British military establishment that he had something to offer. He created the illusion of a German battleship, the 180-metre long Admiral Graf Spree, floating on the Thames.

Suitable impressed, the army put him to work. Maskelyne assembled a team of assistants dubbed the Magic Gang and put into operation a widescale project of camouflage and deception in the south of England intended to defend the nation against a German invasion.

Maskelyne and the Magic Gang were sent to the North Africa where they conducted outrageous operations including making the entire city of Alexandria disappear and reappear one mile from its actual site, and protected the 160km long Suez Canal from German bombers using an invention Maskelyne called Dazzle Lights. One of Maskelyne’s most memorable feats occurred during the battle of El Alamein in 1942. Using a complex arrangement of illlusions including camouflaging thousands of tanks as trucks and creating fake tanks elsewhere, he fooled Erwin Rommel, arguably the most talented Nazi military leader, into believing that the Allied forces were massing south of the town when they were in fact to the north. The result was the most decisive victory over the Germans in Africa.

Maskelyne’s most impressive feat of deception, however, may be his autobiography. He may have made some valuable contributions to the war effort but the stories above probably weren’t them. Much of Magic:Top Secret was a fabrication, either by Maskelyne or his ghost-writer, Frank Stuart. Yet it has received remarkably scant critical analysis and has largely been swallowed whole by subsequent biographers. As recently as 2004, a biographical film of Jasper Maskelyne’s adventures was being considered by Paramount. Director Peter Weir pulled out of the project after speaking to Maskelyne’s son Alistair and discovering how little truth the script contained.

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Operation GARBO

Juan Pujol was, like Eddie Chapman, a British double agent during the Second World War but was his antithesis in almost every other respect. Unlike the flamboyant, womanising former criminal Chapman, Pujol was an unassuming, bespectacled businessman and a loyal husband and father.

Pujol was born in Barcelona and, during the Spanish Civil War, managed to irritate both sides of the conflict. He was imprisoned by both the Republican and Nationalist forces, largely for refusing to tow the fascist and communist lines, respectively. Despite serving in both armies, he avoided firing a single shot during the war.

When the Second World War erupted, Pujol felt compelled to do something to oppose the fascist forces. He offered his services to British intelligence numerous times but was ignored.

Undaunted by the rejections or by his complete lack of intelligence experience, Pujol began spying on the Nazis independently. He convinced the Abwehr that he was a pro-Nazi Spanish government official. The Germans provided him with money and training and ordered him to establish a spy ring in Britain.

For over a year, Pujol single-handedly maintained the deception that he was successfully recruiting and running a large network of spies. In reality, all of his recruits were fictitious. In fact, Pujol had never visited Britain, spoke no English and didn’t understand Britain’s pre-decimal currency system. His information came from tourist guides, train timetables and the library.

His reports were so convincing that, when intercepted by MI6, they precipitated a hunt for the non-existent spies.

In 1942, Pujol was recruited by MI5 and relocated to Britain. The quantity of information Pujol’s spy network, now numbering 27 agents, supplied to the Abwehr convinced the Germans that there was no need to recruit further spies there. Some of the information was legitimate but was timed to arrive when it would be of no use to Germany. When one of his agents died, Pujol convinced the Germans to pay a pension to his ‘widow’.

(If, at this stage, the Abwehr come across as a little on the dim side for an intelligence organisation, it’s worth remembering that the head of the Abwehr, Wilhelm Canaris, was actively working against the Nazis and was most likely in cohoots with MI6).

These inflatable tanks were part of Operation Fortitude.

Pujol’s most valuable work was done as part of Operation Fortitude, the misinformation campaign intended to decieve Germany as to the whereabouts of the D-Day landings. He was instrumental in convincing the Germans that the landings would occur at Pas de Calais rather than Normandy. Pujol was so highly regarded that even after this deception, he maintained their trust and was awarded the Iron Cross.

In 1949, Pujol reportedly contracted malaria in Angola and died. After his MI5-assisted fake death, he moved to Venezuela where he remained until his real death in 1988.

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Double-agents, spies ostensibly acting for one intelligence organisation while in fact working for the enemy, place themselves in a highly vulnerable position. They need to not only provide a credible service to their cover organisation, they must also continually prove their usefulness and loyalty to their true masters. Apart from the threat of being uncovered by those they are exploiting, there are the ever-present fears that they will be betrayed by defectors, lose the trust of their handlers or be exposed as part of a wider strategic move.

But British double-agent Eddie Chapman seems to have lived a life completely at odds with this perception. Prior to the Second World War, Chapman was a professional criminal. He had a successful stint in the thirties as a safe-cracker, often involving the use gelignite.

While on bail for one of these jobs, he escaped to Jersey where he was apprehended again and sent to a Jersey prison. He was still there when war broke out and Germany invaded the Channel islands. Chapman offered his services to the German secret service, the Abwehr, who believed Chapman’s professions of hostility towards Britain and valued his expertise with explosives. He spent a year in training before being parachuted into Cambridgeshire in 1942 on a sabotage mission.

Chapman immediately handed himself over to police. During interrogation by MI5, he was asked to act as a double-agent and was given the codename ZIG-ZAG, a reference to his less than conventional past.

Chapman’s mission for the Germans was to destroy the De Havilland aircraft factory. In January 1943, he reported back to his German handler that he had accomplished his mission. Photographs from a German reconnaissance plane confirmed the destruction of the factory, a feat for which Chapman was awarded Germany’s highest military honour, the Iron Cross.

In fact, the facility was still intact and fully operational. MI5 (possibly with the aid of stage magician Jasper Maskelyne) had faked the attack on the factory. They scattered rubble around the area and covered the building with tarpaulins painted to give the appearance from above of a bombed building. False stories of the factory’s demise were also fed to local newspapers. The Nazis swallowed the ruse hook, line and sinker. Chapman was feted as a hero, inducted into the German army as a First Lieutenant and given a yacht.

Later in the war, he falsely reported to Germany that their V-1 rockets were hitting central London. As a result, they failed to adjust their aim and missed their targets.

Eddie Chapman was one of the most successful and flamboyant spies of the Second World War but eventually, his indiscretions became a liability and MI5 had to let him go. After the war, he befriended his German handler, Stefan von Grunen who attended his daughter’s wedding. He died in 1997.

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The Windows to the Soul Part 2: Colour Vision

In 1844, the founder of modern chemistry John Dalton, died. By his own request, his eyes were removed at autopsy and the vitreous humour examined. Fifty years earlier, Dalton had provided one of the first accounts of colour blindness based on his personal experiences of the condition. He theorised that colour blindness is due to discolouration of the vitreous and he hoped to have this proven after his death.

However, when his eyes were examined, no discolouration was found. Dalton’s theory was wrong but his name became so closely associated with the condition that it was given the term Daltonism. One hundred and fifty years later, in 1995, DNA analysis of Dalton’s eye tissue confirmed that he had a type of red-green colour blindness, but not the type that had historically been assumed. Instead of protanopia (red deficient), Dalton suffered from deuteranopia (green deficient).

Colour blindness affects around ten percent of males and less than one percent of females. It is caused by mutations in genes affecting the colour-detecting cells of the retina, the cone cells. Cone cells contain one of three photopigments, each absorbing light at a different wavelenght. The absence or malformation of a cone cell type results in colour blindness. The difference in colour blindness rates between men and women is due to the way in which the genes for the photopigments are inherited (two of the three genes are on the X chromosome).

A quirk of the system is that mothers of colour blind boys have the potential to be tetrachromatic, possessing four different photopigments – the three standard pigments plus a fourth mutated variant on their second copy of the X chromosome. A tetrachromat may have a vastly different experience of colour than the rest of us, perhaps able to distinguish a hundred times more shades than trichromats. One of the few reported human tetrachromats can see ten colours in a rainbow.

Tetrachromacy may be hard to imagine but it pales in comparison to the planet’s most complex eye, that of the dodecachromatic mantis shrimp. The mantis shrimp or stomatopod is an aggresive marine crustacean best known for its powerful claws that are capable of smashing through aquarium glass. The stomatopod eye, however, is even more impressive. Stomatopod eyes contain sixteen photopigments. Twelve of these enable colour vision that extends into the ultraviolet and infrared regions. The other four detect polarised light. The stomatopod is the only known creature whose eyes can detect circularly polarised light.

Each eye is divided into two hemispheres and a central midband made up of six rows of photoreceptor cells. The midband detects colour and polarised light while the two hemispheres potentially allow depth perception in a single eye.

The reason for this extraordinary level of complexity is most likely a combination of the need to find prey and avoid predators as well as a means of communication between individuals. Perhaps, like the human brain and the tail of the bird-of-paradise, the stomatopod eye is an example of runaway evolution.

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