The toad that's shaking science

When an Austrian biologist accused of scientific fraud killed himself, his critics took it as confirmation that their suspicions were correct. New research, however, indicates that his much-maligned work was a major breakthrough.

A handout picture released 21 January 2008 by the Zoological Society of London press office shows a Betic midwife toad. Exotic amphibians including the Betic midwife toad, whose males carry fertilised eggs around their hind legs, are among the endangered species targeted by a conservation drive launched in London 21 January 2008. The Zoological Society of London (ZSL), which runs London Zoo, wants to protect threatened amphibians whose plight is often overlooked in favour of furrier and fluffier creatures. AFP PHOTO/HANDOUT/ZOOLOGICAL SOCIETY OF LONDON == RESTRICTED TO EDITORIAL USE ==
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When the Austrian biologist Paul Kammerer was found dead, a gun by his side, in September 1926, the reason for his despair seemed obvious. For years there had been rumours that he was a fraud, and a few weeks earlier a leading researcher hinted at proof that Kammerer had invented data to support his crazy ideas about evolution. While his obituaries tried to put a positive gloss on the debacle, many scientists believed his death proved his guilt, and his name was quickly forgotten by all but a few historians. But now the story of Kammerer has taken a dramatic new twist, following research suggesting that his "fraudulent" work was a major breakthrough decades ahead of its time. If confirmed, Kammerer will be seen as one of the pioneers of evolution theory, alongside the likes of Darwin himself.

At the time he performed his notorious experiments, biologists were just beginning to combine Darwin's theory of evolution with the idea of inheritance of traits via genes. No one had any idea what genes actually were, but most biologists were convinced they were the drivers of evolution, via the twin effects of natural selection and mutation. Most biologists, but not all, suspected there had to be more to evolution.

He became intrigued by the ideas of the 18th-century French naturalist Jean Lamarck, who had argued that if creatures acquired some useful trait during their lifetime, they could pass it on to their offspring, so they too would benefit. As an example, Lamarck pointed to the giraffe, which he said was simply a type of antelope that had steadily acquired a longer neck through stretching upwards to pick leaves off trees.

Even at the time, Lamarck's ideas about the inheritance of acquired characteristics faced critics, who pointed out that, for example, the sons of blacksmiths are not born with bulging biceps. In any case, it was far from clear how a lifetime's experiences could end up permanently modifying some trait of a living species. By the start of the 20th century, Lamarck's theory was regarded as patent nonsense by many leading biologists. Yet Kammerer, never one to follow the herd, believed the only way to know for sure was via the scientific method.

He devised an experiment to see if he could force living creatures to acquire a new trait during their lifetime, and then see if it could persist down the generations. Success might not reveal how the process worked, but it would at least show there was more to evolution than organisms just passively waiting for new traits to emerge at random. By the 1920s, Kammerer was making headlines with experiments involving marine creatures that seemed to confirm Lamarck's theory. The most famous centred on an amphibian called the midwife toad.

Unlike most frogs and toads, this creature breeds on dry land, its curious name coming from the way the male carries the fertilised eggs on its back until they are ready to emerge as tadpoles. Kammerer wondered if he could force some midwife toads to give up their normal traits, and instead breed in water, leaving their eggs there as well, rather than moving them around. Kept in a hot, dry enclosure, the toads sought sanctuary in the coolness of water provided by Kammerer, and set about breeding and leaving their eggs there. Over 95 per cent of the eggs failed to turn into tadpoles, but those that did led to toads which now preferred to breed in water. And, just as Lamarck's theory predicted, these eggs in turn produced offspring with the same preference.

Kammerer continued the experiment through six generations of toads, and claimed that they all showed the same acquired trait. More remarkable still, some of the toads also showed signs of acquiring additional new traits, such as modified forelimbs that allowed them to mate more effectively with females in water. Kammerer's apparent confirmation of Lamarckian evolution attracted huge interest - and opprobrium. In 1923, the distinguished English biologist William Bateson launched an attack on the reliability of Kammerer's data in the pages of the journal Nature. Then others joined in, among them the American biologist Kingsley Noble, who claimed to have found evidence of black ink being used to fake the appearance of modified limbs.

Right up until the end, Kammerer insisted he had done nothing wrong - and allowed others to check his claims. In his final note, he hinted that his despair was the result of an unhappy relationship, rather than being "outed" as a fraud. Some biologists performed similar experiments with other creatures, and found similar results. It made no difference: Kammerer's suicide was widely assumed to be proof of guilt, and his claims were forgotten.

Now, more than 80 years after his untimely death at the age of 46, Kammerer's reputation may be about to undergo a major transformation. New research suggests that Kammerer's results are consistent with effects at the heart of an emerging field of biology, known as epigenetics. Put simply, epigenetics focuses on processes in which new traits appear in organisms without any changes in their DNA. Such processes include so-called methylation, in which a small group of molecules becomes attached to DNA, changing its behaviour without altering its genetic information.

According to Dr Alexander Vargas, an evolutionary biologist at the University of Chile, such epigenetic effects may have been triggered by the switch from dry to watery conditions. The result would be the emergence of new traits suited to the new environment - which is precisely what Kammerer claimed to have found. Writing in the current issue of the Journal of Experimental Zoology, Dr Vargas argues that new experiments should be performed, to find out if epigenetic effects really do emerge when eggs are hatched in water.

He adds that if Kammerer's claims are confirmed, the midwife toad could become the organism of choice for biologists studying how epigenetics affect the evolution of life. Historians may yet find the toad a useful way of demonstrating what can go wrong in the evolution of science. Robert Matthews is Visiting Reader in Science at Aston University, Birmingham, England.