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On July 26, 1999, police in the English Channel town of Worthing broke into a house and found the bludgeoned body of Jean Barnes, an 87-year-old spinster. Miss Barnes had not been missed until a neighbour realized that she had not seen her for a while, and called the police. They found her under a blanket on the floor, obviously dead for some time.

To find out how long, police called in the bug man, and with that call set in motion a series of events that helped to illuminate much more than the causes of a crime.

Henry Disney, a Cambridge University researcher and former medical entomologist, is the leading world authority on scuttle flies, also sometimes known as coffin flies because some species breed in human corpses. When they do, the stage of their life cycle can establish the time of death.

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What's at stake is much more than helping to solve murders.


Dr. Disney examined scuttle-fly larvae from the body, and said the victim had been dead for two weeks. But a problem soon cropped up.

Police recovered a note, purportedly from Miss Barnes, cancelling her milk delivery and dated after the time of death set by Dr. Disney. Thinking he must be wrong, they called in bug man No. 2.

This second expert, an accredited forensic examiner, looked at the larvae and said death had occurred even earlier - a full month before the date on the note. Perplexed, the detectives summoned yet another entomologist.

This one checked out both reports and said Dr. Disney's was correct and the second one was nonsense: Not only had it got the insects' species wrong, but the genus too.

With Dr. Disney's dates re-established, the police took another look at the note and solved the case.

The point, though, is that Dr. Disney's dates had been challenged at all. For the Barnes case revealed much more than a bungled scuttle-fly ID.

That someone licensed to interpret insect larvae - the second "expert" - could make such a blunder was an example of a larger crisis that Dr. Disney and other scientists on both sides of the Atlantic have identified: the dwindling of a class of expert and a store of expertise.

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What's at stake is much more than helping to solve murders. It's the ability of science to assess the state of life on Earth at a moment of whirlwind change - as new species are discovered and others go extinct.

A THREAT TO SCIENCE

The science of describing and naming species - of saying what they are - is called taxonomy. A taxonomist is an expert in a taxon - a group of plants or animals. In the classical model, a taxonomist scrutinized the physical traits of a specimen, said where it belonged in the system of classification and named it.

In the words of Harvard University's E.O. Wilson, a leading figure in contemporary biology, "master taxonomists" are a breed that is "fading from the scene. They die and are not being replaced."

Known internationally as the "taxonomic impediment," this problem is a rising issue among those struggling to understand biodiversity. In Britain, the Natural History Museum will deliver an assessment of the state of taxonomy at the end of this month - 18 years after a House of Lords committee first identified the decline in taxonomic research as "a threat to the science underpinning conservation."

The morphological taxonomist, engrossed in a single group and identifying its members by visual inspection, is increasingly an emeritus professor or someone near retirement. Younger scientists are drawn to molecular taxonomy, where powerful new techniques in the study of DNA have revealed interspecies connections never before suspected.

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Such advances, including the Canadian-pioneered use of DNA barcodes to identify species, while undeniably useful, are "not a replacement for the [traditional]taxonomist," says Gary Saunders, who holds a chair in Molecular Systematics and Biodiversity at the University of New Brunswick.

"At times, the DNA-generated answer is wrong," Prof. Saunders says. "A trained taxonomist can look at a molecular result and know that there is cause to question the outcome."

"The risks associated with loss of traditional knowledge also will apply directly to the molecular approaches," says Laurence Packer, a York University bee expert, "as identifications based on the latter ultimately entirely rely upon accuracy in the former."

Just this week, one of Prof. Packer's students - Jason Gibbs - published his discovery of a new bee species. He had plucked the specimen from a flower in downtown Toronto, examined it by microscope, checked the DNA, and "Eureka!"

"I think there's a perception that after a couple of centuries of naming, we've already named everything there is," says Canadian taxonomist Don Lafontaine, a world authority on moths who works for the federal Agriculture Department in Ottawa.

"That may be true with birds and animals, but I recently put out a new catalogue on noctuid moths, and even as I was publishing there were about 2,500 species right here in our own collection that hadn't been identified, and 250 new species of cutworm moths have been described in North America in the past 10 years."

Noctuid moths are a vast family of about 50,000 species. Cutworms, some of which are pests that cost farmers millions of dollars a year, are a larval stage of noctuid moths. Making swift identifications of such animals is crucial to controlling them. Other insect pests, such as the spruce budworm and the pine beetle, can ravage whole environments.

"The loss of people who can identify an insect - there's been enormous concern about that," says Naomi Pierce, Hessel Professor of Biology at Harvard. "I am not a classical taxonomist, I'm part of the new wave. Having said that, I work very closely with taxonomists and I see the problem. It's an amazingly serious one. There's a whole generation of people - you could give them something and they could say what it is. That is being lost because there are no jobs."

The disappearance of traditional taxonomy from universities as molecular taxonomy takes over has orphaned whole collections of insects. Dr. Lafontaine often spends his holidays helping to maintain such uncurated "ghost collections." Fortunately the collection he works with in Ottawa, with 16 million specimens - the third largest of its kind in the world - suffers no such neglect.

An editor of the massive compendium Moths of North America, Dr. Lafontaine is past president of the International Lepidopterists' Society, a research fellow at Washington's Smithsonian Institution and a co-author of Butterflies of Canada. As well as being a curator of Canada's enormous collection of insects, arachnids and nematodes, he maintains a steady flow of scholarly publications and helps amateurs - increasingly important to traditional taxonomy - to prepare their own work for publication.

"When I first wanted to describe a few new taxa that I had found," says Lars Crabo, a Bellingham, Wash., radiologist and distinguished amateur lepidopterist, "I looked to Don for help. My first efforts were really pitiful and Don helped me with encouragement, editorial suggestions and technical advice."

APOCALYPSE NOW

According to Harvard's Prof. Wilson, the loss of such expertise impairs the ability of science to assess the state of life at a time of apocalyptic change - the present - when species are disappearing before we even know what it is they do. "We are like doctors trying to diagnose a patient when we only know 10 per cent of the organs," he said.

As an example, Prof. Wilson cited the nematode - a tiny, all-pervasive phylum of worm that makes its home from polar ice to the Sahara. They are 90 per cent of all life in the deepest ocean trenches, and swarm the soils of our planet.

"They are the most abundant animals on Earth and we hardly know anything about their biology," Prof. Wilson says. "We have counted 20,000 species, but there are certainly a million. They are running the world for us and we don't know how."

Taxonomy faces a staggering enterprise. In the 250 years since Carl Linnaeus invented the system of classification still in wide use, about 1.9 million plants and animals have been identified. The latest estimates put this number at a 10th of what's actually out there - just counting macro-organisms. On the micro side, there could be 100 million species.

New molecular techniques will help scientists sort out this profusion. But as E.O. Wilson and two other distinguished taxonomists cautioned in a 2004 editorial in Science, molecular researchers have benefited from "centuries of banked morphology knowledge [assembled by traditional taxon-

omists] That knowledge, however, is limited to a fraction of Earth's species and will very soon be exhausted."

The name of a species, Don Lafontaine says, is the address to everything that is known about it. If you get the species wrong, all subsequent information will be wrong.

"This has serious implications for human and animal health," he says.

"We are part of a network of tens of thousands of species that surround us and affect our lives. They are critical to our health and wealth and that of our planet. Knowing their names is the first step to understanding, and that ability - for a large portion of life on the planet - is at risk."

"In my own field of entomology," Henry Disney wrote to the House of Lords, "the majority of specialists on large families of small insects are now retired professionals, like myself, and amateurs.

"Since retirement," he added, "I have existed on small grants and occasional fees for undertaking forensic work."

And the Jean Barnes murder?

When Dr. Disney's original estimate of her time of death was confirmed, police realized that something was suspicious about the note to the milkman, since it was dated after her death.

As it turned out, the note was a forgery. The killer had written it days after Miss Barnes had died, to keep people away from the house while he sold off her antiques. Police quickly found a suspect, and when all the evidence was tied to Dr. Disney's dates, the case was solved.

Matthew Hart is a Canadian writer based in London.

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