When marine biologist Katrin Linse recently won the honor of naming a new species, she turned to a centuries-old rulebook.
Sorting through 3,000 crustacean samples pulled from deep water near Antarctica she noticed some that hadn't been described before. The creatures were seemingly related to other tiny shrimplike swimmers thriving on shelves beneath the largely unexplored Ross Sea. But some of their body segments were shorter than they should have been.
After concluding this constituted a new species, the naming part was easy. Epimeria was required for the first name, or genus, already known to comprise some 30 similar species at the time. Free to choose almost anything for the second part, she settled on schiaparelli, after Dr. Stefano Schiaparelli, a biologist "who kindly shared his enthusiasm and knowledge on board" during the Antarctic expedition, Linse wrote in a paper published last week describing the find.
When it comes to naming a brand-new life form, shouldn't the process be more, well, scientific?
Most scientists say that 272 years after it was introduced, the naming system works just fine. Evolutionary theory and molecular biology have transformed our understanding of life. Computers and digital media have more recently upended longstanding theories of information management. But, over nearly three centuries, the classification system used to organize much of our biological knowledge has remained remarkably arbitrary and ancient: The so-called binomial system of genus and species that Linse and thousands of other biologists use today was first proposed by a Swedish biologist born 300 years ago Wednesday, Carolus Linnaeus.
Biological classification may seem like an esoteric problem better left to librarians than field researchers, but it is reaching unprecedented importance as discoveries swell the existing rolls of some 1.8 million known species, and prominent scientists such as E.O. Wilson throw their backing behind an ambitious project to make taxonomic data for all of life on Earth accessible online. Classification systems, meanwhile, have themselves become the subject of intensive study, thanks to the explosion in data-labeling and -sorting procedures allowed by digital media.
Linnaeus, a devout Christian with no concept of evolution, today might barely recognize much of the system he spawned. But his approach was remarkably modern. He bridged religious and scientific conceptions of nature, ordering the world as was most convenient, rather than seeking to describe how it truly was. His goal was not to uncover the hidden connections between organisms, but simply to give labels to ensure biologists could agree on what they were talking about.
"Taxonomy" is a hierarchical browser that visualizes the classification tree found in the Integrated Taxonomic Information System, which incorporates Carolus Linnaeus' centuries-old naming system and organizing principles. Designed for use with a multitouch display screen, shown here, users can dynamically expand branches of the tree and easily navigate from a full overview of the tree to specific details for any of the taxonomic entries in the database. For each of these taxa, information in the database is supplemented with available online resources. Developed by Philip L. Davidson of Perceptive Pixel For more, visit wired.com/video.
The result was a system that's considered as important a scientific framework as the Babylonian calendar or the Earth-centric model of the universe. In other words, much of it was wrong, but it was an amazingly adaptable foundation that future generations could build upon to describe the world, and our place in it, reasonably accurately, scientists say.
"Linnaeus did a masterful job of creating a hierarchy by which we could communicate (about phylogeny)," said Craig Moritz, the director of the Museum of Vertebrate Zoology at the University of California at Berkeley. "That system has really stood the test of time."
Ordering for the Lord
Linnaeus was the son of a preacher, but showed neither the acumen nor the interest in following in his father's footsteps. In his mind, however, his work served religion: "God created, Linnaeus ordered," he once pronounced.
The cover of his Systema Naturae features a man in the Garden of Eden naming new creatures as God creates them using the Linnaean nomenclature.
The first edition of Systema Naturae, published in 1735, organized the natural world in just 11 oversize pages. The 10th edition, published in 1758, introduced the binomial nomenclature still used today. The modern system is an adaptation of his original scheme, ranking progressively more specific groups from kingdom to phylum, class, order, family, genus and species.
Linnaeus became a medical doctor, but was obsessed with botany. He created the system to classify plants based on their genitalia, a controversial choice at the time and one that ultimately failed to capture real evolutionary relationships, eventually opening the door to post-Darwinian attacks. He became obsessed with the importance of stamens and pistils and came up with elaborate analogies to human sexuality and marriage to explain his classification.
Linnaeus got other things wrong, too. He was one of the first to try to scientifically classify humans into different races or species according to place of origin and skin color, placing white Europeans at the top of the heap. He also insisted that creatures like the troglodyte, satyr, hydra and phoenix were real, humanlike creatures.
Linnaean taxonomy has been revised more than once, and has come under increasing pressure since Charles Darwin popularized his theory of evolution with the publication in 1859 of The Origin of Species and later with the cracking of the DNA code.
Time for a Change?
While many see naming conventions as little more than a labeling convenience, molecular biology based on DNA evidence has solved so many evolutionary puzzles and has generated such an unmanageable amount of information that some believe it's time for a taxonomical sea change.
The International Code of Zoological Nomenclature, which sets rules governing animal taxonomies, currently uses an artificial ranking system that doesn't explicitly adhere to evolutionary concepts. But recently a small cadre of evolutionary biologists has argued for reforming the accepted nomenclature to more closely reflect evolution using an approach called phylogenetic taxonomy.
The PhyloCode would create a formal set of rules for phylogenetic nomenclature that associates names with "clades," or groups of organisms that share one common ancestor.
"It makes more sense to tie the names to evolutionary concepts of groups than to ranks, since most biologists agree both that evolution is a unifying biological theory and that ranks are artificial," said zoologist Kevin de Queiroz, a curator at the Smithsonian Institution's National Museum of Natural History. "There has (already) been a movement away from rank-based to tree-based approaches in biology, and the PhyloCode is just the nomenclatural manifestation of this movement."
Naming animals and plants according to evolutionary principles rather than arbitrary ranks is actually closer to how taxonomy worked for Linnaeus, de Queiroz said (read more of his thoughts on PhyloCode here.
He said he's not proposing to replace the taxonomic categories pioneered by Linnaeus. Nor is he proposing to do away with the binomial naming system — but some scientists go further.
"The binomial system for naming species is a necessary evil," says David Hillis, a professor of integrative biology at the University of Texas who says he'd prefer a more precise nomenclature, such as registration numbers for all species. "No one would suggest such an awkward system today, but it is so entrenched that it is virtually impossible to change."
Drowning in DNA Data
DNA sequencing has contributed more to evolutionary biology than any other discovery in history — 99 percent of the Earth's species have been identified in the 50 years since James Watson and Francis Crick discovered the structure of DNA.
Some of those findings have been quite surprising, forcing revisions in classical taxonomic associations.
Some surprising evolutionary relationships — ones that scientists in Linnaeus' time couldn't have predicted based on morphology — emerge from DNA analysis. For example, did you know a beech tree and a cucumber are more closely related than a beech tree and a sycamore tree? Click on the graphic to see more surprising kinships.
For example, molecular data is firmly coming to the conclusion that termites, previously considered to be in a separate order from cockroaches, are actually wood-eating cockroaches that became social. DNA sequencing is also placing whales very close to hippos on the evolutionary tree. Some scientists were skeptical of the early data, but additional molecular data and new fossil finds have strengthened that conclusion.
Nevertheless, although DNA evidence might provide a powerful and testable principle for ordering organisms, some caution the results are not always clear-cut.
"Molecular data, while useful, is not infallible and does often return somewhat confusing results," said Michael Eisen, an evolutionary molecular biologist at the Lawrence Berkeley National Laboratory. "There still remain deep divisions and arguments about particular classifications and how things are grouped together."
The complexity that molecular data adds to taxonomy is illustrated by recent DNA findings in de Queiroz's field of specialization, lizards.
The results have suggested that the root of the lizard tree — the place where lizards branched off from other species — is in a place where scientists hadn't considered before, and that many believe is wrong.
Mapping this new suggested root shows that, if accurate, an unlikely series of evolutionary events (see diagram in gallery) would have had to occur. For example, the ability to apprehend prey with jaws rather than with the tongue would have evolved six times, rather than just once on the old tree.
"When (molecular results) are surprising, they're often wrong," de Queiroz said. "There is a long history of premature conclusions."
As a result, he said, Linnaean-inspired tree systems play an integral role in putting DNA sequence information in perspective. "If anything, the trees have become more important as a result of (molecular biologists') efforts," he said.
Another example is the now-rejected finding that guinea pigs are not rodents. "If that were true, it would be huge," said de Queiroz.
In the end, the debates may only serve to highlight the great strength of the Linnaean system: It was simplicity — not accuracy — that proved the key to its success, and that's precisely why it has survived the computer, internet and DNA revolutions.
As scientists struggle with an amount of information unimaginable in Linnaeus' day, generated by DNA sequencing and the identification of 1.8 million plants and animals (of 5 million to 10 million believed to exist), Linnaean supporters say the taxonomy system — though much-modified over the years — is more important than ever.
"To handle all 10 million different species it is most convenient to sort them into groups (such as) families, orders, classes, etc.," said Birgitta Bremer, a professor at the Royal Swedish Academy of Sciences and director of the Bergius Botanic Garden in Stockholm, Sweden, Linnaeus' home country. "Of course all these different ranks are more or less arbitrary, but as long as they represent natural groups (branches on the tree) it is OK."
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