Fresh findings on the dead dodo


Bird: A recent study offers new insights into the extinct creature long thought of as haplessly dim-witted.

March 15, 2002|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

It may be bad manners to speak ill of the dead. But that has never stopped anyone from maligning the dodo bird.

Extinct for more than 300 years, the homely, flightless and fatally naive bird once native to the island of Mauritius in the Indian Ocean has long been synonymous with loser.

People - or things or ideas - are said to be as "dead as a dodo," or as hapless, or as out of fashion.

Curators at the Oxford University Museum of Natural History in Great Britain once thought so little of the vanished bird that they very nearly threw the best-preserved dodo on the planet into the fireplace during housekeeping in the 1700s.

Luckily, someone stopped them. And a modern group of Oxford scientists has used bits of that same unlikely treasure to make some remarkable, fresh discoveries about the curious dodo.

In a paper published this month in the journal Science, the team of eight zoologists and molecular biologists reports that tiny fragments of DNA extracted from the head and leg of the Oxford dodo have provided evidence linking the stub-winged dodo to fleet-winged ancestral pigeons in Southeast Asia (and, more distantly, to the common street pigeon).

The data suggest that proto-dodos were strong, long-distance fliers that island-hopped across oceans for millions of years. Some of the birds settled on Mauritius, where they lost the need - and, in time, the ability - to fly.

The new discoveries "certainly give [the dodo] a far more colorful history," says Alan Cooper, 36, director of Oxford's Henry Wellcome Ancient Biomolecules Centre and a co-author of the study. "It's not this ungainly, stupid sort of image, but a trans-Indian-Ocean navigator that ... had quite a successful career."

The flight to Mauritius worked out well for the dodo until its disastrous first encounter with humans - shiploads of hungry Portuguese sailors - late in the 1500s.

The dodos could not respond to people as predators. The sailors had never seen the dodos before, either. But they were delighted to find the 50-pound birds edible and too "stupid" to run away.

The rats and pigs that the sailors left behind felt the same way. In less than a century - by 1681 - the dodo was extinct, and its reputation forever sullied.

The species' disappearance was a revelation. "It was the first time Europeans worked out that something could go extinct," Cooper says. "They realized they could do something to cause permanent change to the environment." The dodo became a lasting reminder.

Too late, scholars realized that little had been learned about the dodos beyond a few descriptions written by the Portuguese. Only a handful of specimens - mostly bones - were preserved.

It was presumed that the dodo reached Mauritius somehow from Africa or Madagascar - the nearest big land masses. But people argued over whether the dodos were related to parrots, shorebirds, birds of prey or pigeons.

By the 19th century, scientists were fairly sure dodos were pigeons. "But they're so completely bizarre, so different from all other pigeons, it was thought that they must have diverged [from more familiar types] quite early on," Cooper says.

Even less was known about the "solitaire" - a smaller but equally extinct flightless dodo-like bird that by the late 18th century was eaten to extinction on the even more remote islands of Rodrigues, 400 miles east of Mauritius, and Reunion, 300 miles to the west.

Cooper and his team applied modern genetic science to the questions about the dodo. After the handful of dodo bones in British and European museums proved barren of DNA, they turned to Oxford's dried dodo head and leg. Museum authorities hesitated at first, Cooper says. The specimens, complete with skin, were literary as well as biological relics. They had served as the models for the drawings of Dodo, a character in Lewis Carroll's book Alice's Adventures in Wonderland.

Destroying only a quarter-inch square of tissue snipped from inside the dodo's head, and a similar amount extracted from its leg bone, the scientists were able to isolate and replicate 150 to 200 intact base pairs of mitochondrial dodo DNA.

It was such a small fragment that the risks of contamination by modern DNA were high. At one point, Cooper said, the results were skewed by an intrusion of modern pigeon DNA - probably from droppings tracked into the lab on someone's shoe.

The Oxford team finally isolated usable genetic sequences from the Oxford dodo and from solitaire bones collected in caves on Rodrigues Island. Their results were confirmed by independent analysts at the Natural History Museum in London.

The scientists then compared the dodo and solitaire DNA to samples from 35 other pigeon species around the world. Measuring the genetic changes they found against estimates of the time needed for such mutations to occur, the scientists constructed a sort of pigeon family tree.

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