Explore Magazine Volume 2 Issue 1


Modern Darwin Laments Extinction Of Species

Humans have erased eons of evolution on remote Pacific islands, said a University of Florida researcher who follows in Charles Darwin's footsteps.

In fact, people are overwhelming evolution, wiping out some animal species 300 times faster than new species can evolve, said David Steadman.

``Some islands are like a war zone,'' said Steadman, curator of birds at UF's Florida Museum of Natural History. ``I discovered that no native animals remain on Easter Island.''

In addition to falling prey to hunters, the native species were victims of diseases and animals that humans imported. Rats, mice, cats, dogs, pigs, goats, cattle and donkeys preyed upon the native species and destroyed their habitat.

Steadman --- who has spent a year of his life in 10 trips to the Galapagos Islands --- applies radiocarbon dating, DNA analysis and other modern techniques to study evolution and extinction.

Species extinguished from some of the Galapagos Islands are the famed Galapagos tortoise, the Floreana mockingbird, the sharp-beaked ground finch, the large ground finch, a snake species and the barn owl.

Steadman found even greater destruction when he worked on the Polynesian island chain of Tonga. Only 13 of the 27 species of land birds that once inhabited the island remain.

In the Galapagos, Steadman painstakingly studied a cave on Foreana Island. The mile-long cave, which was formed as a pocket in a lava flow, contains rich layers of fossils that developed because of the unusual digestive system of the barn owl, Steadman believes. For thousands of years, owl after owl carried its prey into the recesses of the cave.

After dining on lizards, birds and other prey, the owls vomited the bones onto the floor. The bones have turned into a treasure chest of fossil wonder.

``The beauty of this site is that we can peel off one layer at time, knowing that each succeeding layer is older than the one before it,'' Steadman said. Steadman carefully collected 7,000 small bone fossils within a single cubic meter of the cave during a 1995 Discovery Channel expedition.

In addition to documenting extinction, Steadman has been able to compare ancestors of various island creatures to their modern counterparts.

Chris Eversole

University of Florida researcher David Steadman (right) watches as his brother, Edward, studies a cave in the Galapagos Islands during one of his 10 trips to the region.