The once-isolated islands of the Galápagos gave Charles Darwin insights into the dynamics of evolution that changed forever the way we think about the world. A century and a half later, scientists are still pursuing the ideas that drove him but are carrying these studies into a wide range of new locations—some exotic, some close to home.
“The evidence is overwhelming that evolution happened largely as Darwin proposed,” says Jerry Coyne, an evolutionary biologist at the University of Chicago and author of Why Evolution Is True. “Working through the engine of evolutionary change—natural selection—we can see evidence of animals’ and plants’ adapting to their environment before our eyes.” Such research took on cosmic importance recently when one of NASA’s Mars rovers found deposits of silica similar to those at the hot springs of Yellowstone Park. On earth such deposits typically contain remains of microscopic life.
Described below are some other places where modern followers of Darwin go for fresh inspiration about how life has adapted to nearly every environment on the globe.
25,000 feet under the sea
At the bottom of one of the world’s deepest ocean trenches, scientists have discovered a thriving colony of highly sociable fish—something they never expected to find there. Researchers had assumed that fish in such a harsh environment would be fragile, solitary, and motionless, conserving their energy due to a meager food supply. But high-definition submersible cameras captured images of abundant life nearly five miles beneath the surface of the Pacific. One camera spotted a cluster of 19 snailfish darting around bait like goldfish in a pond despite near-freezing cold, total darkness, and water pressure of five tons per square inch.
“We expected maybe one or two fish, but to see such a big group was amazing,” says Monty Priede, director of the University of Aberdeen’s Oceanlab, which specializes in robotic exploration of the deep sea. “And this is just the snailfish. There are also a lot of crustaceans, including prawns, living down there. We suspect there are half a million fish at these depths in each of the ocean trenches in the Pacific. Somehow they’ve adapted to the extreme cold and intense pressure.”
Oceanlab researchers made these discoveries last fall during a two-week expedition to the Japan Trench off the northeast coast of Japan, using submersible camera platforms engineered to withstand the extreme conditions. It was part of Oceanlab’s Hadeep project, a collaborative venture with the University of Tokyo investigating life in the so-called hadal region of the ocean (anything more than four miles below sea level). The newfound population of snailfish, which feed on tiny shrimp that scavenge detritus on the ocean floor, are believed to be the deepest living fish ever recorded.
Snailfish are thought to have colonized deep ocean trenches relatively recently, in evolutionary terms. Fish are dependent on oxygen that dissolves in the surface water and then sinks downward, but it is only within the past 70 million years that the deep seas have been oxygenated. “Snailfish are the most advanced of the fish. They produce relatively large eggs, and all of them have various kinds of parental care,” Priede says. “These explorations will help answer some tantalizing evolutionary questions. What are the limits of life? Is it possible to have living systems at even greater pressures? We’re just beginning to find out.”
An Abandoned Copper Mine
Land contaminated by runoff from industrial waste may soon be reclaimed by an unusual army of eco-warriors: metal-eating earthworms. Each deposit of metal at sites where these worms are found? creates a unique evolutionary event, yielding organisms that thrive in highly polluted environments.
Discovered in abandoned mines in England and Wales, these highly evolved superworms devour toxic heavy metals like lead, arsenic, and copper. “They seem to be able to tolerate high concentrations of metals, and exposure to the metal drives the worms’ evolution,” says Mark Hodson, a soil scientist at the University of Reading in England who unraveled the mechanisms that enable these worms to stomach normally lethal poisons.
DNA analysis of lead-tolerant worms unearthed in Cwmystwyth, Wales, revealed subtle changes in the worms’ genetic makeup that were induced by the metal. Researchers used sensitive X-ray technology to track how the worms metabolized metal particles one-thousandth the size of a grain of salt. “These earthworms have developed adaptive mechanisms for dealing with the soil pollution,” Hodson says. “When they ingest the soil, the metal accumulates in their tissues. But they have modified calcium pathways and secrete an enzyme that converts the metal into a less toxic form.” When the worms process the polluted soil, they excrete a slightly different version of the metal that is easier for plants to absorb. Eventually, Hodson says, “we might be able to recruit these earthworms to accelerate the remediation process: Just pop them in the soil and use them to clean up contaminated sites.”
The Wilds of New Guinea
Even though it is only about one-tenth the size of the United States, New Guinea has 7 percent of the world’s biodiversity, making the island a living laboratory for evolutionary biologists like Christopher Austin, who observes firsthand the adaptive mechanisms that spark the creation of novel species. In the past 20 years, Austin, a herpetologist at Louisiana State University’s Museum of Natural Science, has discovered nearly a dozen new species of lizard on the tropical island.
New Guinea’s unusually varied topography and climate have spawned a diverse array of habitats. They range from steamy lowland jungles, swamps, and floodplains to cloud forests, alpine grasslands, and glaciers capping mountains more than 16,000 feet high. The island harbors some of the world’s most unusual organisms, including kangaroos that live in trees and lizards that have green blood.