The little lizards that could
Lizards aren’t known for their smarts, but maybe they should be
Manuel Leal, a behavior ecologist, wants people to give lizards their due respect. Leal and his team recently showed that tropical lizards are surprisingly good at coping with weird problems they’ve never seen before.
“These guys are smarter than people say,” Leal told Science News. Leal, a behavioral ecologist at Duke University in Durham, N.C., spends a lot of time studying the animals that live in tropical rain forests. Behavioral ecologists investigate how animals interact with their environment.
Leal and his colleagues recently collected six tropical lizards — three males and three females — from Puerto Rico. All the animals were a type of anole lizard, called emerald anoles or Anolis evermanni. These small reptiles eat insects, live in trees and change color when excited.
The scientists wanted to know if the emerald anoles could learn how to get food in a new and unfamiliar situation. The team presented each lizard with a small box with two holes. Colored disks — one blue, one yellow — covered each hole.
Beneath the blue disk was a treat — a maggot, which is a small, wormlike insect larva. The yellow disk covered an empty hole. At first, the scientists let the lizards get used to the new device. The lids were placed loosely over the holes, and the lizards were free to knock them out of the way to find out what was inside.
Then came the tests. The scientists attached the lids firmly to the holes and let the lizards do their best to get a maggoty treat. All six lizards knew that the treats were behind the blue disk, but only four — two females and two males — figured out how to remove it and claim their reward. These animals either bit at the side of the disk to whisk it away or used their snouts to pry it off. The two anoles that couldn’t figure out how to remove the blue disk didn’t get to eat the treats.
In another experiment, Leal and his team showed that some of the lizards could still find the treat even if the rules were changed. The scientists switched the disks so that the maggot was hidden beneath the yellow. Two of the four anoles were able to find and feast on the maggot in its new location.
The scientists say their experiments show lizards can do complicated tasks, such as find new ways to get at food and remember what they’ve learned. That kind of adaptation is common among animals like birds and mammals, but scientists like Leal say it’s time to add lizards to the group.
Leal’s group isn’t the only one looking at how lizards learn. Other researchers have seen similar adaptive behaviors in amphibians and other kinds of reptiles, including whiptail lizards and monitor lizards. Together, the studies suggest that these animals can adapt quickly to challenging problems.
Not everyone agrees that lizards have as much adaptive ability as birds and mammals. Alex Kacelnik, a behavioral ecologist at Oxford University in England, told Science News that many animals, including fish and flies, can also spot differences among choices. He says the new study may show some ability in lizards, but “the results shown here are nowhere near what we know in birds and mammals.”
Will lizards finally be recognized as good students? Researchers like Leal hope so, and future studies could help scientists get a peek at what goes on in a lizard’s mind.
POWER WORDS (adapted from the New Oxford American Dictionary)
behavior The way a person or animal acts in response to a particular situation.
ecology The scientific field that looks at how organisms relate to one another and to their physical surroundings. Ecology is a branch of biology, the study of living things.
amphibian A group of animals that depend on the environment to say cool or warm. Amphibians include frogs, toads, newts and salamanders.
larva A young insect. The larval stage of an insect’s life begins when it leaves the egg and ends when it becomes an adult.