Study shows high intelligence of lizards

Aug 1, 2011, 10:42 GMT

Durham, North Carolina - Results of a study by a group of US biologists show tropical lizards share the same level of intelligence as birds and mammals.

The team from Duke University in North Carolina say their findings were 'totally unexpected,' according to biologist Manuel Leal, the study's main author.

According to conventional scientific thinking, lizards have limited cognitive ability compared to birds and mammals. But the tropical Anolis lizard is able to solve problems and even adapt learned abilities to changed circumstances, according to the report's findings which have been published in the journal Biology Letters.

The scientists studied six Anolis evermanni lizards by setting them the task of locating a worm in one of two holes. The hole containing the worm was covered with a lid.

Four of the six lizards successfully completed the test by either lifting the lid with their mouths or by biting into the covering and then removing it. 'This is a completely new form of preying behaviour,' writes Leal and Brian Powell, the study's co-author.

The lizards were also able to use the newly acquired strategy of opening the lid in other circumstances. When both holes were covered with different types of lids, the lizards correctly identified the hole with the worm, proving they had learned to identify the colour of the lid that covered the worm.

Two of the lizards were even able to amend their newly attained knowledge. When Leal and Powell placed the worm in the hole that until then had always been empty, all of the lizards at first tried the wrong hole.

However, two lizards recognised the changed circumstances and found the worm in the new location.

'The ability to adapt behaviour is an indicating sign of an animal with higher intelligence,' says the independent Harvard biologist Jonathan Losos.

Until now lizards were not listed among those creatures. The study's authors believe the Anolis lizard's learning aptitude has contributed to its widespread proliferation in the tropics.