The existence of stone spheres, tombs with stone statues, golden votive offering and polychrome ceramics gave rise to a theory that the island was used only as a cementery for important persons during the pre-Colombian period.  However, remains of domestic pottery and stone farming implements suggest that local Indians inhabited the island 500 years ago.

Although islands tend to have small populations of amphibians and reptiles due to the fact that these two groups of animals are very susceptible to salinity, Caño Island has a wide variety of snakes.  There are also basilisks and green iguanas.  Mammals are scarce on the island and are restricted to three species: a marsupial, a bat and the paca, which was introduced.