Daily Archives: August 1, 2009

The Opposable Thumb

The opposable thumb has played a key role in human evolution:

A discussion of primate characteristics is often included during units on human evolution. One of the characteristics most often identified as being typically primate and having played a role in human evolution is the opposable thumb. It is argued that the eye-hand coordination made possible by both stereoscopic vision and a grasping hand permitted primates to exploit arboreal habitats in a more efficient fashion. That same hand is used by humans today to manipulate tools and, in turn, the environment with a great deal of dexterity.

Recent research has shown that the evolution of the opposable thumb was not unlikely:

An ancestor of mammals first took to the trees before the age of dinosaurs, evolving the first known opposable thumbs on the way, a group of Toronto researchers reports.

The animal, dubbed Suminia getmanovi, lived at a time when other known vertebrates, including both predators and plant-eaters larger than itself, spent all their time on the ground, said University of Toronto paleontologist Robert Reisz, who studied its complete fossil remains with his PhD student Jörg Fröbisch.

“This is a small plant eater that was not only able to get away from the predators by climbing into the trees,” Reisz said in an interview Tuesday, “but also to access an untapped food resource — that is, the leaves of the trees.”

How might one help to front-load the evolution of an opposable thumb? Front-load the appearance of the pentadactyl limb and front-load the appearance of trees. From there, it’s just a matter of time.