Arboreal Clambering and the Evolution of Self-Conception

Abstract

A fundamentally new psychology related to the ability to conceive of limited aspects of the self may have evolved in the ancestor of the great ape/human clade. Existing models of the evolution of primate intelligence do not provide an adequate explanation of the apparent restriction of this phenomenon. We propose that the capacity for self-conception evolved as a psychological mechanism enabling large-bodied, highly arboreal apes to cope with problems posed by the need to negotiate their way through a habitat that was fragile due to their body size. First, we briefly outline the case for believing that a new psychology related to self-conception evolved during the Miocene in the ancestor of the great ape/human clade. Next, we examine the existing models of the evolution of primate intelligence and assess their ability to account for the evolution of self-conception. Finally, we offer details of our alternative model, along with a series of predictions that can be derived from it.

Functional Anatomy and Adaptation of Male Gorillas (Gorilla gorilla gorilla) With Comparison to Male Orangutans (Pongo pygmaeus)

“…Adult male orangutans, the largest-bodied primate to inhabit the canopy, orient their heavy torso in a variety of angles above or below supports (Figure 9). Their limbs can be recruited to act in nonstereotyped positions relative to the body and to each other (Cant, 1992;Povinelli and Cant, 1995). Joint flexibility is crucial to the variety of postures and modes in feeding, nesting, and moving in trees, including vertically climbing, and suspending (Sugardjito and van Hooff, 1986;Cant, 1987;Thorpe and Crompton, 2006).…”

“…As they move across flexible, unstable supports, their considerable mass deforms branches downward and opens gaps between adjacent trees (Grand, 1984). Orangutans solve this problem by distributing their weight over multiple supports, preferably lianas less than 10 cm in diameter (Povinelli and Cant, 1995;van Schaik, 2004;Thorpe et al, 2009). Using their bulk, they sway branches and form bridges to adjacent trees, and use their long and powerful arms and hands to pull in flexible branches to cross gaps.…”

“…They recruit their prehensile feet to grasp nearby branches and propel themselves through the canopy (Chevalier-Skolnikoff et al, 1982;Sugardjito, 1982;Cant, 1987Cant, , 1992Thorpe and Crompton, 2006). Their cognitive skills assist in assessing the biomechanics of branch flexibility and in assuming the most effective body positions to make their way through the canopy (Povinelli and Cant, 1995).…”

Representing space and objects in monkeys and apes

“…At the core of this cognitive flexibility is the question of whether primates use representation to solve problems. Some authors have argued that apes, but not monkeys, are capable of representation as evidenced by their ability to solve invisible displacements, organize food processing routines in a hierarchical fashion, understand tool relations and anticipate the best travel routes (Natale, Antinucci, Spinozzi, & Potì, 1986;Byrne, 1994;Visalberghi, 1993;Povinelli & Cant, 1995). On the other hand, other authors are reluctant to accept a clear-cut dichotomous distinction between representational apes on the one hand, and nonrepresentational monkeys on the other (Anderson, 1996;Tomasello & Call, 1997;Vauclair, 1990a).…”

The rise of the metamind

“…Ants can also be observed to build such bridges. Does the bridging behaviour indicate some level of self-awareness in orangs (cf., Povinelli and Cant 1995) but not in ants? The decision should be based on what I want to call evolutionary parsimony.…”