Forearm rotation and the “origin of the hominoid lifestyle”: A reply to Stern and Larson (2001)

Genetic and developmental basis for parallel evolution and its significance for hominoid evolution

“…Thus, more generalized hominoids simply lost out to species that were better equipped to rapidly colonize similar and more marginalized adaptive niches. Parallel exploration of derived locomotor behaviors such as increased body size, brachiation, vertical climbing, “hang feeding,” and restriction to lush tropical refugia sufficiently limit extant ape competition with sympatric Old World monkeys . Such examples of ecological character displacement provide an important clue to the repeated evolution of suspensory form in hominoids.…”

“…Parallel exploration of derived locomotor behaviors such as increased body size, 1,3,39 brachiation, vertical climbing, "hang feeding," and restriction to lush tropical refugia sufficiently limit extant ape competition with sympatric Old World monkeys. [83][84][85] Such examples of ecological character displacement provide an important clue to the repeated evolution of suspensory form in hominoids. Only humans, with our substantial changes in reproductive strategy and increased reproductive rate, have managed to dramatically surpass the cosmopolitan expansion of the cercopithe-coids.…”

Glenohumeral joint surface characters and its relation to forelimb suspensory behavior in three ateline primates, Ateles, Lagothrix, and Alouatta

“…Although many researchers agree that the shared features of the forelimb and trunk of Ateles and extant hominoids are related to joint mobility, opinions differ regarding whether such features should be attributed to brachiating or climbing locomotor behavior (Andrews and Grove, 1976;Sarmiento, 1995Sarmiento, , 2002Gebo, 1996). For example, Sarmiento (1995) pointed out that many of the shared ateline and hominoid traits, but not all, are observed in lorisines and sloths, and argued that climbing behaviors could account for these traits.…”

The AL 333-160 fourth metatarsal from Hadar compared to that of humans, great apes, baboons and proboscis monkeys: Non-conclusive evidence for pedal arches or obligate bipedality in Hadar hominins

“…Because evolution proceeds as adaptive shifts through structural continuity and localized anatomy in living primates satisfies the mechanical requirements of multiple behaviors, it is logically flawed to exclusively associate localized anatomy to single behaviors. Establishing causal relations between structure and function through mechanical models of localized anatomy, understanding how the mechanical requisites of living primate behaviors are satisfied by localized anatomy and how they ontogenetically modify this anatomy, and constructing evolutionary models of ancestors based on ecology and shared anatomy of living primates are all ingredients essential for accurately reconstructing behavior from skeletal or fossil remains (Sarmiento, 1985(Sarmiento, , 1995(Sarmiento, , 1998(Sarmiento, , 2002Sarmiento and Meldrum, 2011;Sarmiento and Wrangham, 2012). The long-standing debate concerning the locomotor behaviors of Australopithecus afarensis (Harcourt- Smith and Aiello, 2004;Kimbel and Delezene, 2009) evidences the complexity of reconstructing behavior from fossil taxa and casts doubt upon suggestions that any single, atomized anatomical element or character can alone provide conclusive proof for any particular behavior.…”

“…Fully sampling living hominoid diversity and understanding the behavioral correlates of localized anatomy through observations of living animals and modeling of localized anatomical function is instrumental for diagnosing behaviors in fossil forms (Sarmiento, 1985(Sarmiento, , 1995(Sarmiento, , 1998(Sarmiento, , 2002. Evolutionary models reconstructing common ancestral behaviors based on shared anatomy of living taxa present a range of possible behaviors that members of descendant lineages may have practiced, providing a guide to the most likely behaviors and thus the most relevant to test for in fossil members of descendant lineages (Sarmiento, 1995).…”