Primate homeland: forests and the evolution of primates during the Tertiary and Quaternary in Asia

Abstract

Primates evolved in the tropical forests of the Late Paleocene or Early Eocene. The cognitive, locomotor and life-history characteristics that define primates evolved under the equable and generally non-seasonal conditions that distinguish such forests. All primates since have carried the biological imprint of this original association with tropical forests. In Asia, the persistence of tropical forests in Indonesia from the Eocene onward has permitted tarsiers to endure and evolve, while other Eocene primates became extinct on their home continents. Following a disastrous decline in tropical forest distribution and primate diversity at the Late Eocene/Oligocene boundary, forests and primates rebounded during the Late Oligocene and Miocene. The dominant Old World primates of most of the Neogene were hominoids, which inhabited large tracts of woodlands and forests throughout Africa and Eurasia. These relatively large, frugivorous animals were quadrupedal, but many were capable of undertaking bridging postures that allowed them to stretch between arboreal substrates. Hominoids reached the apex of their evolutionary success in the Middle Miocene, then declined—as a result of the slow disappearance of their forest homes—in the Late Miocene, especially after 10 Ma. The extirpation of apes at this time can be traced to their inability to live in more seasonal and open habitats. Old World monkeys originated in forest biomes, but became the dominant primate of the late Neogene because of their ability to live in environments ranging from closed, non-seasonal rainforests to open savannahs and alpine meadows. This adaptability can be traced to their slightly faster life histories and their ability to thrive on a wide range of both high- and low-quality foods.