Pleistocene Human Migration and Adaptation in Southeast Asia

**63**

**Chapter 4**

**Abstract**

**1. Introduction**

Mainland versus Island

and adapted to their present biogeographical distribution.

**Keywords:** primate, ecogeographical rule, body size, biodiversity, Sunda shelf

avoidance and alternate dietary shifts when resources are limited [9].

Mainland and island are two unique bodies of landmasses that hold not only the obvious different area dimension but also a timeline that portrayed dynamic changes on their geographical and ecological features. Southeast Asia that comprises mainland and the patches of island is a home for the primate species diversity with high rate of endemism and provinciality [1]. Since the emergence of primates in the region during Quaternary to recent, 13 genera have been taxonomically recognized: *Homo*, *Pongo*, *Hylobates*, *Symphalangus*, *Nomascus*, *Hoolock*, *Macaca*, *Trachypithecus*, *Presbytis*, *Simias*, *Nasalis*, *Nycticebus*, and *Tarsius* [2]. With the high variability on body mass and body size, Southeast Asian primates, both the mainland and island populations, remain enigmatic when confronted toward ecogeographical "rules," resulting positive [3], contradictive [4, 5], and inconsistent results [6]. However, given their peculiarity in adaptive functional characters among other mammal taxa and their close evolutionary trajectory to human [7], primates share similarities showing their capability in grasping object [2] for faster food procurement and high occasional flexibility in locomotion (e.g., arboreal quadrupedalism, terrestrial quadrupedalism, and bipedalism) [2, 8]. These functional characters support their high adaptability in predator

*Halmi Insani and Masanaru Takai*

Adaptation: Paleobiogeography of

Southeast Asian primates appear to be one of the most successful mammals in the dynamic paleoclimatic changes since at least 1 mya. Human and non-human primates reflect the complex history of a wide range of ecological and geographic variation, which presents to be the source of different systematics and biogeographic models. The past combinative effects of geographic factors (latitude, bathymetric barrier, and duration of island isolation), periodic sea level changes, and the contribution of human and/or non-human primate interaction are crucial subjects in studying the north-to-south, which is from continental to archipelago of Sunda Shelf, dispersal events and phylogeographic analysis of human and non-human primates. Cranial size and shape difference between *Homo erectus* in mainland and island displays peculiarity on the effect of insularity. Data analyses on cranial landmarks of three non-human primate genera provide more clear resolution to reconstruct the complete scenario, whereby insular primates are dispersed

Sunda Shelf Primates Revisited
