*3.2.2 Changes through time*

*Pleistocene Archaeology - Migration, Technology, and Adaptation*

craniodental specimens [25].

in Late Pleistocene.

Mentawai Islands).

*3.2.1 Duration*

Conversely, a higher endemic mammal species diversity was more visible in East Java during the Middle Pleistocene, in the stage of *Stegodon*-*Homo erectus* [32]. Two Hominoidae taxa, *Gigantopithecus* sp. [39] and *Homo erectus*, co-existed in the eastern part of the island during the Middle Pleistocene (**Table 4**). It is also followed by the known primate fossils, including *Trachypithecus auratus*, *Presbytis comata*, *M. nemestrina*, *M. fascicularis*, *Hylobates* sp., and later *Pongo pygmaeus* in the Late Pleistocene [33, 44]. All cercopithecid species are comparable to extant species inhabiting Java Island, while Hominoidae taxa are all extinct. *Gigantopithecus* sp., *Homo erectus*, *Pongo pygmaeus*, and *M. nemestrina*, which have disappeared in recent Java Island, are assumed to indicate the incapability to adapt toward paleoclimatic changes resulting in habitat loss or ecological replacement from rain forest to open woodland and possible human intervention such as hunting. Although this result is likely related to excavation bias where most of the archeological localities are located in East Java [32, 37], the possible intraspecific variation is reported in *Homo erectus*, which is commonly discovered in eastern Java localities, specifically as

With the numerous *Homo erectus* findings in Java Islands, it leads to the high morphological diversity [25] exclusively on cranial morphology. A comprehensive study on comparison of *Homo erectus* cranial morphology between island and mainland population has been investigated showing the peculiar distinction on mainland vs. island population. Zhoukoudian *Homo erectus* represents mainland population (**Table 4**), and the common ancestor of Javan *Homo erectus* demonstrates a less morphological variability to the Early Pleistocene Java *Homo erectus* (that mostly unearthed in Sangiran Dome), while Late-Middle Pleistocene Javan *Homo erectus* are reported to share similarities in cranial shape [25]. It is suggestive that the lower habitat vicariance in mainland during Middle Pleistocene and Java Island during Middle-Late Pleistocene indicates less genetic isolation. Taking this into account, geographic barriers such as volcanic mountains, added with the isolation of Java, might enforce high intraspecific variation during Early-Middle Pleistocene, supported by the extensive paleoclimatic change. Out of Sunda Shelf, the obvious record of this mechanism appears in Wallacea non-human primates inhabiting Sulawesi. High bathymetric boundaries to Sunda Shelf and the islands surrounding, and diversed topographic barrier of Sulawesi contributes to six endemic macaque species; *Macaca nigra, Macaca tonkeana, Macaca maura, Macaca nigrescens, Macaca ochreata*, and *Macaca hecki* that some of the species were found in the archeological cave Leang Burung 2 that occupied with the early human occupation on the island

**3.2 Temporal cost: isolation and endemism from Pleistocene to modern**

Time by duration and particular period falls to the temporal scope of inhabitation of certain population on island is pronounced to impact body size evolution [12]. Higher duration of island isolation increases the chance for ecological release to influence functional characters (e.g., diet, locomotion, and bauplan) among species. The report on paleoinsular mammals has claimed that body size shift on island mammal species occurred when residence time reached more than 10,000 years [12]. While the evidences are prominently strong on terrestrial herbivores, including terrestrial primates (e.g., *Homo floresiensis,* 60,000–100,000 years ago [26]), it also evidently impacts the arboreal non-human primate species or subspecies (e.g., *Macaca fascicularis* and endemic primate species on Simeulue, Lasia, Nicobar,

**76**

According to the previous paleontological works on mammal evolution of Southeast Asia, there is no fossil evidence of primates before ca. 0.9 Ma in Java Island. The first colonization of primates to Java is estimated to occur at the end of Early Pleistocene, when Sunda Shelf fully emerged and then periodically entered Java via Siva-Malayan corridor route during Middle Pleistocene [33]. Along with the balanced mammal association, including *Homo erectus*, this period seemingly shows the suitable ecological condition for arboreal high-adapted non-human primates (*Macaca*, *Trachypithecus*, and *Presbytis*) to adapt to mainly open woodlands in relatively dry climate condition [33]. The long duration allowing the dry landmass that connected recent mainland and island during this period possibly permits the occupation access for a hominine species (elaborated as *Homo* cf. *floresiensis* [42]) to inhabit the oceanic island of Flores.

To date, there is no chronological and geographical comparative study demonstrating body size of non-human primates between fossils and recent on Java Island. It rather revealed the similarities on morphological characters in accordance with the attempt in determining species. So, it was difficult to answer whether Middle Pleistocene non-human primates of Java are the continuously highly adapted species until recent or the extinct species that disappeared in the Middle Pleistocene like other mammals (including *Homo erectus*).

Late Pleistocene displays the rise of tropical rain forest non-human primates (*Hylobates* and *Pongo*) to develop in Sunda Shelf where the Chinese origin fauna enter to exhibit similar association to recent fauna [33]. Primate species/subspecies that became native to some oceanic islands (e.g., *M. siberu*, *M. pagensis*, *H. klossii*, *P. potenziani*, *P. pagensis*, and *Simias concolor* in Mentawai islands, *M. f. condorensis* in Nicobar Islands, *M. f. fusca* in Simeulue Island, *M. f. lasiae* in Lasia Island, and *M. f. tua* in Maratua Island). Considering the limitation of swimming ability (max. Swimming distance limit 100 m in *M. fascicularis* [5]) and large island-mainland distance, dispersal route to the oceanic island is most likely through corridor route over dry landmass, furthermore by passive dispersal, such as natural rafting [5]. The dispersal scenario passing deep sea barrier to reach oceanic islands of Lesser Sunda presumably occurred by human transport during <4.5 ka [5], because swimming is not possible due to the strong sea current in Lombok Strait. This data is supported by the presence of *M. fascicularis* remains in archeological cave aged ca. 7 ka in Timor Island [5, 27].

### **3.3 Ecological cost: fauna association and vegetation**

## *3.3.1 Fauna association*

With limited connection to the diverse mainland fauna, isolated island promotes the poor taxonomic diversity and the imbalanced rate between herbivores and carnivores. Small island has been claimed to reduce the sympatric speciation than large island [31]. This condition drove a disharmonic inter- and intraspecific variation [12]. For instance, in severe ecological condition when food resources are limited in long duration, the large-bodied species tends to expand their territory where small-bodied species fails to compete and being enforced to undergo stronger dietary adaptation. This response to ecological condition led to a radiation into different size classes and morphotypes, which arrives to appear in the form such as anatomical modification (e.g., dental pattern, size, and shape of limb bone) causing genetic radiation [12].

In most case, this disharmonic taxonomic diversity condition dropped the survivability. The heavily impoverished condition leads to some species to extinction, for example, in all Late Pliocene-Early Pleistocene (*Sinomastodon-Megalochelys* stage) species in Java and large- to intermediate-bodied fauna in Flores Island in Late Pleistocene. It is followed by imbalanced condition where the normal ratio between carnivores and herbivores is high. Predator avoidance is suggested to cause the limb bone modification. A species that is not threatened by the carnivores might not often walk and run leading to the less development of limb bones.

### *3.3.2 Vegetation*

The vegetation type of an area derives from mean temperature caused from latitudinal position, geographical topography, seasonality by monsoon, and geological sediments. During Quaternary, the fluctuating temperature prominently contributes to habitat changes. The ecological shift from tropical rainforest to more open environment in Early-Mid Holocene resulted in biodiversity loss in non-human primates; for example, it is shown by the disappearance of *Presbytis comata* (Javan langur) in eastern Java that was previously found in Braholo Cave, East Java (Late Pleistocene to Mid Holocene) [45], and the extinction of Pongo in Java that was formerly discovered in Punung rockshelter, East Java (Late Pleistocene) [46–48]. This open environment niches created the mosaic ecological niche in eastern Java [45, 49] that enforced the early *Homo sapiens* inhabiting Java to hunt the remaining arboreal fauna including non-human primates as food resources. Archeological evidence depicting *Homo sapiens* that consumed monkeys (*Macaca*, *Presbytis*, and *Trachypithecus*) are also discovered in Song Terus cave in the period from 9000 to 5000 years ago [50] and Niah Cave, Borneo [51]. Further ethnographic account resembling this phenomenon is found as butchery marks and burnt bone fragments on cercopithecids assemblage in Punan Vuhang, Sarawak, Borneo [52].
