Crab-eating macaque
The crab-eating macaque, also known as the long-tailed macaque or cynomolgus macaque, is a cercopithecine primate native to Southeast Asia. As a synanthropic species, the crab-eating macaque thrives near human settlements and in secondary forests. The crab-eating macaque has developed attributes and roles assigned to them by humans, ranging from cultural perceptions as being smart and adaptive, to being sacred animals, being regarded as vermin and pests, and becoming resources in modern biomedical research. It has been described as a species on the edge, living on the edge of forests, rivers, and seas, at the edge of human settlements, and perhaps on the edge of rapid extinction.
Crab-eating macaques are omnivorous and frugivorous. They live in matrilineal groups ranging from 10 to 85 individuals, with groups exhibiting female philopatry and males emigrating from natal group at puberty. Crab-eating macaques are the only old-world monkey known to use stone tools in their daily foraging, and they engage in a robbing and bartering behavior in some tourist locations.
The crab-eating macaque is the most traded primate species and also the most popular species used in scientific research. Due to these threats, the crab-eating macaque was listed as Endangered on the IUCN Red List in 2022.
Etymology
Macaca comes from the Portuguese word macaco, which was derived from makaku, a word in Ibinda, a language of Central Africa. The specific epithet fascicularis is Latin for a small band or stripe. Sir Thomas Raffles, who gave the animal its scientific name in 1821, did not specify what he meant by the use of this word.In Indonesia and Malaysia, the crab-eating macaque and other macaque species are known generically as kera.
The crab-eating macaque has several common names. It is often referred to as the long-tailed macaque due to its tail, which is the length of their body and head combined. The name crab-eating macaque refers to it being seen foraging beaches for crabs. Another common name for M. fascicularis, often used in laboratory settings, is the cynomolgus monkey which derives from Greek Kynamolgoi meaning "dog milkers". It has also been suggested that cynomolgus refers to a race of humans with long hair and handsome beards who used dogs for hunting according to Aristophanes of Byzantium, who seemingly derived the etymology of the word cynomolgus from the Greek κύων, cyon 'dog' and the verb ἀμέλγειν, 'to milk', by claiming that they milked female dogs.
Perceptions and terminology
Crab-eating macaques are understood and perceived in many ways: smart, pestiferous, exploited, sacred, vermin, invasive.In 2000 the crab-eating macaque was placed on the list of 100 most invasive species. For example, they are considered an invasive alien species on Mauritius, articles argue for long-tailed macaques spreading seeds of invasive plants, competing with native species like the Mauritian flying fox, and having a detrimental impact on native threatened species. Several authors pointed out that the present evidence indicates that predation on birds by monkeys may have been overestimated. address these accusations and they point out the crab-eating macaques do not prefer primary forest thus it is unlikely that Mauritius macaques were ever a major source of indigenous forest destruction. The primary driver of bird extinction has been habitat destruction by humans. Sussman and Tattersall mention that the Dutch abandoned the island in 1710–1712 due to monkeys and rats destroying plantations, they point out that the human population was low at this time and the crab-eating macaques would have had plenty of primary forest to exploit, yet they chose to brave the dangers of raiding plantations. They do not deny that macaques on Mauritius prey on bird eggs and disseminate seeds of exotic plants yet the major loss of species on Mauritius is due to habitat loss caused by humans – macaques are successful because they prefer secondary forest and disturbed habitats. This is significant because the perception of crab-eating macaques being invasive and destructive to "native" biodiversity are used as a justification for use in biomedical research.
"Weed" and "non-weed" species are distinguished based on that species ability to thrive in close proximity and association with human settlements. This label was not intentionally proposed to disparage crab-eating macaques but this term, like pest and invasive, can affect how people perceive this species and can trigger negative perceptions.
Taxonomy
Previously ten subspecies of Macaca fascicularis, but the Philippine long-tailed macaque is under dispute and is tentatively removed from IUCN Red List assessments, with those individuals included with M.f. fascicularis.- M.f. fascicularis, common long-tailed macaque – Indonesia, Malaysia, Philippines, Thailand, Cambodia, Singapore, Vietnam
- M.f. aurea, Burmese long-tailed macaque – Myanmar, Laos, western and southern Thailand near Myanmar border
- M.f. antriceps, Dark crowned long-tailed macaque – Kram Yai Island, Thailand
- M.f. condorensis, Con Song long-tailed macaque – Con Son Island, Hon Ba Island, Vietnam
- M.f. karimondjiwae, Karimunjawa long-tailed macaque – Karimunjawa Islands, Indonesia
- M.f. umbrosa, Nicobar long-tailed macaque – Nicobar islands, India
- M.f. fusca, Simeulue long-tailed macaque – Simeulue Island, Indonesia
- M.f. lasiae, Lasia long-tailed macaque – Lasia island, Indonesia
- M.f. tua, Maratua long-tailed macaque – Maratua Island, Indonesia
Evolution
The macaque originated in northeastern Africa some 7 million years ago and spread through most of continental Asia by, and subdivided into four groups. The earliest split in the genus Macaca likely occurred ~4.5 mya between an ancestor of the silenus group and a fascicularis-like ancestor from which non-silenus species later evolved. The species of the fascicularis group share a common ancestor that lived 2.5 mya. It is suggested that M. fascicularis are the most plesiomorphic taxon in the fascicularis clade, thus it is argued that M. mulatta evolved from a fascicularis-like ancestor that reached mainland from its homeland in Indonesia around 1 mya.A phylogenetic analysis found evidence that the fascicularis group originated from an ancient hybridization between the sinica and silenus groups ~3.45–3.56 mya, soon after the initial separation of two parent lineages ~3.86 mya. This divergence and subsequent hybridization occurred during rapid glacial-eustatic fluctuations in the early Pleistocene: high sea levels may have led to the initial separation of proto-sinica and proto-silenus while the subsequent lowering of sea levels facilitated the secondary contact needed for hybridization.
Known fossils indicate that crab-eating macaques inhabited the Sunda Shelf since at least early Pleistocene, ~1mya. It is likely that crab-eating macaques were introduced to Timor and Flores, by humans around 4,000–5,000 years ago. Crab-eating macaques are the only species on both sides of the Wallace line.
The possible stages of crab-eating macaque evolution and dispersal were proposed:
- Stage 1: more than, crab-eating dispersed into the Sunda Shelf area. Earliest fossil record of crab-eating macaques was found in Java. They probably reached Java by dry land during a period of glacial advance and low sea levels
- Stage 2: around 160 thousand years ago, dispersal and isolation of progenitors of the strongly differentiated deep water fringing island populations occurred. These include M.f. umbrosa, M.f. fusca, M.f., tua . It is thought that the progenitors of these subspecies reached deep water habitats during the penultimate glacial maximum when sea levels were lower than present. These populations became isolated during the interglacial period around 120 kya
- Stage 3: more than 18 thousand years ago, the differentiation of progenitors of populations of the Indochinese peninsula and northern part of the isthmus of Kra occurred. These subspecies include M.f. aurea and M.f. fascicularis. These two subspecies became differentiated before the last glacial maximum
- Stage 4: 18 thousand years ago, the dispersal and isolation of progenitors of weakly differentiated deep water fringing island populations occurred
- Stage 5: less than 18 thousand years ago, the isolation of the progenitors of shallow water fringing island populations and populations in Penida and Lombok occurred. These subspecies include M.f. karimondjawae, M.f. atriceps, M.f. condorensis, M.f. fascicularis
- Stage 6: 4.5 thousand years ago, the dispersal and isolation of progenitors of populations in eastern lesser Sunda islands, occurred.
Characteristics