Tamarin

Tamarins are small, squirrel-sized primates from Central and South America, classified under the genus *Saguinus* in the family Callitrichidae. They split off first from the rest of the callitrichid family tree, making them the closest relatives to a group that includes lion tamarins, Goeldi's monkeys, and marmosets. These monkeys live in habitats ranging from southern Central America to central South America, specifically in northwestern Colombia, the Amazon basin, and the Guianas.

In terms of classification, early work by Hershkovitz in 1977 listed ten species of *Saguinus*, broken into 33 types based on facial fur patterns. Later studies grouped them into two main lineages using tooth measurements. A major review in 2016 confirmed that tamarins branched off from other callitrichids about 15 to 13 million years ago. Within the genus, six historical species groups were recognized—*nigricollis*, *mystax*, *midas*, *inustus*, *bicolor*, and *oedipus*—but five were upheld, with *Saguinus inustus* placed inside the *midas* group. The smaller-bodied *nigricollis* group began diverging 11 to 8 million years ago, leading researchers to move them into a separate genus, *Leontocebus* (saddle-back tamarins). A 2018 study argued that *Leontocebus* wasn't different enough from *Saguinus* to warrant its own genus, suggesting it become a subgenus instead—a proposal that has gained wide acceptance. The same study found the *mystax* group distinct enough to be placed in the subgenus *Tamarinus*. As of 2021, not all primatologists have agreed to these changes.

Following the 2016 and 2018 reviews, the genus *Saguinus* now contains 22 species and 19 subspecies. These are split into two subgenera. Under the subgenus *Saguinus* are the *midas* group (golden-handed, western black-handed, and eastern black-handed tamarins), the *bicolor* group (pied and Martins's tamarins, with two subspecies of the latter), and the *oedipus* group (cotton-top, Geoffroy's, and white-footed tamarins). The subgenus *Tamarinus* includes the moustached tamarin (with three subspecies), the white-lipped tamarin (with three subspecies), the emperor tamarin (with two subspecies), and the mottle-faced tamarin.

Appearance varies widely among tamarins, from nearly all black to mixes of black, brown, and white. Many species have mustache-like facial hair. Their bodies range in size, with tails adding extra length, and they weigh between certain amounts. In captivity, red-bellied tamarins have lived up to 20.5 years, and cotton-top tamarins up to 23 years.

These monkeys are diurnal and arboreal, living in tropical rainforests and open woodlands. They move quickly through trees by running and jumping. Groups can have up to 40 members, but more often consist of three to nine individuals, sometimes including multiple families. Their diet is omnivorous, including fruits, plant parts, spiders, insects, small vertebrates, and bird eggs.

Females typically give birth to twins after a gestation of about 140 days. Adult males, subadults, and juveniles help care for the young, bringing them to the mother to nurse. Babies start eating solid food around one month old but are not fully weaned for another two to three months, reaching maturity in their second year. Tamarins are almost always polyandrous.

Cotton-top tamarins breed cooperatively in the wild. In experiments, pairs of these monkeys pulled handles on a transparent food apparatus only when both pulled at the same time, showing they understood cooperation. Researchers concluded that this behavior is a cognitive adaptation.

In some areas, saddle-back tamarins (subgenus *Leontocebus*) live alongside *Saguinus* species but occupy lower forest levels. Saddle-backs have longer, narrower hands, possibly an adaptation for searching hidden insects in knotholes, crevices, bromeliad tanks, and leaf litter, while *Saguinus* species forage for insects on exposed surfaces like leaves and branches. This difference in lifestyle was why they were once considered separate genera.

Tamarins spend much of the day foraging but must stay alert for predators from the air and ground. Their small size compared to other primates makes them vulnerable.