U is for Uakari
The bald uakari is most easily recognized by its red face and bald head, from which it derives its name. Some people compare them to old men and babies, because of their baldness; there is no denying this species is uniquely handsome. The striking crimson color is caused by blood-flow beneath the skin, specifically a thinner epidermis coupled with a higher concentration of capillaries in the face. The redness of a female’s face is correlated with her estrogen levels; the redness of a male’s face is indirectly related to his testosterone levels, according to a recent study. A redder face indicates a healthier monkey, since their faces, like ours, grow pale when they’re ill - particularly with malaria, which is rampant in their habitat.
Another distinction that sets the bald uakari apart is its conspicuously short tail, which is only around 6 in (52 cm) long. The bald uakari does not use its tail to travel through the trees; it relies on its arms and legs, as well as its long, furry fingers and toes. Their fur coats are long and cover the whole of their bodies, ranging in color from blonde to orange to brown to red.
Bald uakaris are most commonly monogamous.
A 2016 study revealed that the bald uakari has highly polymorphic color vision. This, researchers believe, aids them in foraging, when they have to be able to determine the colors of food against a leafy background, and also in sexual selection—since the redder the face, the more suitable the mate.
In 1997, the Amazon Basin was the most heavily deforested region in the entire world. If the rainforests continue to be depleted by logging and other practices, we could lose this species entirely.