The study found the first evidence of rapid changes in primate fur pigmentation

and squid can change their colors, but monkeys can't - until humans step in. Researchers found that a usually black, long-haired macaque in Costa Rica began to show unique yellow patches on its tail and legs. This is the first evidence of rapid changes in primate fur pigmentation.
to find out what was going on, the scientists analyzed the fur of one of the monkeys, which changed color. Long-haired macaques usually have a melanin called true melanin (manifested in black, gray, or dark brown), which colors hair and skin cells. In yellow hair, the researchers noted that the melanin turned into a sulfur-containing melatonin. The latter appears in animals with yellow, red or orange hues.
researchers believe the animals ingested sulfur while eating leaves from trees near insecticide-sprayed pineapples, bananas and African palm oil farms. This sulfur may be mixed with the pigment structure of the hair and then changes the overall composition. In recent years, farms in Costa Rica have used many of these pesticides.
color changes can have an important effect on roaring monkeys. Yellow patches make it easier to be found by jaguars and other predators in dense forests. Moreover, this color trend may be spreading. The team found that the area of fur that had been changed in color was increasing, and that some monkeys looked almost entirely yellow. The results are to be published in Mammal Biology. (Source: Xu Xu, China Science Daily)