'Devil monkeys' are attacking people in Thailand, Japan and India. Here's why.

Wildlife tourism thrives on our fascination with animals and primates are particularly attractive animals to tourists. With their human-like faces, complex family dynamics and acrobatic antics, they are a joy to behold.

But recent stories have emerged that portray monkeys in a more sinister light. Reports of "monkey attacks", "devil monkeys," or even "face-ripping, bone-biting monkeys" have become common in the media. Have our primate cousins turned on us?

The recent monkey attacks involve a variety of species in different countries. They include the long-tailed macaque and the pig-tailed macaque in Thailand, Japanese macaques in Japan, and Hanuman langurs in India.

Most of these species are macaques, which are a diverse group of monkeys. But all macaques are sociable, intelligent, relatively large (between 4 kg and 9 kg [9 and 20 pounds]), and comfortable traveling on the ground. They have a flexible diet, but prefer fruit. They also have cheek pouches that allow them to gather food quickly and carry it to a safe place to eat.

Over-habituation

Regardless of species or location, a major factor in monkey bites and attacks is "over-habituation." Habituation is a process used by animal researchers to gain animals' trust so they can follow and record their behavior, with limited impact of the researchers' presence.

But Animals can become unintentionally habituated. Squirrels in a city park who have grown accustomed to handouts are one example, but others include urban foxes in the UK, bears in North America, and, in many parts of the tropics, monkeys.

When Animals lose their fear of humans and become a nuisance, they are over-habituated. In nearly all cases of over-habituation, the main factor is human food. What people eat is irresistible to wildlife. It is nutrient-dense, easy to digest and is available in rubbish bins, unattended backpacks, or even directly from people.