reproduction in plants ks2 Some arthritis, such as rheumatoid arthritis and lupus, affects multiple organs and causes a wide range of symptoms. Unlike other apes, orangutans tend to be more solitary. About the only time they encounter the other person is the place mating or sharing a fruiting tree. They spend roughly 90 percent of time in trees. They walk on all fours when on the ground and unlike the African apes, they use their palms or fists as an alternative to their knuckles. Males will move through the forest making loud howling calls, that may be heard 1.2 miles away, to make certain they stay out of each other's way. They are active in the daytime and at night, they'll build a nest by bending branches in to a platform so they can sleep on within the trees. To protect themselves in the rain and sun they are going to create a shelter from leafy branches, and they are even proven to use large leaves as umbrellas or ponchos. Symptoms of arthritis usually develop over time, but may also occur suddenly. Arthritis is most common in adults over the age of 65, but it can also develop in children, adolescents and young adults. Arthritis is more common in women than men and overweight people.