Self-harm is most common between the ages of 12 and 24. Self-harm is more common in females than males with this risk being five times greater in the 12–15 age group. Self-harm in childhood is relatively rare but the rate has been increasing since the 1980s. Self-harm can also occur in the elderly population. The risk of serious injury and suicide is higher in older people who self-harm. Captive animals, such as birds and monkeys, are also known to participate in self-harming behaviour.