Much is known about orangutan physiology and behavior. Yet there is one thing that is still unsolved – the exact reason why some male orangutans develop a flange while others do not. These large cheek pads certainly have their advantages as we shall see - it’s most certainly about dominance and mating with as many females as possible – so why do they only develop in some males and not others?
First things first – the flange is not a physical signal that a male has reached sexual maturity as was once thought – they already have quite a while back. Even though orangutans are among the slowest mammals to reach reproductive age, between 7 and 10 years of age for the male, they are capable of producing offspring at this age. However, it is rare for the male to mate before the age of 15. Females mature at about 5 years of age but like many great apes undergo a period of infertility in their adolescent years which preclude offspring for between 2 and 4 years and will not produce offspring until they too are well in to their teens.
