In Interview with the Vampire, Claudia, portrayed by Kirsten Dunst in the movie version, becomes a vampire at age 6. Six decades later, she still has the body of a child but the thoughts and desires of a grown woman.
In this way, orangutans are kind of like vampires. They have their own form of arrested development.
When male orangutans hit puberty, they develop distinct traits known as secondary sex characteristics that separate them from females. In addition to being much bigger, males grow longer, shaggier hair on their arms and back and sport giant cheek pads. They also have throat pouches that resemble large double chins, allowing males to beckon females with loud long calls.
Some males are late bloomers, not acquiring these traits until as late as age 30. But looks can be deceiving. Even though these males appear to be youngsters, they are sexually mature and capable of siring offspring.
Scientists think the two different types of adult males—those with secondary sex characteristics and those without—are two alternative mating strategies that evolved in orangutans. A new study published online in the American Journal of Physical Anthropology tries to pinpoint the circumstances under which orangutan arrested development emerges.
To do this, Gauri Pradhan of the University of South Florida and Maria van Noordwijk and Carel van Schaik, both of the University of Zurich, considered the differences between orangutans living in Borneo and those in Sumatra. These Indonesian islands are the only two places in the world where orangutans are still found in the wild. But arrested development is largely limited to Sumatra.
Orangutans in both locations are mostly solitary. They roam the treetops alone, but they live in home ranges that overlap with those of other orangutans. In Sumatra, a female prefers to mate with the dominant male that lives in her neck of the woods. This male always has his full set of male features.
A female finds the dominant male by following the sound of his long call, and when she’s ready to be pregnant, the two enjoy a sort of honeymoon—traveling and mating together for up to three weeks. Other adult-looking males may live in the same area, but females actively avoid their calls and stay hidden from them.
Because the dominant male is so popular, he can be choosy about mates. These males tend to pass over inexperienced females who haven’t yet had a baby. With younger adult females, it’s hard to tell if they are truly ready to become mothers, so it’s a better bet to stick with females who are already moms.
Continue reading (Incl. Pic) at: Why Some Orangutans Never Want to Grow Up
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