Once the dwellers of mainland Southeast Asia, the ancient giant orangutan is now extinct. Today, orangutans are only found in their natural habitat on the two islands of Sumatra and Borneo. These two are classed as different species due to the fact they grew so genetically different from each other. The animals’ drastic change in size is one reason for this. It is known that this modern species shrunk over time from its enormous ancestor, although, details have previously been a little hazy, requiring scientists to do guesswork on the subject matter.

New fossils found

Thanks to new fossil records of 600 recently discovered teeth, we now have an answer to this mystery. These orangutan remains were found scattered across 10 caves in southern China and support a theory claiming a period of declining size starting from around two million years ago.

The study, published in the Journal of Human Evolution, discusses the genome analysis and visual methods used to come to this conclusion. Comparisons found was that the tooth shape remained the same, while size progressively decreased. Plus, researchers from the Chinese Academy of Sciences in Beijing estimate that the ancient orangutans’ average body weight was close to double the amount it is of the modern species today.

Why the declining size?

Fossil records of other ancient Asian animals, such as monkeys and rhinos, also saw a decline in body size around this same period. Scientists think this is due to the colder and drier climate the world was experiencing at this time. A reduced food source pushed evolution to produce smaller animals that needed less energy input.

What can we learn from this?

Understanding the past evolution and genome structure of animals can lead to more in depth information about diseases they may be susceptible to, and also requirements for a healthier life. This information could help animals conservationists cater to the needs of the current orangutan species more successfully.

Studying the evolution of species, especially primates, allows insight into our own evolution. Understanding the natural world is still a huge challenge for science, so any information we can gain no matter what organism may help in the long run. When we grasp how DNA truly works, we can hopefully eradicate genetic diseases and manipulate the genome to live healthier and longer lives.

Source study: Journal of Human Evolution – Evolutionary trend in dental size in fossil orangutans from the Pleistocene of Chongzuo, Guangxi, southern China