Protein sequencing links ancient giant ape with modern orangutan

Nov. 14 (UPI) -- Using a technique called protein sequencing, scientists have linked an extinct giant ape that lived nearly 2 million years ago with the lineage that yielded modern orangutans.

The analysis method demonstrated in the study, published this week in the journal Nature, could help scientists better understand the evolutionary relationships between apes and our earliest human ancestors.

Humans and chimpanzee lineages split some 8 million years ago, but the oldest human DNA yet recovered dates to 430,000 years ago. In hot, humid regions, like the regions of Africa where many scientists suggest the first humans emerged, the oldest human DNA is much younger -- about 14,000 years old.

Because DNA is relatively fragile, it's lifespan is limited. Ancient DNA can only be recovered from remains that have been preserved under just the right conditions.

Proteins are more resilient, and they can be sequenced like DNA to reveal evolutionary relationships between different species, including primates and humans.

"Primates are relatively close to humans, evolutionary speaking," Frido Welker, postdoctoral researcher at the University of Copenhagen's Globe Institute in Denmark, said in a news release. "With this study, we show that we can use protein sequencing to retrieve ancient genetic information from primates living in subtropical areas even when the fossil is two million years old."

For the latest study, scientists recovered proteins from the remains of a giant ape species, Gigantopithecus blacki, that lived in China millions of years ago. Using advanced spectroscopy technologies, light-based tools for studying the chemical makeup of materials, scientists were able to sequence ancient proteins in the ape's dental enamel.

"By sequencing proteins retrieved from dental enamel about two million years old, we showed it is possible to confidently reconstruct the evolutionary relationships of animal species that went extinct too far away in time for their DNA to survive till now," said researcher Enrico Cappellini. "In this study, we can even conclude that the lineages of orangutan and Gigantopithecus split up about 12 million years ago."

Gigantopithecus was first discovered in 1935. The giant ape's fossil record consists of just a few lower jaws and dozens of teeth, making it difficult to know exactly what the primitive primate looked like. Now that scientists know that it's closest living relative is the orangutan, they can begin to more accurately reconstruct the species' physiology.

In the future, scientists hope similar kinds of protein sequencing will reveal details about the evolutionary relationships between early humans and our closest primate relatives.