May 03, 2017

Bonobos or Chimpanzees: Which Are Our Closer Relatives?

A new study shows that bonobos—not chimpanzees, as was once thought—may be more closely linked, anatomically speaking, to humans.
By Kerry Lengyel
Chimpanzees have long been thought to be the species most anatomically similar to humans, but a recent study from Howard and George Washington Universities found that the bonobo may be our closer relative. This finding came after researchers examined 7 bonobos at the Antwerp Zoo in Belgium that had died of natural causes and were being preserved.
 
This is the first study to provide a detailed comparison of the anatomy of all 3 species—humans, chimpanzees, and bonobos.

After examining the muscular system of the bonobos, researchers gained firsthand evidence that the bonobo’s muscles have changed less over time than those of common chimpanzees.

"Bonobo muscles have changed least, which means they are the closest we can get to having a 'living' ancestor," said Bernard Wood, DSc, PhD, professor of human origins at the George Washington Center for the Advanced Study of Human Paleobiology and one of the study researchers.
 
Researchers have been asking themselves for a while which species is more closely linked to humans. It is believed that human and common chimpanzee/bonobo lineages split about 8 million years ago. Common chimps and bonobos split about 6 million years after that.
 
Researchers have been curious to learn about the differences between the 2 ape species today and how each compares anatomically with humans. While some studies have examined the DNA similarities and differences between bonobos and chimpanzees, this study broke ground as the first to compare the apes’ muscles.
 
The study also showed a “mosaic evolution of the 3 species,” meaning that some features are shared by humans and bonobos, some by humans and common chimps, and others by both ape species.
 
“Such a mosaic anatomical evolution may well be related to the somewhat similar molecular mosaic evolution between the 3 species revealed by previous genetic studies: each of the chimpanzees species share about 3% of genetic traits with humans that are not present in the other chimpanzee species,” said Rui Diogo, PhD, associate professor of anatomy at Howard University and lead author of the paper.

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