A scientist discovers that bonobos, common chimpanzees, and gorillas have at least seven muscles that are supposed to be exclusively present in humans after evolutionary processes.

Rui Diogo, an associate professor in the Department of Anatomy at Howard University in Washington, found that apes and several similar species also possess human muscles that are responsible for walking on two legs, using complex tools, as well as creating complex facial expressions and vocal sounds.

Diogo asserted that his discovery challenges the long-established anthropocentric view that evolutionary processes favored special human traits to make people highly adaptable and the most special creatures to survive the planet.

"This study contradicts key dogmas about human evolution and our distinct place on the 'ladder of nature," Diogo contended.

'Uniquely Human' Muscles Found In Apes

Diogo has built his hypothesis after conducting anatomical research on a number of bonobos that died naturally. Diogo, together with colleagues at the University of Antwerp who are all working for the Bonobo Morphology Initiative 2016, dissected the bonobos' bodies to look for the presence of seven distinct muscles.

He also studied previous research on ape anatomy conducted by his colleague Bernard Wood.

Diogo found that these seven muscles, thought to have evolved in humans alone, were in similar or to the extent of being in exact same form in the ape species. The fibularis tertius muscle that gives humans the ability to walk on two legs was found in half of the dead bonobos examined by Diogo.

Diogo also learned that some chimpanzees and gorillas have the arytenoideus obliquus or the laryngeal muscle responsible for humans' supposedly unique vocal ability. The species also have the risorius or the facial muscle that helped humans produced different facial expressions.

Two of the seven bonobos dissected were found to have the adductor pollicis accessorius or the hand muscle that equipped humans with the ability to use complex tools. This muscle extends from the intermediate part of the bonobos' skeletal hand to their thumbs' bones similarly with how the muscle was seen in humans.

Diogo's analysis, published in Frontiers in Ecology and Evolution on April 26, highlighted that the forearm muscle or the flexor digitorum profundus of seven dissected bonobos is as plump as the humans' corresponding forearm muscle or the flexor pollicis longus.

Additionally, in the case of the hylobatids or the gibbons, their forearm muscles are not only as plump like that of humans but also found where the humans' flexor pollicis longus is located. The gibbons also possess the extensor pollicis brevis that was used by humans to create their complex tools.

Lastly, three of the bonobos were recognized to have the adductor hallucis accessories or the muscle foot that have never been associated with primates until now.

Humans Not Unique From Apes After All

Diogo highlighted that most theories about human evolution were built around the assumption that humans are anatomically distinct from apes or that people are more special compared to animals. Previous theories also centered on the notion that evolution made humans highly unique species. His study, however, suggested otherwise.

The next step for Diogo is to examine deeply why these muscles are present in apes or why are they distinct in certain ape species. He would try to find out whether these muscles are really essential for the apes or whether these muscles are also the product of evolutionary processes.

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