Bavarian fossils of likely common ancestor of humans and apes ‘put back start of bipedalism by millions of years’

The distinctive human habit of walking upright may have evolved millions of years earlier than thought, according to researchers who uncovered the remains of an ancient ape in southern Germany.

Excavations from the Hammerschmiede clay pit in Bavaria turned up fossilised bones belonging to a previously unknown baboon-sized ape that lived nearly 12m years ago, long before humans split from their modern-day cousins, the chimpanzees and bonobos.

Analysis of the bones shows that the animal, named Danuvius guggenmosi, had an unusual mix of anatomical features. While its long forearms, curved fingers and powerful, grasping thumbs were hallmarks of life spent dangling from branches, the hips, knees and feet were more human-like and better suited to walking upright, the scientists said.

Facebook Twitter Pinterest Impression of Danuvius guggenmosi. Photograph: Velizar Simeonovski/Nature

“It was astonishing for us to realise during the process of research how similar certain bones were to humans, as opposed to great apes,” said Madelaine Böhme, who led the study at the University of Tübingen. The fossils, which include remains from two females, a male and a juvenile, were excavated between 2015 and 2018.

According to Böhme, the findings suggest that our upright posture can be traced to a common ancestor of humans and great apes that lived in Europe rather than Africa. When D guggenmosi was alive, Bavaria was far hotter than it is today, and streams bordered by gallery forests meandered through the region.

The clay pit haul of fossils included teeth, pieces of jaw and spine, and a big toe that would have been handy for grasping tree branches. Arguably the most important fossils were a forearm and shin bone, which informed the scientists’ speculation about how the ape moved around.

The most complete skeleton, with 21 bones, was thought to belong to a male that stood a metre high and weighed about 30kg. He had a broad chest and the curved, S-shaped spine seen in humans.

Measurements of the teeth placed the ape in an extinct group called the dryopithecins, which lived in Europe in the middle to late Miocene, an epoch that lasted from about 23m years ago to five million years ago. Some researchers believe dryopithecins were the ancestors of the ancient African apes who ultimately gave rise to great apes more generally, including the gorillas, orangutans, chimpanzees, bonobos and humans.

Facebook Twitter Pinterest A big toe bone (centre) of a danuvius, flanked by white reconstructions. Photograph: Christoph Jäckle/Nature

Writing in the journal Nature, the scientists make the case for danuvius employing what they call “extended limb clambering” to get around. Rather than swinging from branches or walking cautiously on branches, extended limb clambering uses both arms and legs equally. “The emerging picture of its locomotion is different from any known living creature,” said Böhme.

Tracy Kivell, at the University of Kent, said the fossils were impressive. In an accompanying article, she wrote: “Together, the mosaic features of D guggenmosi arguably provide the best model yet of what a common ancestor of humans and African apes might have looked like. It offers something for everyone: the forelimbs suited to life in the trees that all living apes, including humans, still have, and lower limbs suited to extended postures like those used by orangutans during bipedalism in the trees.”

“Danuvius shows skeletal adaptations to a form of bipedalism that is previously unknown and shows that bipedalism evolved much earlier than we previously thought,” Kivell said. “Danuvius is not a fossil hominin, but it does help inform how humans may have evolved.”

Some of the most compelling evidence for upright walking in human ancestors comes from Ardipithecus ramidus, a female skeleton dating back 4.4m years that was found in Ethiopia. Ardi, who stood about a metre tall, may not have been the most accomplished of walkers, but much of her skeleton shows adaptations to walking on two feet.