Where did the monkeys come from?

anthropology Sensational skull find: was that what our ancestors looked like?

Scientists have already been able to prove that the common ancestor of humans and chimpanzees lived in Africa about six to seven million years ago on the basis of many revealing fossil finds. They were also able to show how people have developed since then. But what was before that? An international team of researchers, including Fred Spoor from the Max Planck Institute for Evolutionary Anthropology in Leipzig, now has an answer to this question.

"Alesi": Do we all have a common ancestor?

As early as 2014, the Kenyan fossil collector John Ekusi from the Turkana Basin Institute discovered a particularly well-preserved fossil monkey skull in the north of the country. It was hidden in 13 million year old rock formations in the Napudet region, west of Lake Turkana. Collector Ekusi called him "Alesi", derived from the Turkana word "Ales" for "ancestor".

"Alesi" is thus the oldest known fossil of an extinct great ape - and the most significant. All other finds brought only individual teeth and jawbones to light, which allowed little conclusions to be drawn about the appearance and way of life. In addition, due to the lack of skulls, it could never be proven with certainty whether they were really the remains of extinct great apes or other species of apes. For Isaiah Nengo's international team of researchers from the Turkana Basin Institute at Stony Brook University and from De Anza College (USA), this is a unique opportunity to examine the find in detail.

Skull belonged to a toddler monkey

Fred Spoor from the Max Planck Institute for Evolutionary Anthropology in Leipzig was working nearby when the skull was recovered. Since he himself often uses computed tomography as an imaging examination method, he was asked to take the find to the hospital in Nairobi. There he could already see from the images of the teeth that it really was a human ape. Spoor was aware that the European Synchrotron Radiation Facility (ESRF) in Grenoble / France had an extremely sensitive CT device. There, further spectacular pictures of the inner parts of the skull could be made, which were particularly revealing.

We were able to visualize the brain cavity, inner ear and the permanent teeth that had not yet erupted with their daily growth lines. The quality of our images was so good that we could tell from the teeth that the child was about a year and four months old when he died.

Paul Tafforeau, European Synchrotron Radiation Facility (ESRF) Grenoble / France

The not yet erupted permanent teeth in the skull of the young great ape also show that it really belongs to a new species, which the researchers called "Nyanzapithecus alesi".

It is important that the skull has fully developed bony ear canals. This is an important feature that creates a link to the great apes living today.

Ellen Miller, Anthropologist, Wake Forest University (USA)

Extinct great ape species were apparently much smaller

Alesi's skull is about the size of a lemon, and with its particularly small snout, it looks more like a baby gibbon. Chris Gilbert from Hunter College in New York confirms that such an appearance was not only found in gibbons, but also in other extinct great apes and ape species and their relatives.

No climbers like gibbons

The researchers were also able to prove that the new type of behavior was certainly not "gibbon-like" by examining the organ of equilibrium within the inner ear.

Gibbons are known for their quick and acrobatic behavior in trees, but Alesi's inner ear shows that he must have moved more carefully.

Fred Spoor, Max Planck Institute for Evolutionary Anthropology Leipzig and University College London

Alesi is our ancestor and that of all great apes living today

After considering all the research results, first author Isaiah Nengo is certain that Alesi and his relatives were very close to the origins of today's great apes and humans and that they were at home in Africa.

It was of course a special feeling when we all realized what a treasure we were holding in our hands. Up until then there hadn't been anything like it, nothing that would have told us so much about our origins.

Fred Spoor

on the radio | 08/10/2017 | 9:50 a.m.