In 2016, a group of researchers in Germany found two fossilized teeth belonging to an unknown early primate. One of the teeth, the researchers say, is similar to that of closely related human ancestors, which have previously only been found in Africa. Their paper, recently published online ahead of press, prompted dramatic headlines claiming a need to rewrite the history of mankind. But how much of this is true, and how much is hype?
The Findings
The research group, led by Professor Henry Lutz, deputy director of the National Museum in Mainz, had been digging in the sediments of the ancient Rhine riverbed for 17 years when they made the discovery. The excavation site is located near Eppelsheim, an area famous for its primate fossils. Just before the group concluded their work at the site, they found two perfectly preserved fossilized teeth. The finding baffled the scientists, who postponed the publication of their work for more than a year.
“The fossils we’ve found aren’t what we’d expect for the area we found them in,” said Lutz in an interview with ResearchGate. “We don’t know where this new species fits in the family tree.”
The amber-colored fossils, a canine and a molar, are 9.7 million years old. The molar tooth shares characteristics with several primate species, but the real mystery surrounds the diamond-shaped canine. The researchers find that its shape resembles that of early hominins found in Africa, particularly Australopithecus afarensis and Ardipithecus ramidus. These species are best known for the specimens Lucy and Ardi, which are among the oldest known potential human ancestors. However, Lucy and Ardi are 3.2 and 4.4 million years old, several million years younger than the fossil teeth of Eppelsheim.
The upper canine.
“The question arises,” they write in the research paper, “if the newly discovered Eppelsheim species may be related to members of the African hominin tribe.” If this is so, it would mean that this group of primates occurred in Europe before it did in Africa.
“We want to hold back on speculation,” said Lutz. “What these finds definitely show us is that the holes in our knowledge and in the fossil record are much bigger than previously thought.”
Lutz acknowledges that the similarities between the Eppelsheim fossil and the African fossils could also be an example of convergent evolution. In this well-known phenomenon, the same characteristic is developed in isolated populations that are exposed to a similar environmental pressure.
“I think it’s a big luck to experience such an exciting story,” said Lutz. “I did not expect it.”
What Others Think
While the research group at Mainz is evidently excited, other experts are not so convinced. Most of the experts interviewed by National Geographic were skeptical about the significance attributed to the fossils. “The second tooth (the molar), which they say clearly comes from the same individual, is absolutely not a hominin, I would say also not a hominoid,” said Bence Viola, a paleoanthropologist from the University of Toronto.
Rather, experts suggest that the teeth most likely belong to a pliopithecoid, a very distant relative of monkeys, apes and humans that inhabited Eurasia. It is estimated that pliopithecoids split from the evolutionary tree before Old World monkeys separated from apes and humans. Lutz and colleagues also acknowledge in their paper that the molar tooth resembles that of pliopithecoid species.
Pliopithecoid skull fossil.
Paleoanthropologist Dave Begun from the University of Toronto even doubts the canine tooth belongs to a primate, remarking that it looks more like a piece of ruminant tooth to him.
It is common for the discovery and classification of new hominin fossils to be controversial. Indeed, it is not the first time that researchers point to Europe as the home of the oldest human ancestors. According to Lutz, research on the Eppelsheim fossils is just getting started, and will include x-rays to study the tooth enamel to learn about the individual’s developmental stage and age. Only time, and the new research results, will tell what exactly these new fossils mean.