Archaeological discoveries in Dmanisi have shown that two types of ancient humans may have lived outside the African continent. Dental analysis revealed clear differences that cannot be explained by sex or age

 

According to the journal PLOS One, scientists from the University of São Paulo in Brazil are proposing a new perspective on one of the most controversial questions in paleoanthropology: identifying the first humans to leave the African continent. This proposal is based on the famous discoveries at the Dmanisi site in Georgia, where, about a quarter of a century ago, the five oldest human skulls found outside of Africa were discovered.

It was long believed that these remains all belonged to Homo erectus, a human species that began spreading across Eurasia around 1.8 million years ago. However, the Dmanisi skulls exhibit considerable diversity, making their classification into a single species difficult. They vary in size and shape, with skull number 5 particularly noteworthy for its combination of a small skull and a large, prominent face. Some researchers attribute this variation to differences between the sexes, while others believe it suggests the existence of more than one human species.

A research team led by Victor Neri decided to seek an explanation for this discrepancy by studying teeth rather than bone shape, given that skulls can become deformed over millions of years, while tooth enamel, the hardest substance in the human body, retains fine details. The researchers studied the teeth of three Dmanisi specimens, focusing on the shape and size of the tooth crowns.

The results showed that the teeth of Skull 5 were distinctly different from the others, closely resembling those of Australopithecus, an earlier and more primitive human ancestor, while the other two specimens appeared more similar to human teeth. Based on these findings, the researchers propose distinguishing between two human species: Homo georgicus, associated with Skull 5, and Homo caucasi, representing the more advanced group.

To rule out that these differences were solely due to sexual variation, the scientists compared the results to the teeth of modern great apes. The comparison showed that even in species exhibiting clear size differences between males and females, the basic dental features remained similar, whereas the differences in the Dmanisi samples were too large to be explained by sex alone.

Researchers believe that if these results are confirmed, the early history of human dispersal out of Africa may be more complex than currently believed, as it is possible that two different types of hominins left the African continent at the same time, rather than one general type, Homo erectus.