New evidence has shed light on an 800,000-year-old cannibalistic murder. In the mountains of northern Spain, an ancient cave held the scattered skeletal remains of some extinct human ancestors with clear marks of cannibalism – perhaps the result of an unfortunate run-in with a rival group.

In a new study, anthropologists looked at the individuals’ teeth in an attempt to reveal their identity, revealing some surprises: one individual once known as the Boy of Gran Dolina was, in fact, a young female.

“In other words, the Boy of Gran Dolina would really have been the Girl of Gran Dolina”, Cecilia García-Campos, lead study author from the Centro Nacional de Investigación de la Evolución Humana (CENIEH), said in a statement. 

The individuals in the cave, found at Gran Dolina in Spain, belong to the species Homo antecessor, an extinct hominin species that lived in Western Europe during the Lower Paleolithic until around 800,000 years ago. They are known for their unique mixture of modern and archaic features, with some researchers speculating they may represent the last common ancestor for Neanderthals and modern humans.

Reporting in the Journal of Anthropological Science, the new research looked at the H. antecessor teeth found at the site. Since the enamel and dentin dimensions in dental pieces are sexually dimorphic, they can be used to identify whether the individual was a male or female with around 92 percent accuracy. Teeth can also be used to roughly gauge the age of an individual, since they change as they develop. To their surprise, this revealed that individual H3 – previously dubbed Boy of Gran Dolina – was probably a female aged between 9 and 11.

But why would a young female be subjected to such a bloodthirsty display of cannibalism? This is a question that the researchers have previously looked into in another study back in 2019. The skeletal remains of H. antecessor found at Gran Dolina contain teeth marks, butchering marks, and show signs of marrow extraction – which is fairly solid evidence the individuals were chopped up and eaten by a rival group. 

While it may seem brutal by our standards, the act of cannibalism appears to be strictly business. For archaic humans around this time, eating fellow hominins was simply more effective than hunting prey based on the nutrient caloric return and the cost of acquisition. 

“Our analyses show that Homo antecessor, like any predator, selected its prey following the principle of optimizing the cost-benefit balance, and they also show that, considering only this balance, humans were a 'high-ranked' prey type. This means that, when compared with other prey, a lot of food could be obtained from humans at low cost”, said Jesús Rodríguez of CENIEH, speaking in 2019.

That said, others believe that early humans and Neandtherals practiced cannibalism for a very different reason. Some research has shown that they didn’t always eat each other out of nutritional necessity for food, but perhaps sometimes for reasons of aggression or ritual.