New research has discovered an extinct relative of modern humans known as Homo naledi buried their dead and engraved cave walls around 250,000 years ago. The discovery is a surprise as it changes long-held theories that only modern humans and ancient relatives, Neanderthals, could do the activities at this level of complexity. The brains of the Homo Naledi species were a third of the size of modern-day human ones, and so the uncovering of the early practices has been branded as a “landmark finding” by the team of researchers who published their hypothesis in the journal eLife in 2023.

Various experts said the theory did not have enough evidence to conclude that H. naledi buried or memorialised their dead. However, in a revised study published March 28, the researchers provided 250 pages of evidence of purposeful burial among the species.

It was in 2013, in South Africa’s Rising Star cave system, that archaeologists first discovered the remains of H. naledi. Since then, over 1,500 bones from multiple individuals have been uncovered throughout the 2.5-mile-long system, Live Science reports.

The species’ anatomy is well-known thanks to the incredible preservation of the remains. They were bipedal, stood around 1.5 metres tall and weighed approximately 45 kilograms. The remains had dexterous hands and small yet complex brains. Its traits have led to a debate about the complexity of their behaviour.

In a 2017 study published in eLife, the Rising Star team first suggested that the ancient humans purposefully buried their dead in the cave system. In a news conference six years later, paleoanthropologist Lee Burger, the team lead, and his colleagues reinforced the claim with three studies.

This resulted in the most substantial evidence so far that H. naledi intentionally buried their dead and crafted meaningful engravings on the rock above the burials.

The research described two shallow, oval-shaped pits on the floor of one cave chamber that contained skeletal remains consistent with the burial of fleshed bodies covered in sediment and then decomposed. One of the burials potentially included a grave offering, as a single stone artefact was discovered close to the hand and wrist bones.

One expert, who had reviewed the 2023 study and declared it inconclusive, reviewed the new study and wrote: “I now think that the authors provide sufficient evidence for the presence of ‘repeated and patterned’ deliberate burials” by H. naledi.

However, another reviewer believes the new study remains unconvincing and that independent teams should also conduct a full analysis “since science is about replication.”