Deep in an underground cave, archaeologists have discovered a new human ancestor with big thumbs and a tiny brain. But is it a new species? How old are they? And did they deliberately dispose of their dead?
Two years ago, a trio of cavers squeezed through a narrow cave passage that extends 40m underground, and emerged into a chamber whose floor was strewn with human remains. Ancient human remains.
The discovery was made in Rising Star cave, near Johannesberg, in an area known as the Cradle of Humankind – a UNESCO world heritage site that covers 180 square miles area and has produced many important hominid discoveries, but none as curious as this…
After the initial discovery, a special team of super-slim and experienced cave archaeologists were recruited to recover the remains… after all, some of the gaps they had to squeeze through were only 10 inches wide.
Communicating with a command-centre by camera, the all-female team brought over 1,500 bones back to the surface, belonging to at least 15 individuals, including children, young adults and at least one much more elderly individual.
Today, they made their discovery official, and announced a new species of human, which they have named Homo naledi, meaning star.
Who, or what, is Homo naledi? And why is it a ‘Mr Potato Head Disaster’?
The expedition team was led by National Geographic Explorer-in-Residence Lee Berger of the University of the Witwatersrand and the team’s findings are published in open access journal eLife.
Describing naledi, Berger said they were slender, small-brained with long legs and large thumbs. But he also called the discovery “a Mr Potato Head disaster”.
The thing is, Homo naledi seems to be something of a Frankenstein mashup of ‘primitive’ and ‘modern’ features; a tiny brain the size of that of Homo erectus (who appeared around 2 million years ago), a primitive upper body like that of Australopithecus (the genus that predates Homo and spans a period between 4 million and 1.4 million years ago) and curved fingers typical of tree-climbers.
But at the same time, their hands have features suitable for making basic tools, with wrists, palms and arms much like ours, a powerful thumb, and feet and ankles adapted for walking upright.
Is it really a new species?
The question of whether or not this constitutes a new species is, unsurprisingly, proving to be controversial. There are some, like Tim White, from the University of California who says they are probably just an early form of homo erectus, while others like Lee Berger arguing in its favour.
An age old problem
One of the key problems the team now faces is how old the remains are. They could be 3 million years old, or far more recent. Unlike other caves, where remains are encased in cave breccias, or found with other animal species, these ones are not – they were simply lying on the open floor. Until the team is ready to take samples for carbon dating, there are barely any clues as to how long they’ve been there.
Did they dispose of their dead?
But it’s not just Homo naledi’s mixed morphology that’s surprising. The next big question is how so many bodies come to be deposited in such a hard to reach place. There are plenty of contending theories, but one factor suggesting they were intentionally deposited there is that they represent such a broad range of ages. A child or a very elderly person probably wouldn’t have got in there on their own.
They could have been washed into the chamber by a flood, but there are no sediments to suggest this was the case. And as for falling in, surely not just humans would have fallen in, but other animals too? The curious thing is that there are no other animal bones.
Likewise, there are no toothmarks or broken bones or even a huge amount of scattering of the remains to suggest that scavengers were dragging their bodies in and eating them.
Either way, it’s a remarkable discovery and we can’t wait to hear more.
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