The Montshire Museum in Norwich is about to receive a pretty remarkable donation: a cast of the bones of Homo naledi, an early humanoid and perhaps a direct ancestor of us. And thanks to efforts by researchers, those who would like a cast of their own can make one with a 3D printer.
Paleoanthropologist Jerry DeSilva, who joined the faculty at Dartmouth College this summer, was one of the scientists who researched the species after specimens were discovered in a cave in South Africa in 2013. The cave was so hard to access the team of six small women – experienced in both caving and science – had to be found to go in and assess the discovery.
The result was nearly 1,600 fossils and a massive overhaul of scientists' ideas about early human history. "We really want this discovery to be shared by everyone," says DeSilva, whose team helped upload datasets for almost 100 Homo naledi fossils to morphosource.org, which those with access to 3D printers can use to print casts.
DeSilva joined Vermont Edition to talk about the discovery, what it means for our understanding of human history and why his team wants to make the discovery accessible.
Jane Lindholm: Remind us a little bit how the bones of Homo naledi were found in 2013 in this cave in South Africa.
Jerry DeSilva: Professor Lee Berger, who is a South African paleoanthropologist, had been exploring an area in South Africa known as the Cradle of Humankind, for new caves, new places where early humans were, where their remains were deposited. And he made an incredible discovery in 2008 of the cave called Malapa, where he found skeletons of a new species known as Australopithecus sediba.
And he then sent out kind of advertisement out to other cavers and sponsors to look for bones and if they happen to come across bones to let him know. And two very skinny cavers get down into a chamber of a cave system known as Rising Star and they stumble across bones. And they contacted him and said, ‘You know, we found some bones, but we don't know what these things are.’ And he then put together very quickly a team these six women who had excavation experience, archaeological experience. They knew their anatomy. They had caving experience. And they could squeeze through gaps in the rock that were as narrow as 8 inches to get down into this chamber.
And they excavated close to 1,600 fossils of what we now consider a new species of early human that we call Homo naledi. There were photographs that were taken of the bones, and you could tell from the photographs, you could tell from the teeth and the jaw of one of the individuals, that this was not a recent person.
Jane Lindholm: Your specialty is in locomotion. So what did you notice when you were asked to look at these bones?
Jerry DeSilva: In these creatures in particular, I was looking at the feet in the legs, and they were so humanlike. They were so humanlike that I – I wouldn't say feared, but I thought perhaps we had something that was much more recent, much more humanlike, until I saw the skulls. And the skulls were of things that had brains only slightly larger than a modern ape's brain. So it was this wonderful combination of an animal that could move around like us on feet and legs that were so much like yours and mine. But their brains were still quite small.
Jane Lindholm: So talk a little bit more about that theory, because that idea of small brains, but bipedal, is a big deal.
Jerry DeSilva: When you look at human evolution, sort of take a big step back and think about human evolution, we know certain things. We know that humans are most closely related to African apes and in particular to chimpanzees. But we didn't come from chimpanzees, any more than they came from us. Instead, we share a common ancestor with them. And that common ancestor, we suspect from the D.N.A., lived in Africa sometime between 7 million and 10 million years ago ...
What the fossils have revealed for us over and over again, is that bipedalism, upright walking, is one of the first major changes that happens over the course of human evolution. And that brains come much later.
Now, with this new discovery, it is the most obvious example of bipedalism preceding brain enlargement that I've ever seen, where you have feet and legs that almost exactly like yours and mine – there are subtle differences, and we're interested in those subtle differences – in an animal whose brain again is the size of a grapefruit. It's only about the third of the size of a modern human brain today.
And the great thing is that we have lots of individuals. We have the remains of 15 different individuals. And so it's not as though we're basing this on a single discovery. There are lots of these creatures. And it's helping us really understand the biology of what they were like.
Jane Lindholm: It sounds like it's not clear yet whether these this species – and there's also debate, I should say, about whether or not it is a new species that’s been found – but it's not clear yet whether there's a direct line between modern humans and homo naledi, right?
Jerry DeSilva: Right ... In the absence of D.N.A., we do our best to figure out who is related to whom, but one of the things that we keep realizing is, when we draw these family trees and say, 'Well, this one must be related to that one based on these shared similar characteristics,' we then find new fossils of new species that allow us to redraw our family trees. And we're constantly doing that. Which is fun. I mean, in science, you're always excited by new discoveries and the opportunity to revisit some of these old ideas, like who is related to whom.
Jane Lindhom: Lee Berger, the paleontologist who you mentioned whose team discovered these bones, is donating a cast of the specimens to the Montshire Museum. Why?
Jerry DeSilva: Lee and his entire team, we are really passionate about disseminating this information to everyone. This is our story. This is the human story. This is where we came from. And it makes no sense to make these incredible discoveries and then hide the fossils. And ... not allow the world to have access to them. Not only the scientific community, but the entire community, the entire world. Because these really belong to everyone.
These, whether they're ancestors or extinct relatives, these things are part of our history and there's no better place to communicate that than in a science museum, a place where people go to be inspired by questions - big questions like who we are in where we came from.
Jane Lindholm: Is this unusual for a research group to share this widely and this publicly and in a sort of an open source and free way?
Jerry DeSilva: Yeah. I mean certainly you can go to a science museum and see lots of replicas of fossils of early humans. That certainly happens. Oftentimes it takes decades, and it can take even generations for fossils to be shared as widely as we're doing with these after only two years of study. And one of the reasons we've been able to do that is instead of having a small team of researchers working on these fossils, we've had a team of about 60 people working on these fossils, and putting a huge number of hours [in], and have been able to do the scientific, at least the preliminary scientific investigation, quite quickly, and disseminate the information. Again, open source: Anyone can go to a journal called eLIFE and look at what we wrote about these fossils.
And the work is going to continue, though. We have many many many questions still about these creatures. And there's going to be scientific research going on for decades. About who these things are and what they can tell us about our origins in our evolution.
The text of this interview has been slightly condensed; play the audio to hear the full conversation.