Right now, in Michigan, an undergrad is studying the contours of fossils found half way around the world. Fossils that, in fact, continue to reside in their country of origin: South Africa. She hasn’t traveled there; she doesn’t have casts of the fossils themselves. What she does have, and what is steadily becoming available to other organizations, is access to 3D printers.
Jennifer Webb, with help from her advisor, Rachel Caspari, has been comparing 3D replicas of the famous Homo naledi fossils discovered in 2013 to the casts of early Homo sapiens fossils found in the 1960s and 1980s. Both sets of fossils were found in South Africa: Homo naledi in the Dinaledi Chamber of the Rising Star Cave, and Homo sapiens at Klasies River Mouth. But, so far, only one set has been dated.
Jennifer’s goal: to determine the age of the Homo naledi fossils by comparing their physical attributes to this set of Homo sapiens fossils.
“Because the date [of Homo naledi] is unknown,” Jennifer explained, “we can use those traits to look and see if they’re similar [to the Homo sapiens fossils from Klasies River Mouth]. And if they are similar, then they are likely to be of a similar time period or age.”
This is important, as it would help us better understand where on the evolutionary chain Homo naledi can be found, and therefore, what physical attributes and possible social behavior developed when.
Klasies River Mouth Homo sapiens have been dated to about 120,000 years ago. The caves at this location revealed periods of human occupation through sparse human fossils, shell middens and indications of ‘hearth activity’. (Interestingly, one of the eggshells discovered belonged to an ostrich, a species that has not existed in the area since the Late Pleistocene.)
Klasies River Mouth Cave, South Africa; image taken by John Atherton, Flickr
In contrast to the small number of fossils at Klasies River Mouth, roughly 1550 specimens were excavated at Dinaledi Chamber—the largest set of hominin fossils found in the entire continent thus far. Absent evidence of predator damage or remains, the 15 Homo naledi skeletons appear to have been placed in that cave deliberately.
Figure 3. Cartoon illustrating the geological and taphonomic context and distribution of fossils, sediments and flowstones within the Dinaledi Chamber. The distribution of the different geological units and flowstones is shown together with the inferred distribution of fossil material.
DOI: 10.7554/eLife.09561.005
“My professor and I,” said Jennifer, referring to Rachel Caspari, “as long as we’ve known about this species, we’ve always been interested in it.”
But the path to actually studying Homo naledi didn’t appear until this past October, when Central Michigan University opened its Makerbot Innovation Center, making it unique amongst public Midwest universities.
And with access to 3D printers, Jennifer was able to make use of the digital scans and images provided on Morphosource.org.
One of the Homo naledi fossils as it is being printed; image courtesy of Central Michigan University
Rachel Caspari and Jennifer Webb with a 3D replica fossil; photo by Monica Bradburn; courtesy of Central Michigan University
Regular 2D printing has become so fast, so cheap, and so easy. 3D printing, on the other hand, is not necessarily any of those things. At CMU, the cost of 3D printing is $.15 per gram. It can take anywhere from 2 hours to an incredible 24 hours for something to print, depending upon various factors. Most of the Homo naledi fossils took between 2 – 4 hours to create.
Having access to physical replicas of the originals is, indeed, exciting, but one wonders what challenges this might also present.
“3D printers can only be so accurate,” Jennifer replied. “The ones that we use are accurate to .2 millimeter difference. So we would have to factor in that amount of error into any of our analyses.”
“When we’re looking at the 3D-printed [fossils],” she continued, “they no longer have the coloring that the [original] fossils would have, which can also sometimes better indicate any dips or grooves or mounds. The best way we have to go around that is to look at the scans and pictures that we still have access to [from Morphosource] and compare them along with the 3D fossils that we printed.”
While researchers with access to the real Homo naledi fossils could perform isotopic analysis or radiocarbon dating, these procedures are both invasive and destructive to fossils. Jennifer prefers to observe the physical traits themselves, preserving the fossils in their entirety.
“I love to be able to look at a set of bones, examine them, look at all their features and any marks or anything that’s on them and be able to tell a story from that,” she said.
This is no surprise, given that her interest in Forensic Anthropology—her intended course of study for her Masters—was prompted by the show, “Bones,” based on the life of Kathy Reichs.
Bones – Season 5 – “The Proof in the Pudding” – Emily Deschanel, Tamara Taylor and TJ Thyne; Photo by: Michael Desmond/FOX
“I was afraid that, because it was a TV show, in real life it wouldn’t be the same. So I shied away from it in college in the beginning and started off with a different major. And then I discovered a Forensic Anthropology course that was being offered at CMU, and I decided to give that a try. Once I did, I realized that it was very similar; there were a lot of things that were exactly like what they portrayed on TV. So I started getting into it more, and my interest grew.”
Before graduating this December, Jennifer will be presenting her Homo naledi findings to the American Anthropological Association in November.
Many, many thanks to Jennifer Webb for her time and her great responses to my questions! A very special thank you to Rachel E. Perkins for reaching out to me about this story.
Further Reading:
- Geological and taphonomic context for the new hominin species Homo naledi from the Dinaledi Chamber, South Africa, Paul HGM Dirks, Lee R Berger, Eric M Roberts, Jan D Kramers, John Hawks, Patrick S Randolph-Quincey, Marina Elliott, Charles M Musiba, Steven E Churchill, Darryl J de Ruiter, Peter Schmid, Lucinda R Backwell, Georgy A Belyanin, Pedro Bomhoff, K Lindsay Hunter, Elen M Feuerriegel, Alia Gurtov, James du G Harrison, Rick Hunter, Ashley Kruger, Hannah Morris, Tebogo V Makhubela, Becca Peixotto, StevenTucker; eLife, 10 September 2015
- We Are Made of Star Stuff, blog post on Twilight Beasts by K. Lindsay Hunter (one of the authors of the paper above and one Rising Star team who excavated the Homo naledi fossils)
- Fossils Come to Life 8,500 Miles Away, CMU press release by Rachel E. Perkins
Forthcoming books on hominins:
- Seven Skeletons: The Evolution of the World’s Most Famous Human Fossils, Lydia Pyne
- Almost Human, Lee R. Berger and John Hawks
