This story started with a recreational caving trip to the Rising Star cave system northwest of Johannesburg in October 2013.
Two cavers, Rich Hunter and Steven Tucker, decided to take to an unknown section of the cave. Entering what is now called the Chute, Hunter and Tucker lowered themselves 12 meters down to an unexplored chamber of the cave, which was later named the Dinaledi Chamber, Dinaledi being the Sesotho word for Stars, thus the Chamber of Stars. Here, the two discovered a trove of fossil bones, which they photographed, and then showed the photos to Professor Lee Berger at the
Berger’s instincts told him that what they stumbled upon would forever change the understanding of “where we come from” and he proved right – the Dinaledi Chamber turned out to contain 15 fossil skeletons of an extinct species of hominin (human ancestor), provisionally named Homo naledi. The discovery provided evidence for their complex ritualistic behaviour, such as disposal of the dead in a separate chamber, which was long believed to be a uniquely human feature.
As soon as Berger was shown the first photos from the site, he decided to initiate an expedition there and
“Dear Colleagues – I need the help of the whole community and for you to reach out to as many related professional groups as possible. We need perhaps three or four individuals with excellent archaeological/palaeontological and excavation skills for a short term project that may kick off as early as November 1st 2013 and last the month if all logistics go as planned. The catch is this – the person must be skinny and preferably small. They must not be claustrophobic, they must be fit, they should have some caving experience, climbing experience would be a bonus. They must be willing to work in cramped quarters, have a good attitude and be a team player. Given the highly specialised, and perhaps rare nature of what I am looking for, I would be willing to look at an experienced Ph.D. student or a very well trained Masters student, even though the more experience the better (PH.D.’s and senior scientists most welcome). No age limit here either. I do not think we will have much money available for pay – but we will cover flights, accommodation (though much will be field accom., food and of course there will be guaranteed collaboration further up the road). Anyone interested please contact me directly. My deadlines on this are extremely tight so as far as anyone can spread the word, among professional groups. Many thanks, Lee.”
An initial three weeks’ expedition took place in November 2013 to recover the hominin remains from deep inside the Rising Star cave. Accessing the fossils was no easy task – the cavers and scientists had to pass through small holes, climb the Dragon's Back (a 15 meter rock climb within the cave) and then pass down the 12 meter Chute where they would encounter an 18 cm gap.
The Dinaledi Chamber is only accessible by relatively slim individuals, as the area of the cave leading down towards the chamber is extremely confined. Six experienced palaeoanthropologists, archaeologists and anthropologists were chosen to undertake the excavations. After the first expedition, it was evident that the remains of the hominin found in the chamber were in fact the remains of at least 15 individuals, and a second two-week long expedition took place in March 2014 to recover the rest of the material.
The use of traditional excavation recording equipment was rendered useless, and a new approach to collecting high-resolution spatial data was needed.
Due to the constraints of the Rising Star cave and the Dinaledi Chamber, the use of traditional excavation recording equipment was rendered useless, and a new approach to collecting high-resolution spatial data was needed. One of the people that acceded to Berger’s call was
“Together with Professor Berger we decided that this discovery would be the perfect opportunity to use 3D imaging during excavations at the site, which would form part of my PhD,” Kruger says. “During excavations at any palaeotological site, it is essential to record the position of elements recovered from the site to help researchers in piecing the site together later and understanding the context of the fossil material recovered.”
Fossil position recording, usually undertaken with a grid system, or total station, was completed with
Documenting the excavations within the Dinaledi Chamber with Eva served two purposes. First, spatial data about the location, orientation (axial and surface) of every bone was collected. And second, the data recorded during this process was transported to the surface after every scan, to allow for scientists above the ground to provide guidance and direction to the excavators concerning excavations and recovery.
“I was amazed at how simple and accurate such a high-level technology could be in less than ideal conditions,” Kruger says. “The team learnt how to use the scanners in just under an hour. Using this technology significantly sped up the entire recovery process, reducing some tasks that would have taken hours to minutes.”
“With projects like this, the bones have to be documented on their own as well as in relation to the excavation site,” Kruger says. “Normally, this involves manually recording fossil locations and cross referencing with an established grid. Artec’s technology was able to streamline this process immensely, despite extremely challenging and limiting conditions.”
Post-processing was managed in Artec Studio 9 (and more recently
Once alignment was complete, global registration allowed for the scan data to be merged accurately. This produced a 3D mesh representation of the scanned area. The 3D mesh was then overlain with a photographic texture map, which was captured by Artec Eva concurrently at the time of scanning. After compiling each 3D scan, the surface scan was exported and was then stitched together to create a composite surface scan from multiple scans. This allowed for the excavation areas and chamber to be visualised in a 3D environment, through the excavation progress.
The fossils documented with Eva were removed from the site and transported to Wits University, where they were described. This is now the largest fossil hominin find yet to have been made on the continent of Africa, with 1,550 numbered elements recovered. The project that involved some 40 scientists resulted in two scientific articles and a NOVA / National Geographic special documentary “Dawn of Humanity.”