An international team of researchers, including Lincoln Memorial University-DeBusk College of Osteopathic Medicine Assistant Professor of Anatomy Zach Throckmorton, Ph.D., have discovered the most ancient evidence of cancer and bony tumors to be described in the human fossil record. The team led by scientists from the University of the Witwatersrand’s Evolutionary Studies Institute and the South African Centre for Excellence in PalaeoSciences presented its discovery in two papers published in the South African Journal of Science.
Throckmorton, a Rising Star associate at the University of the Witwatersrand’s Evolutionary Studies Institute, served as co-author on the paper titled, “Earliest hominin cancer: 1.7 million-year-old osteosarcoma from Swartkrans Cave, South Africa.” The discovery pushes the oldest date for this disease back from recent times into deep prehistory. Though the exact species to which the foot bone belongs is unknown, it is clearly that of a hominin, or bipedal human relative.
Discovering cancer in an ancient fossil
While many exciting discoveries in paleontology are made in the field by digging up fossils, Throckmorton said, “This discovery shows that fascinating scientific specimens can be found in museums.” According to Throckmorton, the specimen used in his research had already been dug up and was literally just sitting in a museum drawer.
The fossil came from Swartkrans Cave, located approximately 40 kilometers northwest of Johannesburg, Gauteng Province, in an area known as the Cradle of Humankind, and classified in 1999 by UNESCO as a World Heritage Site. Paleoanthropological exploration work by Robert Broom and John Robinson began at Swartkrans in 1948, leading to the discovery of numbers of Paranthropus robustus specimens and fossil remains of Homo ergaster.
Throckmorton said the discovery is incredible because it shows that cancers are not diseases of modern times, but also were suffered by our ancient relatives. While it does appear true that rates of tumors and cancers are accelerating due to environmental toxins, viruses and other tumor-forming factors in the modern (particularly Western) lifestyle, such diseases were present in the past, even without the influence of modern lifestyles.
Throckmorton added, “While we’ve known other ancient animals, even dinosaurs, suffered from cancer, this is the oldest known case of cancer in a close human relative.”
Researchers were able to demonstrate that the partial foot bone of an early hominin relative was affected by an aggressive form of cancer, termed osteosarcoma using Micro-CT imaging. This type of technology is typically used in industrial applications to make sure pieces of machines are working and don’t have microscopic defects.
“In living people, physicians determine a tumor is cancerous by studying a biopsy specimen under a microscope or analyzing its DNA,” Throckmorton said. “We couldn’t do that since the foot bone fossil isn’t alive. So we had to use techniques not commonly employed by paleontologists, and that was fun.”
The researchers looked at the microscopic internal structure of the specimen and compared those images to images of known bone cancers biopsied from living people.
“When we compared our fossil to images of a specific form of bone cancer called parosteal osteosarcoma, we had a match,” Throckmorton said.
Throckmorton concluded, “It’s wonderful to have such fun and productive collaborators in South Africa and the United Kingdom. LMU-DCOM is a relatively young medical school, so I hope our reputation will continue to grow as our professors are involved in exciting research and discoveries.”
Throckmorton joined LMU-DCOM in 2013 after earning his Ph.D. in Anthropology from the University of Wisconsin-Madison. As a physical anthropologist specializing in paleoanthropology, Throckmorton researches interests include anatomical variation and evolutionary anatomy. He specializes in lower limb and especially foot anatomy, function, and evolution. He is a Rising Star Associate at the University of the Witwatersrand in Johannesburg, South Africa, where he studies fossil South African hominins. At LMU-DCOM, Throckmorton is part of the MGA team and teaches in the Anatomical Sciences Master of Science program. Throckmorton is also Rising Star Associate at the University of the Witwatersrand’s Evolutionary Studies Institute. His favorite animal is Tyrannosaurus rex and favorite TV shows are The Simpsons and The X-Files.