. Some of the earliest evidence of
controlled use of fire by humans can be found at Swartkrans, up to 1.5 million years ago. In addition, some of the earliest evidence of modified bone tools has also been found at Swartkrans and Sterkfontein, with the oldest at Swartkrans dating to about 1.8 million years ago. These tools may have been made by
Australopithecus robustus or an early species of
Homo, which both inhabited the cave around the same time. These early tools were first speculated to have been used to dig up
tubers, but they may instead have been used to harvest termites, which were present during Swartkrans's occupation; many of these tools may have been multipurpose. Re-evaluation of wear on stone and bone tools uncovered by Brain in earlier excavations and experiments by researchers have led to the conclusion that termites, a high source of nutrients, were a supplementary food source for early hominids. Bone tools would have allowed for easier extraction of the insects than stones would have. In 2016, the discovery of the earliest known evidence of
cancer in hominins was announced. An
osteosarcoma was found on a partial
left fifth metatarsal from an unclassified hominin. ==Geology==