This story appears in the October 2020 issue of National Geographic magazine.
As a young teen, bioarchaeologist Riaan Rifkin spent vacations exploring an Iron Age settlement near his home north of Pretoria, South Africa. Hooked on the pursuit, Rifkin now searches for much smaller artifacts of prehistoric life: the DNA of ancient pathogens.
“Imagine living in a cave five or 10 or a hundred thousand years ago,” he says. “You never vacuumed or swept. So every meal you had, every visitor you had, everything you did in the cave, there would be bits of DNA of those activities within the sediment.”
With the advent of agriculture and livestock, the Iron Age saw the rise of diseases, such as measles, that spread in crowds. Other illnesses, such as mosquito-borne malaria, predate human settlements. Studying diseases’ origins could help prevent them today.
Ancient humans learned how to combat the maladies of their day. Some 50,000 years ago, cave dwellers slept on aromatic grasses whose insecticidal properties kept ticks and fleas away. Nomadic peoples learned to move their settlements every few weeks before disease-carrying pests converged on them. Today Himba women in southern Africa cover their bodies in a mix of butterfat and red ocher, a culturally important tradition that also acts as sunscreen and bug repellent.
“We’ve managed to reconstruct ancient bacterial genomes dating to about 2,500 years ago from South African samples,” Rifkin says. “I think within a decade or so, we will be able to push this back further and further.” (Read more about what we can learn from past pandemics.)