When you think fossils, you probably think of impressively preserved bones; the last remains of dinosaurs that strolled (or flew) across the Earth eons ago. But it took evolution a long time to work up to dinosaurs. Or any kind of animal, for that matter. For about 2 billion years in Earth's early history (give or take a few hundred million years) single-celled organisms ruled the planet. Then, life started branching out.
In September of 2013, two cave explorers, on a routine exploration in South Africa happened upon a collection of fossils that would soon question our current understanding of humans' ancestral history. While probing a narrow fracture system in the Rising Star Cave System in the Cradle of Humankind World Heritage Site, they found the entrance into a dark cave now known as Dinaledi Chamber. Inside, they discovered a series of fossils, which anthropologists have now identified as a species of hominin distinct from those that make up our family tree — a human ancestor entirely new to science.
There’s some evidence that microbes living inside a rock could be blasted from their home planet, travel through space, and then crash-land on a new planet relatively unscathed. Throughout the ALH84001 debate, scientists assumed fossils could also withstand the grueling journey, but it looks like nobody actually set out to test it—until now.
