Homo naledi genome: Will we ever find this elusive key to human evolution? | Jennifer Raff

Despite the recent announcement of a new haul of Homo naledi fossils, recovering ancient DNA is still proving as difficult as ever

Despite what many people believe, paradigm-shifting moments in science - where our understanding of a particular explanation is challenged by a single finding - are actually quite rare. But one happened in paleoanthropology on 9 May with the publication of three linked papers describing new fossils belonging to the enigmatic hominin Homo naledi.

Many people tend to think of human evolution as a very linear path: from primitive creatures more or less directly to ourselves. But for most of the history of evolution, there were multiple species of hominins running (or climbing) around the African landscape, each with their own unique physical adaptations to the challenges of survival. As with all evolutionary experiments, some of these adaptations proved more successful than others. Based on careful study of fossils spanning millions of years in Africa, paleoanthropologists thought they had a good understanding of how the experiment's results unfolded. Human evolution wasn't a straight progression by any means, but more like a complicated bush, with branches leading off in many directions. Still, there were definite trends that made their way into our textbooks. Hominin lineages with some trait combinations died off without leaving any descendants. In the lineages that persisted, brains got bigger, legs longer, arms shorter, fingers less curved, teeth smaller.