In the above video from National Geographic, paleoartist John Gurche creates the face of Homo naledi, a completely unique human relative. Naledi represents a surprisingly primitive member of the human genus. From The Washington Post's Amy Ellis Nutt:
H. naledi is an unusual combination of the primitive and the modern, the scientists said. Its brain was no larger than a baseball; its shoulders and torso primitive; its fingers long and curved, allowing H. naledi to climb and swing from the trees. At the same time, H. naledi’s wrist bones indicated that it used tools. Its long legs and feet, nearly indistinguishable from those of modern man, allowed it not only to walk upright but also to travel for many miles at a time.
So the species gave Gurche a lot of features to consider. As he explains in the video, he uses comparative anatomy to decide what different bones and fossilized remains might have actually translated to in a living body. To do this, he needs an encyclopedic knowledge of the facial structures of all sorts of living primates to draw from.
Some features — like ears and hair, which can't really be guessed at based on skull remains — are purely speculative, based on those seen on modern humans and apes.
But most of the facial features are determined with precision, using a combination of endless minute factors in the skull. When it comes to naledi's nose, for example, Gurche can point to bone structures that indicate the feature would be at least slightly raised from the face — a characteristic that's more human than ape.
"It's a wonderful thing to be in the position of being the guy who figures out what some ancient species that's never been found before looked like," Gurche says in the video.
Gurche is already famous in the paleo world for building our famous relative Lucy. You can read more on that process here.