Most people are aware that there was once more than one species of hominin. That our lineage had cousins who lived alongside us for most of our prehistory. However, few know the full extent our family tree branched out too.
Our group separated from chimps ~5-7 million years ago. When we first emerged it seems we were just a single lineage, gradually evolving through the generations. The the Australopiths arrived and things started to get interesting.
Most people know the Australopithecines from the famous “Lucy” specimen, a well preserved Australopithecus afarensis from around ~3.2 million years ago. What most people don’t know is that these hominins had begun to change.
By ~3 million years ago there were the beginnings of a split. On the one hand you have the “gracile” Australopithecines. As the name suggests these were relatively dainty creatures characterised by smaller bones. Then there are the robust Australopithecines, the polar opposite to their gracile cousins.
These creatures were tall, bulky beasts increasingly large chewing muscles, suggesting a diet of hard substances like nuts. By ~2.5 million years ago these differences had become so pronounced that the robust Australopithecines had diverged into their own genus: the Paranthropines.
The bodies of these creatures, aside from an increase in robusticity, are pretty much identical to the gracile forms of the time (which were busy evolving intoHomo). They were upright apes that walked exclusively on two legs just like us.
The main difference is the top of the body, commonly known as the “head.” The robusticity had just gone crazy on the face and the skull bones had become much thicker and the muscles for chewing had become significantly larger. As a result the skull developed into a shape far removed from what you or I have under our skins.
Their face stuck out considerably and where their chewing muscles attached to the bone become over-developed to compensate for the larger musculature. They even grew a ridge along the top of their skulls (a sagital crest) to provide extra surface area for the muscles to attach to.
All in all they look very much like a gorilla, actually. They too have the sagital crest and other highly developed muscle attachments, their skull also sticks forwards. Even the teeth seem to be similar.
Basically we’re looking at a branch of humanity that, for one reason or another, evolved a gorilla’s skull. There have been many hypotheses why – perhaps they ate lots of nuts that needed breaking – but that doesn’t distract from the bizzarity of these specimens.
We have what is in essence a human with a gorilla head and that is a concept at least as interesting as neanderthals, or even the hobbit. Yet most have heard of them but not the Paranthropines.