In 2010, scientists discovered two skeletons in a cave in Malapa, South Africa that belong to the Australopithecus sediba. The two skeletons were found in a pit within the cave among numerous other animal bones. The primates most likely fell into the pit, died, and over time their skeletons were covered and preserved the remains. The scientists just published several studies in the journal Science about these skeletons and how they might be a closer link to us than other early species already known. A. sediba is very interesting as it is almost 2 million years old and contains features that are both similar to humans and apes.
The pelvis of A. sediba is more broad and short like humans, instead of being flatter and flaring like an ape. The pelvis also dashes the theory that humans developed a broad pelvis to accommodate large brain growth during birth. However, A. sediba had a brain case that was shaped like a humans, but had smaller brains (about 440cc which is smaller than Lucy’s brain and she’s older!). The hands are more human like with a precision grip, which ‘involves the thumb and fingers but not the palm. Other primates are capable of some precision grips, but humans are unique in their ability to apply force with these grips and use them for fine manipulations.’ Even though A. sediba had this precision grip and mostly likely built tools, scientists believe that A. sediba still spent time climbing trees (which is an ape feature). The foot of A. sediba may have contained an arch and a human like ankle joint, but it possessed an ape like heel and lower tibia.
This find is so fascinating as A. sediba could be one of our direct ancestors that started our family tree. The evolution of humans went from Australopithecus, Homo habilis, Homo erectus, Homo heidelbergensis, and then Homo sapiens. The problem with H. habilis is that it contains some primitive features and might be older. Since A. sediba contains features that are both human and ape like, it may be a more direct ancestor to H. erectus, who is one of our direct ancestors. Meaning that H. habilis might now be a considered a distant cousin to humans, or even a dead end.
Whatever the scientific community decides to make of these findings, there are many gaps in the area of human evolution. Not all species will be found and identified, but we will be able to determine who our ancestors are. The discovery and implications of Australopithecus sediba might be profound and alter our family tree.
Check out articles to read more about this: http://news.nationalgeographic.com/news/2011/09/110908-apes-humans-evolution-australopithecus-sediba-lee-berger-science/, http://www.bbc.co.uk/news/science-environment-14824435