Australopithecus Categorizing

Categorizing ancients species into clades is a tricky business. The scientific community will always disagree about one factor or another and as D. Curnoe states “Another problem with coding character states is the handling of variation within species. While this form of variation is usually ignored by palaeoanthropologists, when characters are recognized as varying, their treatment as a separate state adds considerable error to cladograms.” (Curnoe 2003) D. Curnoe is an example of an extreme clumper wishing to look through the fossil record with out the tiresome, and not always effect categorizing. I personally find myself on this side of the court in multiple occasions. Within the genus Homo, as ancient man becomes more and more modern, categorizing becomes especially tricky, not every species follows the “proposed synapomorphies of homo”.
The controversy surrounding Australopithecus sediba claims that it was categorized into the wrong clade.
The discoverer or the A. sediba claims that it is a “Australiopith with Homo like characteristics”. The A. sediba falls into a funny place on the cladistic time line, it shares traits with both genus’. Dr. Lee Berger and his associates decided on the classifications, based on “a combination of primitive and derived characters of the cranium and postcranium” (Berger et al., 2009). There is not doubt however that A. sediba does share some of the “proposed synapomorphies of homo” that where discussed, most namely the reduction in tooth size. While some part of me believes the categorizing of a species we do not have a larger amount of information on is arbitrary, I do believe that the classification was made by the discoverer, to the best of his knowledge, and so we should accept it for the time being, however that does not mean that it isn't subject to change in the future as we discover more about the
species. The day that Homo Naledi was released to the public my phone was buzzing all day asking about my opinion on the matter, after reading the article online, I was left puzzled. The peculiar place which the fossils where found, the odd proportions, the incredibly small brain size, and the modern(tool using) wrist didnt seem to add up for me. I was taken aback by how quickly all of the information had been released, and while I applaud the idea to make the findings open source so many scientist have access to it, I do not like how quickly the specimen was classified. While classification is (for the most part) all about the morphology of the fossil findings, and how closely they follow the basic, already established synapomorphies of a genus. In this example H. Naledi most notably is believed to have an anatomically modern wrist, which looks like it evolved for tool use. I personally think that H. Naledi, may not necessary belong in the genus Homo. I feel that scientists are quick to try and fill in the huge gap between the Australopithecines and Homo, which is why I applaud(although I do not necessary agree with) Bergers decision to place A. sediba into the Australopithecines, apparently erring on the side of caution. People tend to romanticize the idea of a “missing link”. For people outside of the scientific community, and some inside of it the “missing link” is the link between the panins and the hominins. For many modern scientist this missing link is the one between the Australopithecines and Homo. It is a golden goose chase and does not in anyway better science. Classifying a species without a proper date or proper stratigraphic analysis of the site is a little hasty. I believe that A. sediba, and H. Naledi may be candidates for a possible new genus, unlike species like Kenyanthropus H. Naledi has ample evidence and specimens. The findings are still new, and who knows what we will know about H. Naledi in five or ten years. Homo Habalis, is another spices we do not know much about, we have found few fossils, however the fossils that have been found show some very interesting things. In many ways H. habalis appears rather primitive, the classification into the genus homo was largely due to its small more human like teeth, and larger brain case. The species also has some inconsistencies, it’s curved like fingers for example, that seem to be evolved for climbing, along with it’s primitive writs. For the time being we do not know as much as many would like about the H. habilis, until more, less fragmentary fossils are discovered it will be difficult to learn more. Many believe that the first human ancestor out of Africa was Homo Erectus, however the possibility that H. habilis migrated out of Africa is not so far fetched when looking at Homo Floresiensis. This odd specimen found in Asia, more specifically the island of Flores in Indonesia. Because the first assumed hominin outside of Africa is Homo Erectus, many believe that that is who H. Floresiensis evolved from. The small brain capacity, and more primitive body proportions make me believe that the tiny hominin actually evolved from H. habilis. The lack of evidence of such a primitive lineage outside of Africa does make this idea pure speculation, for the time being. Homo erectus is one of the most famous hominins ever discovered. The species is incredibly wide spread, believed by many to be the firsts hominin that migrated out of Africa, the first of the species being found in Java, and more specimens found in sites that scatter Europe and Asia. The jump from the more primitive H. habilis to a species that stayed in camps, and could potentially maintain and control the use of fire is incredible. H. erectus checks of many of the “proposed synapomorphies of homo”. The modern leg proportions, indicate that H. erectus was using it’s environment in a way that no other hominin before it had. whether it evolved this long legged walking posture in order to hunt better, avoid predators, or adapt to the changing climate H. erectus is a marvel. It is very well known for its exceedingly large brow ridge, and small teeth. The brain size of H. erectus is also impressive. A species often associated with H. erectus is Homo ergaster. This is the species that is mainly found in Africa. Those of the species who did not migrate to Asia or Europe. H. ergaster has some notable differences from it’s globe trotting cousin, the lack of sagittal crest for one, the smaller brain size and the more rounded skull. While they still have a brow ridge, H. ergasters brow ridge is not as impressive. These two species have many of the synapomorphies of homo, an Expanded Brain, Tool use and anatomical change of the wrist and hand(modern tool use, as seen with the acheulean hand axe, human-like body proportions, and a reduction in Chewing muscles and tooth size. These hominins are the first to show that recognizable spark of humanity. The final species in my cladogram is Homo sapien. This intern breaks down into three(known) sub species, homo sapien neanderthal, Homo Sapien Denisovans, and Homo sapien sapien. While we know that H. sapien sapien, and H. sapien neanderthal, were both morphologically different, we know that they where intact a breeding population, this is why I have classified them this way. In order to show them as a unique sub species with some basic different morphological and geographical features, how ever still similar enough to breed with each other and produce(at least female) fertile offspring. I am generally a clumper when it comes to categorizing hominins. I do how ever understand the importance of using a cladogram for the purpose of learning and organizing synapomorphies. One day when we have more viable DNA samples from these fossils we will be able to categorize them accordingly. Maybe H. erectus and H. ergaster are much like H.s. sapien and H.s. neanderthals, in a way that they can successfully breed together, or maybe all of these hominins were truly all separate species, until we learn more it is all speculation.