Pathological Modern Human or Evolutionary Offshoot Essay
Pathological Modern Human or Evolutionary Offshoot
Upon initial discovery of the skeletons at Liang Bau cave on the island of Flores in Indonesia in 2003, these enigmatic skeletons were appropriately dubbed ,”Hobbits” by Australian and Indonesian researchers because of their small stature and curious bone structure. The location of the skeletons themselves is interesting because of the remoteness of the island from the Asian continent. This leads one to wonder how these people’s ancestors came to the island in the first place close to 800,000 years ago. It is highly debated whether or not these tiny skeletons are evidence of an offshoot of one of our evolutionary ancestors or examples of modern humans with pathologies that caused the deformities. If these skeletons are proved to be a new species in our genus, it would be a profound implication since these peoples were contemporary with modern humans as recently as 13,000 years ago and may have had some interaction.
A recent study indicated that these humans were indeed a new species of the genus Homo, and had distinct characteristics, such as cranial morphology that was different from modern humans with pathologies like dwarfism or microcephalism (Kubo 2013). If they are indeed a new species, it leaves open the possibility of other unknown species of the genus Homo that might have been mischaracterized as a pathological deformity. Before going into the recent evidence for Homo Floresiensis being a distinct species of Homo, I’d like to establish some information that was known about these peoples. The skeletons that were discovered had an average height usually around one meter tall, weighing about twenty kilograms, and had a lifespan of approximately thirty years of age. Evidence from archaeological sites indicates that this pupulace utilized fire, along with stone tools and weapons. One of the most astonishing facts is that these people, who would have a stature close to a three year-old child, worked together and planned jointly in order to hunt big-game animals like the pygmy Stegodon, which could weigh up to a thousand kilograms.
Although they had brains about the size of grapefruits with capacities around 400cc; compared to the average cranial capacity of modern humans, 1350cc; thisjoint communication and planning indicates that they had high cognitive capacity despite their small endocranial volume. There is additional evidence that shows that these people also hunted Komodo Dragons, giant rodents, and lizards, along with other small game animals, like fish, frogs, birds, snakes, and tortoises (Mayell 2004). Although it is unknown how these people first arrived on the island, it is known that they arrived around eight hundred and forty thousand years ago. It is postulated that these people who first came were most likely normal sized Homo Erectus from the Asian mainland, as evidence by their high degree of prognathism, lack of chins, and heavy brow ridge (Mayell 2004).
Because the skeletons of Floresiensis also shows other primitive traits in their bone morphology, an alternative theory is that they came from an even older unknown ancestor is not excluded (Ghosh 2013). It is thought that the original inhabitants of this island shrunk over a long period of time by a process called Island Dwarfing that is evident in other animal species. It is likely that over tens of thousands of years their bodies shrunk because environmental conditions favored it. And it is no wonder that this process is the likely answer, because islands typically have a limited food supply, a small amount of predators, and other animals competing for resources, which would lead to the body gradually shrinking in order to reduce the daily energy requirements. One skeptical approach to this theory is that perhaps these people came to the island already dwarfed, due to the lack of larger bodied ancestors being found. It is unfortunate that these people have not survived into the modern era, which would allow us to have more solid information on their daily lives and physical traits, they went extinct along with their food sources about thirteen thousand years ago due to a volcanic eruption (Mayell 2004). Although there are many people who are skeptical that these miniature skeletons are indeed a new species, there is ample evidence that would indicate that these people are indeed a whole new species in the long line of our evolutionary history.
At Liang Bau limestone cave, the site of the original discovery, many stone artefacts in the forms of complex tools and weapons were found dated to around one hundred thousand years ago, associated with the Late Pleistocene era. Because of the complexity of these artefacts, some claim that they were created by modern Homo Sapiens. This claim though, is ruled out by the evidence found at Mata Menge, a sitelocated about fifty kilometers to the east. Researchers at this site have noted that there is specific similarities and apparent continuity between the stone artefacts found there and the more recent artefacts found at Liang Bau cave (Brumm 2006). The authenticity of these complex stone artefacts is demonstrated by similar older finds in the Soa Basin, at the sites of Boa Lesa, Kobatuwa, and Mata Menge, which were all dated to around eight hundred thousand years ago, all showing similarities and technological development leading towards the more recent artefacts found at Liang Bau (Brumm 2006).
Aside from the stone artefacts found dated to eight hundred thousand years ago that prove that the newer stone artefacts at Liang Bau were not made by modern H. Sapiens, there is even more convincing evidence in the bones of Homo Floresiensis that indicate that they are indeed a new species that evolved separately from the rest of the Homo Erectus population. Or perhaps from an even older undocumented ancestor that was dispersed into Southeast Asia (Jungers 2009). The female Homo Floresiensis skeleton that was found, dubbed LB1, was relatively intact, and researchers have been studying her bones to find clues to her evolutionary origin. Researchers initially looked at the morphology of the three wrist bones of LB1 for clues as to her evolutionary origin, this is a good way of determining evolutionary history because modern and upper paleolithic Homo Sapiens and Neandertals all have certain exclusive features of their wrist bone morphology that is absent in other species. Because of this, looking at the formation of the wrist bones of Homo Floresiensis allow us to get an idea of whether or not they evolved from early Sapiens and Neandertals, or from an even earlier ancestor.
LB1’s wrist morphology shares primitive features that is associated with African Ape-Human clade, while absent in modern humans. When compared to the bone morphology of our more recent evolutionary ancestors, it seems to indicate that it is unlikely that some unknown pathology is responsible for these primitive features being present (Tocheri 2007). Perhaps even more convincing is the fact that modern wrist bone morphology was not evident until as recently as eight hundred thousand years ago, which was contemporary with H. Floresiensis arrival on the island; and because they lack this feature, it seems to indicate that they were from an older ancestor that was established on the island before this distinct morphology formed. The wrist bones themselves were not the only bones under scrutiny
by researchers, they also looked at the feet of H. Floresiensis, and it yielded surprising information that strengthened the probability that these peoples were indeed a separate species of the genus Homo. Upon inspecting the feet morphology of LB1, it was discovered that the feet were exceptionally long relative to the tibia and femur. This trait is not evident in any hominin species, but is found in certain African apes. The combination of the unusual lower-limb proportions and primitive pedal phalanges indicate that LB1 had distinct differences in biomechanical function from modern humans, and would have had a unique kinetic motion (Jungers 2009).
This, along with the wrist morphology of LB1, all seem to indicate that they evolved from an early primitive ancestor, and making it extremely unlikely that these primitive bone morphologies were all caused by pathologies or some unknown disease. Perhaps the most important evidence for H. Floresiensis as a separate species and not simply a case of repeated pathologies or diseases, is the morphology of the skull relative to know pathologies or genetic diseases. Researchers compared a virtual endocast of LB1’s brain relative to endocasts from great apes, Homo Sapiens, Homo Erectus, a human pygmy, a human microcephalic, an Australopithecus Africanus, and a Paranthropus Aethiopicus. The data derived from these comparisons concluded that LB1’s cranial morphology is not consistent with a microcephalic or a pygmy, based on its’ morphometric, allometric, and shape data; with the only similarities being a small endocranial volume (Falk 2005). More recent research done this year has determined that LB1’s endocranial volume is a bit higher than previously thought, now at 426 cc, compared to the previous measurement of 400 cc.
This is significant because when paired with the body-to-brain ratio, it indicates that as H. Floresiensis shrunk, its’ brain scaled down to compensate for the reduction of body mass; which implies in the past H. Floresiensis brain and body was larger and could have descended from an earlier small-brained ancestor or the larger brained H. Erectus (Kubo 2013). Although the brain is still extremely small when compared to modern humans, “LB1 has frontal and temporal lobes and a lunate sulcus in a derived position, which is consistent with capabilities for higher cognitive processing” (Falk 2005). This conclusion indicates that it is a likely possibility that H. Floresiensis is a separate species, based on the fact that these bone
morphologies are unlikely to occur simply from pathologies or defects, and are not consistent with modern cases of such pathologies. Also, their arrival on the island is contemporary with when modern wrist morphology was developed, and because they lack this morphology along with the standard lower-limb proportions, to me it indicates that they were evolved from an older and more primitive ancestor down our evolutionary line, and should be considered a new species.
This find initially was significant because people started to research and think about the possibility that these “hobbits” were indeed a new species. And as more research was done on their bone morphology, it became even more significant because the additional research increased the probability that this was truly a new species, and not just a case of an unknown pathology or disease. The implication that this is a new species has far reaching and significant effects; it shows us that our evolutionary history was not as straightforward as we once thought, and that evolution took us through a few twists and turns to get where we are today (Ghosh 2013). This should cause archaeologists to be more open minded about our evolutionary history, and consider other undiscovered evolutionary paths we are unaware of. And maybe this being accepted as a new species will lead to the discovery of other past forms of Homo that we have overlooked as being the effects of a pathology or disease. I would definitely consider this one of the more interesting and important finds of the twenty-first century.
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2004 National Geographic News. Web Page, http://news.nationalgeographic.com/news/2004/10/1027_041027_homo_floresiensis.html, accessed May 5, 2013
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