Is Ardi a Link to Human Ancestry?

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The four feet tall, 4.4 million years old hominid fossil African species ‘Ardipithecus ramidus’  was found in Ethiopia, around the year 1994. The hairy and long-armed ‘Ardi’ is a female member of this species. After ample amount of researches and reconstructions, ‘Ardi’ was eventually introduced to the world in October, 2009. TIME magazine named her “Scientific Breakthrough of the Year.” All the researches pointed out that the retrieved fossil was somehow related to the human bloodline. The creature is said to be an unusual primate. It possessed a tiny brain and firm big toe for climbing up trees, but at the same time featured small human-like teeth and pelvic arch, which might have allowed it to walk like humans. However, controversies brewed against Ardi’s researchers, claiming that, the characters of Ardi posited as relating exclusively to humans also exist in apes and ape fossils that we consider not to be in the human lineage. Now, a new research led by ‘paleoanthropologist’ William Kimbel (published online on January 6, 2014), once again suggests that her species was more closely related to early humans, not to other apes.

Humans and the Chimpanzees, we see now diverged from about 6-8 million years ago. The differences between us and Chimpanzees (evolutionarily) are very clear now, but it was not easy to spot the divergence in ancient species, at the earlier stages of split. New findings of those ancestral species were not clear representations of one descendant or another. Ardi’s place in the human evolution was mainly insisted for its mixed bag features of both the species. However, scientists were quick to point out that the small, canine-teeth of human beings was also found in the ancient non-hominin (human) species (including Oreopithecus and Ouranopithecus). They proposed that the canine teeth were a result of shifts in dietary behavior and a change in ecological conditions. However, the new research studies have given fresh evidences to support the ‘human lineage’ theory because of the valuable studies conducted at cranial base.

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 Tim White of the University of California and his field-research team after recovering the fossil remains of Ardipithecus ramidus (in Ethiopia) painstakingly worked for years to piece together ‘Ardi’, from more than 100 crushed fossil fragments. It is important to note that the researchers against the lineage theory didn’t question White’s scrupulous work or the veracity of the evidence. They were only contradicted from the results White attained by the evidence. One of the important evidence demonstrated by White (apart from the aforementioned teeth) is the placement of a hole at the cranial base of the skull, which suggests that Ardi’s species were upright walkers. For us, humans, the joints of the spine with the skull are more forwardly located than in apes. These shape differences in spine affects the way the bones are arranged in the base of skull. In this way, many experts have isolated bone fragments from human to ape. So, the pelvis part of Ardi naturally indicated bipedalism (having two feet). These beliefs were overthrown by arguing that the traits were not unique to find out bipedalism in the species.

Cranial base of 'Ardipithecus ramidus'

Cranial base of ‘Ardipithecus ramidus’

The new researches conducted on cranial base, however, strongly indicate bipedality (at least partial). It proves that the Ardi’s skull allowed for a connection with the nerves, spine and blood vessels, which were organized more like a human. “Fossils don’t come with their birth certificates attached” said scientific journal, “Nature’s” editor Henry Gee and so we can be sure that further analysis will be going on to make sure whether ‘Ardi’ is hominin or not. Even, the ‘paleoanthropologist’ William Kimbel adds that, “The Ardi cranial base fills some important gaps in our understanding of human evolution above the neck, but it opens up a host of new questions…just as it should!

 

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