Australopithecus Afarensis - Assignment Example

Rolian and Gordon (2013, p. 393) acknowledge the conclusions were also based “on the ability to assign phalanges to a single individual, and to the correct side and digit”. Rolian and Gordon (2013) argue that none of the assignments is secure. According to Rolian and Gordon (2013), the challenge arises from the sample composition and taphonomy of A. L. 333.
Fossil species considered
In the study, Rolian and Gordon focused on Australopithecus afarensis species. The A. L. 333 hominins are majorly teeth and bones fossils discovered in Hadar, Ethiopia. The fossils have been dated to have existed during the Pliocene period.
Main ancestral and derived traits
Ardipithecus ramidus is considered to have been the ancestral hominid to Australopithecus afarensis. Consequently, the ancestral traits evident in Australopithecus afarensis include bipedalism and tooth morphology. The derived trait from Australopithecus afarensis is in relation to the hand morphology of modern humans. The hominins are also considered to have been bipedal.

The methodology used to examine the fossil
Rolian and Gordon employed a re-sampling approach in the study. The re-sampling approach comprised a wholesome assemblage of the complete hand elements from Hadar (Rolian and Gordon). Additionally, the approach accounts for the uncertainties associated with identifying phalanges. The uncertainties are due to unidentified taphonomic factors in samples from fossils. The factors led to a bias in the estimation of the manual proportions. Rolian and Gordon re-sampled hand long bone lengths in extant hominoids, as well as in Australopithecus afarensis. Subsequently, Rolian and Gordon obtained the confidence limits for distributions of the manual proportions in the extant hominoids. The analysis procedure adopted by Rolian and Gordon was a four-step procedure. Rolian and Gordon first drew subsamples then subsequently matched the fossil assemblage. Rolian and Gordon then derived the metrics of the manual proportions. Finally, the researchers then derived the re-sampled population distributions.

Major findings of the study
Rolian and Gordon (2013) established that the ratios obtained were within the range for Homo and Gorilla. The ratios were found to be overlapping the respective 95% confidence intervals for gorilla and Homo. With regards to digital proportions, Rolian and Gordon (2013) established a slight variation. The digital proportions of Australopithecus afarensis were “often inside the lower confidence intervals of Homo, and marginally outside those of Gorilla” (Rolian and Gordon, 2013, p. 393). However, Rolian and Gordon's points showed that the proportions were still in the full range of the proportions, even though, the trend is occasionally reversed. According to Rolian and Gordon (2013), the reversals were a result of the ratio of Australopithecus afarensis being almost equivalent to the confidence intervals’ boundaries. In addition, Rolian and Gordon found that Australopithecus afarensis phalangeal proportions. Values obtained were also occasionally within the Pan’s full distribution ranges.

Importance of the Findings
One implication is that the metacarpal proportions of Australopithecus afarensis “were not as derived towards Homo as previously described, but rather are intermediate between gorillas and humans” (Rolian and Gordon, 2013. P. 393). According to the findings, Australopithecus afarensis was not able to produce precision grips as efficiently as modern humans. Consequently, the findings account for the lack of lithic technology for Australopithecus afarensis. Read More