|
Mrs. Ples is the popular nickname for the most complete skull of an ''Australopithecus africanus'' ever found in South Africa. Many Australopithecus fossils have been found near Sterkfontein, about 40 kilometres northwest of Johannesburg, in a region of the Transvaal now designated as the Cradle of Humankind World Heritage Site. Mrs. Ples was discovered by Robert Broom and John T. Robinson on April 18, 1947. Because of Broom's use of dynamite and pickaxe while excavating, Mrs. Ples’ skull was blown into two pieces and some fragments are missing. Nonetheless, Mrs./Mr. Ples is one of the most perfect pre-human skulls ever found. The nickname ″Mrs. Ples″ was coined by Broom's young co-workers. It derives from the scientific designation ''Plesianthropus transvaalensis'' (near-man from the Transvaal), that Broom initially gave the skull, later subsumed into the species ''Australopithecus africanus.'' In scientific publications the specimen is referred to by its catalogue number, STS 5.〔http://www.ditsong.org.za/naturalhistory.htm〕 The genus ''Australopithecus'', of which there are several species, is considered the likely precursor of the genus ''Homo'', to which all humanity belongs. Though its cranium is comparable to a chimpanzee's, Australopithecus walked upright, as humans do. This was a surprise to anthropologists at the time, because it had been assumed that the big brain of Homo had preceded, or at least evolved in tandem with our upright gait. Mrs. Ples, whose cranial capacity is only about 485 cubic centimetres,〔 http://www.sciencemag.org/content/283/5398/9.2.full ''Endocranial Capacity of Early Hominids''], Charles A. Lockwood, William H. Kimbel. Science 1 January 1999:Vol. 283 no. 5398 p. 9〕 was one of the first fossils to reveal that upright walking had evolved well before any significant growth in brain size. The sex of the specimen is not completely certain and so ''Mrs. Ples'' may in fact be ''Mr. Ples''. Moreover, X-ray analysis of the specimen's teeth (''see below'') has suggested it was an adolescent. Hence a designation of ''Miss Ples'' or ''Master Ples'' is also possible. The paleoanthropologist, Prof. Federick E. Grine, has studied the dental morphology of Mrs./Mr. Ples with a view to finally establishing Mrs./Ms. Ples' sex.〔Grine, F E, Weber, G W, Plavcan, J M, et al. (2012). Sex at sterkfontein: ‘mrs. ples’ is still an adult female. Journal of human evolution, 62(5), 593-604.〕 Using the Computed Tomography (CT) scans of STS 5 from the experiments of Weber et. al., they compared them to CT scans of more recently discovered ''A. africanus'' skulls from Sterkfontein. These scans allowed Grine to reconstruct images of the roots of the teeth, in order to see how the molar and canine teeth developed. This study concluded that Mrs./Mr. Ples was indeed a middle-aged female. However, the question is not entirely settled, since other studies have come to the opposite conclusion. Some experts have suggested that a partial skeleton, known only by its catalogue number of STS 14, which was discovered in the same year, in the same geological deposit and in proximity to Mrs. Ples, may belong to this skull. If correct, this would make Mrs. Ples the South African counterpart to the famous Lucy fossil. This skull, along with others discovered at Taung, Sterkfontien, and Makapangsgat offered compelling evidence in favour of Charles Darwin's hypothesis that humanity's origin lay in Africa.〔Thackeray, D. (n.d.). "MRS PLES" AND OUR DISTANT RELATIVES. Retrieved February 28, 2015, from http://www.scienceinafrica.com/old/index.php?q=2001/may/ples.htm〕 The fossil has been dated by a combination of palaeomagnetism and uranium-lead techniques to around 2.05 million years.〔Herries, A.I.R., Shaw, J. 2011. Palaeomagnetic analysis of the Sterkfontein palaeocave deposits; age implications for the hominin fossils and stone tool industries. J. Human Evolution. 60, 523-539.〕〔Herries, A.I.R., Shaw, J. 2011. Palaeomagnetic analysis of the Sterkfontein palaeocave deposits; age implications for the hominin fossils and stone tool industries. J. Human Evolution. 60, 523-539.〕 In 2004, Mrs. Ples was voted 95th in the SABC3's and e.tv's ''Great South Africans'' Top 100 list.〔Great South Africans (TV series)#The list〕 ==See also== * List of human evolution fossils * Taung Child 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mrs. Ples」の詳細全文を読む スポンサード リンク
|