|Catalog number||STS 5|
|Common name||Mrs. Ples|
|Place discovered||Sterkfontein, South Africa|
|Date discovered||18 April 1947|
|Discovered by||Robert Broom, John T. Robinson|
Mrs. Ples is the popular nickname for the most complete skull of an Australopithecus africanus specimen ever found in South Africa. Many fossils of this species, which are considered to be the distant relatives of all humankind, have been found in the Sterkfontein area, in what has been designated the Cradle of Humankind World Heritage Site, which is situated approximately 70 kilometres southwest of Pretoria. Mrs. Ples was discovered by Robert Broom and John T. Robinson on 18 April 1947. Mrs. Ples’ skull is a little bit fractured. Because of Broom's use of dynamite and pickaxe when excavation, the artifact has been blown into two pieces. Nonetheless, Mrs./Mr. Pless is one of the most perfect pre-human skulls. The cranial capacity is about 485 cubic centimeters. The catalog number for Mrs. Ples is STS 5.
The nickname Mrs. Ples was derived from the scientific designation Plesianthropus transvaalensis (near-man from the Transvaal), initially given to the skull by Broom; the nickname itself was coined by young coworkers of Broom. This species is believed to be a distant relatives of the human race. Cranium like a chimpanzee but it definitely stood upright like humans do.
The sex of the skull is not completely certain and so Mrs. Ples may in fact be Mr. Ples. In addition, X-ray analysis of the roots of the teeth of Mrs. Ples has suggested that it was a sub-adult, so a designation of Miss Ples or Master Ples is also possible. However, recent studies have opened new ideas about the gender of Mrs./Mr. Ples.
A certain scientist, Federick E. Grine, had tried some experimentation considering the gender of Mrs./Mr. Ples. Using the Computed Tomography (CT) scans of the Sts 5 from Weber et. al. experiments, they used CT scans of other A. africanus crania from Sterkfontein for comparison. These Ct scans shows a recreated construction images of the teeth roots in order to see the molar and canine development roots. By doing so, these reconstructions might lead them to finally understand Mrs./Ms. Ples' gender. This study had led them to a conclusion that Mrs./Mr. Ples was indeed a middle-aged female species. However, it is not entirely sure since there are other studies that indicated that she/he is of the opposite gender.
Some experts have suggested that a partial skeleton, known only by its catalogue number of STS 14 that was discovered in the same year, in the same geological deposit and in proximity to it, may belong to this skull. If correct, this would make Mrs. Ples the South African counterpart to the famous Lucy fossil. The discoveries of these skulls, along with the Sterkfontien and Makapangsgat, is one tangible evidence about Charles Darwin's hypothesis that human ancestors started in Africa.
The fossil has been dated by a combination of palaeomagnetism and uranium-lead techniques to around 2.05 million years.
- Endocranial Capacity of Early Hominids, Charles A. Lockwood, William H. Kimbel. Science 1 January 1999:Vol. 283 no. 5398 p. 9
- 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.., Hopley, P., Adams, J., Curnoe, D., Maslin, M. 2010. Geochronology and palaeoenvironments of the South African early hominin bearing sites: a reply to ‘Wrangham et al., 2009: Shallow-Water Habitats as Sources of Fallback Foods for Hominins’ Am. J. Phys. Anthro. 143, 640–646.
- Images of STS 5
- Tattersall, Ian, Schwartz, Jeffery (2000). Extinct Humans. Westview Press, Boulder CO. pp. 65–66. ISBN 0-8133-3482-9.
- 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.
- 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
- STS 5. (n.d.). Retrieved February 28, 2015, from http://humanorigins.si.edu/evidence/human-fossils/fossils/sts-5
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