A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2014. / In the present thesis the use of convergence as a tool in functional analyses was investigated, with special focus on comparisons using distantly related species (“convergence approach”). Guidelines for the convergence approach were forumlated and applied in the evaluation of selected hypotheses on the contextualization of early hominins. Additionally, comprehensive reviews on water use in primates were carried out, with special focus on hominoids, including humans. The first description (and video footage) of swimming and diving behaviour in a common chimpanzee (Pan troglodytes) and an orangutan (Pongo pygmaeus) were presented here, along with swimming behaviour in other great apes (without video footage). Hypotheses on the loss of instinctive swimming in hominoids were discussed and the Saci last common ancestor hypothesis was proposed. This model suggests that the loss of swimming ability in hominoids is best explained as a consequence of phylogenetic constraints linked to the adaptation to an arboreal life in the last common ancestor of this taxon.
Furthermore, several hypotheses on early hominin evolution were reviewed. It was pointed out that several of these hypotheses have similar methodological flaws in the use of analogies to corroborate specific arguments. A hypothesis on the emergence of the habitual bipedalism in early hominins was outlined, arguing that this trait did not evolve in association with a locomotory advantage or for other reasons usually presented in the literature, but as a signal to advertise unprofitability – as a warning signal in an anti-predator strategy. It was argued that fossil evidence does not allow a high resolution of inference concerning incipient traits – traits which are not optimized to fulfil a certain function after a functional change.
The consideration of different lines of evidence presented in this thesis indicate that the topic “water use” must be considered in discussions on early hominin evolution. The fact that humans regularly and intensively interact with water can be considered as an indication that in some part of human phylogeny after the hominin/panin split, swimming and diving ability was specifically selected. However, contrary to the view of several proponents of the aquatic hypotheses, it was demonstrated that humans are not absolutely unique concerning their ability to learn to swim and to dive. It is therefore also conceivable that our ability to learn to swim is associated to our cognitive abilities and is not a product of specific selection in our past.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/16924 |
| Date | 06 February 2015 |
| Creators | Bender, Pedro Renato |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf, application/pdf, application/pdf |
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