acase@tulane.edu / The goal of this study is to explore the phylogenetic relationships in the most confusing period during hominin evolution: the relatively speciose period between ca. 3 Ma and 1 Ma, when several distinct, yet closely related, hominin species lived contemporaneously in overlapping regions of Africa. Though our knowledge of these species’ morphology has grown considerably in recent years, there is still confusion regarding how these species were related to one another. Most commonly, these questions are investigated using phylogenetic analytical methods such as maximum parsimony, and the issue is rarely clear-cut. Researchers have long debated the best methods for selecting taxa and characters to be used in analysis.
While maximum parsimony is a useful analytical tool when investigating certain sets of taxa, it has shortcomings when applied to closely related species, especially if introgression and reticulation occurred between those species. To date, scholars have interpreted the period in hominin history between 3 Ma and 1 Ma in terms of simple bifurcating tree-like relationships without considering that the relationships between taxa could be more complex. This study investigates the possibility of reticulate relationships between hominin taxa during this period by employing novel analytic methods more
commonly used in used in evolutionary biology. Specifically, a previously published character data set from thirteen hominin taxa is employed. The data are analyzed using maximum parsimony, the DELTRAN character optimization method, and a distance matrix method for examining the structure of the data and to identify sources of character conflict.
This study demonstrates conflicting signals in the data set indicate that relationships between hominin taxa are likely more complex than can be accounted for in tree-like interpretations. Unfortunately, analytical tools specifically designed to identify reticulation and introgression are not currently available for morphological data of this type. In the future, it would be beneficial if software were developed to analyze reticulate relationships using these types of data. Genetic data indicate that in the late Pleistocene, Neandertals interbred with modern humans (and also with the Denisovans); this study suggests that among earlier hominin taxa, phylogenetic relationships were also more complex than has been previously proposed. / 1 / Joanna Gautney
| Identifer | oai:union.ndltd.org:TULANE/oai:http://digitallibrary.tulane.edu/:tulane_74370 |
| Date | January 2016 |
| Contributors | Gautney, Joanna (author), Holliday, Trenton (Thesis advisor), School of Liberal Arts Anthropology (Degree granting institution) |
| Publisher | Tulane University |
| Source Sets | Tulane University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | electronic, 225 |
| Rights | No embargo, Copyright is in accordance with U.S. Copyright law. |
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