So far ranging and residence patterns amongst early hominins have been indirectly inferred from morphology, stone tool sourcing, comparison to living primates and phylogenetic models. An international team of researchers including Sandi Copeland, Vaughan Grimes and Michael Richards of the Max Planck Institute for Evolutionary Anthropology in Leipzig/Germany have now investigated landscape use in Australopithecus africanus (with fossils from sites dating between 2.8-2.0 million years ago) and Paranthropus robustus (with fossils from sites dating between 1.9-1.4 million years ago) from the Sterkfontein and Swartkrans cave sites in South Africa using strontium isotope analysis.
Skull of a Paranthropus robustus from Swartkrans Cave in South Africa. Darryl de Ruiter
This method helps identify the geological substrate on which an animal lived during tooth mineralization. The researchers show that a high proportion of small, but not large, hominin teeth had non-local strontium isotope compositions. Given the relatively high levels of sexual dimorphism in early hominins, the smaller teeth probably represent females, indicating that females were more likely than males to disperse from their natal (i.e. where they were born) groups. This is similar to the dispersal pattern found in chimpanzees, bonobos, and many human groups, but dissimilar to that of most gorillas and other primates. (Nature, June 2nd, 2011)
Established paleontological and archaeological techniques provide little tangible evidence for how early hominins used and moved across landscapes. For example, home range size has been estimated based on a rough correlation with body mass, and models of early hominin dispersal have relied on behaviors common among hominoids and presumed to be present in a common ancestor. “However, the highly uncertain nature of such reconstructions limits our understanding of early hominin ecology, biology, social structure, and evolution”, says Sandi Copeland of the Max Planck Institute for Evolutionary Anthropology.
Copeland and colleagues have now used a geochemical proxy, strontium isotope analysis of tooth enamel, to investigate early hominin landscape use. Strontium is ingested and incorporated in trace quantities into mammalian teeth. First, the researchers determined strontium isotopes in plant specimens that were collected within a 50 km radius of the Sterkfontein and Swartkrans caves in order to establish the background of biologically available strontium across the region. They then sampled a series of hominin tooth crowns by employing a relatively new method for measuring strontium isotopes in teeth that is called laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). This method is almost non-destructive as it leaves only tiny traces on the enamel surface. The researchers found that although there is no significant difference between the proportion of non-locals in P. robustus (36 %) and A. africanus (25 %), there are significant differences between subsets of hominins defined by tooth size.
“The strontium isotope data suggest differences in landscape use between males and females”, says Sandi Copeland and explains: “Because strontium was incorporated into the teeth before adulthood, when the hominins were probably travelling with their mothers, the data are unlikely to reflect differences in foraging areas between adult males and adult females. Rather, the strontium isotopes probably indicate that females preferentially moved away from residential groups”.
The hominins’ female but not male dispersal pattern is similar to the one found in chimpanzees, bonobos, and many human groups, but dissimilar to that of most gorillas and other primates. This suggests that early hominin social structure was not like that of gorillas in which one or few males dominate groups of females.
The small proportion of non-local large hominins could indicate that male australopiths had small home ranges, which would be surprising given that the evolution of bipedalism is commonly attributed to the need to move over large distances. The results could also imply that male australopiths preferred the types of resources found on dolomite landscapes. This study was the first to apply this method to early fossil hominins, and lays the groundwork for future studies of other fossil species, including Australopithecus and Paranthropus in East Africa, and later hominins belonging to our genus Homo.
The following institutions contributed to this study: Max Planck Institute für Evolutionary Anthropology, Leipzig, Germany; University of Colorado, Boulder, USA; Texas A&M University, College Station, USA; Oxford University, Oxford, UK; University of Cape Town, Cape Town, South Africa; University of Zurich, Zurich, Switzerland; Memorial University, St. John’s, Canada; University of British Columbia, Vancouver, Canada.
Original publication:Sandi R. Copeland, Matt Sponheimer, Darryl J. de Ruiter, Julia A. Lee-Thorp, Daryl Codron, Petrus J. le Roux, Vaughan Grimes & Michael P. Richards
Barbara Abrell | Max-Planck-Gesellschaft
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences