@article{TrauthBergnerFoersteretal.2015,
  author    = {Trauth, Martin H. and Bergner, Andreas G. N. and Foerster, Verena and Junginger, Annett and Maslin, Mark A. and Sch{\"a}bitz, Frank},
  title     = {Episodes of environmental stability versus instability in Late Cenozoic lake records of Eastern Africa},
  series = {Journal of human evolution},
  volume    = {87},
  journal   = {Journal of human evolution},
  publisher = {Elsevier},
  address   = {London},
  issn      = {0047-2484},
  doi       = {10.1016/j.jhevol.2015.03.011},
  pages     = {21 -- 31},
  year      = {2015},
  abstract  = {Episodes of environmental stability and instability may be equally important for African hominin speciation, dispersal, and cultural innovation. Three examples of a change from stable to unstable environmental conditions are presented on three different time scales: (1) the Mid Holocene (MH) wet dry transition in the Chew Bahir basin (Southern Ethiopian Rift; between 11 ka and 4 ka), (2) the MIS 5-4 transition in the Naivasha basin (Central Kenya Rift; between 160 ka and 50 ka), and (3) the Early Mid Pleistocene Transition (EMPT) in the Olorgesailie basin (Southern Kenya Rift; between 1.25 Ma and 0.4 Ma). A probabilistic age modeling technique is used to determine the timing of these transitions, taking into account possible abrupt changes in the sedimentation rate including episodes of no deposition (hiatuses). Interestingly, the stable-unstable conditions identified in the three records are always associated with an orbitally-induced decrease of insolation: the descending portion of the 800 kyr cycle during the EMPT, declining eccentricity after the 115 ka maximum at the MIS 5-4 transition, and after similar to 10 ka. This observation contributes to an evidence-based discussion of the possible mechanisms causing the switching between environmental stability and instability in Eastern Africa at three different orbital time scales (10,000 to 1,000,000 years) during the Cenozoic. This in turn may lead to great insights into the environmental changes occurring at the same time as hominin speciation, brain expansion, dispersal out of Africa, and cultural innovations and may provide key evidence to build new hypotheses regarding the causes of early human evolution. (C) 2015 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{MaslinShultzTrauth2015,
  author    = {Maslin, Mark A. and Shultz, Susanne and Trauth, Martin H.},
  title     = {A synthesis of the theories and concepts of early human evolution},
  series = {Philosophical transactions of the Royal Society of London : B, Biological sciences},
  volume    = {370},
  journal   = {Philosophical transactions of the Royal Society of London : B, Biological sciences},
  number    = {1663},
  publisher = {Royal Society},
  address   = {London},
  issn      = {0962-8436},
  doi       = {10.1098/rstb.2014.0064},
  pages     = {12},
  year      = {2015},
  abstract  = {Current evidence suggests that many of the major events in hominin evolution occurred in East Africa. Hence, over the past two decades, there has been intensive work undertaken to understand African palaeoclimate and tectonics in order to put together a coherent picture of how the environment of Africa has varied over the past 10 Myr. A new consensus is emerging that suggests the unusual geology and climate of East Africa created a complex, environmentally very variable setting. This new understanding of East African climate has led to the pulsed climate variability hypothesis that suggests the long-term drying trend in East Africa was punctuated by episodes of short alternating periods of extreme humidity and aridity which may have driven hominin speciation, encephalization and dispersals out of Africa. This hypothesis is unique as it provides a conceptual framework within which other evolutionary theories can be examined: first, at macro-scale comparing phylogenetic gradualism and punctuated equilibrium; second, at a more focused level of human evolution comparing allopatric speciation, aridity hypothesis, turnover pulse hypothesis, variability selection hypothesis, Red Queen hypothesis and sympatric speciation based on sexual selection. It is proposed that each one of these mechanisms may have been acting on hominins during these short periods of climate variability, which then produce a range of different traits that led to the emergence of new species. In the case of Homo erectus (sensu lato), it is not just brain size that changes but life history (shortened inter-birth intervals, delayed development), body size and dimorphism, shoulder morphology to allow thrown projectiles, adaptation to long-distance running, ecological flexibility and social behaviour. The future of evolutionary research should be to create evidence-based meta-narratives, which encompass multiple mechanisms that select for different traits leading ultimately to speciation.},
  language  = {en}
}