a b s t r a c t
Current evidence suggests that all of the major events in hominin evolution have occurred in East Africa.
Over the last 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 East Africa
has varied in the past. The landscape of East Africa has altered dramatically over the last 10 million years.
It has changed from a relatively flat, homogenous region covered with mixed tropical forest, to a varied
and heterogeneous environment, with mountains over 4 km high and vegetation ranging from desert to
cloud forest. The progressive rifting of East Africa has also generated numerous lake basins, which are
highly sensitive to changes in the local precipitation-evaporation regime. There is now evidence that the
presence of precession-driven, ephemeral deep-water lakes in East Africa were concurrent with major
events in hominin evolution. It seems the unusual geology and climate of East Africa created periods of
highly variable local climate, which, it has been suggested could have driven hominin speciation,
encephalisation and dispersal out of Africa. One example is the significant hominin speciation and brain
expansion event at ~1.8 Ma that seems to have been coeval with the occurrence of highly variable,
extensive, deep-water lakes. This complex, climatically very variable setting inspired first the variability
selection hypothesis, which was then the basis for the pulsed climate variability hypothesis. The newer of
the two suggests that the long-term drying trend in East Africa was punctuated by episodes of short,
alternating periods of extreme humidity and aridity. Both hypotheses, together with other key theories of
climate-evolution linkages, are discussed in this paper. Though useful the actual evolution mechanisms,
which led to early hominins are still unclear and continue to be debated. However, it is clear that an
understanding of East African lakes and their palaeoclimate history is required to understand the context
within which humans evolved and eventually left East Africa.
© 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license
a b s t r a c tCurrent evidence suggests that all of the major events in hominin evolution have occurred in East Africa.Over the last two decades, there has been intensive work undertaken to understand African palaeoclimateand tectonics in order to put together a coherent picture of how the environment of East Africahas varied in the past. The landscape of East Africa has altered dramatically over the last 10 million years.It has changed from a relatively flat, homogenous region covered with mixed tropical forest, to a variedand heterogeneous environment, with mountains over 4 km high and vegetation ranging from desert tocloud forest. The progressive rifting of East Africa has also generated numerous lake basins, which arehighly sensitive to changes in the local precipitation-evaporation regime. There is now evidence that thepresence of precession-driven, ephemeral deep-water lakes in East Africa were concurrent with majorevents in hominin evolution. It seems the unusual geology and climate of East Africa created periods ofhighly variable local climate, which, it has been suggested could have driven hominin speciation,encephalisation and dispersal out of Africa. One example is the significant hominin speciation and brainexpansion event at ~1.8 Ma that seems to have been coeval with the occurrence of highly variable,extensive, deep-water lakes. This complex, climatically very variable setting inspired first the variabilityselection hypothesis, which was then the basis for the pulsed climate variability hypothesis. The newer of
the two suggests that the long-term drying trend in East Africa was punctuated by episodes of short,
alternating periods of extreme humidity and aridity. Both hypotheses, together with other key theories of
climate-evolution linkages, are discussed in this paper. Though useful the actual evolution mechanisms,
which led to early hominins are still unclear and continue to be debated. However, it is clear that an
understanding of East African lakes and their palaeoclimate history is required to understand the context
within which humans evolved and eventually left East Africa.
© 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license
การแปล กรุณารอสักครู่..
