Publication Date:
2017-06-22
Description:
The termination of the African Humid Period in northeastern Africa during the early
Holocene was marked by the southward migration of the rain belt and the
disappearance of the Green Sahara. This interval of drastic environmental changes
was also marked by the initiation of food production by North African huntergatherer
populations and thus provides critical information on human-environment
relationships. However, existing records of regional climatic and environmental
changes exhibit large differences in timing and modes of the wet/dry transition at
the end of the African Humid Period. Here we present independent records of
changes in river runoff, vegetation and erosion in the Nile River watershed during
the Holocene obtained from a unique sedimentary sequence on the Nile River fan
using organic and inorganic proxy data. This high-resolution reconstruction allows
to examine the phase relationship between the changes of these three parameters
and provides a detailed picture of the environmental conditions during the
Paleolithic/Neolithic transition. The data show that river runoff decreased gradually
during the wet/arid transition at the end of the AHP whereas rapid shifts of
vegetation and erosion occurred earlier between 8.7 and ,6 ka BP. These
asynchronous changes are compared to other regional records and provide new
insights into the threshold responses of the environment to climatic changes. Our
record demonstrates that the degradation of the environment in northeastern Africa
was more abrupt and occurred earlier than previously thought and may have
accelerated the process of domestication in order to secure sustainable food
resources for the Neolithic African populations.
Type:
Article
,
PeerReviewed
Format:
text