https://nat.au.dk/en/about-the-faculty/news/show/artikel/climate-played-a-crucial-role-in-human-migration-from-africa
A green corridor through the Sahara emerged
precisely during the period when our earliest
ancestors migrated from Africa. This is shown
by new research from Aarhus University.
...
About 2.1 million years ago, the first humans -
Homo erectus - migrated from Africa. The journey
went through northeastern Africa and the Middle
East – areas that are mainly covered by desert
today – and onwards to Europe and Asia.
For a long time, researchers have speculated on
how Homo erectus could cross the dry and
merciless desert, where there was neither food,
water nor shade.
New research from Aarhus University now suggests
that Homo erectus may not have walked through
the desert when they left Africa, explains Rachel
Lupien, who is one of the researchers behind the
new results.
...
Our results show that the Sahara, precisely in
the period when the first Homo erectus migrated,
was greener than at any other time in the 4.5
million year period we studied. They were
therefore most likely able to walk through a
green corridor out of Africa.
...
https://www.nature.com/articles/s43247-023-01034-7
Low-frequency orbital variations controlled
climatic and environmental cycles, amplitudes,
and trends in northeast Africa during the
Plio-Pleistocene
Abstract
The eastern Mediterranean sapropels, paced by
insolation, provide a unique archive of
African monsoon strength over the Late
Neogene. However, the longer-term climate of
this region lacks characterization within the
context of changes in ice volume, sea surface
temperature gradients, and terrestrial
ecosystems. Here, we examine C28 n-alkanoic
acid leaf wax hydrogen and carbon isotopes in
sapropels, sourced from northeast Africa,
along with vegetation-corrected precipitation
isotopes, derived from astronomically dated
sediment cores from ODP 160 Sites 966 and 967
since 4.5 million years ago. Despite sampling
only wet-phase sapropels for African monsoon
variability, we find a larger range in
hydrogen isotopes than previously published
data across wet-dry precession cycles,
indicating the importance of long-term
modulation of Green Sahara phases throughout
the Neogene. An influence of orbital
properties on regional monsoonal
hydroclimate is observed, controlling up to
50% of total hydrogen isotope variance, but
large changes outside of these typical
frequencies account for at least 50% of the
total variance. This secular trend may
track changes in ice volume, tropical sea
surface temperature, sea surface temperature
gradients, or even lower-frequency orbital
cycles. Long-term hydroclimate and
environmental shifts provide new contexts
for milestone events in northeast African
hominin dispersal and evolution.
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