Date: September 23rd, 2017 3:04 PM
Author: Cruel-hearted shrine cuckold
http://www.cell.com/cell/pdf/S0092-8674(17)31008-5.pdf
Early Levantine Farmer-Related Admixture in an
~3,100-Year-Old Pastoralist from Tanzania
Western-Eurasian-related ancestry is pervasive in eastern Africa
today (Pagani et al., 2012; Tishkoff et al., 2009), and the timing of
this admixture has been estimated to be 3,000 BP on average (Pickrell et al., 2014). We found that the 3,100 BP individual
(Tanzania_Luxmanda_3100BP), associated with a Savanna
Pastoral Neolithic archeological tradition, could be modeled as
having 38% ¡À 1% of her ancestry related to the nearly 10,000-
year-old pre-pottery farmers of the Levant (Lazaridis et al.,
2016), and we can exclude source populations related to early
farmer populations in Iran and Anatolia. These results could be
explained by migration into Africa from descendants of pre-pottery
Levantine farmers or alternatively by a scenario in which
both pre-pottery Levantine farmers and Tanzania_Luxmanda_
3100BP descend from a common ancestral population that lived
thousands of years earlier in Africa or the Near East. We fit the
remaining approximately two-thirds of Tanzania_Luxmanda_
3100BP as most closely related to the Ethiopia_4500BP
(p = 0.029) or, allowing for three-way mixture, also from a source
closely related to the Dinka (p = 0.18; the Levantine-related
ancestry in this case was 39% ¡À 1%) (Table S4).
While these findings show that a Levant-Neolithic-related population
made a critical contribution to the ancestry of presentday
eastern Africans (Lazaridis et al., 2016), present-day Cushitic
speakers such as the Somali cannot be fit simply as having
Tanzania_Luxmanda_3100BP ancestry. The best fitting model
for the Somali includes Tanzania_Luxmanda_3100BP ancestry,
Dinka-related ancestry, and 16% ¡À 3% Iranian-Neolithic-related
ancestry (p = 0.015). This suggests that ancestry related to the
Iranian Neolithic appeared in eastern Africa after earlier gene
flow related to Levant Neolithic populations, a scenario that is
made more plausible by the genetic evidence of admixture of
Iranian-Neolithic-related ancestry throughout the Levant by the
time of the Bronze Age (Lazaridis et al., 2016) and in ancient
Egypt by the Iron Age (Schuenemann et al., 2017).
Direct Evidence of Migration Bringing Pastoralism to
Eastern and Southern Africa
In contrast to the Malawi and Zanzibar individuals, all three
ancient southern Africans show affinities to the ancestry predominant
in present-day Tuu speakers in the southern Kalahari
more than to present-day Juj¡¯hoan speakers in the northern
Kalahari (Figures S2B and S2C). However, the 1,200 BP sample
from the western Cape that is found in a pastoralist context
has a specific similarity in clustering analyses to present-day
Khoe-Khoe-speaking pastoralist populations such as the
Nama (Figure 1B), and like them it has affinity to three groups:
Khoe-San, western Eurasians, and eastern Africans. This supports
the hypothesis that a non-Bantu-related population carried
eastern African and Levantine ancestry to southern Africa by at
least around 1,200 BP, providing direct evidence for claims previously
made based on analysis of present-day populations
(Pickrell et al., 2014).
We used our modeling framework to show that the South_
Africa_1200BP pastoralist individual from the western Cape is
consistent with being a mixture of just two streams of ancestry
relative to non-southern African populations, with 40.3% ¡À 2.3%
ancestry related to the Tanzania_Luxmanda_3100BP individual
(54% ¡À 7% when restricting analysis to sequences with postmortem
damage) and the remainder being related to the South_
Africa_2000BP hunter-gatherers (Table S5). This supports the
hypothesis that the Savanna Pastoral Neolithic archaeological
tradition in eastern Africa is a plausible source for the spread of
herding to southern Africa. Even the Juj¡¯hoan San group with
the least genetic affinity to eastern Africans (Ju_hoan_North),
have 9% ¡À 1% of their ancestry most closely related to Tanzania_
Luxmanda_3100BP, consistent with previous findings that the ancestries
of all present-day San and Khoe were affected by agropastoralist
migrations in the last two millennia (Pickrell et al., 2014).
(http://www.autoadmit.com/thread.php?thread_id=3741075&forum_id=2#34277313)