Genetic study details complex ancestry of East Africa's Swahili people

Genetic Technologies

29/03/2023 16:38

By Will Dunham
       March 29 (Reuters) - A study of centuries-old DNA has
deciphered the complex ancestry of coastal East Africa's Swahili
people, revealing how a cosmopolitan and prosperous medieval
civilization arose thanks in large part to women from Africa and
men arriving from Persia.
    Researchers said on Wednesday they examined the DNA of 80
people from five sites in Kenya and Tanzania dating to about
1250 to 1800 AD. More than half of the genetic input in many of
them traced to female ancestors from Africa's east coast while a
significant contribution also came from Asia, of which about 90%
came from men from Persia - modern Iran - and 10% from India. 
    After around 1500 AD, the bulk of the Asian genetic
contribution shifted to Arabian sources, the study showed.
    The Swahili coast region stretches roughly from the Somali
capital Mogadishu at the north to Tanzania's Kilwa island at the
south and also includes parts of Kenya and Malawi and the Indian
Ocean archipelagoes of Zanzibar and Comoros. 
    The medieval Swahili people in city-states such as Mombasa
and Zanzibar exported goods from the African interior including
ivory, gold, ebony and sandalwood, as well as slaves, to
destinations across the Indian Ocean. They also were among the
first practitioners of Islam among sub-Saharan people.
    "The sex-bias in the African-Asian admixture raises
questions about the social dynamics and gender roles. On the one
hand, you have Persian men mixing with African women, which
might highlight social inequalities, usually with the female
mixing population of a lower status," said Harvard University
geneticist Esther Brielle, lead author of the study published in
the journal Nature.
    "However, in this case, because Bantu populations in East
Africa often have more matrilineal tendencies, African women
likely had more autonomy in choosing their partners for building
a family. And the situation could have been that powerful
trading families in Africa and Asia formed economically
beneficial marriage ties," Brielle added.
    It may be, the researchers said, that the African women and
their communities chose to form families with Persian princes or
traders, reinforcing trade networks of African and Persian
merchants.
    People of African and Asian origins began to mix in the
region by around  1000 AD, the study showed. The genetic
findings reflected the Swahili people's cosmopolitan nature.
Their Swahili language is of African origin, the predominant
religion of Islam was imported from the Middle East and the
cuisine shows Indian and the Middle Eastern influences. 
    "The roots of the Swahili language can be traced back over
1,500 years as part of the Bantu language family. This
demonstrates the indigenous nature of this society and shows us
that the genetic input from Persia was not part of a wholesale
population movement," said study co-author Stephanie
Wynne-Jones, a professor of African archaeology at the
University of York in England.
    The Swahili culture reached its apex from the 12th to 15th
centuries, declining with the arrival of the Portuguese during
the 16th century.
    "The genetic data provides new information that challenges
previous colonial assumptions about the origins of Swahili
people and their advances being attributed to foreigners,"
Brielle said.
    The evidence of Indian ancestry adds a surprising new layer
to the history of the East African coast, Brielle added.
    There has been a long debate among some scholars over
Swahili origins, though modern Swahili people have an oral
history embracing both African and Asian roots. For instance,
one text based on oral tradition traces the founding of Kilwa to
the arrival of a Persian prince.
    "It is exciting that the results are consistent with the
indigenous oral histories of the Swahili people. These findings
bring out the African contributions, and indeed the Africanness
of the Swahili without marginalizing the Persian-Indian
connection," University of South Florida anthropologist and
study co-author Chapurukha Kusimba said.

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 (Reporting by Will Dunham in Washington; Editing by Daniel
Wallis)
 ((Will.Dunham@thomsonreuters.com))