Can Genetics help unravel the Afroasiatic cradle?
MahE9 BEN HAMED1,2, LounE8s CHIKHI3 and Pierre DARLU2

1 Laboratoire Dynamique du Langage, UMR5596, Lyon, France
2 GE9nE9tique EpidE9miologique et Structure des populations humaines,

U535, Villejuif, France
3 UMR Evolution et DiversitE9 Biologique, Toulouse, France

Mahe.Ben-Hamed@ish-lyon.cnrs.fr

       The location of the Afroasiatic cradle and the routes of 
expansion of this linguistic family have long been debated. Two 
scenarios compete. The first scenario (Militarev et al., 1992) connects 
the history of this linguistic family with the expansion of the major 
Eurasian linguistic phyla which are themselves thought to have been 
brought during the agriculturalist revolution in the Near-East about 
10-13,000 years ago. This scenario is supported by the Russian  
linguistic school and the Nostratic tenants who consider the Afroasiatic
is related to the Nostratic macro-family. .On the contrary, afrasian 
historical linguists support a second scenario where the Afro-Asiatic is
thought to have originated in eastern Lower Nubia and to be at least  
15,000 years old (Ehret, 1979, 1995).  It has been difficult to clearly
demonstrate the superiority of any of the two scenarios as tenants from
both sides have sometimes used the same methodologies to reach opposite
conclusions. Moreover, some of the methodologies used such as linguistic
palaeontology and glottochronology are often criticised among the 
linguistic community. One possible explanation for obtaining such 
paradoxical conclusions is that there might be methodological 
deficiencies in the way the issue is handled (Ben Hamed and Darlu, 
2003). The debate is thus left wide open, and it remains as topical now
as it was when Afro-Asiatic was first established as a linguistic 
phylum, at the beginning of the 20th Century (Cohen, 1924).

       Given the existing controversy among linguists and the scarcity 
of archaeological data to solve the Afroasiatic homeland puzzle (McCall,
1998), it is legitimate to ask whether genetic data could be as useful 
as it has been on similar issues on other linguistic groups. In a 
research context favouring multidisciplinary approaches, reconciling the
three approaches would certainly be a significant improvement. .    
Currently, the Anatolian scenario is probably the most appealing for it
is both synthetic and parsimonious. It provides a powerful explanation 
for the expansion of this and other linguistic families. Indeed, a demic
diffusion scenario starting in the same region is becoming increasingly
supported in the case of Indo-European and some of the other Nostratic 
branches. If confirmed this would identify the Fertile Crescent as the 
cradle of the neighbouring linguistic diversity, and the demic diffusion
model as a paradigm for the study of populations92 evolution in these 
regions at least.

       In the present talk we will take an indirect approach to the 
problem, which cannot on its own answer the whole cradle issue, but 
which can test the consistency of the genetic data with specific  
linguistic scenarios. Both scenarios imply migratory events.  
Correlatively, in the demic model of a linguistic family expansion, 
admixture patterns between the migrating people and the local demes are 
expected. Provided appropriate parental hypotheses 96 i.e. which 
population represents the migratory wave, and which will represent the 
substratum submitted to admixture- it is possible to infer admixture   
patterns from the observed genetic frequencies of present-day 
populations. We confront here different admixture methods relying on   
different assumptions in order to embrace all the evolutionary forces 
that can shape the admixture profile of the populations under study 
(Chikhi et al., 2001; Bertorelle and Excoffier, 1998; Wijsman, 1984). 
The profiles thus obtained are confronted with each of the scenarios   
proposed for Afro-asiatic.

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