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Ancient Local Evolution of African mtDNA Haplogroups in Tunisian Berber Populations
Frigi et al.
Human Biology (August 2010 (82:4)
Abstract
Our objective is to highlight the age of sub-Saharan gene flows in North Africa and particularly in Tunisia. Therefore we analyzed in a broad phylogeographic context sub-Saharan mtDNA haplogroups of Tunisian Berber populations considered representative of ancient settlement. More than 2,000 sequences were collected from the literature, and networks were constructed. The results show that the most ancient haplogroup is L3*, which would have been introduced to North Africa from eastern sub-Saharan populations around 20,000 years ago. Our results also point to a less ancient western sub-Saharan gene flow to Tunisia, including haplogroups L2a and L3b. This conclusion points to an ancient African gene flow to Tunisia before 20,000 years BP. These findings parallel the more recent findings of both archaeology and linguistics on the prehistory of Africa. The present work suggests that sub-Saharan contributions to North Africa have experienced several complex population processes after the occupation of the region by anatomically modern humans. Our results reveal that Berber speakers have a foundational biogeographic root in Africa and that deep African lineages have continued to evolve in supra-Saharan Africa.
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Ancient Local Evolution of African mtDNA Haplogroups in Tunisian Berber Populations
Frigi et al.
Human Biology
August 2010 (82:4)
Discussion
In this study we attempted to better elucidate the ancient African genetic
background in the northwest African area, particularly in Tunisia. To this aim, we
focused our study on Berber populations that are considered representative of the
ancient North African populations that probably derived from Neolithic Capsians.
During historic times, Berbers experienced a long and complicated history with
many invasions, conquests, and migrations by Phoenicians, Romans, Vandals,
Byzantines, Arabs, Bedouins, Spanish, Turks, Andalusians, sub-Saharans (communities
settled in Jerba and Gabes in the 16th–19th centuries), and French (Brett
and Fentress 1996). During these invasions, Berbers were forced back to the mountains
and to certain villages in southern Tunisia (Fadhlaoui-Zid et al. 2004).
At present, they are restricted to some isolates in the south who maintain the Berber
language and to some populations in the north who lack an origin language.
Many genetic studies on Tunisian Berber populations demonstrate the heterogeneity
of Berbers with respect to European and sub-Saharan African contributions
and the mosaic structure of Tunisian Berber populations with an absence of ethnic,
linguistic, and geographic effects (Cherni et al. 2010).
In the present work, mtDNA data show a diversified distribution of African
haplogroups. However, a question remains concerning the date of the sub-Saharan
African inputs. Our results demonstrate an ancient local evolution in Tunisia of
some African haplogroups (L2a, L3*, and L3b). The most ancient haplogroup is
L3*, which would have been introduced from eastern sub-Saharan populations to
North Africa about 20,000 years ago. The Siwa oasis sample studied by Coudray
et al. (2009) contains sub-Saharan haplogroups L0a1, L3i, L4*, and L4b2, which
are different from our Tunisian samples, in agreement with the heterogeneity of
Berbers already shown in Tunisia.
Stevanovitch et al. (2004) suggested that the Gurna population in Egypt has
conserved the trace of an ancestral genetic structure from an ancestral East African
population characterized by a high haplogroup M1 frequency. This haplogroup is
also present in three Berber populations (Kesra, Matmata, and Sned) with variable
frequencies. In each of these populations, haplogroup L3* is also present.
The association of both eastern African haplogroups in the Berber populations is
a strong argument in favor of eastern African gene flow in Berbers. Other genetic
and archaeological studies confirmed the crucial idea that an ancient population in
East Africa constituted the basis of the ancestors of all African Upper Paleolithic
populations—and their subsequent present-day descendants (Bengtson 2008; Keita
2004; Relethford 2000; Zakrzewski 2003, 2007).
Moreover, Berber languages spoken exclusively by North African populations
belong to the Afro-Asiatic language. Diakonoff (1998) showed an exclusively
African origin (Diakonoff, 1981, 1988) for the family. He explicitly described
proto-Afro-Asiatic vocabulary as consistent with non-food-producing vocabulary
and linked it to pre-Neolithic cultures in the Levant and in Africa south of Egypt.
Moreover, Ehret. (2003) suggested that early Afro-Asiatic languages were spread
by Mesolithic foragers from Africa into the Levant. On the contrary, Diamond
and Bellwood (2003) suggested that food production and the Afro-Asiatic
language family were brought simultaneously from the Near East to Africa by demic
diffusion—in other words, by a migration of food-producing peoples. The evidence
presented by Wetterstrom (1993) does not support this latter suggestion,
however, and indicates that early African farmers in the Fayum initially incorporated
Near Eastern domesticates into an existing indigenous foraging strategy and
only over time developed a dependence on horticulture.
In conclusion, the crucial linguistic finding is that the three deepest clades
of the Afro-Asiatic family are localized in Eritrea and Ethiopia. All the other languages
of the family outside that region belong to subclades of just one of those
deep clades. This kind of cladistic distribution is a basic criterion of the
genetic argument for the genetic lineage origins well understood by geneticists. It applies
to linguistic history as well.
Our results also point to a less ancient western African gene flow to Tunisia
involving haplogroups L2a and L3b. Thus the sub-Saharan contribution to northern
Africa starting from the east would have taken place before the Neolithic. The
western African contribution to North Africa should have occurred before the Sahara’s
formation (15,000 years BP). It seems likely that an expansion would have
taken place in the Sahel zone starting about the time of a gradual climatic return
to wetter conditions, when the Senegal River cut through the dunes (Burke et al.
1971). For subhaplogroup L2a1 (data not shown) we found some haplotypes that
the Tunisian Berbers shared with Mauritanians and western sub-Saharan populations
speaking a Niger-Congo language (studied by Salas et al. 2002).
This suggests that the people who brought these markers to the Berber populations most
likely came from West African populations that spoke languages belonging to the
Niger-Congo family when the Sahara became drier. However, this contribution
of West African haplotypes and of other haplotypes, such as those belonging to
haplogroup L1b1, could have been introduced to North Africa more recently.
Indeed, this West African contribution was difficult to date, because few
haplotypes belonging to western African haplogroups have been observed, most
of them being divergent. This result can be interpreted in different ways. Ancient
western African mtDNA contributions could have disappeared from North Africa
as a result of recent flows, or the situation observed now could be the result of a
strong drift effect on ancient western African lineages, particularly those belonging
to haplogroups L2a and L3b. A strong Iberian gene flow may have contributed
to the decrease in African haplogroups. Indeed, most of the older hypotheses
about North African population settlement used to suppose an Iberian or an eastern
origin. The dates for subhaplogroups H1 and H3 (13,000 and 10,000 years,
respectively) in Iberian and North African populations allow for this possibility.
Kefi et al.’s (2005) data on ancient DNA could be viewed as being in agreement
with such a presence in North Africa in ancient times (about 15,000–6,000 years
ago) and with the fact that the North African populations are considered by most
scholars as having their closest relations with European and Asian populations
(Cherni et al. 2008; Ennafaa et al. 2009; Kefi et al. 2005; Rando et al. 1998).
However, considering the general understanding nowadays that human settlement of
the rest of the world emerged from eastern northern Africa less than 50,000 years
ago, a better explanation of these haplogroups might be that their frequencies reflect
the original modern human population of these parts of Africa as much as or
more than intrusions from outside the continent. The ways that gene frequencies
may increase or decrease based on adaptive selection, gene flow, and/or social
processes is under study and would benefit from the results of studies on autosomal
and Y-chromosome markers.
Since the end of the extreme Saharan desiccation, lasting from before
25,000 years ago up to about 15,000 years ago, the Sahara has had post- and pre-
Holocene cyclical climatic changes (Street and Grove 1976), and corresponding increases
and decreases in population are probable. Wetter phases with better habitats
perhaps allowed for increased colonization and gene and cultural exchange.
Desiccation would have encouraged the emigration and segmentation of populations,
with resultant genetic consequences secondary to drift producing more
variation. During the last glacial period, the Sahara was even bigger than it is
today, extending south beyond its current boundaries (Ehret 2002). About 13,000
years ago, large parts of the Sahara were as dry as the desert is now (White and
Mattingly 2006). The end of the glacial period brought more rain to the Sahara,
especially from about 8500 to 6000 BC (Fezzan Project 2006). By around 3400
BC, the monsoon retreated south to approximately where it is today, leading to the
gradual desertification of the region (Kröpelin 2008). Thus the Sahara, through its
cyclical environmental changes, might be seen as a microevolutionary “processor”
and/or “pump” of African people that “ejected” groups to the circum-Saharan
regions in times of increasing aridity.
Indeed, it must be noted that the high frequencies of cDe, P, and V antigens
and low frequencies of FY antigens in some Berber-speaking groups (Chamla
1980; Mourant et al. 1976) indicate affinities with tropical Africans. These data
may indicate recent or ancient gene flow from sub-Saharan Africa, a common immediate
pre-Holocene ancestral group, or chance resemblance.
Our findings are in accordance with other studies on Y-chromosome markers
that have shown that the predominant Y-chromosome lineage in Berber communities
is the subhaplogroup E1b1b1b (E-M81), which emerged in Africa, is
specific to North African populations, and is almost absent in Europe, except in
Iberia (Spain and Portugal) and Sicily. Molecular studies on the Y chromosome in
North Africa are interpreted as indicating that the southern part of Africa, namely,
the Horn/East Africa, was a major source of population in the Nile Valley and
northwest Africa after the Last Glacial Maximum, with some migration into the
Near East and southern Europe (Bosch et al. 2001; Underhill et al. 2001).
Hence, contrary to the suggestion that mtDNA haplogroups were introduced
mostly from Iberia, it seems that Y-chromosome markers have an eastern
African origin with an ancient local evolution in North Africa. These observations
are in agreement with the proposal that the ancient communities ancestral
in language to more recent Berber communities absorbed a lot of females from
the existing pre-Holocene populations. This would indicate that the North African
populations arose from admixture rather than from local evolution, leading
to an intermediate genetic structure between eastern sub-Saharan Africans and
Eurasians. Rock paintings in North Africa that show people of different phenotypes
living together are a strong argument for our hypothesis (Hachid 1982,
1992, 1998).
In conclusion, our findings parallel the more recent findings of both archaeology
and linguistics on the prehistory of Africa. The present study suggests that
sub-Saharan contributions to North Africa have experienced several complex population
processes after the occupation of the region by anatomically modern humans.
Our results reveal that Berber speakers have a foundational biogeographic root in
Africa and that deep African lineages have continued to evolve in supra-Saharan Africa.
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Biocultural Emergence of the Amazigh in Africa: Comment on Frigi et al. (2010)
S. O. Y. Keita. Human Biology (August 2010) (82:4)
Frigi et al. [2010 (this issue)] present some new findings on a population of
Amazigh—Berber speakers in Tunisia. Although their study is not exhaustive,
they provide an outline of human population history in the Maghreb and a general
discussion of its mtDNA diversity. Their work is important in inviting researchers
to think about the concepts of continuity and change in biology, culture, language,
and identity in a geographic space. Their presentation helps in understanding the
complexity of examining the ancestry and emergence of Berber origins in Africa
as a local process and encourages the consideration of many questions about how
the human biology and culture of a known population or ethnolinguistic group can
be conceptualized through space and time.
Berber- (Tamazight-) speaking communities are thought to represent the
clearest known descendants of the ancient indigenous populations of Africa west
of the northern Nile valley in the supra-Saharan and northern Saharan regions
(Brett and Fentress 1996; Camps 1982; Desanges 1981). “Indigenous” here can
refer only to those whom we can perceive as having had the longest tenure on
the land, using available historical evidence. However, there are questions. What
constitutes “historical evidence” for earlier periods? Should it include archaeology,
paleontology, historical linguistics, skeletal biology, and genetics, as broadly
advocated by a historical anthropological approach (e.g., Kirch and Green 2001;
Mace et al. 2005)? Or is it only to be based on the interpretation of texts from
the ancient Egyptian, Greco-Roman, or Islamic periods [e.g., see comments by
Brett and Fentress (1996), Desanges (1981), Norris 1982, and Snowden (1971)]?
How is the varied evidence to be ranked in importance, reconciled when it seems
to be in contradiction, and analyzed synthetically? A simplistic positivism has to
be avoided in discussions of any facet of human history because various pathways
could lead to similar results. What is the role of evolutionary mechanisms—adaptive
selection, gene flow, drift, sexual selection—in explaining the biology of
some of the ancestors of Berber speakers at the deepest time levels and of living
Amazigh as well? Frigi et al. (2010) do not address all these questions directly,
but their work implicitly acknowledges their importance and provides a new framework
for investigation.
Braudel’s (1980) concept of different levels of history can be adapted and
adopted in a modified form as levels of biocultural or bioethnic history, to further
consider Frigi and colleagues’ contribution, which implicitly acknowledges
the contingent and multidimensional character of population interactions through
time against an evolutionary background.
Another issue of some interest is the (mis)labeling of Berbers as “Eurasian”
migrants from the Near East: Did they arrive as a unit from Asia or Europe, as
a settler colonist “package” with a persistent identity analogous to Europeans in
South Africa, or did the biology, language, and culture of the Amazigh emerge
primarily from a set of interactions in Africa involving African peoples at base,
that is, as a part of authentic African historical and biological processes? There are
no ancient Berber communities outside Africa, and the idea of simple demic diffusion
of Berbers as a people to the Maghreb (e.g., Arredi et al. 2004) from the Near
East is not supported. It is of some interest that even Coon and Hunt (1965), using
a raciotypological paradigm now long discredited, postulated a massive invasion
of Africa by “Caucasians” in the Pleistocene and therefore thought that Berber
language and identity had entered the Maghreb from more southerly regions in
Africa. Frigi and colleagues suggest that several populations over time were involved
in the biological ancestry of the current Berber speakers, and this is consistent
with archaeological evidence of actual migration in the mid- to late Holocene
(Camps 1982) as well as historical documentation. Craniofacial diversity has been
documented in the region before Vandal and Arab migrations (Keita 1990).
It is important to remember that biology, language, and culture are not intrinsically
or obligatorily correlated, a principle established some time ago (Boas
1940). It is not particularly surprising that one can sometimes find markers that
will correlate across biology and culture at some levels—but the issue is how this
came to be and when, and what it represents historically and socially. There is
always the question of whether the correlation is an artifact of recent events or
of “primordial” ontology. A language or language family can be adopted slowly
or rapidly by nonnative speakers. The current biological profile of a region may
predate (or postdate) the language spoken there. Communities may adopt (nonlinguistic)
cultural practices from others without greatly changing language or
biology; or they may become primarily integrated linguistically and politically
but not biologically or exhibit other permutations of these variables, such as total
biocultural assimilation. The biology of a particular ethnolinguistic group or community
may change based on intermarriage if the social rules allow the offspring
to become group members. Such matings may have occurred long before the
recall of communal memory, whether in texts or oral tradition. Relatively nonethnocentric
polygamous societies or populations may have cultural descendants
who are genealogically heterogeneous when viewed over a millennium.
Frigi et al. (2010) suggest these possibilities as factors in their consideration
of the asymmetric assimilation of females of non-African origin into Berber-speaking
populations whose males currently have a predominance of lineages defined by
the African M35/81 biallelic marker. It is interesting that these “non-African”
mtDNA lineages are usually predominant while being diverse (Coudray et al.
2009; Fadhlaoui-Zid et al. 2004; Khodjet-el-Khil et al. 2008). The existence of
mtDNA lineages common to Saami and some Amazigh groups (Achilli et al.
2005) is likely to be explained by the migration of females bearing these lineages
from a region in northern Europe (perhaps in the ranks of the Vandals or far more
ancient back-migrations to Africa), whether they were ethnically Saami or not.
However, there may have been other locales where these lineages once existed.
Circular reasoning in syntheses involving multiple disciplines has to be
avoided. The criteria and methods for a given discipline usually have to be given
equal weight, and their results should be considered independently before an effort
at synthesis is made. For example, a hypothesis about the place of origin of
a language family or phylum must be based on linguistic evidence and methods,
not on DNA or craniofacial patterns. Likewise the place of origin of a particular
genetic variant or lineage has to be based on genetic data, principles, and models,
not on archaeological data. The locale of origin of a particular culture or
archaeological industry is subject to analyses based on methods and theory that
are specific to the relevant disciplines.
The only exception to these “rules” is if a
calculated date of origin of a genetic variant found in a given locale predates the
existence of people in that place. Although the notion of population ties together
both biology and culture broadly conceived, it cannot be claimed that continuity
in one necessarily means continuity in another. If the question is about physical
population migration, then the same conclusion reached from every discipline
independently would seem to best support the claim (Rouse 1986). However, it
cannot be said absolutely that there was no movement if all lines of evidence do
not point in the same direction. The idea of Occam’s razor may sometimes mean
accepting the reality of human complexity and an inability to reconcile evidence
with preconceived models.
Frigi et al. (2010) have provided a general temporal framework for Maghreb
population history, from the Paleolithic to French colonization. This is appropriate
given the evidence for early modern human behavior and life history in the
Maghreb (Bouzouggar et al. 2007; T. Smith et al. 2007), the diversity of various
epi-Paleolithic and Neolithic cultures in or near the region associated with climatic
changes (Lubell et al. 1984; Rahmani 2003, 2004; Sereno et al. 2008; Sheppard
and Lubell 1990), and the interactions with known “peoples” at later dates
(Bennett 1960; Brown 1968; Desanges 1981; Hirschberg 1960; Nebel 2002).
In reviewing data from multiple disciplines, Frigi and colleagues have given the region’s
populations a multidimensional existence. In providing evidence for the
ongoing microevolution in the Maghreb of ancient mtDNA lineages that emerged
in Africa and evidence of later gene flow from multiple directions, they have revealed
that this region has biological continuity with the deep past as well as change.
Frigi and colleagues may have inadvertently revealed peoples whose ancestors
had a level of cultural flexibility in accepting outsiders as mates. As noted,
the male and female histories of a population may be different in their sources
(Wilkins 2006), although they are now seen as part of a recognizable biocultural
entity with a categorically singular identity. How is the emergence of the Amazigh
peoples in the geographic range of their homeland to be understood in terms of
culture, language, and biology? In some sense the question is about origins, a
term that can be confusing because of its various meanings. It can be applied to
different aspects of a population—which can be disarticulated and can change as a
function of time. Ancestry must not be confused with explanation, or gene history
with population or culture history. Known ancestors and the “ancestors of one’s
genes” are not the same things necessarily (Weiss and Long 2009).
Can a narrative of “origins” be constructed on the basis of an internal perspective
of the dynamics of the human communities of northwestern Africa, considered
through time? Or is this region simply an appendage of other places?
Sometimes the Amazigh, by use of the term “Eurasian” in a categorical model of
analysis, are placed in a raciotypological model without reference to evolution
and their indigenous emergence in Africa. (It can be ventured that this is largely
based on nonevolutionary ideas about phenotype, notions of bounded unchanging
populations, problematic assumptions about language families, and certain old
attitudes and theories about Africa.)
Frigi and colleagues have documented the deep-time biological connections
of current Berber speakers to Africa. The migration of “Europeans” and “Asians”
is also discussed. There has been continuity and change in the population from
original settlement. It is important to remember that high levels of gene flow and
biocultural assimilation could lead to great biological heterogeneity in a population
whose language family or culture does not change. Frigi and colleagues address
the idea of the indigenous, although not explicitly, and lay the groundwork
for more nuanced future discussions. They suggest a complex biogeographic history
not reducible to raciotypological constructs or outdated simplistic theories
of colonization and migration. They provide a basis for a rich discussion by acknowledging
the interactions of known peoples in the Maghreb and unknown
actors of a deeper past. The issue of what is indigenous is seen to be one of definition,
turning on what aspect of a population or region is ranked as its “defining”
characteristic, and whether this may change or could have changed over time.
The term indigenous unfortunately is connected to a discourse about the West and
non-West and sometimes has a negative sensibility and hence may not be the best
word, but a discussion of this issue is beyond the scope of this presentation.
Of course “indigenous” is a relative term when the temporal scope of human
evolution and history is considered, and it even seems to depend to a degree on
what part of the world is under discussion. Europe can serve as a good example. If
it is asked who are the “indigenous” Europeans, there would probably be a request
to clarify the time depth, given that modern humans are not native to Europe and
arrived there from elsewhere.
(The next question therefore is at what point do they become “European” and what
precisely does this mean: current limb proportions,
skin color, genetic variation, language, the presence of Neanderthal DNA?) Does
“indigenousness” require residency back to the upper Paleolithic, the Neolithic,
and so on? Is it only a biological phenomenon requiring a “drop” of Neanderthal
blood or a linguistic phenomenon requiring the speaking of Indo-European languages?
Or if the question is who were the indigenous inhabitants of northern,
southern, western, eastern, or central Europe, the answers would necessarily take
on a different tone, based on other information.
Are the Basque speakers the indigenous inhabitants of Europe, if currently
spoken language phyla and families are used as “population markers,” a problematic
assumption? Basque predates Indo-European, and there is some indication
of some level of biological distinctiveness (Alonso et al. 2005). The fact that
historical linguists (e.g., Ehret 2002; Nichols 1997) can reconstruct the existence
of culture-linguistic units for a proto-language family (e.g., Adamawa) or phylum
(e.g., Niger-Congo), which may have migrated, does not mean that they are suggesting
that the people making up such entities connote genetic units or Mendelian
breeding populations. It also does not mean that the speakers of such proto-entities
had a common molecular or social genealogical origin at foundation, or that the
linguists are suggesting this.
Defining “origins” or “indigenous” becomes one of
perspective. How much “Basque ancestry” would a European population have to
have for the label of “indigenous European” to apply? If none, why not? (What is
the relationship between cultural and biological genealogy?) Can it be assumed
that the Basques of today biologically represent those of the past “accurately”?
The post-Paleolithic European assimilation of males from Africa and Asia bearing
younger genetic variants is documented (Cruciani et al. 2004, 2007): Are such
ancient admixed populations to be viewed as “less” European or non-European?
Are Nordics or the Basques the “standard” European? Is language, biology, culture,
geography, or something else the arbiter of European-ness? In practice, this
question seems to be little asked in studies of Europeans: All these groups and
nationalities are considered European with little question. Aegean peoples are not
presented as “hybrids.” The linguistic and genetic diversity is not a factor in the
designation of “indigenous” for Europe.
But in the case of Africa there seems to be a problem with diversity for
some scholars. The Indo-European language phylum, in the standard evidence-based
interpretation, did not originate in the European heartland (Ehret, personal
communication, 2010). Most people in Europe today speak Indo-European
languages—now considered as “indigenous” as Basque. What does it mean for
the concept of European if Europe’s major language phylum did not originate
in what is considered Europe proper? How much of the spread of early Indo-European
was due to outright settler colonization and how much to language
shift—these are questions that will likely be debated for some time. Are the
Finns, Saami, and Hungarians (or their “original” ancestors)—all non-Indo-
European-speaking—to be considered Europeans? Apparently so. Contrast this
with ideas held by some about Berbers as “Eurasians” who speak a language family
that belongs to a phylum whose proto-parent emerged in Africa using
standard historical linguistic criteria and whose major history and differentiation
occurred in Africa (Ehret 2002; Greenberg 1963; Nichols 1997). In discussions
about Europe, geography seems to be enough to define what is “indigenous”—
with the exception of the Turks. This contrast deserves review by students of the
sociology of knowledge.
The European example is relevant to the discussion of Berbers because of
the use of terms by some researchers that imply that Berbers are not an African
development, an African people, in their beginning and current state. Calling the
Amazigh “Eurasian” based primarily on skin color without a discussion of process
in history, language, evolution, and Y-chromosome variants can easily be
seen as problematic when literature about Europe is examined carefully. The possibility
of asymmetric gene flow with more Eurasian females being assimilated
into the ancient Maghreb—and their lineages simply differentially surviving in
greater frequencies—is addressed in a preliminary fashion by Frigi et al. (2010)
and further engages us in the history of social interactions that may influence
population biology.
Returning to the Amazigh, the findings and comments of Frigi et al. (2010)
on Tunisian Berbers, and Berbers in general, suggest a new way of looking at
the Maghreb region of Africa. Their review and analysis offer the opportunity to
begin to develop a new and nuanced narrative about the peopling of the region,
one that avoids the biases of past writings. Their findings of ongoing evolution
in the Maghreb of ancient mtDNA lineages that originated in Africa, synthesized
with the evidence of the assimilation of migrants (mainly female?) from Europe and
the Near East, the predominance of uniquely African Y-chromosome lineages, and
the observation that Berber is the only extant indigenous language in the region
suggest the workings of both biological and cultural processes. There are clearly
different levels of biological and cultural history. Except in situations of migrationist
settler colonialism associated with the annihilation or conquest of local
peoples, groups emerge from local elements and new additions—all influenced
by the social and physical environments. This view of populations as assemblages
and processes is different from a notion of them as essentialist primordial entities
with fixed traits having continuity over time. In any geographic space groups can
interact at various levels with various strictures; languages can be adopted partly
or fully, and social rules may allow the acceptance of offspring by foreign females
but not males, or vice versa. It is possible for a group to view itself as genealogically
homogeneous by memory but to evince a genetic heterogeneity of lineages
obtained in the remote past. “Admixture” in the late Pleistocene in the deep background
of a regional population is to be differentiated from gene flow between
known historical entities.
Frigi and colleagues’ suggestion that supra-Saharan Africans are an indigenous
development with a complex story is a corrective to past models. The settlement
of the coastal Maghreb in the Middle and Late Stone Age is a part of the
settlement of the world outside Saharo-tropical Africa. The early modern human presence
in the Maghreb suggests that that region played a role in modern human
developments (Bouzouggar et al. 2007). Even if whole communities later came
from outside Africa into the Maghreb (before the Phoenicians), which is not knowable,
they became thoroughly assimilated into the autochthonous population—
which adopted some of its culture (Camps 1982), and their descendants are a
part of the emergence of the much later Amazigh world. Less arid climatic conditions
in the early to mid-Holocene Sahara allowed for the interaction of various
peoples who no doubt contributed to the population history, as observed by Frigi
et al. (2010). Saharan developments likely help to explain the Berber emergence,
because, based on recent work [see Kuper and Kropelin (2006) and Sereno et al.
(2008)], the desert was likely the site of a metapopulation and cultural differentiation.
Whether the early Saharan rock paintings depict only Africans of varying
phenotypes or such Africans and Asians (as suggested by Frigi and colleagues)
can be debated, but the net result was assimilation into Amazigh communities,
because there are no Berbers in Europe or Asia. The light skin color of Mediterranean
Africa may be the result of adaptive evolution or drift, given the length of
time of modern people in Africa, including the Maghreb, or gene flow, but more
likely some combination.
The Maghreb has several Neolithic traditions (Camps 1982; Phillipson
2005), which might indicate different peoples or simply cultural adoption or adaptation
by heterogeneous populations who became unified under singular cultural
practices and one language family. The Neolithic Capsian tradition shows continuity
with previous cultures, with evidence of these accepting domesticated sheep
and goat into a local subsistence pattern, thus becoming Neolithicized with a pastoralist
economy (Rahmani, 2003, 2004; Sheppard and Lubell 1990). A. B. Smith
(2005) and McDonald (1998) indicate the importance of pastoralism in the Holocene
Sahara, and this economy may help in the understanding of Berber emergence.
In the coastal Maghreb various Neolithic and post-Neolithic interregional
interactions are in evidence, based on archaeology and the eventual settlements of
the Phoenicians, Romans, Vandals, and others (Camps 1982).
In aggregate, over time, these peoples, along with the later importation of Europeans
(Bennett 1960; Davis 2004), would seemingly have contributed far more to the current biological
picture than has been realized. The much later trans-Saharan trade in enslaved
individuals no doubt played a role in genetic contributions, but the egress from a
desiccating Sahara with subsequent population formations would explain some
of the younger “sub-Saharan” variation, be it from western or eastern Africa. The
“Eurasian” component seems to have come in over a longer period of time, as
noted earlier. A small amount of gene flow per generation into a population or
geographic region can drastically change its original gene frequencies in only a
few thousand years, as noted by Cavalli-Sforza (1991).
The development of a narrative of the population history of the Maghreb requires
careful analysis using several approaches. Frigi and colleagues have made
an important contribution to studies of African human biology and culture in suggesting
the complexity of Maghreban population history.
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