Y chromosomes in North African populations

Y-chromosome DNA haplotypes in North African populations

The frequency distribution of Y-chromosome haplotypes at DNA polymorphism p49/TaqI was studied in a sample of 505 North Africans from Mauritania, Morocco, Algeria, Tunisia, Libya, and Egypt. A particulary high frequency (55.0%) of Y-haplotype 5 (A2,CO,DO,F1,11 ) was observed in these populations, with a relative predominance in those of Berber origin. (E3b1b, probably)  Examination of the relative frequencies of other haplotypes in these populations, mainly haplotype 4 (the “African” haplotype), haplotype 15 (R1b probably) (the “European” haplotype), and haplotypes 7 and 8 (the “Near-East” haplotypes), permit useful comparisons with neighboring peoples living in sub-Saharan Africa, Europe, and the Near East.

Because they relate to paternal ancestry, variations in DNA sequences that are specific to the nonrecombinant part of the human Y chromosome are particularly interesting from an evolutionary point of view. The probes 49f and 49a (locus DYSI ), located at Yq.11.2 (Quack et al. 1988), are able to identify 18 genomic TaqI fragments (named alphabetically, A-R), most of them being male specific. Among these the A, B, C, D, E, and I fragments can be either present or absent in males, or show variations in size (Lucotte and Ngo 1985). In the first group studied (Ngo et al. 1986), which included 50 Caucasians, 15 Africans, and 10 Asians living in Paris, 16 combinations of these DNA polymorphisms, or haplotypes (numbered 1-16), were detected. The present study examines haplotype frequencies in populations of North Africa.

In pre-Neolithic times (about 7000-3000 BP) the Mediterranean and Red Sea coasts of North Africa were populated by white, Hamite-speaking peoples, who have come to be called Berbers and Egyptians. In Pharaonic Africa (3000 years BP) the population had suffered drastic changes, with agricultural Egypt having 1 million people. Climatic changes had dried northern Africa by around 8000-4000 years BP; the forest line had retreated towards the Equator from about the 16th parallel by 3000 years BP, and the Sahara had assumed the characteristics it has today. Heavy migrations towards the North sent people to the Mediterranean coast, the Iberian peninsula, and the Canary islands.

The population of North Africa has followed the general Maghreb demographic movements. In Neolithic times, a scattering of Berber pastoralists and cultivators existed there; however, they remained at a Neolithic level of civilization, while other Mediterranean peoples were evolving through the Bronze and Iron Ages. Around 1000 years BP, the Phoenicians came upon a stone-age Neolithic culture in the Maghreb; they established Carthage (in Tunisia) only to be overthrown by the Romans in 146 BP. At this time there were 100,000 Phoenicians and 500,000 Berbers in Tunisia, plus another 2.5 million Berbers in the rest of North Africa. During the 7th century CE, Arabs invaded North Africa, imposing their religion and language on the Berbers, a process that culminated with the Bedouin reaching the Maghreb in the 11th century. Later arrivals to North Africa in colonial times included the Portuguese and Spanish in Morocco; the French in Morocco, Algeria, and Tunisia; the Italians in Libya; and the Turks in Egypt.

A main problem of Mediterranean ethnography has been the lack of DNA markers from southern Mediterranean populations (Arnaiz-Villena et al. 1995). Bosch et al. (1997) have recently synthetized evidence from classical genetic markers in North Africa. In the present study, p49 TaqI Y– haplotypes were studied in a sample of 7 North African populations, and haplotypic comparisons were made with other African, European, and Asiatic populations previously studied for these haplotypes. (Persichetti et al. [1992] studied a small sample of 34 unrelated Egyptian males for this haplotype.) The approach in the haplotype diversity measures adopted here extends our previous work on Y-haplotype distributions in Europe (Lucotte and Hazout 1996), using Shannon entropy (H) as a measure of heterozygosity, numbers of haplotype equivalents as expected H, and genetic distances as the difference between 2 entropies: the first being calculated after grouping the haplotype distributions of two compared samples, and the second corresponding to the weighted sums of the entropies calculated for each sample.

Subjects and Methods

Samples and Populations. All 505 samples studied (Figure 1) correspond to unrelated adult North African males, whose origin is based on the birthplace of their fathers and (at least) grandfathers. The Mauritanian sample is composed of 25 males, collected previously for anthropological studies concerning African populations (Lucotte et al. 1994). The Berber sample consisted of 74 Berbers native to Morocco and living near Marrakech. The main part of the North African sample is composed of 102 unrelated males (excluding those of Berber origins) born in Morocco, of 141 males from Algeria, and of 73 males from Tunisia, all living in Paris. Also included are 38 Libyan and 52 Egyptian males (originating from the northern part of Egypt), from whom blood samples were collected in their countries of origin.

After haplotype 5, the most commonly found haplotype in our series is haplotype 11, with a frequency of 7.7%, rising to 21.1% in Egypt. Interestingly, this haplotype is relatively frequent in some Indian populations (Lucotte et al. 1990) and in populations of Semitic origin (Lucotte and David 1992; Santachiara-Benerecetti et al. 1993). The preponderance of this haplotype has probably contributed to the differentiation of Egyptian and Libyan populations from others.

The third most commonly found haplotype in North Africa is haplotype 12, with a frequency of 7.1 % in our series, rising to a maximum value of 26% in Tunisia). This haplotype has been shown to be the major haplotype in Sardinians (Persichetti et al. 1992), and indicates a shared component of North African peoples with more northern Mediterranean peoples.

Haplotype 4, confined to sub-Saharan Africa (Torroni et al. 1990; Spurdle and Jenkins 1992; Lucotte et al. 1994), was present at a low frequency (4.4%) in our series, the most elevated value (8.5%) being observed in Algeria (the largest country in North Africa). Haplotype 15, mainly present in Western Europe (Ngo et al. 1986; Lucotte and Hazout 1996), was rarely found in North Africa (4.2%); its most elevated value (10.7%) was found in Morocco (a country with a strong French presence since the beginning of the century).

Haplotypes 7 and 8, frequently found in the Near East (Lucotte and David 1992; Lucotte et al. 1993; Santachiara-Benerecetti et al. 1993; Ritte et al. 1993; Lucotte et al. 1996), were present in our series at a mean level between 3.2% and 6.3%, respectively. Together they represent, in the populations studied, 17.3% of haplotypes in Egypt (the most eastern of the North African countries), 12.7% in Morocco, and 8.5% in Algeria (these last 2 countries having an important Semitic component). For Egypt, a similar value of 15% was obtained by Persichetti et al. (1992).

Acknowledgments. The authors acknowledge P. Galzot and N. Gerard for DNA extraction and hybridization experiments. We thank also F. Legrand for genealogical studies and blood samples of the Berbers studied here. We acknowledge also S. Hazout for help in the biostatistical treatment of data.

Two major population groups are found in North Africa, Berbers and Arabs. Berbers are divided into several subgroups, the most important one including Berbers from Morocco. Moroccan Berbers belong to 3 main communities: northern Berbers living in the Rif mountains, central Berbers living in the Atlas mountains, and southern Berbers living in the anti-Atlas and the Souss valley. Tuaregs are Berber people, and Berbers are also found in Algeria, Tunisia, Libya, Egypt, and among some western residual groups in Mauritania and Senegal (Camps 1980). The origin of the Berber people has not been clearly established. They may be descendants of Capsian and later Neolithic peoples (Murdock 1959). We do know that the Berber kingdoms declined under the impact of Greek invasions, Roman Punic wars, and Roman settlements in the area (Julien 1978), and that the Arab presence dates from an Arab invasion of North Africa during the 7th century. All 16 Y-haplotypes were found in the 7 North African populations studied here, but with varying frequencies among groups. As has been found for Egypt (Persichetti et al. 1992) haplotype 5 is the major haplotype found in North Africa, being present at a frequency of 55% in our series. This haplotype is found at an elevated frequency (68.9%) in Berbers from Morocco, and at relatively lower frequencies in Mauritania (40%), Egypt (40.3%), and Libya (44.7%).These last 3 populations are characterized by a strong Arabic component. The non– Berber population from Morocco and populations from Algeria and Tunisia showed intermediate values (57.8%, 56.7%, and 53.4%, respectively). An apparently increasing east-west cline in haplotype 5 frequencies is shown from Egypt to Morocco in the present study, probably reflecting both the historical Arabic expansions and the preponderance of Berbers in western countries.

It looks like R1b was the first Caucasian male Y chromosome in North Africa in the Paleolithic, it managed to accompany the Mt DNA U southwards in the Bantu expansion. The current Berber DNA marker E3b1b (or whatever it’s being called now) has been dated to the Neolithic expansion, and has only really made it as far South as the Tuaregs in the Southern Sahara. It seems it’s quite a common DNA marker in Egypt though ( says here 40%) so it seems Egyptians are of substantial Berber ancestry, with mostly Arab and a little bit of Sub Saharan African. It seems that the Arab invasion of North Africa really just converted the indigenous people instead of wiping them out.

This would probably explain why ancient Egyptians have slightly lighter hair on average than modern Egyptians… Berbers are a little lighter haired than Arabs. Ancient Egyptians also group pretty closely to Berbers for just about all features like skull, hair and teeth.

One response to “Y chromosomes in North African populations

  1. I think the original M35 (E3b1 or whatever it’s called this week)mutation was somewhere in Ethiopia over 30,000 years ago; it’s just the later clades that are mostly North Africa/middle Eastern in origin. It’s on a Cruciani paper..

    “We obtained an estimate of 25.6 thousand years (ky) (95% CI 24.3–27.4 ky) for the TMRCA of the 509 haplogroup E3b chromosomes, which is close to the 30±6 ky estimate for the age of the M35 mutation reported by Bosch et al. (2001) using a different method. Several observations point to eastern Africa as the homeland for haplogroup E3b—that is, it had (1) the highest number of different E3b clades (table 1), (2) a high frequency of this haplogroup and a high microsatellite diversity, and, finally, (3) the exclusive presence of the undifferentiated E3b* paragroup.”

    They disagree with the NG, but I’ll stick with the published papers until I have a good reason to change. I don’t know the NG source, sorry. I’ve gone with the E3b1 Y chromosome being brought North long the Nile by the expansion of the Halfan culture starting about 24,000 years ago. The later E3b1 mutations all seem to be pretty sepcific to Arabs, SE Europe and North Africa.

    I think the Y chromosome dates always seem too young; I think they’d need to be about 50% older to start matching population movements in North Africa. Maybe they should try matching a few to calibrate them, the same way they do with carbon 14 and tree rings.

    Glad you think the blog is well put together.

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