Egyptian Y chromosome study shows a complicated ancestry.

Y-chromosome analysis in Egypt suggests a genetic regional continuity in Northeastern Africa.

Laboratoire d’Anthropologie Biologique (CNRS FRE 2292); Musée de l’Homme MNHN, Paris, France.

The geographic location of Egypt, at the interface between North Africa, the Middle East, and southern Europe, prompted us to investigate the genetic diversity of this population and its relationship with neighboring populations. To assess the extent to which the modern Egyptian population reflects this intermediate geographic position, ten Unique Event Polymorphisms (UEPs), mapping to the nonrecombining portion of the Y chromosome, have been typed in 164 Y chromosomes from three North African populations. The analysis of these binary markers, which define 11 Y-chromosome lineages, were used to determine the haplogroup frequencies in Egyptians, Moroccan Arabs, and Moroccan Berbers and thereby define the Y-chromosome background in these regions. Pairwise comparisons with a set of 15 different populations from neighboring European, North African, and Middle Eastern populations and geographic analysis showed the absence of any significant genetic barrier in the eastern part of the Mediterranean area, suggesting that genetic variation and gene flow in this area follow the “isolation-by-distance” model. These results are in sharp contrast with the observation of a strong north-south genetic barrier in the western Mediterranean basin, defined by the Gibraltar Strait. Thus, the Y-chromosome gene pool in the modern Egyptian population reflects a mixture of European, Middle Eastern, and African characteristics, highlighting the importance of ancient and recent migration waves, followed by gene flow, in the region.

Results

Y-Chromosome Biallelic Profiles. Allelic profiles of the 11 Y-chromosome lineages in the total sample of 164 North African samples are shown in Table 1. Of a total of 8 Y-chromosome Hgs observed, only two reached a frequency of > 10% (Hgs 21 and 9). Hg 21* is present at high frequency in Egypt (44%) and at higher frequencies in Moroccan Arabs (69%) and Moroccan Berbers (76%). This lineage shows the highest frequencies in North Africa with a decreasing frequency gradient towards the south, and it is also present at moderate frequencies in the northern Mediterranean basin. Hg 9** is the second most common lineage in the Egyptian population (35%) and is also present, although at lower frequencies, in the two NW African populations examined (Moroccan Arabs 14%; Moroccan Berbers 4%). This haplogroup shows the highest frequencies in the Fertile Crescent, and it has been suggested to be a genetic signature of migrations from the Middle East associated with Neolithic farmer expansions (Semino et al. 1996; Rosser et at. 2000; Quintana-Murci et al. 2001).

Other lineages are present at lower values in both Egyptian and NW African populations. Hg 1, which is present in Egyptians (8%) and NW Africans (Arabs 6%; Berbers 4%), indicates a limited degree of gene flow from Europe to North Africa, since it has been predominantly found in Europe, with increasing frequencies from the Middle East to northwestern Europe (Semino et al. 1996; Rosser et al. 2000). Hgs 2 and 26 are found at moderate and low frequencies, respectively, in the three populations. However, little information can be deduced from these lineages since they are present in both Europe and Asia and do not show any informative geographic variation along the Eurasian landscape. Hgs 7 and 8 are typically sub-Saharan African lineages, and they have been suggested to be genetic signatures of Khoisan and Bantu language families, respectively. They have not been recorded outside Africa (Hammer et al. 1998; Rosser et al. 2000), and their presence is unusual in North Africa (Bosch et al. 1999). In agreement with Bosch et al. (1999), Hg 7 is not observed in NW Africa and is present in two individuals from Egypt. Hg 8, which is considered to be of sub-Saharan origin, was found in one Egyptian, three Moroccan Berbers, and two Moroccan Arabs. One Egyptian individual was found with an Hg 4 Y chromosome. This lineage has not been observed in any European nor African populations, but it is present at high frequencies (-45%) in some East Asian populations, such as the Japanese and Tibetans (Karafet et al. 1999).

Classical genetic studies show a high degree of genetic heterogeneity in the modern Egyptian population, suggesting that this population is descended from a mixture of African, Asian, and Arabian stock (Mahmoud et al. 1987; Hafez et al. 1986). Genetic heterogeneity within the Egyptian gene pool is also supported by more recent studies using autosomal STR markers (Klintschar et al.

Related Results
Y-chromosome DNA haplotypes in North African populations
Population history of North Africa: Evidence from classical genetic markers

Here, we used ten Y-chromosome binary markers to define the male-specific gene pool in the Egyptian population and two NW African populations, in order to test contrasting hypotheses on the inter- and intrapopulation relationships and, in a more general context, the peopling processes of North Africa. The results of Y-chromosome haplogroup profiling in Egypt parallels previously published studies of autosomal loci, by demonstrating that Y-chromosome lineages, which are present at high frequencies in modern African (Hgs 7, 8, 21), European (Hg 1), and Middle Eastern (Hg 9) populations, are also found in the modern Egyptian population. The high incidence of Hg 21 in North African (44%-76%), and more especially among NW African, samples can be regarded as an autochthonous genetic layer of the region. This lineage may have originated somewhere in North Africa -20,000 YBP and remained in North Africa and the Middle East for 10,000 years, before it spread towards southern Europe (Hammer et al. 1998). The relatively low incidence of this lineage in Egypt, compared with the Moroccan populations, is probably due to substantial population movements from neighboring countries to Egypt, thereby effectively reducing the frequency of Hg 21 within Egypt. This is highlighted by the geographic distribution of Hg 9 in modern populations. From coalescence analysis, the polymorphism defining Hg 9 has been dated to approximately 14,800 YBP (Hammer et al. 2000). It shows its highest frequencies in the Fertile Crescent with a decreasing frequency cline towards Europe, North Africa, and India. This cline has been interpreted as the consequence of the Neolithic demic diffusion process of farmer economy from the Middle East towards Europe and South Asia (Semino et al. 1996; Rosser et al. 2000; Quintana-Murci et al. 2001). Interestingly, Hg 9 is also present at relatively high frequencies (25%) in the Ethiopian population, highlighting the extent to which Semitic peoples have left substantial traces in the Ethiopian gene pool at different times (Passarino et al. 1998). Hg 9 frequencies observed in Egypt are intermediate between those observed in the Middle East and those in NW Africa, suggesting an east-west cline of decreasing frequencies along the North African coast. It is interesting to note that within the Nile Valley, there is no evidence indicating the presence of agriculture technology before 4700 BC (Kasule 1998), a date confirmed by the oldest solid evidence of food production on the western side of the Nile delta (Hassan 1988). These agricultural food resources are considered to have been introduced from the Levant

One single individual belonging to Y-chromosome lineage Hg 4 was identified. This lineage, which has not been reported in European and African populations and shows highest frequencies in East Asia, was proposed to represent the ancestral state of the YAP lineage (Hammer et al. 1998). Lineages that are clearly derived from Hg 4 (Hgs 21 and 8) make up by far the major part of the sub-Saharan African Y-chromosome gene pool. The phylogeographic distribution of this lineage, with a high frequency in some East Asian populations (~45%), has been used to support a “back-to-Africa” migration of individuals carrying Asian Y chromosomes into the sub-Saharan African gene pool (Hammer et al. 1998). However, with the characterization of new diagnostic markers that refine further the Y-chromosome phylogeny, the exact geographic origin of Hg 4 is not clear (Underhill et al. 2001). One Egyptian individual with an Hg 4 Y chromosome is insufficient to determine the geographical origin of the Alu insertion defining this lineage and may well be due to recent gene flow. Hg 8, which is the most characteristic lineage among sub-Saharan African populations and is derived from Hg 4, has been associated with the Bantu expansions 3000-4000 years ago (Hammer et al. 1998). Here, we found Hg 8 in only one individual from Egypt and in 4%-6% of the Moroccan samples, indicating minimal gene flow from sub-Saharan Africa. We also detected low levels of another sub-Saharan Y-chromosome lineage in Egypt, Hg 7, supporting the findings by Karafet et al. (1999). Although Hg 7 is typical of Khoisan populations, it has been observed in East Africans, Gambians, and East Bantus, and its presence in Egypt is probably due, once again, to limited gene flow from East Africa, perhaps through the Nile Valley.

Our analyses suggest that migration patterns and gene flow between the southern and northern shores of the Mediterranean Sea have been very different in its western extreme (Gibraltar) compared to the eastern region (Egypt). The topology of the minimal spanning tree (Figure 1), which connects NW Africa to the Middle East and Europe through Egypt, indicates a low level of gene flow through the Gibraltar Strait. This scenario is in agreement with the spatial pattern of genetic variability described elsewhere using Y-chromosome markers, autosomal Alu-insertion polymorphisms, and autosomal STR markers (Bosch et al. 2000a, 2000b, 2001; Comas et al. 2000), where a sharp genetic discontinuity between NW Africa and the Iberian Peninsula was reported. Geographic analysis of genetic variation (Figure 2) supports a genetic barrier between SW Europe and NW Africa, the intensity of which decreases from the western to the eastern part of the North African continent. In contrast with the pattern observed in the western Mediterranean region, the MDS plot (Figure 1) indicates an intermediate genetic position of Egypt between North Africa, southern Europe, and the Middle East. In addition, the geographic analysis of genetic variation (Figure 2) provides no evidence for the existence of a genetic barrier between the southern and northern shores of the eastern part of the Mediterranean basin. The isolation-by-dislance model may well explain the genetic relationships between Egypt and the surrounding African, European, and Middle Eastern populations. This is an opposite pattern to that observed in NW Africa, where the presence of a genetic barrier is incompatible with this model. This conclusion is reinforced by Mantel-test correlations between genetic and geographic variability, since the correlation index almost doubles (0.494 –> 0.820) when populations encompassed by the first genetic barrier (defined by the Gibraltar Strait, Figure 2) are withdrawn from the analysis.

In conclusion, our analyses have identified a genetic regional continuity between the northeastern part of Africa (Egypt), the Middle East, and southern Europe. In agreement with the ethnohistorical connections between NE Africa and the Middle East, the genetic data confirm that Egypt, occupying an intermediate position along these routes, has been an important contact zone between the three continents. This is in sharp contrast with the pattern observed between NW Africa and the Iberian Peninsula where no regional continuity along the Gibraltar Strait is observed. However, the previous observation of a continuum of gene flow in another African strait, the Bab-el-Mandeb Strait (Quintana-Murci et al. 1999) highlights the need to consider each geographic feature independently, rather than to extrapolate general conclusions on their influence on gene flow. Moreover, given the absence of recombination for most of the Y chromosome, which behaves effectively as a single genetic locus, the direct inference of population processes from Y-chromosome variation is not without risks. Different factors, such as different effective population sizes, differences in male vs. female cultural and social habits and selection, could affect Y-chromosome variation and distribution in human populations. Future studies integrating data from multiple independent loci (mtDNA, autosomal markers) may reveal additional information on the population structure and the peopling processes of North Africa.

Morocco and North African Mitochondrial DNA study

Human mitochondrial DNA sequence variation in the Moroccan population of the Souss area

Various populations have contributed to the present-day gene pool of Morocco, including the autochthonous Berber population, Phoenicians, Sephardic Jews, Bedouin Arabs and sub-Saharan Africans.

Objective: The primary objective of the study was to complete a genetic description of the Berber-speaking population in the Souss region of southern Morocco, based on mitochondrial DNA (mtDNA) sequence analysis.

Subjects and methods: The first hypervariable segment of the mtDNA control region was sequenced in a sample of 50 individuals from the Souss Valley, and the results compared with the extensive body of data available on mtDNA sequence variation in Europe and sub-Saharan Africa.

Results: Thirty-four different sequences were found; an estimated 68% of the sequences occurred throughout Europe, West Asia and North Africa, 26% originated in sub-Saharan Africa, and 6% belonged to the North African specific haplogroup U6. The Souss Valley mtDNA sequences indicated the presence of two populations which expanded at different times: the West Eurasian sequences in the Souss sample had a smaller average number of pairwise differences than pairs of sub-Saharan sequences.
Conclusion: Detailed knowledge of the possible geographic origin of each sequence facilitated an interpretation of both internal diversity parameters and between-population relationships. The sub-Saharan admixture in the Souss Valley matched the south-north cline of sub-Saharan influence in North Africa, also evident in the genetic distances of North African populations to Europeans and sub-Saharan Africans.

Unfortunately I can’t paste the relevant table neatly, but I can reproduce it here for the genetic origins of each population. This gives a very good outline of the genetic composition of North Africa

•                                      North African         Sub Saharan           Eurasian
• Souss                                    6%                             26%                       68%
• NC Morocccan Berber      8.3%                          3.3%                      88.4%
• Moroccan Arab                6.5%                          21.9%                    71.8%
• Mozabite                         31.8%                        11.8%                    56.4%
• Saharawi                          8%                             44%                       48%
• Mauritanian                   20%                            43.3%                    36.7
• Tuareg                             7.7%                           84%                       7.7%
• Egyptian                          1.5%                           30.9%                     67.6%
• Nubian                             0%                              40.5%                    59.5%

As you can see, North central Berbers have a very low amount of Sub Saharan ancestry, but the southern Tuaregs who have reached down into Mali show a very high level. Other DNA studies have shown the European admiture into North Africans to be around 4%, the Eurasian Mt DNA comes from the paleolithic westward expansion one Eurasian, and the later Neolithic expansion of Eurasian into North Africa about 6,000 years ago.

Previously, it was believed that the expansion took place from East Africa, but more recent Y chromosome studies by Cruciani have shown a very young age for most Y chromosomes in North Africa, with an origin in the near East.

A rather fuzzy chart showing the genetic distances between various populations . It can be seen that Moroccan Berbers are very similar to the Spanish . My apologies for the poor definition. Essentially, Berbers are a Caucasian people native to North Africa with varying degrees of sub Saharan ancestry, more as you go Southwards.

I would just like to comment the the Egyptian DNA figures appear to match Southern Egypt, in particular a study of Gurna I saw. I am fairly sure there’s rather less African DNA at the delta end. It was rather a surprise to see how much of the Nubian ancestry was Eurasian though.

Berber and Arab DNA in Europe from the Moorish occupation

North African Berber and Arab Influences in the Western Mediterranean Revealed by Y-Chromosome DNA Haplotypes

We have analyzed Y-chromosome diversity in the western Mediterranean area, examining p49a,f TaqI haplotype V and subhaplotypes Vb (Berber) and Va (Arab). A total of 2,196 unrelated DNA samples, belonging to 22 populations from North Africa and the southern Mediterranean coast of occidental Europe, have been typed. Subhaplotype Vb, predominant in a Berber population of Morocco (63.5%), was also found at high frequencies in southern Portugal (35.9%) and Andalusia (25.4%). The Arab subhaplotype Va, predominant in Algeria (53.9%) and Tunisia (50.6%), was also found at a relatively high frequency in Sicily (23.1%) and Naples (16.4%); its highest frequency in Iberia was in northern Portugal (22.8%) and Andalusia (15.5%). In Iberia there is a gradient of decreasing frequencies in latitude for both subhaplotypes Va and Vb, related to eight centuries of Muslim domination (8th to 15th centuries) in southern Iberia.

During the 7th century A.D., Muslim people coming from the Arabian peninsula and the Middle East invaded North Africa. The most important population movement relating both sides of the Mediterranean Sea was the conquest of the Iberian peninsula by North African populations (with recruited Berbers), soon after the first Muslim invasion. More than eight centuries (8th to 15th centuries) of Muslim domination in the southern part of Iberia imparted an important cultural legacy (Conrad 1998) and probable gene exchanges between North African and Iberian populations.

Variations in DNA sequences specific to the nonrecombinant part of the Y chromosome, relating to paternal ancestry, are particularly interesting from a human population genetics point of view. The first published and most informative probe used in Southern blots for this objective is p49 (locus DYSl), which is able to identify at last five TaqI male-specific fragments (A, C, D, F, and I) that are polymorphic between individuals (Lucotte and Ngo 1985). Sixteen main corresponding haplotypes (numbered I-XVI) were identified using the p49 probe on DNA samples of unrelated males living in France (Ngo et al. 1986). Only recently has the molecular basis of the p49 TaqI polymorphisms been established (Jovelin et al. 2003); the polymorphisms correspond to variable TaqI sites located in the four DAZ genes located in the AZF-c region of the Y chromosome.

In fact, the conventional p49 TaqI polymorphisms were the most popular markers used in various populations because of their ability to detect more than 100 different haplotypes [for a compilation on the subject until the end of 1995, see Poloni et al. (1997)]. Haplotype XV (A3,C1,D2,F1,I1) was the most widespread haplotype in our initial study (Ngo et al. 1986). Haplotype XV was also predominant in the first European study we published (Lucotte and Hazout 1996), with elevated frequencies in French Basques. The geographic distribution of haplotype XV in Europe reveals a gradient of decreasing frequencies from this Basque focus toward eastern peripheral countries (Lucotte and Loirat 1999) but also toward southwestern countries. According to the Y Chromosome Consortium (2002) nomenclature, haplotype XV corresponds to the M173 lineage (Diéterlen and Lucotte 2005).

Haplotype V  (E3b1b) (A2,C0,D0,F1,I1) is the most frequent haplotype in North Africa (Lucotte et al. 2000), with a particularly high frequency (55%) in the populations with a relative predominance of Berber origin. Our previous study on the subject examined the relative frequencies of haplotype V in four Iberian populations compared with a Berber population living in North Africa (Lucotte et al. 2001). The highest frequency of haplotype V (68.9%) was observed in Berbers from Morocco, and the geographic distribution of haplotype V revealed a gradient of decreasing frequencies with latitude in Iberia (40.8% in Andalusia, 36.2% in Portugal, 12.1% in Catalonia, and 11.3% in the Basque Country) (Lucotte et al. 2001); such a cline of decreasing haplotype V frequencies from the south to the north in Iberia clearly established a gene flow from North Africa toward Iberia.

According to the Y Chromosome Consortium (2002) nomenclature, haplogroup E is characterized by the mutations SRY4064, M96, and P29 on a background defined by the insertion of an Alu element (YAP + ). The third clade, E3 (defined by the mutation P2), of haplogroup E is further subdivided into two monophyletic forms, the second one (E3b) being characterized by mutations M35 and M125. All of the 110 p49 TaqI haplotype V subjects from Morocco (51 Berbers and 59 Arabs) that we had previously tested correspond to haplogroup E3b.

In the present study we have subdivided haplotype V into its Berber (Vb) and Arab (Va) components in order to distinguish the relative contributions of these two ethnicity-specific markers in the gene pools of the populations living in Iberia and in other populations in the northern part of the western Mediterranean area.

DNA Samples. This study concerns 2,196 unrelated male DNA samples (Table 1). We collected 904 new unrelated males subjects, from three different countries (Portugal, France, and Italy): 79 from North Portugal and 59 from South Portugal; 243 from the Marseilles region of France; 192 from Genoa, 64 from Rome, and 128 from Naples in continental Italy; 39 from Sicily; and 100 from Sardinia. All these new samples correspond to adult males, whose origin is based on the local birthplace of their fathers and (at least) grandfathers. We have obtained informed consent from each of the French subjects studied.

We add for comparison the following subjects, already tested as bearing haplotype V in previous studies: 11 subjects from Mauritania, 51 Berbers from Morocco, 59 Arabs from Rabat, 80 subjects from Algeria, 39 subjects from Tunisia, and 17 subjects from Libya (Lucotte et al. 2000); 29 Spaniards from Sevilla (Lucotte et al. 2001); 4 Spaniards from Barcelona and 9 French Catalans from Perpignan (Lucotte and Loirat 1999); 11 French Basques, 1 subject from Montpellier, and 7 subjects from Grasse in France and 6 subjects from Milan in Italy (Lucotte and Hazout 1996); and 44 subjects from Corsica (Lucotte et al. 2002).

Results

Table 1 summarizes the frequencies we obtained for haplotype V and sub-haplotypes Vb and Va in the 22 study populations. For the 2,196 males typed, 491 (22.3%) bear haplotype V. The frequency of haplotype V is 35.5% in Portugal, with a more elevated proportion in the south (49.2%) than in the north (25.3%). The frequency of haplotype V in the Marseilles region (11.1%) has a value similar to the mean value in continental France (9%). In Italy the highest frequency is attained in Sicily (28.2%), followed by Naples at 17.2%. As previously shown (Lucotte et al. 2000), haplotype V is found at the highest frequency (68.9%) in Berbers from Marrakech in Morocco; an apparently increasing east-west cline in haplotype V frequencies is shown in North Africa from Libya (44.7%) to Rabat (57.7%), with intermediate values for Tunisia (53.4%) and Algeria (56.7%). In Spain haplotype V is much more frequent (40.9%) in the south of the country [in Andalusia (Sevilla)] than in the north (12.9%) [in Catalonia (Barcelona)].

Subhaplotype Vb is the Berber subhaplotype because its most elevated relative value (63.5%) is obtained for the Berber population of Marrakech. In the non-Berber population of Rabat in Morocco, the frequency of subhaplotype Vb is only 20.6%, whereas the frequency of subhaplotype Va (Arab) is 37.3%. In order of decreasing values, the subhaplotype Vb frequencies are 40% in Mauritania, 35.9% in South Portugal, 25.4% in Andalusia, and 15.8% in Libya. Low frequencies of subhaplotype Vb are found in Sicily (5.1%), Algeria (2.8%), Tunisia (2.7%), and North Portugal (2.5%); frequencies less than 2% are found in French Basques (1.9%), in Naples (0.8%), and in Corsica (0.6%), Subhaplotype Vb is absent in Catalonia (Barcelona and Perpignan), in the south of France (Montpellier, Grasse, and the region of Marseilles), in continental Italy (Milan, Genoa, and Rome), and in Sardinia.

Table 2 summarizes the frequencies of subhaplotype Vb in North Africa, Iberia, the south of France, and Italy. The maximum value (63.5%) concerns the Berber population, but this frequency is notably lower (9.3%) for other populations from North Africa. In southern Iberia an elevated value (30%) is observed, but the frequency of subhaplotype Vb is only 1.8% in northern Iberia. These frequencies are less than 1% in France and Italy.

Figure 2 shows the isofrequency map of subhaplotype Vb in the western Mediterranean area (coordinates on the map: x = longitude, y = latitude). From the Berber focus in Berbers from southern Morocco, the frequencies of subhaplotype Vb decrease in North Africa to the north of Morocco and to the east in Algeria and Tunisia. For Iberia the most elevated value of subhaplotype Vb frequencies is in southern Portugal; relatively elevated values are observed in Andalusia, moderate values are observed in the southern part of Spain, and low values are seen in Catalonia.

In the present study all haplotype V non-subhaplotype Vb subjects are termed subhaplotype Va (Arab) subjects. Their maximum relative frequencies are 53.9% (Algeria), 50% (Tunisia), and 37.3% (Rabat) in North Africa. Table 3 summarizes the frequencies of subhaplotype Va in North Africa, Iberia, southern France, and Italy. The maximum value (45.8%) is found in North Africa. In northern Iberia a slightly more elevated value is observed (20%) compared to southern Iberia (14.6%). A frequency of 10.3% is seen in France, and in Italy the 14.6% value observed in the south is relatively more elevated than in the north (3.4%).

Figure 3 gives the isofrequency map of subhaplotype Vb. In North Africa frequencies decrease from east to west and southward. For southern Europe the map shows the relatively higher percentages observed in the south of Italy versus the north and (to a lesser degree) in the north of Iberia versus the south.

In our PCR assay the 68 Moroccan subjects with subhaplotype Vb (47 Berbers and 21 Arabs) were tested for the M81 marker: All subjects were positive for the M81 marker, so subhaplotype Vb is homologous with subhaplogroup E3b2. The 38 Moroccan non-Berber subjects were further tested for the M78 marker: Only 31 of them (80.8%) were positive for the M78 marker; we conclude that, in Morocco at least, subhaplotype Va corresponds only partly to subhaplogroup E3b1.

P49a,f TaqI haplotype V, which is homologous with haplogroup E3b according to the Y Chromosome Consortium (2002) nomenclature, is the predominant Y-chromosome haplotype in North Africa (Lucotte et al. 2000), where its geographic distribution shows an east to west cline. In the present study we have extended the research of haplotype V frequencies (Lucotte et al. 2001) in various European populations located in the western Mediterranean basin to include France, Portugal, and Italy. The frequency of haplotype V in the Marseilles region is 11.1%, a value similar to the main value we obtained previously for continental France (Lucotte and Hazout 1996). In continental Italy we observed the highest haplotype V frequency in Naples (17.2%); Sicily, with a frequency of 28.2%, corresponds to the most elevated value we observed for Italy. In South Portugal the frequency of haplotype V is very high (49.2%); we had previously obtained a similar value for Libya and for Mauritania. The frequency of haplotype V for North Portugal (25.3%) is similar to the value we obtained for Sicily in the present study.

Related Results
Y-chromosome DNA haplotypes in North African populations

To better divide haplotype V into its ethnic components, we have subdivided it into subhaplotypes Vb (Berber) and Va (Arab). We have established that subhaplotype Vb is the Berber haplotype, because it is present at very elevated frequencies (63.5%) in our Berber population from Morocco but at relatively low frequencies (20.6%) in our non-Berber population of Rabat. Such a distinction of a Berber component was also realized by Scozzari et al. (2001), because they observed that the haplogroup they named 25.2 was also more frequent in the Berber population from Morocco than in Arabs. Our present results show that subhaplotype Vb frequencies in North Africa decrease from west to east, starting from the Berber focus in Morocco; in the western Mediterranean area subhaplotype Vb is at low frequencies along the south coast of Europe but occurs at relatively elevated frequencies in southern Iberia (peaking at 35.9% in South Portugal). Flores et al. (2004), in their important study of various locations in Iberia, observed that subhaplogroup E3b2 is more frequent in southern Iberia, attaining a maximum value of 11.5% in the region of Málaga.

In the present study all the non-subhaplotype Vb subjects bearing haplo-type V are classified as subhaplotype Va (Arab); they probably correspond to a heterogeneous group representing various ethnicities (our results concerning the incomplete correspondence between subhaplotypes Va and E3b1 in Morocco suggest that). We have shown here that in North Africa the focus of subhaplotype Va frequencies is in Algeria (53.9%) and Tunisia (50.6%); from this focus frequencies of subhaplotype Va decrease in the south and the west of the region.

Subhaplotype Va attains substantial frequencies along the southern coast of Europe; these frequencies reached relatively elevated frequencies in France (Perpignan, 11.8%) and in southern Italy (Naples, 16.4%; Sicily, 23.1%). For Iberia, relatively more elevated values are attained for Andalusia (15.5%) and for North Portugal (22.8%). Brion et al. (2004) also showed relatively higher frequencies of haplogroup E* (xE3a) (up to 18.3%) in their study concerning northern Iberia.

We had previously established (Lucotte et al. 2001) that haplotype V showed a gradient of decreasing frequencies with latitude in Iberia, and we interpreted this pattern as a consequence of the historical Islamic occupation of the peninsula (Conrad 1998). The results reported in the present study concerning subhaplotypes Vb and Va (subhaplotype isofrequencies maps given in Figures 2 and 3) have again shown both of these gradients. From this perspective, the opposite pattern of gradient frequencies observed in Iberia for the western European haplotype XV (Diéterlen and Lucotte 2005) is reconciled with the slow reconquest of the Iberian peninsula from the north by the Christians, which lasted seven centuries and ended in Granada in 1492.

Unfortunately I can’t find the diagrams for this piece. This shows a larger Arab and Berber than the other study I’ve seen into this. I shall have to have another look at it. Notably, for all you Afrocentrists who think Moors were black Africans, there are only Arab and Berber Y chromosomes found. Sub Saharan ancestry only shows up at trace in these studies.

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.
Discussion

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.

Egyptian Y chromosomes

Y-chromosome Haplotypes in Egypt

G. Lucotte *, G. Mercier
International Institute of Anthropology, Paris, France

ABSTRACT

We analyzed Y-chromosome haplotypes in the Nile River Valley in Egypt in 274 unrelated males, using the p49a,f TaqI polymorphism. These individuals were born in three regions along the river: in Alexandria (the Delta and Lower Egypt), in Upper Egypt, and in Lower Nubia. Fifteen different p49a,f TaqI haplotypes are present in Egypt, the three most common being haplotype V (39.4%), haplotype XI (18.9%), and haplotype IV (13.9%). Haplotype V is a characteristic Arab haplotype, with a northern geographic distribution in Egypt in the Nile River Valley. Haplotype IV, characteristic of sub-Saharan populations, shows a southern geographic distribution in Egypt. Am J Phys Anthropol 121:000-000, 2003. © 2003 Wiley-Liss, Inc.

..

As for mtDNA (Krings et al., [1999]), the present study on the Y-chromosome haplotype shows that there are northern and southern Y-haplotypes in Egypt. The main Y-haplotype V is a northern haplotype, with a significantly different frequency in the north compared to the south of the country: frequencies of haplotype V are 51.9% in the Delta (location A), 24.2% in Upper Egypt (location B), and 17.4% in Lower Nubia (location C). On the other hand, haplotype IV is a typical southern haplotype, being almost absent in A (1.2%), and preponderant in B (27.3%) and C (39.1%). Haplotype XI also shows a preponderance in the south (in C, 30.4%; B, 28.8%) compared to the north (11.7% in A) of the country. In mtDNA, sequences of the first hypervariable HpaI site at position 3592 allowed Krings et al. ([1999]) to designate each mtDNA as being of northern or southern affiliation, and proportions of northern and southern mtDNA differed significantly between Egypt, Nubia, and the Southern Sudan.

It is interesting to relate this peculiar north/south differentiation, a pattern of genetic variation deriving from the two uniparentally inherited genetic systems (mtDNA and Y chromosome), to specific historic events. Since the beginning of Egyptian history (3200-3100 B.C.), the legendary king Menes united Upper and Lower Egypt. Migration from north to south may coincide with the Pharaonic colonization of Nubia, which occurred initially during the Middle Kingdom (12th Dynasty, 1991-1785 B.C.), and more permanently during the New Kingdom, from the reign of Thotmosis III (1490-1437 B.C.). The main migration from south to north may coincide with the 25th Dynasty (730-655 B.C.), when kings from Napata (in Nubia) conquered Egypt.

Concerning less frequent Y-haplotypes in Egypt, haplotype VIII is characteristic of Semitic populations, originating in the Near East (Lucotte et al., [1993]). For example (Lucotte et al., [1996]), the frequency of haplotype VIII is 26.2% among North African Jews (where it represents the majority haplotype) and 77.5% among Jews from the island of Djerba (Tunisia), reaching 85.1% among Oriental (from Iraq, Iran, and Syria) Jews. Similarly, haplotype VII had a general geographical distribution fairly identical to that of haplotype VIII (which it often accompanies as a secondary haplotype); haplotype VII distinguishes itself by increased preponderance north of the Mediterranean and in Eastern Europe (Lucotte et al., [1996]). Haplotype XV is the most widespread Y-haplotype in Western Europe (Lucotte and Hazout, [1996]), where its frequency decreases from west to east (Semino et al., [1996]; Lucotte and Loirat, [1999]). Haplotypes VIII, VII, and XV are less common haplotypes in Egypt (7.3%, 6.6%, and 5.5%, respectively), and tend to be located in the north of the country, near the Mediterranean coast. Possibly haplotypes VIII, VII, and XV represent, respectively, Near East, Greek, and Roman influences.

Life would be so much easier if they just put down the recognised name for the haplotypes. Now I’ll actually have to engage my brain. V is M81(68.9% among Moroccan Berbers where it is in the wide majority) and XI is M78.

So they are DNA testing some of the Egyptian mummies.

Egypt Mummies Moved for DNA Tests; Pharaoh Among Them?Andrew Bossone in Cairo
for National Geographic News

June 6, 2008
Three mummies have been moved from the Valley of the Kings in Luxor to the Egyptian Museum in Cairo to begin extensive studies of their origins, Egyptian authorities recently announced.

Two female mummies found in a tomb known as KV21 and one male mummy found outside the tomb of Pharaoh Seti II, who ruled Egypt from 1200 to 1194 B.C., will undergo CAT scans and DNA analysis.

Finally. I’d love to see a decent break down of their DNA types. My insider at the British museum told me they hadn’t had any luck the few times they’d tried sampling theirs, and that the samples were too fragile to start wrenching around to get at their teeth.

Apparently the mummy ‘Ginger’ is in a stable condition now, his head isn’t peeling anymore, which is nice. I still can get hold of the results of the tests the Egyptians ran on the others.

Different male and female migration into Britain in the stone age.

Genetic evidence for different male and female roles during cultural transitions in the British Isles

Human history is punctuated by periods of rapid cultural change. Although archeologists have developed a range of models to describe cultural transitions, in most real examples we do not know whether the processes involved the movement of people or the movement of culture only. With a series of relatively well defined cultural transitions, the British Isles present an ideal opportunity to assess the demographic context of cultural change. Important transitions after the first Paleolithic settlements include the Neolithic, the development of Iron Age cultures, and various historical invasions from continental Europe. Here we show that patterns of Y-chromosome variation indicate that the Neolithic and Iron Age transitions in the British Isles occurred without large-scale male movements. The more recent invasions from Scandinavia, on the other hand, appear to have left a significant paternal genetic legacy. In contrast, patterns of mtDNA and X-chromosome variation indicate that one or more of these pre-Anglo-Saxon cultural revolutions had a major effect on the maternal genetic heritage of the British Isles.

So, a lot of women settlers moved in, but not men. As you can see from the pie charts, the Basque and Celtic populations do show a lot of similarity in Y chromosome distribution. The large blocks of light yellow would be haplotype R1b.

Genetic link between the British and Basques

An abridged version of this article

Professor Stephen Oppenheimer of Oxford University, says 81% of the Welsh have DNA evidence which shows a common link to ancestors who came to Britain from northern Spain as the ice age ended.

Most people in Scotland, Ireland and Wales were assumed to be descended from Celtic farming tribes who migrated here from central Europe up to 6,500 years ago. The English were thought to largely take their genetic line from the Anglo-Saxon invaders of the Dark Ages who supposedly wiped out the Celts in England.

But that’s all part of a “Celtic myth”, says Professor Oppenheimer in The Origins of the British: A Genetic Detective Story.

“The majority of the gene pool of the British Isles is very ancient and dates to the era after the last great Ice Age. It has nothing to do with Celts or Anglo-Saxons or any more recent ethnic labels.

“The Ice Age made Britain a polar desert and there was nobody living here around 13,000 BC until the first settlers came to the British Isles from the Basque country of northern Spain between 15,000 and 7,500 years ago.

“Something like three-quarters of the ancestors of our modern gene pool arrived then.

“The ancestors of some 88% of the Irish, 81% of the Welsh, 79% of the Cornish, 70% of Scots and 68% of the English arrived here during that period. None of the later immigrations contributed anything more than 5% to the gene pool.”

Apparently, Y chromosome haplotype R1b is the majority in Wales, and it was probably the norm in the North African Oranian culture before the E3b1b replaced it in the Neolithic (conquest pattern) as you see it a lot of R1b in black Africans, but not E3b1b. I’m thinking… Afro Asiatic may have made itself the dominant language in North Africa very early on, with elements of it’s grammar making it’s way into the Celtic languages via the IM culture. There seem to have been some African Mt L haplotypes in Spain that couldn’t be attributed to the Berbers/Moors (can’t remember source), and the microlithic technology crossed over from North Africa in the paleolithic.

They need to break down the R1b family better so we can trace population movements better.

There’s a mention of E3b1 being present in England as well in the Capelli study (2003) but I can’t find a break down of what types! This is put down to the Roman occupation, but it could have been anyone.

Explains why I look like a pasty Spaniard.

An Afro Asiatic connection to Celtic languages.

It seems that Celtic languages show some grammatical similarities to Afro Asiatic languages. 

North Africans may have beaten Celts to Ireland
The Sunday Times – 28th May 2000

WHEN the Celts landed in Ireland 2,500 years ago, they may have been met by a population of North Africans, scientists now believe, writes Jan Battles.

Linguists say a study of Irish and other Celtic languages has produced possible evidence that when the Celts invaded Ireland and Britain there were already Afro-Asiatic speakers here. Celtic languages – Irish, Scots Gaelic and Welsh – incorporate grammatical traits found in Afro-Asiatic tongues that are otherwise unrelated, according to research published last week in Science magazine.

Other Celtic languages that were spoken in continental Europe and have since died out did not have these grammatical quirks. Afro-Asiatic languages are currently spoken in countries across Northern Africa and the Near East. This points to the possibility that there was early contact between Celtic and North African populations in the British Isles.

Orin Gensler, of the Max Planck Institute for Evolutionary Anthropology in Germany, said the similarities would be explained if, when Afro-Asiatic people learnt Celtic from the new immigrants, they “perpetuated aspects of their own grammar into the new language”. Gensler has studied many grammatical features found in both Celtic and Afro-Asiatic languages. He found many of the shared features were rare in other languages.

Linguists have discovered surprising differences between Celtic languages and related languages such as French, while seeing striking resemblances between Celtic and Afro-Asiatic languages that are spoken in countries including Morocco, Tunisia and Algeria.

Gensler examined features of the languages such as the order of words in a sentence. In Gaelic and Welsh the standard sentence structure is verbsubject-object, which is a rare sequence. This is also the case in many Afro-Asiatic languages. Celtic languages that used to be spoken in  continental Europe had the verb in the final or middle position.

Berniece Wuethrich, author of the Science article, said: “The only other non-linguistic evidence that could point towards this connection is in blood type, but it is not definitive. Irish and British people have different proportions of blood types to most Europeans. Where there are comparable proportions is in the Atlas mountains in Northern Africa, home of the Berber people.” Berber is a branch of the Afro-Asiatic language group.

Geneticists say there is no evidence of North African ancestors in Irish genes. “There is no particular correspondence between northwest Africa and this island but that is not to say we won’t find something,” said Dr Dan Bradley of the department of genetics at Trinity College. “There is no good genetic evidence to support what the linguists are saying. You have to keep an open mind though.”

While in general clues about the identity of prehistoric inhabitants are gleaned from archeological remains and DNA, linguists say that certain elements of a language can preserve information about ancient times.

It is widely known that when the Celts invaded Ireland there were people already here. Man is first believed to have arrived on Irish shores about 9,000 years ago – the earliest-known archeological evidence for human habitation dates to 7,000BC.

Archeologists are not sure of the origins of prehistoric immigrants to Ireland. A team of scientists in Dublin and Belfast, including Bradley, is studying the genes of modern Irish people to find evidence of these origins, a project which is partly funded by the government’s millennium fund

These oddities of grammar still persist in the English language spoken in Ireland. They do have a slightly different way of composing a sentence.

 ‘ What would you be wanting with your Guinness?’

Instead of

‘What do you want with your Guinness?’

My current theory on this is that the neolithic famers brought an Afro Asiatic language associated with Anatolia into Europe, that was later replaced by Indo European. very much a work in progress, that theory.

The Great Lakes comet in Clovis America.

Someone posted a comment about this on another page. I’d never heard of it before, so thanks for the info. It might have had a substantial effect on early populations in America though, and triggered the cooling event of the Earth’s climate known as the Younger Dryas.

Did a comet wipe out prehistoric Americans?

 The Clovis people of North America, flourishing some 13,000 years ago, had a mastery of stone weaponry that stood them in good stead against the constant threat of large carnivores, such as American lions and giant short-faced bears. It’s unlikely, however, that they thought death would come from the sky.

According to results presented by a team of 25 researchers this week at the American Geophysical Union meeting in Acapulco, Mexico, that’s where the Clovis people’s doom came from. Citing several lines of evidence, the team suggests that a wayward comet hurtled into Earth’s atmosphere around 12,900 years ago, fractured into pieces and exploded in giant fireballs. Debris seems to have settled as far afield as Europe.

Jim Kennett, an oceanographer at the University of California, Santa Barbara, and one of the team’s three principal investigators, claims immense wildfires scorched North America in the aftermath, killing large populations of mammals and bringing an abrupt end to the Clovis culture. “The entire continent was on fire,” he says.

Lead team member Richard Firestone, a nuclear analytical chemist at the Lawrence Berkeley National Laboratory in California, says the evidence lies in a narrow 12,900-year-old carbon-rich layer of sediment found at eight well-dated Clovis-era sites and a peppering of sediment cores across North America, as well as one site in Belgium.

In this layer the team detected several different types of extraterrestrial debris, including nanodiamonds that are only ever found on Earth in meteorites; tiny carbon spherules that form when molten droplets cool rapidly in air; and cage-like carbon molecules containing the rare isotope helium-3, far more abundant in the cosmos than on Earth.

“You might find some other explanation for these individually,” says Firestone, “but taken together, it’s pretty clear that there was an impact.” The team says the agent of destruction was probably a comet, since the key sediment layer lacks both the high nickel and iridium levels characteristic of asteroid impacts.

The team’s findings will almost certainly stir intense controversy and debate, for many geologists remain sceptical of impact hypotheses in general.

“There is a tendency in this field to label any circular feature a crater,” says geomorphologist Michael Oskin of the University of North Carolina in Chapel Hill. But Asish Basu, a geochemist at the University of Rochester, New York, thinks the team’s methods are sound, and finds the case for an extraterrestrial explosion convincing. “I think it is a very straightforward case of an impact.”

Exactly where the explosion might have occurred is uncertain, but several clues point to the north of the continent. Levels of the apparent extraterrestrial debris, for example, are highest at the Gainey archaeological site in Michigan, just beyond the southern reach of North America’s primary ice sheet 12,900 years ago. Moreover, levels decrease the further you go from Gainey, suggesting that the comet blew up largely over Canada – perhaps over Ontario or the Hudson Bay region.

However, this cosmic wallop does not seem to have left behind any obvious crater. In all probability, says Arizona-based geophysicist and team member Allen West, “whatever hit us was a low-density object” that fragmented as it entered the atmosphere. The disintegrating pieces could then have blown up in a series of massive aerial explosions. Alternatively, some might have crashed into the 3-kilometre-thick ice sheet. West notes that such craters “would have been ice-walled and basically melted away at the end of the last ice age”, leaving few traces.

If the team’s impact theory holds up under scrutiny it could help explain three mysterious events that coincided around 12,900 years ago.

At this key time, the climate changed abruptly in the northern hemisphere, suddenly cooling in a period known as the Younger Dryas. In addition, the distinctive Clovis culture seems to have vanished in North America, while at least 35 genera of the continent’s mammals went extinct – including mammoths, mastodons, camels, ground sloths and horses.

For years, many researchers have chalked up the onset of the Younger Dryas to a major change in North America’s plumbing. Near the end of the last ice age, meltwater from the continent’s principal ice sheet flooded into proglacial lakes in the centre of North America, and from there drained southward into the Mississippi river.

But by 12,900 years ago, the ice had retreated sufficiently from the northern Atlantic coast to let meltwater rush suddenly eastward. As an estimated 9500 cubic kilometres of fresh water poured into the Atlantic, it switched off the ocean’s salinity-driven “conveyor belt” current, shutting down the Gulf Stream that carries heat from the tropics to eastern North America. It was this that triggered the Younger Dryas cooling, say many palaeoclimate experts.

 However, some of the comet proponents now propose a different trigger for the cold spell. The massive airbursts over Canada could have destabilised the continental ice sheet, opening new drainage channels to the east. Additionally, dust and debris from the explosions may have darkened the ice, absorbing solar heat and accelerating melting. “What we suggest is that the meltwater outflow from the proglacial lakes and from the temporarily melting ice sheet was the result of extraterrestrial impact,” says Kennett.

The comet-strike also offers a third and radical hypothesis for the massive extinction of mammals, which for years palaeontologists have blamed on the sudden Younger Dryas freeze, combined with the hunting prowess of newly arrived Clovis bands. In the 12,900-year-old carbon-rich layer at Murray Springs, Arizona, and in sediment cores taken from the Carolina Bays (see “Marks of a comet?”, below), chemist Wendy Wolbach of DePaul University in Chicago has detected significant quantities of soot – a product of the intense heat of wildfires.

Moreover, geologist Luanne Becker at the University of California, Santa Barbara, has detected a chemical signature of wildfire – polycyclic aromatic hydrocarbons – in samples taken from three of the team’s study sites. Kennett and other team members say this suggests the cometary explosions ignited wildfires that swept across much of southern North America, wiping out large populations of animals. “I don’t want to sound catastrophic here,” he says, “but this is wild stuff. There is significant evidence of massive biomass burning.”

If they are right, the cataclysm could also have devastated bands of Clovis hunters.

Archaeologist Al Goodyear of the University of South Carolina, Columbia, reported at the Acapulco meeting that there is indirect evidence of a human disaster in what is now the south-eastern US. Chert points fashioned in the distinctive Clovis style disappear, and a new type of tool appears in the archaeological record: redstone points, judged on stylistic grounds to date from 12,750 years ago. Numbers of Clovis points outnumber redstones by 4 to 1. “If the number of points are diagnostic of the number of people there, which is a pretty reasonable assumption,” notes West, “there was at least a 70 per cent decline” in the human population in the region.

Nonetheless, many researchers are likely to greet such apocalyptic scenarios with deep scepticism. Palaeontologist Paul Koch of the University of California, Santa Cruz, says he is intrigued by the new evidence of an impact, but he is far from persuaded by some of the team’s sweeping claims. “I’m not convinced yet there were [widespread] wildfires,” says Koch. “But if an impact just triggered the Younger Dryas, that in itself is a pretty big issue.”
Gerta Keller, a Princeton University geologist, has similar reservations. “Some of the conclusions may be a bit over the top,” she says, particularly the claims of continent-wide fires. Kennett and his colleagues are braced for the critics. “You watch it,” he jokes, “there will be blood on the streets.”

This might explain why the earlier peoples of America  were overcome by the Clovis newcomers (some sites are much older than 30,000 years in South America). A major meteor impact could have wiped out the Northern part of the population, and the side effects (fires) further South made life very difficult for survivors, drastically reducing their numbers.