Fig. 1

Simplified Y-chromosomal phylogeny and inferred past or observed present-day distribution of relevant Y-chromosomal lineages. a Calibrated phylogenetic tree of Y-chromosomal lineages discussed in the text. Green shading represents the period when the present-day Sahara Desert was green and fertile. Lineages represented by filled pentagons have undergone very rapid expansions. b The Green Sahara period 5–12 kya. Green shading indicates that the present-day Sahara Desert was green and fertile. The colors within the large oval represent the four Y-chromosomal haplogroups deduced to be present in the region at this time; specific locations are not implied. The arrows indicate the inferred origins of these haplogroups to the north or south, but specific origins and routes are not implied. c The present-day distributions of the four Green Saharan Y-chromosomal haplogroups. Yellow shading indicates the Sahara Desert. Each circle represents a sampled population, with the presence or absence of the four Green Saharan haplogroups shown by the colored sectors; other haplogroups may also be present in these populations, but are not shown. The small arrows indicate the inferred northwards and southwards movements of these haplogroups when the Sahara became uninhabitable. Figure based on data from [1]