Crossing the Red Sea: phylogeography of the hamadryas baboon, Papio hamadryas hamadryas (original) (raw)
Related papers
Comprehensive View of the Population History of Arabia as Inferred by mtDNA Variation
Objectives: Genetic and archaeological research supports the theory that Arabia was the first region traversed by modern humans as they left Africa and dispersed throughout Eurasia. However, the role of Arabia from the initial migration out of Africa until more recent times is still unclear. Materials and Methods: We have generated 379 new hypervariable segment 1 (HVS-1) sequences from a range of geographic locations throughout Yemen. We compare these data to published HVS-1 sequences representing Ara-bia and neighboring regions to build a unique dataset of 186 populations and 14,290 sequences. Results: We identify 4,563 haplotypes unevenly distributed across Arabia and neighboring regions. Arabia contains higher proportions of shared haplotypes than the regions with which it shares these haplotypes, suggesting high levels of migration through the region. Populations in Arabia show higher levels of population expansion than those in East Africa, but lower levels than the Near East, Middle East or India. Arabian populations also show very high levels of genetic variation that overlaps with variation from most other regions. Conclusion: We take a population genetics approach to provide a comprehensive view of the relationships of Ara-bian and neighboring populations. We show that Arabian populations share closest links to the Near East and North Africa, but have a more ancient origin with slower demographic growth and/or lower migration rates. Our conclusions are supported by phylogenetic studies but also suggest that recent migrations have erased signals of earlier events. Am J Phys Anthropol 000:000–000, 2015. V C 2015 Wiley Periodicals, Inc.
Genetic Stratigraphy of Key Demographic Events in Arabia
2015
At the crossroads between Africa and Eurasia, Arabia is necessarily a melting pot, its peoples enriched by successive gene flow over the generations. Estimating the timing and impact of these multiple migrations are important steps in reconstructing the key demographic events in the human history. However, current methods based on genome-wide information identify admixture events inefficiently, tending to estimate only the more recent ages, as here in the case of admixture events across the Red Sea (~8–37 generations for African input into Arabia, and 30–90 generations for “back-to-Africa” migrations). An mtDNA-based founder analysis, corroborated by detailed analysis of the whole-mtDNA genome, affords an alternative means by which to identify, date and quantify multiple migration events at greater time depths, across the full range of modern human history, albeit for the maternal line of descent only. In Arabia, this approach enables us to infer several major pulses of dispersal between the Near East and Arabia, most likely via the Gulf corridor. Although some relict lineages survive in Arabia from the time of the out-of-Africa dispersal, 60 ka, the major episodes in the peopling of the Peninsula took place from north to south in the Late Glacial and, to a lesser extent, the immediate post-glacial/Neolithic. Exchanges across the Red Sea were mainly due to the Arab slave trade and maritime dominance (from ~2.5 ka to very recent times), but had already begun by the early Holocene, fuelled by the establishment of maritime networks since ~8 ka. The main “back-to-Africa” migrations, again undetected by genome-wide dating analyses, occurred in the Late Glacial period for introductions into eastern Africa, whilst the Neolithic was more significant for migrations towards North Africa.
Plio-Pleistocene faunal turnovers and their implications for hominin dispersals have recently received considerable attention. Exploration and palaeontological study of faunal exchanges has traditionally centred on East Africa, North Africa and the Levant in Southwest Asia. Despite this attention, considerable debate surrounding the timings, rates, and directions of hominin dispersals remain. Notwithstanding its close geographical proximity to these regions and a landmass of over 3 million km 2 , the Arabian Peninsula has largely been excluded from these discussions, mostly owing to the paucity of its Pleisto-cene vertebrate record. However, recent palaeoenvironmental studies have demonstrated that Arabia experienced periods of climatic amelioration during the Pleistocene, resulting in the establishment of large, perennial water sources and open-grasslands; conditions vastly different than today. This interpretation is further underpinned by archaeological and palaeontological data, and it is now clear this region is important for understanding faunal and hominin movements between Africa and Eurasia. Examination of the Arabian Middle to Late Pleistocene fossil record in a biogeographical context indicates the composite nature of the Arabian faunal record, with Eurasian and African intrusions present in addition to well-established endemics. Open grassland habitats and taxonomic similarities between Pleistocene Arabia on the one hand, and the Levant and Africa on the other, suggests that hominin dispersal into Arabia did not require significant behavioural and/or technological innovations, while subsequent climatic deterioration likely resulted in hominin retreat/extirpation.
Communications Earth & Environment
The evolution of the present-day African savannah fauna has been substantially influenced by the dispersal of Eurasian ancestors into Africa. The ancestors evolved endemically, together with the autochthonous taxa, into extant Afrotropical clades during the last 5 million years. However, it is unclear why Eurasian ancestors moved into Africa. Here we use sedimentological observations and soluble salt geochemical analyses of samples from a sedimentary sequence in Western Iran to develop a 10-million-year long proxy record of Arabian climate. We identify transient periods of Arabian hyperaridity centred 8.75, 7.78, 7.50 and 6.25 million years ago, out-of-phase with Northern African aridity. We propose that this relationship promoted unidirectional mammalian dispersals into Africa. This was followed by a sustained hyperarid period between 5.6 and 3.3 million years ago which impeded dispersals and allowed African mammalian faunas to endemically diversify into present-day clades. After t...
New Oligocene primate from Saudi Arabia and the divergence of apes and Old World monkeys
Nature, 2010
It is widely understood that Hominoidea (apes and humans) and Cercopithecoidea (Old World monkeys) have a common ancestry as Catarrhini deeply rooted in Afro-Arabia. The oldest stem Catarrhini in the fossil record are Propliopithecoidea, known from the late Eocene to early Oligocene epochs (roughly 35-30Myr ago) of Egypt, Oman and possibly Angola. Genome-based estimates for divergence of hominoids and cercopithecoids range into the early Oligocene; however, the mid-to-late Oligocene interval from 30 to 23Myr ago has yielded little fossil evidence documenting the morphology of the last common ancestor of hominoids and cercopithecoids, the timing of their divergence, or the relationship of early stem and crown catarrhines. Here we describe the partial cranium of a new medium-sized (about 15-20kg) fossil catarrhine, Saadanius hijazensis, dated to 29-28Myr ago. Comparative anatomy and cladistic analysis shows that Saadanius is an advanced stem catarrhine close to the base of the hominoid-cercopithecoid clade. Saadanius is important for assessing competing hypotheses about the ancestral morphotype for crown catarrhines, early catarrhine phylogeny and the age of hominoid-cercopithecoid divergence. Saadanius has a tubular ectotympanic but lacks synapomorphies of either group of crown Catarrhini, and we infer that the hominoid-cercopithecoid split happened later, between 29-28 and 24Myr ago.