Ancient DNA and deep population structure in sub-Saharan African foragers

Multiple lines of genetic and archaeological evidence suggest that there were major demographic changes in the terminal Late Pleistocene epoch and early Holocene epoch of sub-Saharan Africa(1-4). Inferences about this period are challenging to make because demographic shifts in the past 5,000 years have obscured the structures of more ancient populations(3,5). Here we present genome-wide ancient DNA data for six individuals from eastern and south-central Africa spanning the past approximately 18,000 years (doubling the time depth of sub-Saharan African ancient DNA), increase the data quality for 15 previously published ancient individuals and analyse these alongside data from 13 other published ancient individuals. The ancestry of the individuals in our study area can be modelled as a geographically structured mixture of three highly divergent source populations, probably reflecting Pleistocene interactions around 80-20 thousand years ago, including deeply diverged eastern and southern African lineages, plus a previously unappreciated ubiquitous distribution of ancestry that occurs in highest proportion today in central African rainforest hunter-gatherers. Once established, this structure remained highly stable, with limited long-range gene flow. These results provide a new line of genetic evidence in support of hypotheses that have emerged from archaeological analyses but remain contested, suggesting increasing regionalization at the end of the Pleistocene epoch. DNA analysis of 6 individuals from eastern and south-central Africa spanning the past approximately 18,000 years, and of 28 previously published ancient individuals, provides genetic evidence supporting hypotheses of increasing regionalization at the end of the Pleistocene.info:eu-repo/semantics/publishedVersio

Anatomical and functional evidence for trace amines as unique modulators of locomotor function in the mammalian spinal cord

The trace amines (TAs), tryptamine, tyramine, and β-phenylethylamine, are synthesized from precursor amino acids via aromatic-L-amino acid decarboxylase (AADC). We explored their role in the neuromodulation of neonatal rat spinal cord motor circuits. We first showed that the spinal cord contains the substrates for TA biosynthesis (AADC) and for receptor-mediated actions via trace amine-associated receptors (TAARs) 1 and 4. We next examined the actions of the TAs on motor activity using the in vitro isolated neonatal rat spinal cord. Tyramine and tryptamine most consistently increased motor activity with prominent direct actions on motoneurons. In the presence of N-methyl-D-aspartate, all applied TAs supported expression of a locomotor-like activity (LLA) that was indistinguishable from that ordinarily observed with serotonin, suggesting that the TAs act on common central pattern generating neurons. The TAs also generated distinctive complex rhythms characterized by episodic bouts of LLA. TA actions on locomotor circuits did not require interaction with descending monoaminergic projections since evoked LLA was maintained following block of all Na+-dependent monoamine transporters or the vesicular monoamine transporter. Instead, TA (tryptamine and tyramine) actions depended on intracellular uptake via pentamidine-sensitive Na+-independent membrane transporters. Requirement for intracellular transport is consistent with the TAs having much slower LLA onset than serotonin and for activation of intracellular TAARs. To test for endogenous actions following biosynthesis, we increased intracellular amino acid levels with cycloheximide. LLA emerged and included distinctive TA-like episodic bouts. In summary, we provided anatomical and functional evidence of the TAs as an intrinsic spinal monoaminergic modulatory system capable of promoting recruitment of locomotor circuits independent of the descending monoamines. These actions support their known sympathomimetic function

Late Pleistocene to Holocene human palaeoecology in the tropical environments of coastal eastern Africa

The ecological adaptations that stimulated the dispersal and technological strategies of our species during the Late Pleistocene remain hotly disputed, with some influential theories focusing on grassland biomes or marine resources as key drivers behind the rapid expansion and material culture innovations of Homo sapiens within and beyond Africa. Here, we present novel chronologically resolved, zooarchaeological taxonomic and taphonomic analysis, and stable isotope analysis of human and faunal tooth enamel, from the site of Panga ya Saidi (c. 78–0.4 ka), Kenya. Zooarchaeological data provides rare insights into the fauna associated with, and utilized by, Late Pleistocene-Holocene human populations in tropical coastal eastern Africa. Combined zooarchaeological and faunal stable isotope data provide some of the only dated, ‘on-site’ archives of palaeoenvironments beyond the arid interior of eastern Africa for this time period, while stable isotope analysis of humans provides direct snapshots of the dietary reliance of foragers at the site. Results demonstrate that humans consistently utilized tropical forest and grassland biomes throughout the period of site occupation, through a transition from Middle Stone Age to Later Stone Age technological industries and the arrival of agriculture in the region. By contrast, while coastal resources were obtained for use in symbolic material culture, there is limited evidence for consumption of marine resources until the Holocene. We argue that the ecotonal or heterogeneous environments of coastal eastern Africa may have represented an important refugium for populations during the increasing climatic variability of the Late Pleistocene and Holocene, and that tropical environments were one of a diverse series of ecosystems exploited by H. sapiens in Africa at the dawn of global migrations.1. Introduction 2. Background to the site and methodology 2.1. Late Pleistocene and Holocene human environments in eastern Africa and the potential of Panga ya Saidi 2.2. Zooarchaeology, stable isotope analysis, and tropical human palaeoecology 3. Materials and methods 3.1. Zooarchaeological sample and analytical methods 3.2. Stable carbon and oxygen isotope analysis of human and faunal tooth enamel 3.3. Statistical analysis 4. Results 4.1. Panga ya Saidi faunal assemblage overview and formation 4.2. Macromammalian remains at Panga ya Saidi and environmental implications 4.3. Faunal stable carbon and oxygen isotope results from Panga ya Saidi 4.4. Human stable carbon and oxygen isotope result from Panga ya Saidi 5. Discussion 5.1. A new palaeoenvironmental record for Late Pleistocene and Holocene eastern Africa 5.2. Strength in diversity: Late Pleistocene human palaeoecology in eastern Africa and beyond 6. Conclusion

Kisese II Rockshelter, Tanzania

Located in the UNESCO World Heritage Center in Kondoa, Tanzania, the Kisese II rock shelter (4.49° S, 35.81° E,) preserves an extensive record of intermittent human use over at least the last 45,000 years, maintaining a varying role over time as a habitation site, a place for burial, and a canvas for making rock art. An archaeological investigation of the site was initiated in 1951 by Louis and Mary Leakey but was never published. During this time, the Leakeys were conducting extensive field research in Kondoa in search of archaeological evidence that could be used to refine the age of the rock paintings in the area. At Kisese II they placed a c. 4 × 2 m trench and reached over 4 m depth. The abundance of finds and the unusual depth of the archaeological deposit at Kisese II compared to the other nearby tested locations prompted the Leakeys to enlist the help of Ray Inskeep to continue investigating the site. The site provides evidence for changes in how stone tools, ostrich eggshell beads, and ochre technologies were made and used, and the archaeological deposit appears to sample the Last Glacial Maximum, an interval of climate dynamism not well-preserved in many other eastern African localities

A monumental cemetery built by eastern Africa's first herders near Lake Turkana, Kenya

Monumental architecture is a prime indicator of social complexity, because it requires many people to build a conspicuous structure commemorating shared beliefs. Examining monumentality in different environmental and economic settings can reveal diverse reasons for people to form larger social units and express unity through architectural display. In multiple areas of Africa, monumentality developed as mobile herders created large cemeteries and practiced other forms of commemoration. The motives for such behavior in sparsely populated, unpredictable landscapes may differ from well-studied cases of monumentality in predictable environments with sedentary populations. Here we report excavations and ground-penetrating radar surveys at the earliest and most massive monumental site in eastern Africa. Lothagam North Pillar Site was a communal cemetery near Lake Turkana (northwest Kenya) constructed 5,000 years ago by eastern Africa's earliest pastoralists. Inside a platform ringed by boulders, a 119.5-m(2) mortuary cavity accommodated an estimated minimum of 580 individuals. People of diverse ages and both sexes were buried, and ornaments accompanied most individuals. There is no evidence for social stratification. The uncertainties of living on a "moving frontier" of early herding-exacerbated by dramatic environmental shifts-may have spurred people to strengthen social networks that could provide information and assistance. Lothagam North Pillar Site would have served as both an arena for interaction and a tangible reminder of shared identity

A monumental cemetery built by eastern Africa's first herders near Lake Turkana, Kenya

Monumental architecture is a prime indicator of social complexity, because it requires many people to build a conspicuous structure commemorating shared beliefs. Examining monumentality in different environmental and economic settings can reveal diverse reasons for people to form larger social units and express unity through architectural display. In multiple areas of Africa, monumentality developed as mobile herders created large cemeteries and practiced other forms of commemoration. The motives for such behavior in sparsely populated, unpredictable landscapes may differ from well-studied cases of monumentality in predictable environments with sedentary populations. Here we report excavations and ground-penetrating radar surveys at the earliest and most massive monumental site in eastern Africa. Lothagam North Pillar Site was a communal cemetery near Lake Turkana (northwest Kenya) constructed 5,000 years ago by eastern Africa&rsquo;s earliest pastoralists. Inside a platform ringed by boulders, a 119.5-m2 mortuary cavity accommodated an estimated minimum of 580 individuals. People of diverse ages and both sexes were buried, and ornaments accompanied most individuals. There is no evidence for social stratification. The uncertainties of living on a &ldquo;moving frontier&rdquo; of early herding&mdash;exacerbated by dramatic environmental shifts&mdash;may have spurred people to strengthen social networks that could provide information and assistance. Lothagam North Pillar Site would have served as both an arena for interaction and a tangible reminder of shared identity.</p