Characterizing genetic diversity in Africa is a crucial step for most analyses reconstructing the evolutionary history of anatomically modern humans. However, historic migrations from Eurasia into Africa have affected many contemporary populations, confounding inferences. Here, we present a 12.5× coverage ancient genome of an Ethiopian male ("Mota") who lived approximately 4500 years ago. We use this genome to demonstrate that the Eurasian backflow into Africa came from a population closely related to Early Neolithic farmers, who had colonized Europe 4000 years earlier. The extent of this backflow was much greater than previously reported, reaching all the way to Central, West, and Southern Africa, affecting even populations such as Yoruba and Mbuti, previously thought to be relatively unadmixed, who harbor 6 to 7% Eurasian ancestry.

The oral microbiome plays key roles in human biology, health, and disease, but little is known about the global diversity, variation, or evolution of this microbial community. To better understand the evolution and changing ecology of the human oral microbiome, we analyzed 124 dental biofilm metagenomes from humans, including Neanderthals and Late Pleistocene to present-day modern humans, chimpanzees, and gorillas, as well as New World howler monkeys for comparison. We find that a core microbiome of primarily biofilm structural taxa has been maintained throughout African hominid evolution, and these microbial groups are also shared with howler monkeys, suggesting that they have been important oral members since before the catarrhine–platyrrhine split ca. 40 Mya. However, community structure and individual microbial phylogenies do not closely reflect host relationships, and the dental biofilms of Homo and chimpanzees are distinguished by major taxonomic and functional differences. Reconstructing oral metagenomes from up to 100 thousand years ago, we show that the microbial profiles of both Neanderthals and modern humans are highly similar, sharing functional adaptations in nutrient metabolism. These include an apparent Homo-specific acquisition of salivary amylase-binding capability by oral streptococci, suggesting microbial coadaptation with host diet. We additionally find evidence of shared genetic diversity in the oral bacteria of Neanderthal and Upper Paleolithic modern humans that is not observed in later modern human populations. Differences in the oral microbiomes of African hominids provide insights into human evolution, the ancestral state of the human microbiome, and a temporal framework for understanding microbial health and disease.

North American archaeologists often designate spurs on scrapers as gravers or use them as temporal markers for the Paleoindian Period. The functional and stylistic aspects of spurred scrapers are explored here through an ethnoarchaeological study of stone scraper procurement, production, use, and discard among the Gamo of southern Ethiopia. This research demonstrates that the presence of so-called “graver” spurs does not have a functional significance, but is the result of inexperience and/or the waning strength of the hideworker. Furthermore, spurred scrapers occur in abundance at villages where breakage rates also are high, reflecting the presence of a number of inexperienced hideworkers. Lastly, this paper explores the relationship between the experience of the knapper and tool standardization. The analysis suggests that in lineage-based learning systems more-experienced hideworkers assist less-experienced hideworkers, and thus blur any relationship between experience and standardization.

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 Africa1–4. Inferences about this period are challenging to make because demographic shifts in the past 5,000 years have obscured the structures of more ancient populations3,5. 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.

Archaeologists continue to describe Stone Age women as home bound and their lithic technologies as unskilled, expedient, and of low quality. However, today a group of Konso women make, use, and discard flaked stone tools to process hides, offering us an alternative to the man-the-toolmaker model and redefining Western "naturalized" gender roles. These Konso women are skilled knappers who develop their expertise through long-term practice and apprenticeship. Their lithic technology demonstrates that an individual's level of skill and age are visible in stone assemblages. Most importantly, they illustrate that women procure high-quality stone from long distances, produce formal tools with skill, and use their tools efficiently. I suggest in this article that archaeologists should consider women the producers of Paleolithic stone scrapers, engaged in bipolar technology, and as such perhaps responsible for some of the earliest-known lithic technologies.