Descent
The Impact of the Prehistoric Out of Africa Migration on Cultural Diversity
Oded Galor, Marc Klemp & Daniel Wainstock
NBER Working Paper, May 2023
Abstract:
Evidence suggests that the prehistoric Out of Africa Migration has impacted the degree of intra-population genetic and phenotypic diversity across the globe. This paper provides the first evidence that this migration has shaped cultural diversity. Leveraging a folklore catalogue of 958 oral traditions across the world, we find that ethnic groups further away from East Africa along the migratory routes have lower folkloric diversity. This pattern is consistent with the compression of genetic, phenotypic, and phonemic traits along the Out of Africa migration routes, setting conditions for the emergence and proliferation of differential cultural diversity and economic development across the world.
Human scalp hair as a thermoregulatory adaptation
Tina Lasisi et al.
Proceedings of the National Academy of Sciences, forthcoming
Abstract:
Humans are unique among mammals in having a functionally naked body with a hair-covered scalp. Scalp hair is exceptionally variable across populations within Homo sapiens. Neither the function of human scalp hair nor the consequences of variation in its morphology have been studied within an evolutionary framework. A thermoregulatory role for human scalp hair has been previously suggested. Here, we present experimental evidence on the potential evolutionary function of human scalp hair and variation in its morphology. Using a thermal manikin and human hair wigs at different wind speeds in a temperature and humidity-controlled environment, with and without simulated solar radiation, we collected data on the convective, radiative, and evaporative heat fluxes to and from the scalp in relation to properties of a range of hair morphologies, as well as a naked scalp. We find evidence for a significant reduction in solar radiation influx to the scalp in the presence of hair. Maximal evaporative heat loss potential from the scalp is reduced by the presence of hair, but the amount of sweat required on the scalp to balance the incoming solar heat (i.e., zero heat gain) is reduced in the presence of hair. Particularly, we find that hair that is more tightly curled offers increased protection against heat gain from solar radiation.
The role of genetic selection and climatic factors in the dispersal of anatomically modern humans out of Africa
Raymond Tobler et al.
Proceedings of the National Academy of Sciences, 30 May 2023
Abstract:
The evolutionarily recent dispersal of anatomically modern humans (AMH) out of Africa (OoA) and across Eurasia provides a unique opportunity to examine the impacts of genetic selection as humans adapted to multiple new environments. Analysis of ancient Eurasian genomic datasets (~1,000 to 45,000 y old) reveals signatures of strong selection, including at least 57 hard sweeps after the initial AMH movement OoA, which have been obscured in modern populations by extensive admixture during the Holocene. The spatiotemporal patterns of these hard sweeps provide a means to reconstruct early AMH population dispersals OoA. We identify a previously unsuspected extended period of genetic adaptation lasting ~30,000 y, potentially in the Arabian Peninsula area, prior to a major Neandertal genetic introgression and subsequent rapid dispersal across Eurasia as far as Australia. Consistent functional targets of selection initiated during this period, which we term the Arabian Standstill, include loci involved in the regulation of fat storage, neural development, skin physiology, and cilia function. Similar adaptive signatures are also evident in introgressed archaic hominin loci and modern Arctic human groups, and we suggest that this signal represents selection for cold adaptation. Surprisingly, many of the candidate selected loci across these groups appear to directly interact and coordinately regulate biological processes, with a number associated with major modern diseases including the ciliopathies, metabolic syndrome, and neurodegenerative disorders. This expands the potential for ancestral human adaptation to directly impact modern diseases, providing a platform for evolutionary medicine.
The sinister story of a gauche deliverer and his corrie-fisted tribesmen: Ehud and the left-handed artillery
Alex Stewart & Alan Millard
Laterality: Asymmetries of Brain, Behaviour, and Cognition, Spring 2023, Pages 192-208
Abstract:
Bias against left-handers is well-documented and seen in the etymology of “left” and “right” in most languages. The subject of this study, Ehud, lived between the exodus of the Hebrew slaves from Egypt and the establishment of the Israelite kingdom (c1200–1000 BC), at the transition between the Late Bronze Age and Iron Age 1. His left-handedness was crucial to his deliverance of the proto-nation from tyranny, recorded in Judges in the Hebrew Bible. The description of Ehud as left-handed (’iṭṭēr yaḏ-yεmînô) is used once more in the Hebrew Bible, also in Judges, to describe the artillery of Ehud’s tribe. The words apparently mean “bound/restricted in the right hand”, sometimes interpreted as “ambidextrous”. This is unlikely: ambidexterity is uncommon. The artillery used the sling with either hand, but Ehud used his left (śεm’ōl) hand to draw his sword. śεm’ōl, used throughout the Hebrew Bible, means left, without bias or derogatory implications. We suggest that ‘iṭṭēr yaḏ-yεmînô was a right-handed bias towards left-handed people, but Ehud’s left-handed victory was recognized as significant. Significant enough that (a) the language changed and the biased description was dropped in favour of simple description, and (b) the army changed with the development of left-handed slingers (artillery).
An unexpected demographic regime: The western necropolis of the Greek colony of Himera (Sicily, Italy) (550-409 BCE)
Norma Lonoce et al.
Journal of Archaeological Science, forthcoming
Abstract:
We present the results of a paleodemographic assessment of 2865 graves excavated in the western necropolis of the ancient Greek colony of Himera in Sicily. Himera provides an outstanding opportunity to understand the demographic dynamics of Ancient Sicily as it was abandoned and never repopulated, thus offering a completely intact record. Not only has a remarkably large sample been collected and is currently under study, but historical sources allow to precisely date the years in which the city's necropolises were used. Children under the age of 5 were typically buried in pots, meaning that the number of children who died at ages 0 and 1–4 can be reliably estimated. Such data on child death is very rare in paleodemographic studies. Thanks to these exceptional characteristics, together with the application of demographic methods already employed in previous studies (Barbiera et al., 2021) and a comparison of our results with other contemporary Greek necropolises, we can discern a plausible mortality regime for Himera. Our analyses reveal that in the western necropolis of Himera (mid-6th to late 5th century BC) the mortality of children and young people was relatively low, and likely compensated by a more pronounced mortality of adults. Life expectancy at birth was plausibly between 25 and 30 years of age. These findings are further supported by data from the Greek cities of Metaponto and Akraiphia, as well as preliminary results for the eastern necropolis of Himera (late-7th to late 6th century BC).
Northwest African Neolithic initiated by migrants from Iberia and Levant
Luciana Simões et al.
Nature, forthcoming
Abstract:
In northwestern Africa, lifestyle transitioned from foraging to food production around 7,400 years ago but what sparked that change remains unclear. Archaeological data support conflicting views: (1) that migrant European Neolithic farmers brought the new way of life to North Africa or (2) that local hunter-gatherers adopted technological innovations. The latter view is also supported by archaeogenetic data. Here we fill key chronological and archaeogenetic gaps for the Maghreb, from Epipalaeolithic to Middle Neolithic, by sequencing the genomes of nine individuals (to between 45.8- and 0.2-fold genome coverage). Notably, we trace 8,000 years of population continuity and isolation from the Upper Palaeolithic, via the Epipaleolithic, to some Maghrebi Neolithic farming groups. However, remains from the earliest Neolithic contexts showed mostly European Neolithic ancestry. We suggest that farming was introduced by European migrants and was then rapidly adopted by local groups. During the Middle Neolithic a new ancestry from the Levant appears in the Maghreb, coinciding with the arrival of pastoralism in the region, and all three ancestries blend together during the Late Neolithic. Our results show ancestry shifts in the Neolithization of northwestern Africa that probably mirrored a heterogeneous economic and cultural landscape, in a more multifaceted process than observed in other regions.