Tales From the Past
Laughter and its role in the evolution of human social bonding
Robin Dunbar
Philosophical Transactions of the Royal Society: Biological Sciences, 7 November 2022
Abstract:
In anthropoid primates, social grooming is the principal mechanism (mediated by the central nervous system endorphin system) that underpins social bonding. However, the time available for social grooming is limited, and this imposes an upper limit on the size of group that can be bonded in this way. I suggest that, when hominins needed to increase the size of their groups beyond the limit that could be bonded by grooming, they co-opted laughter (a modified version of the play vocalization found widely among the catarrhine primates) as a form of chorusing to fill the gap. I show, first, that human laughter both upregulates the brain's endorphin system and increases the sense of bonding between those who laugh together. I then use a reverse engineering approach to model group sizes and grooming time requirements for fossil hominin species to search for pinch points where a phase shift in bonding mechanisms might have occurred. The results suggest that the most likely time for the origin of human-like laughter is the appearance of the genus Homoca 2.5 Ma.
Archaeological adhesives made from Podocarpus document innovative potential in the African Middle Stone Age
Patrick Schmidt, Tabea Koch & Edmund February
Proceedings of the National Academy of Sciences, 4 October 2022
Abstract:
Studying the earliest archaeological adhesives has implications for our understanding of human cognition. In southern Africa, the oldest adhesives were made by Homo sapiens in the Middle Stone Age. Chemical studies have shown that these adhesives were made from a local conifer of the Podocarpaceae family. However, Podocarpus does not exude resin, nor any other substance that could have been recognized as having adhesive properties. Therefore, it remains unknown how these adhesives were made. This study investigates how Podocarpus adhesives can be made, comparing their mechanical properties with other naturally available adhesives. We found that Podocarpus tar can only be made by dry distillation of leaves, requiring innovative potential, skill, and knowledge. This contrasts with our finding that the Middle Stone Age environment was rich in substances that can be used as adhesives without such transformation. The apparent preference for Podocarpus tar may be explained by its mechanical properties. We found it to be superior to all other substances in terms of its adhesive properties. In addition, the condensation method that allows producing it can be recognized accidentally, as the processes take place above ground and can be triggered accidentally. Our findings have implications for establishing a link between technology and cognition in the Middle Stone Age.
Footprint beds record Holocene decline in large mammal diversity on the Irish Sea coast of Britain
Alison Burns et al.
Nature Ecology & Evolution, October 2022, Pages 1553–1563
Abstract:
Long-term monitoring along the Irish Sea coast of Britain at Formby has identified hundreds of animal and human footprints in 31 discrete sediment beds. A new programme of radiocarbon dating shows that the Formby footprints span at least 8,000 years of the Holocene Epoch from the Mesolithic period to Medieval times. In a landscape largely devoid of conventional archaeology and faunal records, we show how species data from the footprint stratigraphy document long-term change in both large mammal diversity and human behaviour. The footprint beds record shifting community structure in the native fauna through an era of profound global change. As sea levels rose rapidly in the Early Holocene, men, women and children formed part of rich Mesolithic intertidal ecosystems from ~9,000 to 6,000 cal BP, with aurochs, red deer, roe deer, wild boar, beaver, wolf and lynx. Doggerland was reclaimed by the sea in this period. In the agriculture-based societies that followed, after 5,500 cal BP human footprints dominate the Neolithic period and later beds, alongside a striking fall in large mammal species richness. Stacked footprint beds can form multimillennial records of ecosystem change with precise geographical context that cannot be retrieved from site-based fossil bone assemblages.
Genetic adaptation of skin pigmentation in highland Tibetans
Zhaohui Yang et al.
Proceedings of the National Academy of Sciences, 4 October 2022
Abstract:
Strong ultraviolet (UV) radiation at high altitude imposes a serious selective pressure, which may induce skin pigmentation adaptation of indigenous populations. We conducted skin pigmentation phenotyping and genome-wide analysis of Tibetans in order to understand the underlying mechanism of adaptation to UV radiation. We observe that Tibetans have darker baseline skin color compared with lowland Han Chinese, as well as an improved tanning ability, suggesting a two-level adaptation to boost their melanin production. A genome-wide search for the responsible genes identifies GNPAT showing strong signals of positive selection in Tibetans. An enhancer mutation (rs75356281) located in GNPAT intron 2 is enriched in Tibetans (58%) but rare in other world populations (0 to 18%). The adaptive allele of rs75356281 is associated with darker skin in Tibetans and, under UVB treatment, it displays higher enhancer activities compared with the wild-type allele in in vitro luciferase assays. Transcriptome analyses of gene-edited cells clearly show that with UVB treatment, the adaptive variant of GNPAT promotes melanin synthesis, likely through the interactions of CAT and ACAA1 in peroxisomes with other pigmentation genes, and they act synergistically, leading to an improved tanning ability in Tibetans for UV protection.
Socio-economic dynamics of Magdalenian hunter-gatherers: Functional perspective
Eugénie Gauvrit Roux
PLoS ONE, October 2022
Abstract:
The beginning of the Middle Magdalenian is marked by an increase in the density and geographic extension of evidences of human occupation across western Europe. The Early Middle Magdalenian (19,5–17,5 ka cal. BP) thereby extends from Poland to Spain, and the sharing of the flint-knapping concepts and the circulation of raw materials show the existence of networks active over this wide area. In parallel, part of the production of art, ornaments, microliths, bone industry, and the proportions of hunted ungulates vary regionally and allow to identify distinct technical traditions. Departing from a palethnographic approach at a regional scale, this paper aims at participating in renewing our understanding of the mechanisms of regionalisation during the period, and among past societies of hunter-gatherers. The reflection is based on the techno-functional analysis of stone tools from two cave sites of west-central France that are at the heart of the definition of two technical traditions: La Marche (Magdalenian with Lussac-Angles points) and the Blanchard cave (Magdalenian with navettes). Inter-site comparisons of the functioning and management of stone tools, and of subsistence strategies show the sharing of techno-economical norms, expressing the adhesion to a wider community of practice. The long-term occupation of at least part of the caves and the high density of sites in the Vienne, the Creuse, the Gartempe, and the Charente Valleys, indicate the strong regional implantation of human societies. This strong territoriality (effective and symbolic) is likely a major factor to understand the specificity of the EMM expressions in the area, as well as the sharing, in the same economic territory, of technical norms and of part of the system of symbolic representation.