Old Homes
An economic model and evidence of the evolution of human intelligence in the Middle Pleistocene: Climate change and assortative mating
Bruce Petersen
PLoS ONE, August 2023
Abstract:
A main objective of this paper is to provide the first model of how climate change, working through sexual selection, could have led to dramatic increases in hominin brain size, and presumably intelligence, in the Middle Pleistocene. The model is built using core elements from the field of family economics, including assortative mating and specialization and complementarities between mates. The main assumptions are that family public goods (e.g., conversation, shelter, fire) were particularly cognitively intensive to produce and became increasingly important for child survival during glacial phases. Intermediate climates (e.g., not the depths of severe glacial phases) create the largest gains from specialization, encouraging negative assortative mating. In contrast, severe glacial phases encourage positive assortative mating because of the rising importance of family public goods. One testable hypothesis is that absence of severe glacial phases should have led to stasis in brain size. Two other testable hypotheses are that severe glacial phases should have led to speciation events, as well as increases in brain size. The evidence shows that there was a million-year stasis in cranial size prior to the start of the severe glacial phases. This stasis is broken by a speciation event (Homo heidelbergensis), with the oldest fossil evidence dated near the close of the first severe glacial phase. In the next 300 kyr, there are two additional severe glacial phases, accompanied by considerable increases in cranial capacity. The last speciation event is Homo sapiens, with the earliest fossils dated near the end of the last of these two glacial phases.
The archaeology of orality: Dating Tasmanian Aboriginal oral traditions to the Late Pleistocene
Duane Hamacher et al.
Journal of Archaeological Science, forthcoming
Abstract:
Aboriginal people have lived in Australia, continuously, for tens of thousands of years. Over that time, they developed complex knowledge systems that were committed to memory and passed to successive generations through oral tradition. The length of time oral traditions can be passed down while maintaining vitality is a topic of ongoing debate in the social sciences. In recent years, scientists have weighed into the debate by studying traditions that describe natural events, such as volcanic eruptions and meteorite impacts, which can be dated using scientific techniques. Here, we bring together a trans-disciplinary team of scholars to apply this approach to Tasmanian Aboriginal (palawa) oral traditions that were recorded in the early nineteenth century. These traditions describe the flooding of the Bassian Land Bridge connecting Tasmania to mainland Australia and the presence of a culturally significant “Great South Star”, identified as Canopus (α Carinae). Utilising bathymetric and topographic data of the land and sea floor in the Bass Strait, we estimate the Bassian Land Bridge was finally submerged approximately 12,000 years ago. We then calculate the declination of the star Canopus over the last precessional cycle (26,000 years) to show that it was at a far southerly declination (δ < −75°) between 16,300 and 11,800 years ago, reaching its minimum declination approximately 14,000 years ago. These lines of evidence provide a terminus ante quem of the Tasmanian traditions to the end of the Late Pleistocene. This paper supports arguments that the longevity of orality can exceed ten millennia, providing critical information essential to the further development of theoretical frameworks regarding the archaeology of orality.
Climate shifts orchestrated hominin interbreeding events across Eurasia
Jiaoyang Ruan et al.
Science, 11 August 2023, Pages 699-704
Abstract:
When, where, and how often hominin interbreeding happened is largely unknown. We study the potential for Neanderthal-Denisovan admixture using species distribution models that integrate extensive fossil, archaeological, and genetic data with transient coupled general circulation model simulations of global climate and biomes. Our Pleistocene hindcast of past hominins’ habitat suitability reveals pronounced climate-driven zonal shifts in the main overlap region of Denisovans and Neanderthals in central Eurasia. These shifts, which influenced the timing and intensity of potential interbreeding events, can be attributed to the response of climate and vegetation to past variations in atmospheric carbon dioxide and Northern Hemisphere ice-sheet volume. Therefore, glacial-interglacial climate swings likely played an important role in favoring gene flow between archaic humans.
The Myth of Man the Hunter: Women’s contribution to the hunt across ethnographic contexts
Abigail Anderson et al.
PLoS ONE, June 2023
Abstract:
The sexual division of labor among human foraging populations has typically been recognized as involving males as hunters and females as gatherers. Recent archeological research has questioned this paradigm with evidence that females hunted (and went to war) throughout the Homo sapiens lineage, though many of these authors assert the pattern of women hunting may only have occurred in the past. The current project gleans data from across the ethnographic literature to investigate the prevalence of women hunting in foraging societies in more recent times. Evidence from the past one hundred years supports archaeological finds from the Holocene that women from a broad range of cultures intentionally hunt for subsistence. These results aim to shift the male-hunter female-gatherer paradigm to account for the significant role females have in hunting, thus dramatically shifting stereotypes of labor, as well as mobility.
Extreme glacial cooling likely led to hominin depopulation of Europe in the Early Pleistocene
Vasiliki Margari et al.
Science, 11 August 2023, Pages 693-699
Abstract:
The oldest known hominin remains in Europe [~1.5 to ~1.1 million years ago (Ma)] have been recovered from Iberia, where paleoenvironmental reconstructions have indicated warm and wet interglacials and mild glacials, supporting the view that once established, hominin populations persisted continuously. We report analyses of marine and terrestrial proxies from a deep-sea core on the Portugese margin that show the presence of pronounced millennial-scale climate variability during a glacial period ~1.154 to ~1.123 Ma, culminating in a terminal stadial cooling comparable to the most extreme events of the last 400,000 years. Climate envelope–model simulations reveal a drastic decrease in early hominin habitat suitability around the Mediterranean during the terminal stadial. We suggest that these extreme conditions led to the depopulation of Europe, perhaps lasting for several successive glacial-interglacial cycles.
Threads of memory: Reviving the ornament of a dead child at the Neolithic village of Ba`ja (Jordan)
Hala Alarashi et al.
PLoS ONE, August 2023
Abstract:
In 2018, a well-constructed cist-type grave was discovered at Ba`ja, a Neolithic village (7,400–6,800 BCE) in Southern Jordan. Underneath multiple grave layers, an 8-year-old child was buried in a fetal position. Over 2,500 beads were found on the chest and neck, along with a double perforated stone pendant and a delicately engraved mother-of-pearl ring discovered among the concentration of beads. The first was found behind the neck, and the second on the chest. The meticulous documentation of the bead distribution indicated that the assemblage was a composite ornament that had gradually collapsed, partly due to the burying position. Our aim was to challenge time degradation and to reimagine the initial composition in order to best explore the significance of this symbolic category of material culture, not as mere group of beads, but as an ornamental creation with further aesthetic, artisanal and socioeconomic implications. The reconstruction results exceeded our expectations as it revealed an imposing multi-row necklace of complex structure and attractive design. Through multiple lines of evidence, we suggest that the necklace was created at Ba`ja, although significant parts of beads were made from exotic shells and stones, including fossil amber, an unprecedented material never attested before for this period. The retrieval of such an ornament from life and its attribution to a young dead child highlights the significant social status of this individual. Beyond the symbolic functions related to identity, the necklace is believed to have played a key role in performing the inhumation rituals, understood as a public event gathering families, relatives, and people from other villages. In this sense, the necklace is not seen as belonging completely to the realm of death but rather to the world of the living, materializing a collective memory and shared moments of emotions and social cohesion.
Insights into the genetic histories and lifeways of Machu Picchu’s occupants
Lucy Salazar et al.
Science Advances, 28 July 2023
Abstract:
Machu Picchu originally functioned as a palace within the estate of the Inca emperor Pachacuti between ~1420 and 1532 CE. Before this study, little was known about the people who lived and died there, where they came from or how they were related to the inhabitants of the Inca capital of Cusco. We generated genome-wide data for 34 individuals buried at Machu Picchu who are believed to have been retainers or attendants assigned to serve the Inca royal family, as well as 34 individuals from Cusco for comparative purposes. When the ancient DNA results are contextualized using historical and archaeological data, we conclude that the retainer population at Machu Picchu was highly heterogeneous with individuals exhibiting genetic ancestries associated with groups from throughout the Inca Empire and Amazonia. The results suggest a diverse retainer community at Machu Picchu in which people of different genetic backgrounds lived, reproduced, and were interred together.