South Arabia’s prehistoric monument landscape shows social resilience to climate change

PLOS One | https://doi.org/10.1371/journal.pone.0323544 May 28, 2025 14 / 24 Accretive construction continued with a new syntax as boat graves after 1100 cal BP. Although each element (a grave) was assembled as one episode, our measured volumes are the total accretive clusters of graves, accumulated as succes- sive burial events. While different in geographical range, in total stone volume these clusters do not significantly differ from the triliths that preceded them. Discussion Over previous decades, archaeologists have studied desert monuments as singular types and classified their forms and uses—mustatils, graves, tombs, alignments, triliths, tumuli, megaliths, burials, sacrifices, markers, ritual theaters—without engaging a holistic perspective. Monuments had culturally specific meanings [53,96]. Seeing all these features as monu- ments focuses on their common potential as proxies for patterned human behavior. By emphasizing and quantifying com- mon features, we arrive at an empirical model and synthetic understanding of dedicated pastoralists’ use of monument technology for social and community resilience to climate change. Fig 6. The mean center and standard distance (1 SD) of the monument types. The mean center is shown as a labelled colored point with the corre- sponding circle showing standard distance. Platforms (green), Scabs (orange), HCTs (blue), Triliths (purple) and Boat graves (red). https://doi.org/10.1371/journal.pone.0323544.g006 Table 2. The results of the collocation analysis.

Chronologically preceding type Chronologically successive type Proportion of monuments significantly collocated Proportion of monu- ments significantly isolated Platforms (7500–6000 cal BP) SCABS (7500–5000 cal BP) 4/23 0/23 SCABS (7500–5000 cal BP) HCT (5200–4000 cal BP) 8/135 0/135 HCT (5200–4000 cal BP) Trilith (2300–1700 cal BP) 0/165 100/165 Trilith (2300–1600 cal BP) Boat graves (1100–750 cal BP) 1/22 12/22 https://doi.org/10.1371/journal.pone.0323544.t002