Dietary strategies of Pleistocene Pongo sp. and Homo erectus on Java (Indonesia)

Abstract

During the early Pleistocene, Java was inhabited by a high variety of hominid and hominin taxa with hitherto unclear seasonal dietary demands. We undertook the first geochemical analyses of Pongo sp., Homo erectus and mammalian Pleistocene teeth from Sangiran. We reconstructed past dietary strategies at daily resolution and inferred sub-seasonal ecological patterns. Histologically-controlled spatially-resolved elemental analyses by LA-ICPMS, confirmed the preservation of authentic biogenic signals despite very weak diagenetic overprint. The Sr/Ca record of mammals is in line with expected trophic positions, contextualizing fossil hominid diet. Herbivorous Pongo sp. displays marked seasonal cycles with ~3-month-long strongly elevated Sr/Ca peaks, reflecting highly nutritional plant food during monsoon seasons. Lower Sr/Ca signals suggest different food availability during the dry season. In contrast, omnivorous Homo erectus shows low and less accentuated intra-annual Sr/Ca variability. We infer that Homo erectus maintained its nutritional demands independent of seasonal fluctuations by exploiting the regional diversity of high-quality food resources.

Oxygen isotopes in orangutan teeth reveal recent and ancient climate variation

“…Tooth enamel is most commonly sampled with hand-held drills to recover the isotopic composition of oxygen inputs from water and food preserved in the hydroxyapatite (e.g., Janssen et al, 2016;Roberts et al, 2020;Kubat et al, 2023). This coarse drilling method yields spatially and temporally blurred powdered samples formed over a substantial and unknown period of time, however, precluding the identification of precise seasonal environmental patterns.…”

“…This may be especially timely given that recent work examining modern fauna compositions in African landscapes has cautioned that fossil herbivore assemblages tend to overestimate the extent of ancient grasslands in comparison to woodlands (Negash and Barr, 2023; also see Sokolowski et al 2023). Fine-scaled tooth sampling may also allow an expansion of inferences from δ 18 O values of bulk-sampled Asian hominin remains (Janssen et al, 2016;Roberts et al, 2020;Kubat et al, 2023), which are difficult to interpret for understanding seasonal rainfall dynamics in tropic environments (Green et al, 2022). Such information could better inform debates about whether humans employed arid savannah corridors to avoid dense tropical forests, or whether humans were adept at colonizing such environments during their consequential migration throughout island Southeast Asia.…”

Evolutionary ecology of language origins through confrontational scavenging

“…Possessing Oldowan lithic technology (sharp stone flakes suitable to cut through very tough hides-one of the key factors in the construction of the new niche), H. erectus may have had access to a large amount of meat in a mega-herbivore carrion days before it exploded owing to internal gas production and became available to concurrent scavengers lurking around. There is isotopic evidence that the proportion of meat consumption increased following the origin of H. erectus, most markedly around 1.65 Ma [19][20][21], a view strengthened by palaeoecological, archaeological and anthropological analyses [22][23][24]. The supply of mega-herbivore carcasses may have been indeed large compared with the density of early hominin scavengers subsisting on them: the number of 2-million-year-old hominin mandibles found in the Omo-Turkana Basin is more than two orders of magnitude smaller than the pooled number of mandibles from the same time of Giraffidae, Elephantidae, Hippopothamidae and Bovidae, many species of which are large herbivores with hides initially impenetrable for scavengers or predators other than H. erectus [25], and the rest still large enough to be worth the cooperative effort necessary to confront other scavengers to possess them.…”