Rethinking the ecological drivers of hominin evolution

Microhabitat Variability in Human Evolution

“…Nevertheless, investigations into hominin resource use and microhabitat variability have largely been limited to Oldupai Gorge due to its number of documented archaeological sites, geographic extent, and well-defined stratigraphy (Barboni et al, 2010;Blumenschine et al, 2012;Magill et al, 2015;Itambu, 2019;Patalano, 2019;Mercader et al, 2021). Sampling at other paleoanthropological locations on the other hand, has mostly focused on proxy records collected in lake basin or ocean cores that track long-term climatic trends and regional environmental signals (Faith et al, 2021). Classifying paleo-microhabitats is also contingent on the taphonomy of environmental proxies (Table 2).…”

“…Biogenic silica, pollen, and plant wax biomarkers (Godwin, 1934;Faegri and Iversen, 1989;Piperno, 2006;Sachse et al, 2012;Diefendorf and Freimuth, 2017;Cabanes, 2020;Patalano et al, 2021), are three additional proxies most often applied for plant landscape reconstructions (Table 2), and when used effectively, have the potential to produce a clear ecological context into which hominin behavior can be interpreted (e.g., Mercader et al, 2021). By taking a multi-proxy approach to studying non-analog ecosystems and microhabitat variability, it is possible to overcome some of the problems inherent with undertaking regional climate-ecosystem comparisons for human origins studies (Faith et al, 2019;Faith et al, 2021).…”

“…The evolutionary significance of climatic and environmental variability has been reviewed elsewhere within the context of human origins (Vrba et al, 1989;Potts, 1996;1998a;Vrba, 2007;Maslin and Trauth, 2009;Potts, 2013;Maslin et al, 2015;Faith et al, 2021). Early explanations of human evolution focused on intrinsic stimuli whereby a simple transition from one habitat type to another (forest to grassland, for example) set the stage for speciation or specific hominin characteristics like bipedalism and tool use (Dart, 1925;Washburn, 1960;Wilson, 1979;Wolpoff, 1980;Coppens, 1994).…”

“…Yet, linking hominin landscape ecology and climate variability to technological, morphological, or behavioral changes remains challenging as clear cause-and-effect relationships between specific climatic events and major evolutionary occurrences are difficult to establish. This is often due to temporal and spatial gaps in paleoclimatic, paleoenvironmental, and archaeological records (Marean et al, 2015;Faith et al, 2019;Faith et al, 2021). Additionally, recent discoveries of the earliest stone tools (i.e., the Lomekwian) from Kenya dating to 3.3 Ma (Harmand et al, 2015), the earlier appearance of H. erectus in southern Africa at 2.0 Ma (Herries et al, 2020), and the likelihood that Acheulean biface shaping emerged gradually out of bifacial core reduction during the Oldowan (Duke et al, 2021) are not evidently linked with major climate and environmental events.…”

“…Indeed, particular caution must be adopted when studying paleoclimate and paleoecology within a human evolutionary framework, as hominin habitat-types are not always synchronous with changes in regional or global climate (Blumenthal et al, 2017;Groucutt, 2020;Faith et al, 2021;Trauth et al, 2021). That is, landscape response data (most commonly, records of vegetation change), are often used as a climate proxy even though it is well established that ecosystems do not necessarily exhibit a linear response to global or regional climate drivers (Holling, 1973;Bennett et al, 2021).…”