Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA; Division of Anthropology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA.
Center for the Advanced Study of Human Paleobiology, The George Washington University, 800 22nd Street NW, Washington, DC 20052, USA; Department of Organismal Biology and Anatomy, University of Chicago, 1027 East 57th Street, Chicago, IL 60637, USA.
J Hum Evol. 2018 Sep;122:70-83. doi: 10.1016/j.jhevol.2018.04.014. Epub 2018 Jun 30.
The ecological and selective forces that sparked the emergence of Homo's adaptive strategy remain poorly understood. New fossil and archaeological finds call into question previous interpretations of the grade shift that drove our ancestors' evolutionary split from the australopiths. Furthermore, issues of taphonomy and scale have limited reconstructions of the hominin habitats and faunal communities that define the environmental context of these behavioral changes. The multiple ∼1.5 Ma track surfaces from the Okote Member of the Koobi Fora Formation at East Turkana provide unique windows for examining hominin interactions with the paleoenvironment and associated faunas at high spatiotemporal resolution. These surfaces preserve the tracks of many animals, including cf. Homo erectus. Here, we examine the structure of the animal community that inhabited this landscape, considering effects of preservation bias by comparing the composition of the track assemblage to a skeletal assemblage from the same time and place. We find that the track and skeletal assemblages are similar in their representation of the vertebrate paleocommunity, with comparable levels of taxonomic richness and diversity. Evenness (equitability of the number of individuals per taxon) differs between the two assemblages due to the very different circumstances of body fossil versus track preservation. Both samples represent diverse groups of taxa including numerous water-dependent species, consistent with geological interpretations of the track site environments. Comparisons of these assemblages also show a pattern of non-random hominin association with a marginal lacustrine habitat relative to other vertebrates in the track assemblage. This evidence is consistent with behavior that included access to aquatic foods and possibly hunting by H. erectus in lake margins/edaphic grasslands. Such behaviors may signal the emergence of the adaptative strategies that define our genus.
引发人类适应策略出现的生态和选择压力仍未被很好地理解。新的化石和考古发现对驱动我们祖先与南方古猿进化分野的等级转变的先前解释提出了质疑。此外，埋藏学和规模问题限制了对人类栖息地和动物群的重建，这些栖息地和动物群定义了这些行为变化的环境背景。东图尔卡纳的库比福拉组奥科特阶的多个约 150 万年前的足迹表面为研究人类与古环境和相关动物群的相互作用提供了独特的窗口，其分辨率高且时间和空间尺度大。这些表面保存了许多动物的足迹，包括疑似直立人。在这里，我们研究了居住在这个景观中的动物群落的结构，通过将足迹组合的组成与同一时间和地点的骨骼组合进行比较，考虑了保存偏差的影响。我们发现，足迹和骨骼组合在其对脊椎动物古群落的表现上相似，具有可比的分类丰富度和多样性水平。由于身体化石与足迹保存的情况非常不同，均匀度（每个分类群的个体数量的均衡性）在两个组合之间存在差异。两个样本都代表了多样的分类群，包括许多依赖水的物种，与足迹地点环境的地质解释一致。对这些组合的比较还显示了人类与边缘湖泊生境的非随机关联模式，相对于足迹组合中的其他脊椎动物而言，这种关联模式具有非随机性。这种证据与包括获取水生食物和可能由直立人在湖泊边缘/土壤草地中狩猎的行为一致。这些行为可能标志着定义我们属的适应策略的出现。
