Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.
Proc Natl Acad Sci U S A. 2013 Jun 25;110(26):10501-6. doi: 10.1073/pnas.1222568110. Epub 2013 Jun 3.
Hominin fossil evidence in the Turkana Basin in Kenya from ca. 4.1 to 1.4 Ma samples two archaic early hominin genera and records some of the early evolutionary history of Paranthropus and Homo. Stable carbon isotopes in fossil tooth enamel are used to estimate the fraction of diet derived from C3 or C4 resources in these hominin taxa. The earliest hominin species in the Turkana Basin, Australopithecus anamensis, derived nearly all of its diet from C3 resources. Subsequently, by ca. 3.3 Ma, the later Kenyanthropus platyops had a very wide dietary range--from virtually a purely C3 resource-based diet to one dominated by C4 resources. By ca. 2 Ma, hominins in the Turkana Basin had split into two distinct groups: specimens attributable to the genus Homo provide evidence for a diet with a ca. 65/35 ratio of C3- to C4-based resources, whereas P. boisei had a higher fraction of C4-based diet (ca. 25/75 ratio). Homo sp. increased the fraction of C4-based resources in the diet through ca. 1.5 Ma, whereas P. boisei maintained its high dependency on C4-derived resources.
肯尼亚图尔卡纳湖盆地的人化石证据可追溯到约 410 万至 140 万年前，样本中包含了两种古老的早期人类属，并记录了一些傍人属和人属的早期进化历史。化石牙齿珐琅质中的稳定碳同位素被用来估计这些人类分类群的饮食中源自 C3 或 C4 资源的部分。图尔卡纳湖盆最早的人类物种南方古猿源泉种几乎完全依赖 C3 资源作为其饮食来源。随后，在大约 330 万年前，更晚的肯尼亚平脸人具有非常广泛的饮食范围——从几乎完全基于 C3 资源的饮食到以 C4 资源为主的饮食。大约 200 万年前，图尔卡纳湖盆的人类已经分为两个不同的群体：属于人属的标本提供了其饮食中 C3 与 C4 资源的比例约为 65/35 的证据，而粗壮傍人则有更高比例的 C4 饮食（约 25/75 比例）。人属通过约 150 万年的时间增加了饮食中 C4 资源的比例，而粗壮傍人则保持了对 C4 衍生资源的高度依赖。
