Friday, October 02, 2009
Science 2 October 2009:
Vol. 326. no. 5949, pp. 60 - 61
from Introduction to the Special Issue, by Brooks Hanson, "Light on the Origin of Man"
This issue presents 11 papers authored by a diverse international team (see following pages) describing an early hominid species, Ardipithecus ramidus, and its environment. The hominid fossils are 4.4 million years old, within this critical early part of human evolution, and represent 36 or more individuals, including much of the skull, pelvis, lower arms, and feet from one female. The papers represent three broad themes. Five focus on different parts of the anatomy that are revealing for human evolution. These show that Ardipithecus was at home both moving along trees on its palms and walking upright on the ground. Three characterize Ardipithecus's habitat in detail, through analysis of the hosting rocks and thousands of fossils of small and large animals and plants. These show that Ardipithecus lived and ate in woodlands, not grasslands. The first paper presents an overview, and it and the last two papers trace early human evolution and synthesize a new view of our last common ancestor with chimps. One conclusion is that chimps have specialized greatly since then and thus are poor models for that ancestor and for understanding human innovations such as our ability to walk.