Bioscience

Emergence of Modern Humans in East Asia Predated by 60,000 Years

In November 2007, researchers found a cave deposit containing mammal fossils on the Mulan Mountain of Chongzuo City and collected two human tooth fossils and several mammal fossils from it. In May 2008, Prof. Jin Changzhu found a piece of fragmentary archaic human mandible and a large number of symbiotic mammal fossils in the trial excavation of this cave, which was named Zhiren Cave. According to stratigraphic correlation and faunal analysis, 230Th-234U disbalance uranides method and isotope dating method, the age of archaic humans in the Zhiren Cave was 100,000-113,000 years ago. In the past two years, the research group led by Prof. Liu Wu of the Institute of Vertebrate Paleontology and Paleoanthropology, in cooperation with relevant research institutes at home and abroad, carried out in-depth research on the Zhiren Cave human fossils. Through studies of the characteristics of the Zhiren Cave human fossils by means of morphological observation, laser scanning, geometric morphometric analysis and other means, researchers found that the Zhiren Cave human mandible presents a series of derived characteristics of modern humans, which are significantly different from those of archaic Homo sapiens but are similar to those of living humans. These fossil characteristics indicate that the Zhiren Cave humans are early modern humans in the transition stage from archaic Homo sapiens to modern humans. Their series of significant discoveries indicate that the emergence of early modern humans or origin of modern humans in East Asia dates from at least 100,000 years ago, which predates the oldest previously known modern humans in this region by at least 60,000 years. This week, the Proceedings of the National Academy of Sciences (PNAS) published a thesis on this research online. Wu Xinzhi, member of CAS and one of the authors of this thesis, pointed out that the Zhiren Cave human fossils provide a new intermediate link for the continuous evolution of archaic humans. He also pointed out that the mandible from the Klasies River Mouth of Africa is normally considered as the important fossil evidence supporting the theory that modern humans originated in Africa; however, the age and morphology of the Zhiren Cave human mandible are similar to and even earlier than those of the mandible from the Klasies River Mouth. It indicates that not only Africa but also China has experienced the course of evolution from archaic humans to modern humans. The hypothesis of “continuous evolution with hybridization” of China’s archaic humans is more in line with the reality of history and provides frim support to the multi-regional human evolution hypothesis and further challenges the “out-of-Africa” model for modern human origins.

Research Progress on Invasion Mechanism of Exotic Plants

Dr. Ni Guangyan of the Ecosystem and Physiology Research Group of the South China Botanical Garden, CAS, with the guidance of Prof. Callaway of the University Montana and Prof. Peng Shaolin of the Sun Yat-Sen University, worked in joint efforts with Prof. Schaffner of CABI Europe - Switzerland, through comparative research of the competitive effects of Acroptilon repens on native North American species to effects on related species from the native range of Acroptilon in Uzbekistan, found that Acroptilon had stronger competitive effects against native North American species than against species native to Uzbekistan. They also compared the competitive interactions among these North American and Eurasian species, in the absence of Acroptilon. The results demonstrated there was no difference in the competitive effects among Eurasians and North Americans, which is inconsistent with previous hypothesis. Further research showed this phenomenon that invasive plants greatly stunt the growth of native plants is related to the allelopathic effects of their roots. The effect of root secretion of Acroptilon repens on species from North America is significantly different from its effect on species from Uzbekistan. The effect is species specific. For example, it stunts the growth of Koeleria macrantha and Vulpia octoflora from North America, but promotes the growth of Cichorium intybus from Eurasia. This indicates that in the future research on biological invasion mechanism, it is necessary to link allelopathic effects with competitive effects and conduct more comparative research in geologic scale, to better understand the invasion mechanism of invasive plants. This result was recently published in the Biological Invasions (2010, 12: 3653-3663).