Saturday, July 15, 2017

An updated age for the Xujiayao hominin from the Nihewan Basin, North China: Implications for Middle Pleistocene human evolution in East Asia

Hong Ao, Chun-Ru Lui, Andrew P. Roberts, Peng Zhang, Xinwen Xu
Journal of Human Evolution
Volume 106, May 2017, Pages 54-65
(Link) open access

from the paper:

Implications for hominin evolution

The Xujiayao Homo fossils have mixed characteristics associated with European Neanderthals, Asian H. erectus, and modern H. sapiens (Jia and Wei, 1976; Jia et al., 1979; Wu, 1980; Bae, 2010; Wu et al., 2013, 2014; Wu and Trinkaus, 2014; Xing et al., 2015), which makes it difficult to affiliate the Xujiayao hominins to “classic” H. erectus, modern humans, or Neanderthals. Thus, the Xujiayao hominins were assigned to archaic H. sapiens (Jia and Wei, 1976; Jia et al., 1979; Wu, 1980; Wu and Poirier, 1995), although this unique term in China is controversial as noted by later studies (e.g., Rightmire, 1998; Dennell and Petraglia, 2012). Our updated chronology makes the Xujiayao Homo fossils among the oldest archaic H. sapiens in China. They are contemporaneous with the earliest archaic H. sapiens remains in eastern China from Chaoxian (310–360 ka; Shen et al., 2010). Combining the archaic H. sapiens remains from New Cave (248–269 ka; Shen et al., 2004a) at Zhoukoudian, Dali (∼270 ka; Xiao et al., 2002) and Jinniushan (∼260 ka; Rosenberg et al., 2006), it appears that archaic H. sapiens occupied a vast area across China during the mid-Pleistocene. Unlike some African mid-Pleistocene Homo individuals that were associated with Acheulian stone tools (Rightmire, 2008), the archaic H. sapiens from Xujiayao and other East Asian sites (e.g., Jinjiushan and New Cave) were associated with a relatively simple Oldowan-like technology (Bae, 2010; cf. Fig. 4). Despite having a simple technology, the Xujiayao hominins were able to successfully obtain regular sources of animal fat and protein that probably helped them to survive harsh mid-latitude northeast Asian winters. Surface modifications on long bone midshafts indicate that the Xujiayao hominins were skilled large mammal (e.g., horse) hunters and had access to high utility (meat-bearing, marrow-rich) long bones (Norton and Gao, 2008), which was important for overwintering in the >40°N temperate zone.

Homo erectus occupation of East Asia started at 1.7–1.6 Ma and persisted to ∼400 ka as suggested by fossils from Yuanmou Basin (∼1.7 Ma; Zhu et al., 2008), Nanjing (580–620 ka; Zhao et al., 2001), Hexian (400–420 ka; Grün et al., 1998), and Yunxian (0.936 Ma; Dennell, 2015) in South China and Gongwangling (1.62–1.63 Ma; Zhu et al., 2015), Chenjiawo (0.65 Ma; An and Ho, 1989), and Zhoukoudian (0.4–0.77 Ma; Shen et al., 2001, 2009) in North China (Fig. 10). In Africa, H. erectus was giving way to Homo heidelbergensis during the terminal Early Pleistocene to the earliest mid-Pleistocene (ca 600–800 ka; Rightmire, 1998, 2008, 2009, 2013). Until now, Homo fossils with unambiguous affinities to H. heidelbergensis have not been reported from East Asia (Bae, 2010), although some divergences of Yunxian crania from the standard H. erectus pattern imply links to H. heidelbergensis (Rightmire, 1998; Stringer, 2002). Whether H. heidelbergensis dispersed to East Asia remains enigmatic. Further in-depth study of Homo fossils and more material are needed to assess the history of H. heidelbergensis in Asia. However, persistence of H. erectus in East Asia to at least 400 ka, when H. heidelbergensis was giving way to Homo neanderthalensis in Europe (Rightmire, 1998), does not support the replacement of H. erectus by H. heidelbergensis in East Asia (Groves and Lahr, 1994; Etler, 2004). Coexistence of H. heidelbergensis and H. erectus is possible if the presence of early mid-Pleistocene H. heidelbergensis is documented in East Asia. Based on more precise recent ages for various Homo fossils established in recent years and without regard to previous imprecise ages that were underestimated by U-series dating of bones, it is possible that archaic H. sapiens (370–250 ka) may have not interacted with the older H. erectus (1700–400 ka) or younger modern H. sapiens (<150 ka) in East Asia, as indicated by our updated Chinese Homo chronostratigraphy in Figure 10.

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