Size variation in early human mandibles and molars from Klasies River,South Africa: Comparison with other middle and late Pleistocene assemblages and with modern humans

Previous studies of the Middle Stone Age human remains from Klasies River have concluded that they exhibited more sexual dimorphism than extant populations, but these claims have not been assessed statistically. We evaluate these claims by comparing size variation in the best‐represented elements at the site, namely the mandibular corpora and M₂s, to that in samples from three recent human populations using resampling methods. We also examine size variation in these same elements from seven additional middle and late Pleistocene sites: Skhūl, Dolní Věstonice, Sima de los Huesos, Arago, Krapina, Shanidar, and Vindija. Our results demonstrate that size variation in the Klasies assemblage was greater than in recent humans, consistent with arguments that the Klasies people were more dimorphic than living humans. Variation in the Skhūl, Dolní Věstonice, and Sima de los Huesos mandibular samples is also higher than in the recent human samples, indicating that the Klasies sample was not unusual among middle and late Pleistocene hominins. In contrast, the Neandertal samples (Krapina, Shanidar, and Vindija) do not evince relatively high mandibular and molar variation, which may indicate that the level of dimorphism in Neandertals was similar to that observed in extant humans. These results suggest that the reduced levels of dimorphism in Neandertals and living humans may have developed independently, though larger fossil samples are needed to test this hypothesis. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.     

Does KNM-ER 1481A establish Homo erectus at 2.0 myr BP?

Kennedy (1983) has proposed that the KNM-ER 1481A femur represents Homo erectus and establishes the presence of this species at ca. 2.0.myr BP. A reconsideration of her criteria for taxonomic attribution indicates that its morphology implies only that it is an archaic member of the genus Homo. Its geochronological position, in conjunction with its morphology, suggest that it is best referred to H. habilis.     

对人类进化全过程的思索

本文从人类的诞生,人类发展过程的连续与间断,人类进化过程中体质发展的不平衡性和现代人的进化等４方面来论述人类进化的全过程．     

中国直立人与早期智人的牙齿形态鉴别

对直立人与早期智人的上颌牙齿特征的比较表明 :直立人牙齿的长宽尺寸 ,除中门齿唇舌径外 ,与早期智人的相应值很难区分 -早期智人的长宽尺寸多在直立人相应值的变异范围之内 ;直立人牙齿的观察性特征几乎都能在早期智人某些成员中见到。这意味着直立人与早期智人可能并无“种”而只有“亚种”这一分类级别上的差异 ,把直立人并入智人种这一建议是可取的。对若干化石地点的单个牙齿进行的重新鉴定表明 :桐梓、沂源、郧县梅铺、洛南和淅川的人类牙齿不一定是代表直立人的 ,有可能是代表早期智人的。     

郧县人类头骨化石与周口店直立人头骨的形态比较

对郧县人类头骨化石与周口店直立人头骨作了形态上的比较以检验直立人特征在郧县头骨化石上的表现情况．比较项目包括眶上圆枕、枕骨圆枕、枕平面与项平面之间的转折情况、眶后收缩、颅骨最大宽位置、颅盖低平情况、前额后倾情况和颅容量．结果表明,在郧县人类头骨化石的这些特征项目中,有的因头骨破损和变形而难以肯定．其余的则应是早期智人的特征．从形态上讲,郧县人类头骨化石目前还难肯定是属于直立人,而有可能属于智人,如果认为“直立人”和“智人”是两个不同的物种的话．     

脑膜中动脉的形态变异及其在人类进化上的意义

对现代人、直立人、早期智人、晚期智人脑膜中动脉前支和后支压迹的形态的观察和对比发现：从直立人到现代人脑膜中动脉管径从粗到逐渐变细,分枝从简单到逐渐复杂,前支趋向于增大,后支趋向于缩小,呈现出一定的规律性,有地域性差异。作者认为脑膜中动脉的这种分布形式间接地反映了直立人向智人演化及现代人类形成过程中,大脑各部分比例的变化和功能的日益复杂对供血需求的影响。在研究颅骨与大脑之间的关系上及脑演化上,脑膜中动脉有一定的意义。     

贵州盘县大洞发现的人类牙齿化石

对在盘县对大洞发现的一枚人类上颌内侧门齿和一枚人类下颌犬齿的观察研究显示,门齿齿冠舌侧面铲形结构,齿结节,指状突及犬齿的齿带等结构具有某些与北京猿人牙齿的相似的特征;但在这些结构的复杂程度及齿冠测量特征等方面又呈出早期智人的特点。     

Taxonomic affinity of the early Homo cranium from Swartkrans,South Africa

A quantitative analysis that employs randomization methods and distance statistics has been undertaken in an attempt to clarify the taxonomic affinities of the partial Homo cranium (SK 847) from Member 1 of the Swartkrans Formation. Although SK 847 has been argued to represent early H. erectus, exact randomization tests reveal that the magnitude of differences between it and two crania that have been attributed to that taxon (KNM-ER 3733 and KNM-WT 15000) is highly unlikely to be encountered in a modern human sample drawn from eastern and southern Africa. Some of the variables that differentiate SK 847 from the two early H. erectus crania (e. g., nasal breadth, frontal breadth, mastoid process size) have been considered to be relevant characters in the definition of that taxon. Just as the significant differences between SK 847 and the two early H. erectus crania make attribution of the Swartkrans specimen to that taxon unlikely, the linkage of SK 847 to KNM-ER 1813, and especially Stw 53, suggests that the Swartkrans cranium may have its closest affinity with H. habilis sensu lato. Differences from KNM-ER 1813, however, hint that the South African fossils may represent a species of early Homo that has not been sampled in the Plio-Pleistocene of eastern Africa. The similarity of SK 847 and Stw 53 may support faunal evidence which suggests that Sterkfontein Member 5 and Swartkrans Member 1 are of similar geochronological age. © 1993 Wiley-Liss, Inc.     

中国古人类牙齿尺寸演化特点及东亚直立人的系统地位

对中国境内不同时代人类牙齿测量数据的发析显示,中国古人类牙齿尺寸的总体演化趋势与世界其它地区人类一致,呈缩小变化,其中一个表现特点是中国直立人与早期智人在牙齿尺寸上不差别不大,但作者根据对中国古人类化石形态特征,生存年代等方面的综合分析认为中国直立人在化石形态,生存年代等方面均与智人有明显的不同,取消直立人,将其并入智人意见的证据还是不够充分的,目前仍宜将直立人与智人作为人属内两个不同的种来看待,     

CRANIAL SIZE VARIATION AND LINEAGE DIVERSITY IN EARLY PLEISTOCENE HOMO

A recent article in this journal concluded that a sample of early Pleistocene hominin crania assigned to genus Homo exhibits a pattern of size variation that is time dependent, with specimens from different time periods being more different from each other, on average, than are specimens from the same time period. The authors of this study argued that such a pattern is not consistent with the presence of multiple lineages within the sample, but rather supports the hypothesis that the fossils represent an anagenetically evolving lineage (i.e., an evolutionary species). However, the multiple‐lineage models considered in that study do not reflect the multiple‐species alternatives that have been proposed for early Pleistocene Homo. Using simulated data sets, I show that fossil assemblages that contain multiple lineages can exhibit the time‐dependent pattern of variation specified for the single‐lineage model under certain conditions, particularly when temporal overlap among fossil specimens attributed to the lineages is limited. These results do not reject the single‐lineage hypothesis, but they do indicate that rejection of multiple lineages in the early Pleistocene Homo fossil record is premature, and that other sources of variation, such as differences in cranial shape, should be considered.     

A SINGLE LINEAGE IN EARLY PLEISTOCENE HOMO: SIZE VARIATION CONTINUITY IN EARLY PLEISTOCENE HOMO CRANIA FROM EAST AFRICA AND GEORGIA

The relationship between Homo habilis and early African Homo erectus has been contentious because H. habilis was hypothesized to be an evolutionary stage between Australopithecus and H. erectus, more than a half‐century ago. Recent work re‐dating key African early Homo localities and the discovery of new fossils in East Africa and Georgia provide the opportunity for a productive re‐evaluation of this topic. Here, we test the hypothesis that the cranial sample from East Africa and Georgia represents a single evolutionary lineage of Homo spanning the approximately 1.9–1.5 Mya time period, consisting of specimens attributed to H. habilis and H. erectus. To address issues of small sample sizes in each time period, and uneven representation of cranial data, we developed a novel nonparametric randomization technique based on the variance in an index of pairwise difference from a broad set of fossil comparisons. We fail to reject the hypothesis of a single lineage this period by identifying a strong, time‐dependent pattern of variation throughout the sequence. These results suggest the need for a reappraisal of fossil evidence from other regions within this time period and highlight the critical nature of the Plio‐Pleistocene boundary for understanding the early evolution of the genus Homo.     

The handaxe reconsidered

The Acheulean handaxe is one of the longest‐known and longest‐surviving artifacts of the Palaeolithic and, despite its experimentally tested functionality, is often regarded as puzzling. It is unnecessary to invoke a unique‐for‐mammals genetic mechanism to explain the handaxe phenomenon. Instead, we propose that two nongenetic processes are sufficient. The first is a set of ergonomic design principles linked to the production of sturdy, hand‐held cutting tools in the context of a knapped‐stone technology that lacked hafting. The second is an esthetic preference for regular forms with gradual curves and pleasing proportions. Neither process is a cultural meme but, operating together in a cultural context, they can account for all of the supposedly puzzling time‐space patterns presented by handaxes.     

An archaic character in the Broken Hill innominate E. 719

The additional hominid material from Broken Hill, Kabwe, Zambia, is only dubiously associated with the hominid cranium from the site and is often considered to be anatomically modern in morphology. This study identifies an archaic feature, previously recognised in Pliocene and earlier Pleistocene innominates, in the Broken Hill innominate E. 719. An acetabulo-cristal buttress of cortical bone 10 mm thick is present, and this can be clearly distinguished from the morphology present in a comparative sample of large recent Homo sapiens innominates. This observation increases the likelihood that some of the additional specimens from Broken Hill are indeed of comparable antiquity to the hominid cranium and extends the range of hominids in which the feature has been recognised.     

非洲和中国直立人某些颅骨特征的比较--中国与非洲人类头骨特征对比之一

针对学术界有关非洲与亚洲直立人关系的争论,本文对一些用来支持非洲早期直立人从直立人中分离出来而归入匠人的主要形态学证据进行了检验,用于研究的标本包括迄今在东非发现的年代最早的直立人KNM－ER 3733、KNM－ER 3883和KNM－WT15000头骨化石,这些石是被提倡非洲与亚洲的直立人分离两个种的学者归入匠人的主要标本,对这些非注早期直立人与中国直立人18项头骨特征对比显示：一些被认为是局限于亚洲直立人的独有特征在上述非洲直立人头骨都有出现,存在于非洲直立人与中国直立人之间的颅骨特征上的差别主要体现在特征的表现程度与方式的不同,作者认为根据本文对比的颅骨特征,非洲直立人与中国直立人在颅骨形态上非常相似,他们之间的形态差异反映了直立人具有较宽的形态变范围,认为亚洲直立人具有特化的衍生性状的观点在本文不能得到支持。     

THE EVOLUTION OF EARLY HOMO: A REPLY TO SCOTT

Scott presents a welcome reply to our article, “A single lineage in early Pleistocene Homo” (Van Arsdale and Wolpoff 2012 ). However, Scott's reply mischaracterizes and fails to directly address the hypothesis of a single lineage that we test. Additionally, the approach taken by Scott fails to replicate the methods used in our analysis. As Scott himself suggests, our null hypothesis of a single evolving lineage in early Homo remains without refutation. Although many evolutionary scenarios might explain the complex pattern of variation present in the early Homo fossil record, the most parsimonious remains that of a single lineage displaying evolutionary change over time.     

南京2号人类头骨化石的复位和形态

南京2号人类头骨化石仅保留部分的额骨、顶骨、枕骨和颞骨,为一不完整的颅盖骨。其顶骨和枕骨有数条断裂缝,各断块之间有程度不一的错动,致使该颅盖骨显得外形异常。本项研究是对该颅盖骨的错动部分进行复位,结果表明,南京2号头骨有较大的顶骨、较小的上枕鳞相对宽度、可能较大的颅容量。这些形态提示该头骨与直立人有所不同而与早期智人相近。该头骨所具有的角圆枕、颞鳞顶缘形状、枕骨圆枕发育程度、枕骨的枕平面与项平面过渡情况、枕内隆突点与枕外隆突点的距离、头骨骨壁厚度、脑膜中动脉分支情况、头骨枕面观之轮廓线样式等形态细节,还很难作为可靠的依据把南京2号头骨鉴定为直立人。南京2号头骨很大可能是属于智人亚种(Homo sapiens sapiens)中的一员。     

1981年发现的安徽和县猿人化石

本文记述1981年在安徽和县发现的人的五枚牙齿化石、额骨眶上部残片及顶骨残片一块。研究表明,大多数形态特征与北京猿人非常相似,但也有较北京猿人进步的特征。和县猿人无疑地属直立人(Homo erectus),和县猿人的门齿与元谋猿人的门齿,在形态特征上存在较大的差别。