The taxonomic implications of cranial shape variation in Homo erectus

The taxonomic status of Homo erectus sensu lato has been a source of debate since the early 1980s, when a series of publications suggested that the early African fossils may represent a separate species, H. ergaster. To gain further resolution regarding this debate, 3D geometric morphometric data were used to quantify overall shape variation in the cranial vault within H. erectus using a new metric, the sum of squared pairwise Procrustes distances (SSD). Bootstrapping methods were used to compare the H. erectus SSD to a broad range of human and nonhuman primate samples in order to ascertain whether variation in H. erectus most clearly resembles that seen in one or more species. The reference taxa included relevant phylogenetic, ecological, and temporal analogs including humans, apes, and both extant and extinct papionin monkeys. The mean cranial shapes of different temporogeographic subsets of H. erectus fossils were then tested for significance using exact randomization tests and compared to the distances between regional groups of modern humans and subspecies/species of the ape and papionin monkey taxa. To gauge the influence of sexual dimorphism on levels of variation, comparisons were also made between the mean cranial shapes of single-sex samples for the reference taxa. Results indicate that variation in H. erectus is most comparable to single species of papionin monkeys and the genus Pan, which included two species. However, H. erectus encompasses a limited range of variation given its extensive geographic and temporal range, leading to the conclusion that only one species should be recognized. In addition, there are significant differences between the African/Georgian and Asian H. erectus samples, but not between H. ergaster (Georgia+Africa, excluding OH 9 and Daka) and H. erectus sensu stricto. This finding is in line with expectations for intraspecific variation in a long-lived species with a wide, but probably discontinuous, geographic distribution.     

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。     

中国直立人形态特征的变异——颅骨测量数据的统计分析

近年,亚洲直立人化石特征的变异及其意义引起了学术界较多的关注。不断有学者提出周口店直立人无论在非测量性特征,还是在测量特征方面都具有不同于印度尼西亚及非洲直立人的表现特点,有人甚至对将周口店直立人化石特征作为直立人的典型特征的观点提出了置疑。为进一步探讨这些有争议的问题,本文采用多变量统计分析方法对33件非洲和欧亚地区直立人颅骨测量数据进行了分析。我们发现亚洲大陆的周口店和南京直立人与生活在东南亚群岛的印度尼西亚直立人具有不同的颅骨测量特征。中国标本以较窄的前额部和枕部,以及宽阔的颅骨中部为特点。而印度尼西亚标本的额部和枕部的宽度与颅骨中部的宽度相对较为接近。非洲直立人在这些颅骨测量特征的表现上与印度尼西亚直立人接近,呈现出相对宽阔的额部和枕部。中国的和县直立人在颅骨测量特征的表现上与印度尼西亚和非洲直立人接近,而与周口店和南京直立人明显不同。基于这些发现,本文就直立人头骨测量特征的稳定性、周口店直立人颅骨特征的表现特点、东亚直立人的地区变异与时代变化、头骨形态与测量特征的对应性等问题进行了讨论。     

中国直立人牙齿特征变异及其演化意义

以往研究发现,中国直立人化石呈现较大的形态变异。对于这种变异程度及造成变异的原因,在古人类学界有不同的认识。有学者提出在直立人阶段,中国古人类已经呈现明显的区域性差异,但也有人认为这些差异似乎没有规律性。近年,本文作者采用不同方法对若干地点的中国直立人牙齿特征及其变异进行了系列研究,取得了一些新的发现和认识。本文在回顾总结这些研究的基础上,结合对其它一些地点中国直立人牙齿特征的观测对比,对中国直立人牙齿特征表现特点及变异作了进一步的分析。本研究发现,中国直立人牙齿特征具有较大的变异范围。这些变异似可分为两种主要类型,元谋、建始、郧县梅铺、和县牙齿呈现出较多的原始特点,代表一种原始类型;周口店、沂源等地点的标本特征相对进步,表现出更多的典型直立人特征。其它一些地点的直立人化石呈现出混合或中间状态。值得注意的是部分呈现出原始牙齿特征类型的中国直立人的生存年代相对较晚,其牙齿特征的原始性与生存时代不具有对应关系。作者认为中国直立人牙齿特征类型反映了更新世早期和中期不同直立人群的演化状态。原始类型牙齿特征的形成不仅与演化时序性和地理分布有关,还在一定程度上反映了一些中国直立人群的演化隔离。     

Cranial base morphology and temporal bone pneumatization in Asian Homo erectus

The external morphological features of the temporal bone are used frequently to determine taxonomic affinities of fossils of the genus Homo. Temporal bone pneumatization has been widely studied in great apes and in early hominids. However, this feature is rarely examined in the later hominids, particularly in Asian Homo erectus. We provide a comparative morphological and quantitative analysis of Asian Homo erectus from the sites of Ngandong, Sambungmacan, and Zhoukoudian, and of Neandertals and anatomically modern Homo sapiens in order to discuss causes and modalities of temporal bone pneumatization during hominid evolution. The evolution of temporal bone pneumatization in the genus Homo is more complex than previously described. Indeed, the Zhoukoudian fossils have a unique pattern of temporal bone pneumatization, whereas Ngandong and Sambungmacan fossils, as well as the Neandertals, more closely resemble the modern human pattern. Moreover, these Chinese fossils are characterized by a wide midvault and a relatively narrow occipital bone. Our results support the point of view that cell development does not play an active role in determining cranial base morphology. Instead, pneumatization is related to available space and to temporal bone morphology, and its development is related to correlated morphology and the relative disposition of the bones and cerebral lobes. Because variation in pneumatization is extensive within the same species, the phyletic implications of pneumatization are limited in the taxa considered here.     

Metric and non-metric randomization methods, geographic variation, and the single-species hypothesis for Asian and African Homo erectus

This paper proposes a statistical test of the single-species hypothesis using non-metric characters as a complement to statistical tests using more traditional metric characters. The sample examined is that of Asian and African Homo erectus. The paleoanthropological community is divided on the taxonomic distinction of these fossils, with workers arguing both for and against the species-level distinction between Asian and African populations. Previous arguments have focused on patterns of apparent morphological differentiation between the African and Asian cranial samples. To assess this question, three tests were performed that compared the range of variation in the fossil sample to a single-species group with a similar geographic distribution; this comparative sample was composed of 221 modern humans from Africa and Asia. For the first test, 23 metric characters were analyzed on the fossil and comparative samples. Using resampling procedures, the variation for these characters was examined, recreating 1000 samples from the human analogs and comparing the CV distributions of these samples to the CVs of the fossil group. The second test used the metric data to calculate a Euclidean distance between the African and Asian fossil samples. This distance was compared to a distribution of Euclidean distances calculated between 1000 randomly selected samples of African and Asian modern humans. For the third test, a grading scale was created for ten non-metric characters that encompassed the total morphological variation found in the fossil and modern human samples. The Manhattan distance between the Asian and African fossil samples was calculated and compared to a distribution of distances calculated between 1000 randomly selected samples of African and Asian moderns. The first two tests, using the metric data, failed to falsify the null hypothesis. However, in the third test, using non-metric data, the total Manhattan distance for the fossil sample approached the 100th percentile of the resampled distances calculated from the moderns. The implications of the contrasting results are discussed.     

Out of Africa and back again

If the genusHomo did indeed originate in Africa, then it must have spread by about 2 m.y. ago into Asia where it is represented at 1.8 m.y. ago byHomo erectus fossils. This latter species in turn eventually spread back into Africa, as indicated by the 1.4 m.y. old OH 9 calvaria from Olduvai, and into Europe, as indicated by the 800,000 year old Ceprano calvaria from Italy. These hominids are associated only with Oldowan style artefacts of cores, choppers and flakes and were apparently not conversant with Acheulean handaxe technology. It seems that they most probably evolved viaHomo heidelbergensis into the Neanderthals. Meanwhile, a completely separate development originating withHomo ergaster of about 1.7 m.y. ago in Africa and possessing Acheulean handaxe technology evolved via such forms as Ndutu and Steinheim intoHomo sapiens.     

Gamma-ray spectrometric dating of late Homo erectus skulls from Ngandong and Sambungmacan, Central Java, Indonesia

Hominid fossils from Ngandong and Sambungmacan, Central Java, Indonesia, are considered to be the most anatomically derived and youngest representatives of Homo erectus. Nondestructive gamma-ray spectrometric dating of three of these Homo erectus skulls showed that all samples underwent uranium leaching. Nevertheless, we could establish minimum age estimates of around 40ka, with an upper age limit of around 60 to 70ka. This means that the Homo erectus of Java very likely survived the Toba eruption and may have been contemporaneous with the earliest Homo sapiens in Southeast Asia and Australasia.     

On the taxonomic affinities of the Dmanisi mandible (Georgia)

The recent discovery of unexpectedly ancient human remains has fuelled interest about the first dispersion of Homo outside Africa. The Dmanisi mandible is perhaps one of the most interesting findings, as it supposedly represents one of the oldest hominids outside of Africa. Recently, different interpretations have been published about this specimen. Our comparison of the Dmanisi mandible with a large sample of mandibles and teeth has led us to a new interpretation. In our view, the Dmanisi mandible exhibits a unique combination of traits. Some of its features, taken in isolation, may be attributed to morphological extremes within the genus Homo. The architecture of the mandible as well as the morphology and dimensions of incisors, canines, and P3s are clearly primitive. However, dental traits such as the reduction of the talonid in the P4s and a distally decreasing molar series seems to be derived. Some combinations of these traits are found in specimens of Homo ergaster and differ from those generally present in later hominids. Thus, we propose that the Dmanisi mandible might be taxonomically classified as Homo sp. indet. (aff. ergaster). Furthermore, some aspects of the dentition in Dmanisi display close similarities to Asian Homo erectus. If the 1.8–1.6 Myr dating for the Dmanisi mandible is correct, the differentiation of the Asian branch of the genus Homo could be regarded as a very ancient event. Am J Phys Anthropol 107:145–162, 1998. © 1998 Wiley-Liss, Inc.     

Evidence of amelogenesis imperfecta in an early African Homo erectus

The teeth of the Homo erectus child (Garba IV) recovered from Melka Kunture Ethiopia and dated to 1.5 Ma are characterized by generalized enamel dysplasia, reduced enamel radio-opacity, and severe attrition. This combination of features is found in a large group of hereditary, generalized enamel dysplasias known as amelogenesis imperfecta (AI). SEM studies carried out on epoxy replicas of teeth from the Garba IV child, confirmed that the defects noted were developmental and not due to diagenesis. The enamel prism arrangement is abnormal and there are deep vertical furrows lacking enamel on both buccal and lingual surfaces of all molars. The lesions differ from those characteristic of linear enamel hypoplasia that form discrete horizontal lesions or pits within otherwise normal enamel. We propose that the Garba IV child is the earliest example of AI and provides a link between palaeoanthropology and molecular biology in investigations of the evolutionary history of genetic disorders.     

印度纳尔玛达地区发现的粗壮智人化石及其与亚洲直立人的连续性

1999年,在印度西部的纳尔玛达(Narmada)河的一条支流——奥尔桑(Orsang)河谷发现了一具孤立的智人头骨,这对于了解印度人类进化历史和南亚直立人与最古老的亚洲智人(或AMH,解剖学上现代的人)之间的联系有着重要的意义。化石是在古老的河流沉积物中发现的。对主体沉积和颅内沉积物的红外光释光(IRSL)测年结果显示,其年代为3—5万年。然而,对化石的直接测年(放射性碳加速器质谱测年AMS)结果表明,其年代最小为4981—5579年前。头骨被归类为圆颅型智人。头骨上最引人注意的特征是颅外有亚洲直立人头后部很发达的角圆枕。头骨最宽处在下部(颞骨)如直立人,这样的情况从来不见于智人。这可能是由于乳突的气窦化而形成的。乳突上脊发育,从破损的眉间区(20mm)可以看到很宽的额窦。所有这些粗壮的特征都表明Orsang头骨和晚期亚洲直立人之间具有遗传连续性。     

Fractal dimension of the middle meningeal vessels: variation and evolution in Homo erectus, Neanderthals, and modern humans

The middle meningeal vascular network leaves its traces on the endocranial surface because of the tight relationship between neurocranial development and brain growth. Analysing the endocast of fossil specimens, it is therefore possible to describe the morphology of these structures, leading inferences on the cerebral physiology and metabolism in extinct human groups. In this paper, general features of the meningeal vascular traces are described for specimens included in the Homo erectus, Homo neanderthalensis, and Homo sapiens hypodigms. The complexity of the arterial network is quantified by its fractal dimension, calculated through the box-counting method. Modern humans show significant differences from the other two taxa because of the anterior vascular dominance and the larger fractal dimension. Neither the fractal dimension nor the anterior development are merely associated with cranial size increase. Considering the differences between Neanderthals and modern humans, these results may be interpreted in terms of phylogeny, cerebral functions, or cranial structural network.     

Relationship of cranial robusticity to cranial form,geography and climate in Homo sapiens

Variation in cranial robusticity among modern human populations is widely acknowledged but not well‐understood. While the use of “robust” cranial traits in hominin systematics and phylogeny suggests that these characters are strongly heritable, this hypothesis has not been tested. Alternatively, cranial robusticity may be a response to differences in diet/mastication or it may be an adaptation to cold, harsh environments. This study quantifies the distribution of cranial robusticity in 14 geographically widespread human populations, and correlates this variation with climatic variables, neutral genetic distances, cranial size, and cranial shape. With the exception of the occipital torus region, all traits were positively correlated with each other, suggesting that they should not be treated as individual characters. While males are more robust than females within each of the populations, among the independent variables (cranial shape, size, climate, and neutral genetic distances), only shape is significantly correlated with inter‐population differences in robusticity. Two‐block partial least‐squares analysis was used to explore the relationship between cranial shape (captured by three‐dimensional landmark data) and robusticity across individuals. Weak support was found for the hypothesis that robusticity was related to mastication as the shape associated with greater robusticity was similar to that described for groups that ate harder‐to‐process diets. Specifically, crania with more prognathic faces, expanded glabellar and occipital regions, and (slightly) longer skulls were more robust than those with rounder vaults and more orthognathic faces. However, groups with more mechanically demanding diets (hunter‐gatherers) were not always more robust than groups practicing some form of agriculture. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.     

Energetics in Homo erectus and other early hominins: the consequences of increased lower-limb length

Previous studies of daily energy expenditure (DEE) in hominin fossils have estimated locomotor costs using a formula that was based on six species, all 18 kg or less in mass, including no primates, and that has a number of other problems when applied in an ecological context. It is well established that the energetic cost of human walking is lower than that of representative mammals, particularly for individuals with long lower limbs. The current study reevaluates the daily energy expenditures of a variety of hominin species using more appropriate approaches to estimating locomotor costs. To estimate DEE for primates, I relied on published data on body mass, day range, and the percentage of time spent in various activities. Based on those data, I calculated a value for nonlocomotor DEE. I then used a variant of a method that I have suggested elsewhere to calculate the daily cost due to locomotion (DEEL) and summed the two to calculate total DEE. The more up-to-date methods for calculating the cost of travel result in lower estimates of this aspect of the energy budget than seen in previous studies. Values obtained here for DEE in various representatives of Australopithecus are lower than reported previously by around 200 kcal/day. Taking into account the greater economy of human walking, particularly the effect of the longer lower limbs found in many later Homo species, also results in lowered estimates of DEE. Elongation of the lower limbs in H. erectus reduced relative travel costs nearly 50% in comparison to A.L. 288-1 (A. afarensis). The present method for calculating DEE indicates that female H. erectus DEE was 84% greater than that of female Australopithecus; this disparity is even larger than that suggested by previous workers.     

中国蜘蛛抱蛋属一新记录种——合瓣蜘蛛抱蛋

首次报道中国蜘蛛抱蛋属一新记录种——合瓣蜘蛛抱蛋Aspidistra connata H.-J.Tillich,该种与辐花蜘蛛抱蛋A.subrotata Y.Wanet C.C.Huang相似,但叶片长椭圆形至长卵状椭圆形,花被顶端8～10裂,裂片线形,顶端联合不分开,形成一个笼状包围着雌蕊可与后者区别。凭证标本存放于广西植物标本馆(IBK)。     

亚洲玉米螟与欧洲玉米螟混生区的研究

生殖隔离试验、形态鉴定、网室内性信息素活性反应和食性试验的结果表明 :张家口苍耳中的玉米螟与新疆伊宁的欧洲玉米螟同种 ,而为害玉米的优势种与广东阳山的亚洲玉米螟同种。张家口为害玉米的种群中 ,有部分雄蛾对欧洲玉米螟性信息素及苍耳中的雌处女蛾具有反应。苍耳和玉米中的种群在玉米、谷子、高梁、苍耳、草和大马蓼等 6种寄主上均可产卵和取食为害 ,并能正常完成生活史。研究结果证实张家口为亚洲玉米螟和欧洲玉米螟混生区 ,而且在玉米中很可能有少量欧洲玉米螟与亚洲玉米螟混生。