人类历史有多长

人类起源是大家关心的问题。唯心主义者往往信口开河编造种种谎言蒙骗和吓唬轻信的人们,妄图达到其不可告人的目的。“法轮大法”会长李洪志说人是外星掉下来的,就是一个例子。他有证据吗？没有。他还说过有美国科学家发现过踩在２－６亿年前的三叶虫化石上的人类脚印（而且据他说还是穿了鞋的）化石,似乎是提出了化石证据,但是他能说出这个科学家的名字吗？资料刊登在什么学术刊物？有照片吗？实物现存何处？有哪些科学家检验过并且认可这些发现？他没有说,也肯定说不出来。这正表明他宣扬的是伪科学。唯物主义者对人类来源问题却是根…     

生态学的新进展——评《人类生态学》

由云南大学周鸿教授主编 ,高等教育出版社出版的《人类生态学》一书 ,是一本面向 2 1世纪高等人才培养的一门基础课程教材。这本教材是新世纪出版的第一本知识内容全面系统、具有特色和创新的人类生态学。该书的出版 ,标志着新时代的中国教育思想和生态科学出现了巨大变革。教育是一种手段 ,它的时代使命是培养适应社会当前发展、更着重于未来发展需要的各种专业人才。中国教育部把生态学纳入 2 1世纪高等教育的基础教学内容 ,并精心组织了《人类生态学》教材的编写及出版。这是中国教育改革的一项高瞻远瞩的战略决策。从 1972年开展第一个…     

由小见大--解读古代人类生活之谜

考古,简单的说就是通过研究古代人类留下的生活遗物、遗迹、遗址等,来复原他们当时的生活状况。但是有人曾经说过,古代人类能够遗留下来的东西仅占当时他们所拥有的1％,而被我们考古工作发现的仅仅是这1％之中的1％。如何通过这些少之又少的痕迹复原当时复杂的人类活动呢?考古学家们动用了各种方法。微痕,就如同警察手中所持的放大镜一样,为我们展现当时生活生产场景增加了一个新的工具。     

比较基因组学和人类基因组研究

在人类基因组计划突飞猛时地开展的同时,模式生物基因组计划也在轰轰烈烈地进行,并取得许多实质性的进展,是人类对于模式生物基因组有了更广泛更深刻的认识。这些知识的积累,从根本上推动了人类基因组计划的进行。     

人类对气候的适应

在长期的进化中,人类的体质特征出现了种种差异。正是体质特征的多样化,才使人类能够适应各种不同的气候环境。发汗机能的获得人类能适应炎热酷暑,一个重要的原因是获得了发汗机能。人类祖先出现在气候比今天温暖的第三纪,与各种灵长类动物栖息于非洲大陆绵延不绝的热带森林中。从第三纪后期开始,气温骤降,造成森林消退草原扩大,包括人类祖先在内的许多哺乳动物便迁往食物丰富的热带草原去生活。与枝叶茂密的森林不同,草原上阳光直射引起辐射温度升高,白天特别酷     

雌酚酮体外影响骨生长的形态学研究

目的：从组织形态学角度综合考察雌酚酮在体外对骨吸收和骨形成的影响。方法：１６ｄ胎龄雌性小鼠尺骨在含有雌酚酮的ＢＧＪｂ培养基中旋转培养４８ｈ后,测量骨总长和骨干长度;Ｈ．Ｅ染色,光镜下计数破骨细胞和肥大软骨细胞。结果：当雌酚酮浓度为１０＾－７ｍｏｌ／Ｌ时,长骨总长和骨干长均比对照组显著增加;破骨细胞减少,肥大软骨细胞增加。结论：雌酚酮在体外可抑制骨吸收,促进骨形成。     

A Procedure for Preparing Undecalcified and Unembedded Bone Sections for Light Microscopy

We have developed a procedure for light microscopic investigation of undecalcified and unembeddedbone sections. Biopsy samples of human metatarsus and femur and rat femur were fixed in aldehydes and sectioned with a cutting machine equipped with a diamond saw blade. Free sections 100-150 μm thick, stained with toluidine blue and von Kossa, did not show artifacts following the cutting, and the spatial relations of mineralized and nonmineralized components remained intact. Compact and trabecular bone, bone marrow and all cell types appeared well preserved and easily recognizable. Our procedure provides a simple and rapid method for preparing bone sections which undergo no chemical treatment other than fixation. This method is a useful alternative to standard histological protocols for studying bone specimens.     

Therapeutic potentials and modulatory mechanisms of fatty acids in bone

Bone metabolism is a lifelong process that includes bone formation and resorption. Osteoblasts and osteoclasts are the predominant cell types associated with bone metabolism, which is facilitated by other cells such as bone marrow mesenchymal stem cells (BMMSCs), osteocytes and chondrocytes. As an important component in our daily diet, fatty acids are mainly categorized as long‐chain fatty acids including polyunsaturated fatty acids (LCPUFAs), monounsaturated fatty acids (LCMUFAs), saturated fatty acids (LCSFAs), medium‐/short‐chain fatty acids (MCFAs/SCFAs) as well as their metabolites. Fatty acids are closely associated with bone metabolism and associated bone disorders. In this review, we summarized the important roles and potential therapeutic implications of fatty acids in multiple bone disorders, reviewed the diverse range of critical effects displayed by fatty acids on bone metabolism, and elucidated their modulatory roles and mechanisms on specific bone cell types. The evidence supporting close implications of fatty acids in bone metabolism and disorders suggests fatty acids as potential therapeutic and nutritional agents for the treatment and prevention of metabolic bone diseases.     

Scaling of Haversian canal surface area to secondary osteon bone volume in ribs and limb bones

Studies of secondary osteons in ribs have provided a great deal of what is known about remodeling dynamics. Compared with limb bones, ribs are metabolically more active and sensitive to hormonal changes, and receive frequent low‐strain loading. Optimization for calcium exchange in rib osteons might be achieved without incurring a significant reduction in safety factor by disproportionally increasing central canal size with increased osteon size (positive allometry). By contrast, greater mechanical loads on limb bones might favor reducing deleterious consequences of intracortical porosity by decreasing osteon canal size with increased osteon size (negative allometry). Evidence of this metabolic/mechanical dichotomy between ribs and limb bones was sought by examining relationships between Haversian canal surface area (BS, osteon Haversian canal perimeter, HC.Pm) and bone volume (BV, osteonal wall area, B.Ar) in a broad size range of mature (quiescent) osteons from adult human limb bones and ribs (modern and medieval) and various adult and subadult non‐human limb bones and ribs. Reduced major axis (RMA) and least‐squares (LS) regressions of HC.Pm/B.Ar data show that rib and limb osteons cannot be distinguished by dimensional allometry of these parameters. Although four of the five rib groups showed positive allometry in terms of the RMA slopes, nearly 50% of the adult limb bone groups also showed positive allometry when negative allometry was expected. Consequently, our results fail to provide clear evidence that BS/BV scaling reflects a rib versus limb bone dichotomy whereby calcium exchange might be preferentially enhanced in rib osteons. Am J Phys Anthropol 151:230–244, 2013. © 2013 Wiley Periodicals, Inc.     

Regional program for bone allograft harvesting following multiorgan procurement in Pomeranian Academy of Medicine in Szczecin

In Poland, up to 1999, the bones for allograft preparations had been procured only in mortuaries of forensic medicine departments. The increasing demand for bone transplantations greatly exceeds the supply resulting in a long waiting time for bone allografts. In November 1999, for the first time in Poland, the group of orthopedic surgeons from the Pomeranian Academy of Medicine started the regional program for bone harvesting following vascularized organ procurements. The aim of this paper is to present the technical details and limitations of bone harvesting that occurred in 10 out of 25 multiorgan procurements. This revised version was published online in July 2006 with corrections to the Cover Date.     

The influence of plane of section on the identification of bone tissue types in amniotes with implications for paleophysiological inferences

The proportion of woven bone (WB) to parallel-fibered bone has been extensively used to infer bone growth rates and resting metabolic rates of extinct organisms. The aim of this study is to test in a variety of amniotes how reliably WB content can be measured using transverse sections. For this, we analyzed femoral transverse mid-diaphyseal thin sections of 14 extant and extinct taxa and the corresponding longitudinal sections for comparative purposes. We used the following characters to identify WB in transverse sections because they are known to be distinct from those observed in parallel-fibered bone: an isotropic bone matrix at tissue scale; an anisotropic microlamellar arrangement in former osteoblast secretory territories at cellular scale; no alignment between osteocytes; and canaliculi running radially from large irregular osteocyte lacunae. Our null hypothesis predicts no differences between the amount of WB quantified in the transverse and longitudinal sections of a given long bone. Qualitatively, when a stripe or a patch of WB was identified in a transverse section, the corresponding stripe or patch of WB was always found at the same location in the corresponding longitudinal section. Quantitatively, a Wilcoxon signed-rank nonparametric paired test did not detect a significant difference in the WB content of the two section planes. Thus, the null hypothesis is not rejected. Considering that paleohistology is a destructive method, we recommend a workflow to efficiently establishing the proportion of WB: quantifying it in transverse sections; preparing and analyzing longitudinal sections only in cases where an ambiguity remains; reanalyzing the corresponding transverse sections.     

Bone strain magnitude is correlated with bone strain rate in tetrapods: implications for models of mechanotransduction

Hypotheses suggest that structural integrity of vertebrate bones is maintained by controlling bone strain magnitude via adaptive modelling in response to mechanical stimuli. Increased tissue-level strain magnitude and rate have both been identified as potent stimuli leading to increased bone formation. Mechanotransduction models hypothesize that osteocytes sense bone deformation by detecting fluid flow-induced drag in the bone''s lacunar–canalicular porosity. This model suggests that the osteocyte''s intracellular response depends on fluid-flow rate, a product of bone strain rate and gradient, but does not provide a mechanism for detection of strain magnitude. Such a mechanism is necessary for bone modelling to adapt to loads, because strain magnitude is an important determinant of skeletal fracture. Using strain gauge data from the limb bones of amphibians, reptiles, birds and mammals, we identified strong correlations between strain rate and magnitude across clades employing diverse locomotor styles and degrees of rhythmicity. The breadth of our sample suggests that this pattern is likely to be a common feature of tetrapod bone loading. Moreover, finding that bone strain magnitude is encoded in strain rate at the tissue level is consistent with the hypothesis that it might be encoded in fluid-flow rate at the cellular level, facilitating bone adaptation via mechanotransduction.