Evidence for age-related changes in the circadian activity rhythm of the diurnal primate Callithrix jacchus: a case report

Many cross-sectional studies have shown that circadian rhythms change with age, but such age-related modifications are gradual and may be insufficiently described by cross-sectional studies. In this case study, circadian activity rhythm (CAR) was evaluated longitudinally, in both LD (12:12) and LL conditions, on two occasions in a single male marmoset: when ‘adult’ (3 y.o.) and when ‘old’ (9 y.o.). When adult, the CAR synchronized with positive phase angles for the onset and offset of activity. In LL, the rhythm free-ran with τ < 24 h. When old, the animal showed a significant phase delay of its activity rhythm with respect to the LD cycle (t-test, p < 0.01) and a reduction on total daily activity (t-test, p < 0.01), with signs of lesser stability, greater fragmentation and some loss of photic synchronization. In LL, the period free-ran with τ > 24 h. We conclude that aging is associated with attenuation of photic synchronization and expression of CAR in LL in the marmoset. Further studies with a larger number of individuals are needed to confirm these findings.     

Adaptations for social cognition in the primate brain

Studies of the factors affecting reproductive success in group-living monkeys have traditionally focused on competitive traits, like the acquisition of high dominance rank. Recent research, however, indicates that the ability to form cooperative social bonds has an equally strong effect on fitness. Two implications follow. First, strong social bonds make individuals'' fitness interdependent and the ‘free-rider’ problem disappears. Second, individuals must make adaptive choices that balance competition and cooperation—often with the same partners. The proximate mechanisms underlying these behaviours are only just beginning to be understood. Recent results from cognitive and systems neuroscience provide us some evidence that many social and non-social decisions are mediated ultimately by abstract, domain-general neural mechanisms. However, other populations of neurons in the orbitofrontal cortex, striatum, amygdala and parietal cortex specifically encode the type, importance and value of social information. Whether these specialized populations of neurons arise by selection or through developmental plasticity in response to the challenges of social life remains unknown. Many brain areas are homologous and show similar patterns of activity in human and non-human primates. In both groups, cortical activity is modulated by hormones like oxytocin and by the action of certain genes that may affect individual differences in behaviour. Taken together, results suggest that differences in cooperation between the two groups are a matter of degree rather than constituting a fundamental, qualitative distinction.     

晚第三纪武汉地区的化石木对当地古气侯的指相

研究了我国地质年代为晚第三纪,地理位置在湖北省武汉市新洲县阳逻镇２２个树种的化石木其中裸子植物７种,被子植物１５种。中国被子植物化石木是笔者１９８７年首镒发掘和鉴定的。武汉地区发掘的这１５种均是热带或亚热带的被子植物,特别是苏木科的顶果木蝶蝶形花科的海南红豆和大戟科的秋枫更是武汉地区今日未见的典型热带阔叶树种。     

Seroprevalence of specific viral infections in confiscated orangutans (Pongo pygmaeus)

A serological survey of confiscated orangutans was conducted to determine the prevalence of specific viral infections cross reacting with human viruses. Antibodies specific for human hepatitis A (HAV) and B (HBV) viruses, herpes simplex viruses (HSV), and human T-lymphotropic virus (HTLV types I and II), as well as for the simian type D retroviruses (SRV types 1 to 3) and simian immunodeficiency virus (SIV) were tested in samples from 143 orangutans. Results revealed a high prevalence of potential pathogens. The most prevalent viral infection found was HBV (59.4% prevalence) of which 89.4% of infected individuals seroconverted to the non-infectious state and 10.6% remained as chronic carriers. Antibodies to HAV, HSV, HTLV-1, and SRV were also detected but at a lower prevalence. There was no evidence of lentiviral infections in this group of animals. The results confirm the importance of quarantine and the need for diagnostic differentiation of virus infections to determine if they are of human origin or unique orangutan viruses.     

Optimal digestive strategies for arboreal herbivorous mammals in contrasting forest types: Why Koalas and Colobines are different

Abstract The eucalypt forests of temperate eastern Australia contrast with many forests in tropical Australia, Asia, Africa and Central America in terms of degrees of sclerophylly, concentrations of nutrients in foliage, types and amounts of chemical challenges posed for herbivores, and the range of alternatives to foliage as food. Comparisons between digestive strategies employed by arboreal herbivorous marsupials and primates inhabiting these forests reveal several trends: (i) foregut-fermenters occur only in tropical and sub-tropical forests, whereas caecum and caecum-colon fermenters occur in both temperate eucalypt and the tropical forests; (ii) the arboreal marsupials and primates (koalas, greater gliders, ringtail possums and sportive lemurs) that are the most folivorous are caecum or caecum-colon fermenters with colonic specializations for selective retention of small panicles of digesta; (iii) no caecum or caecum- colon fermenters lacking colonic separation mechanisms achieve consistently high degrees of folivory; (iv) even the most folivorous foregut-fermenting arboreal marsupials (tree kangaroos) or primates (colobus monkeys) include a substantial proportion of high-quality components (fruits or seeds) in their diet. Caecum or caecum-colon fermentation with colonic separation is postulated to be essential for a high degree of folivory in small mammals because it offsets potential limits on intake of high-fibre food and minimizes losses of faecal nitrogen that otherwise would be prohibitive. This digestive strategy is common among folivores in eucalypt forests because the low abundance of large seeds and fleshy fruits limits folivory-frugivory and folivory-granivory. Foregut fermentation employing a sacciform/ tubiform forestomach (as in tree kangaroos and colobus monkeys) is postulated to be optimal for mixed leaf/fruit and leaf/seed diets that are available in many tropical forests, assuming it allows high-fibre meals to be retained for microbial fermentation while permitting low-fibre meals to pass rapidly to the hindstomach for acid/enzymic digestion. However, foregut fermentation appears innappropriate for either primary frugivory or exclusive folivory due to the inefficiency of microbial digestion of simple sugars and constraints on microbial fermentation as a primary energy source for small mammals.     

内蒙古霍林河煤田罗汉松科几种丝炭化木化石的研究

对采自内蒙古霍林河煤田霍林河组下含煤段的丝炭化木化石进行了扫描电镜观察和描述。经鉴定属于Ｐｏｄｏｃａｒｐｏｘｙｌｏｎ ｄａｃｒｙｄｉｏｉｄｅｓ ｓｐ．ｎｏｖ。、Ｐｏｄｏｃａｒｐｏｘｙｌｏｎ ｓｐ．、Ｐｈｙｌｌｏｃｌａｄｏｘｙｌｏｎ ｓｐ．１和Ｐｈｌｌｏｃｌａｄｏｘｙｌｏｎ ｓｐ．２。Ｐｏｄｏｃａｒｐｏｘｙｌｏｎ和Ｐｈｙｌｌｏｃｌａｄｏｘｙｌｏｎ是罗汉松科的两种古老的木材类型。     

杉科植物的起源、演化及其分布

本文根据对杉科的系统发育、现代分布和化石分布的研究,结合古地理和古气候资料,讨论了杉科的起源、演化和现代分布格局的成因。杉科基本上是一个亚热带科,我国长江、秦岭以南至华南一带是其现代分布中心。东亚中高纬度的东北地区可能是其起源中心和早期分化中心。起源时间为早侏罗纪或晚三叠纪。杉科植物的各种类型很可能在早白垩纪甚至晚侏罗纪就已分化出来。杉科植物于东亚起源后,在当时劳亚古陆尚未完全解体、气候分带现象尚不甚明显的情况下跨越欧亚大陆散布到北美,并扩散到南半球。自晚白垩纪,白令陆桥和北大西洋陆桥对其在北半球的散布发挥了重要作用。杉科植物目前虽处于衰退状态,但在地质史上却曾经经历过极其繁盛的时代。在中生代中晚期和早第三纪,杉科植物种类繁多,广布于北半球,向北扩散到北极圈内的高纬度地区,是当时的大科。大多数现存属曾分别有过3个或2个分布中心：水松属、落羽杉属和北美红杉属在东亚、北美西部和欧洲;水杉属在东亚和北美西部;柳杉属、杉木属,很可能也包括台湾杉属在东亚和欧洲;巨杉属在欧洲、北美和东亚。在晚白垩纪和第三纪,现存属特别是水松属、落羽杉属、水杉属、北美红杉属和巨杉属,曾是北半球森林植被的重要组成成分。南半球也曾有少量种类,分布亦远较现代普遍。杉科在白垩纪的多样性达到鼎盛,具所有的现代属和大量的化石器官属,但在以后漫长的历史发展过程中,由于地质变迁、气候变化,大量类群绝灭。晚第三纪全球性的气温下降迫使杉科逐渐从高纬度地区撤出。第四纪冰期气候的剧烈恶化使杉科分布区进一步显著退缩至中、低纬度地区,最后在欧洲全部消失,仅在东亚、北美及澳大利亚的少数几个植物 “避难所”中残存下来。现今各属多分布于环太平洋地区极为狭窄的局部范围,在分布区内呈现出孤立或星散的残遗分布式样。杉科现存各属均为古老的孑遗或残遗类群。     

Basicranial flexion,relative brain size,and facial kyphosis in Homo sapiens and some fossil hominids

Comparative work among nonhominid primates has demonstrated that the basicranium becomes more flexed with increasing brain size relative to basicranial length and as the -upper and lower face become more ventrally deflected (Ross and Ravosa [1993] Am. J. Phys. Anthropol. 91:305–324). In order to determine whether modern humans and fossil hominids follow these trends, the cranial base angle (measure of basicranial flexion), angle of facial kyphosis, and angle of orbital axis orientation were measured from computed tomography (CT) scans of fossil hominids (Sts 5, MLD 37/38, OH9, Kabwe) and lateral radiographs of 99 extant humans. Brain size relative to basicranial length was calculated from measures of neurocranial volume and basicranial length taken from original skulls, radiographs, CT scans, and the literature. Results of bivariate correlation analyses revealed that among modern humans basicranial flexion and brain size/basicranial length are not significantly correlated, nor are the angles of orbital axis orientation and facial kyphosis. However, basicranial flexion and orbit orientation are significantly positively correlated among the humans sampled, as are basicranial flexion and the angle of facial kyphosis. Relative to the comparative sample from Ross and Ravosa (1993), all hominids have more flexed basicrania than other primates: Archaic Homo sapiens, Homo erectus, and Australopithecus africanus do not differ significantly from Modern Homo sapiens in their degree of basicranial flexion, although they differ widely in their relative brain size. Comparison of the hominid values with those predicted by the nonhominid reduced major-axis equations reveal that, for their brain size/basicranial length, Archaic and Modern Homo sapiens have less flexed basicrania than predicted. H. erectus and A. africanus have the degree of basicranial flexion predicted by the nonhominid reduced major-axis equation. Modern humans have more ventrally deflected orbits than all other primates and, for their degree of basicranial flexion, have more ventrally deflected orbits than predicted by the regression equations for hominoids. All hominoids have more ventrally deflected orbital axes relative to their palate orientation than other primates. It is argued that hominids do not strictly obey the trend for basicranial flexion to increase with increasing relative brain size because of constraints on the amount of flexion that do not allow it to decrease much below 90°. Therefore, if basicranial flexion is a mechanism for accommodating an expanding brain among non-hominid primates, other mechanisms must be at work among hominids. © 1995 Wiley-Liss, Inc.     

Sexual selection and sperm competition in primates: What are male genitalia good for?

One hundred twenty-five years ago, in The Descent of Man and Selection in Relation to Sex,¹ Charles Darwin proposed the theory of sexual selection, as distinct from natural selection, to explain why, in some species, males have such magnificent ornaments and, in other species, such impressive weapons. He suggested two processes, which we now term female choice and male-male competition: either females choose particularly ornate males or, alternatively, relatively passive females accept the winner of fights among males. By now, knowledge of species in which the females are more brightly colored or aggressive than males has led to a more general formulation of the principle of sexual selection, in which, instead of “females”, we write “the sex with the lower potential reproductive rate”, and, instead of “male”, “the sex with the higher potential reproductive rate”.²