Effects of deprivation on exercise play in nursery school children

The incidence of exercise play outdoors was observed in nursery school children aged three to four years, after a short or long period of confinement indoors. For both boys and girls there was a greater incidence of exercise play after the long period of confinement, the levels of exercise play decreasing with time. No sex differences were obtained. The results are considered in relation to theories of the functional significance of exercise play.     

The upper paleolithic of Europe: An overview

The Upper Paleolithic of Europe, 40,000–10,000 years ago, presents one of the richest, most complex records for the anatomy and cultural adaptations of fossil hominids in the world. New chronological information points to roughly simultaneous appearance of certain Upper Paleolithic technological traits in both SE and SW Europe, while growing evidence suggests a significant degree of biological and cultural continuity between the Middle and Upper Paleolithic. On the other hand, there is considerable evidence that evolution continued to operate in both domains throughout the course of the late Upper Pleistocene, apparently in adaptive relationship to the major environmental changes of the Upper Pleniglacial and Tardiglacial. Spectacular developments in the realms of art and ideology may be understood in the special biogeographical, social, and economic conditions of Europe at the height of the Last Ice Age; both ended rather abruptly with the onset of the Holocene as the landscapes of Europe underwent pervasive upheavals.     

蔚县盆地2019-2020年旧石器考古调查

作为广义泥河湾盆地的重要组成部分,蔚县盆地也曾是更新世期间古人类生存活动的重要地区。2019-2020年度在蔚县盆地开展了新一轮的旧石器考古调查工作,发现并确认18处旧石器和动物化石地点,获得35件石制品以及少量动物化石。从文化遗存的出露层位来看,泥河湾河湖相地层和黄土堆积是遗物埋藏的主要地貌部位。石制品类型包括石锤、石核(含细石核)、废片和工具;原料以火山岩、燧石和石英岩为主;石核剥片和工具修理均主要采用锤击法。技术类型总体上包含了简单石核石片技术和细石叶技术两套组合。结合相关地貌、地层对比资料以及石制品的类型特征,初步推测新地点的时代分别为中更新世和晚更新世,其中含细石叶技术制品地点的年代应为晚更新世晚期。     

Modeling effects of local extinctions on culture change and diversity in the paleolithic

The persistence of early stone tool technologies has puzzled archaeologists for decades. Cognitively based explanations, which presume either lack of ability to innovate or extreme conformism, do not account for the totality of the empirical patterns. Following recent research, this study explores the effects of demographic factors on rates of culture change and diversification. We investigate whether the appearance of stability in early Paleolithic technologies could result from frequent extinctions of local subpopulations within a persistent metapopulation. A spatially explicit agent-based model was constructed to test the influence of local extinction rate on three general cultural patterns that archaeologists might observe in the material record: total diversity, differentiation among spatially defined groups, and the rate of cumulative change. The model shows that diversity, differentiation, and the rate of cumulative cultural change would be strongly affected by local extinction rates, in some cases mimicking the results of conformist cultural transmission. The results have implications for understanding spatial and temporal patterning in ancient material culture.     

Lifting the cloak of invisibility: the effects of changing optical conditions on pelagic crypsis

While transparency, cryptic coloration, and counterilluminationare all highly successful cryptic strategies for pelagic species,they become less effective when confronted with varying opticalconditions. Transparent species are susceptible to detectionby reflections from their body surface, particularly at shallowdepths. Colored and mirrored species are vulnerable to detectionwhen viewed from certain angles, or at certain times of day.Counterilluminating species must cope with the changes in theangular distribution and spectra of downwelling light at differentdepths. In all cases the vulnerabilities are more pronouncedat shallow depths and essentially negligible at depths greaterthan 200 m. The results suggest interesting adaptations bothfor crypsis (e.g., anti-reflection coatings, variable coloration,variable filters for photophores) and for visual detection (e.g.,circling, crepuscular predation), all of which are potentiallyfruitful topics for future research.     

Determining the role that ecological and developmental constraints play in controlling disparity: examples from the crinoid and blastozoan fossil record

It is widely believed that morphological constraints are responsible for the observed pattern of decreasing major morphological innovation in both the Metazoa and Metaphytes over geological time. This is readily seen as the decreasing trend of origination of higher taxa: phyla, classes, and orders. Currently, there are two competing evolutionary hypotheses that have been proposed to explain this phenomenon: (1) the empty ecospace hypothesis and (2) the developmental constraint hypothesis. To distinguish between hypotheses 1 and 2, the change of morphological innovation before and after several mass extinction events was measured in the Crinoidea and Blastozoa. Mass extinction intervals provided a means in which to remove ecospace limiting constraints and allow the developmental constraint hypothesis to be thoroughly tested. Within the Crinoidea, disparity was measured before and after three mass extinctions. Within the Blastozoa, disparity was measured before and after two mass extinctions. For each taxon, three suites of characters were analyzed: ecological, nonecological, or "developmental" and a combination of the two previous suites plus 50 additional characters. Four different measures of disparity were used to analyze each character suite. In the majority of the cases investigated, disparity rebounds to comparable levels or in some cases higher levels in both the Crinoidea and Blastozoa. The results indicate that developmental constraints are not responsible for the decrease in disparity throughout the geologic range of the taxa. The more likely scenario is that increasingly structured ecological guilds have made it much more difficult to allow large increases in disparity.     

Principal Contradictions in the Child's Developing Mind

In this chapter we recapitulate our investigations over the past fifteen years and present our interpretation concerning the basic line and mechanism of psychological development in preschool age.     

New Data on the Ontogeny of the Child's Sleep-Wake Rhythm

The present study is part of a broader body of research concerning the ontogeny and regulations of the young child's sleep-wake rhythm. It was carried out with 12 children admitted to a day-care center from 4 or 5 months of age. None of the children showed any anomalies or functional disorders. The method used in this study consisted in organizing a data collection on the alternations of wakefulness and sleep as well as on the children's behavior throughout the 24-h period, both in their family and at the day-care center from 4 to 15 months of age. The main findings are (a) the circadian rhythm of wakefulness and sleep is clearly set up as early as at 4 months of age and consolidates between 6 and 7 months; (b) some ages are characterized by significant changes in the daily distribution and duration of sleep spans: 6 to 7 months; 10to 12months; 13to 15 months; (c) these changes suggest the existence of several ultradian rhythmicities which become successively prevailing from one age to the next throughout child development. The longitudinal study of the young child's sleep-wakefulness rhythm allows better evaluation of the influence of developmental factors in its structuralization and formulation of new hypotheses on its disorders and dysfunction. Individual factors are under study.     

Metric dental change in the European upper paleolithic and mesolithic.

Evolutionary trends for dental reduction are presented for European Upper Paleolithic and Mesolithic samples. The analysis demonstrates that the greatest decrease in tooth size occurs between the two divisions of the Upper Paleolithic, while little and insignificant change characterizes the Late Upper Paleolithic/Mesolithic transition. Trends for tooth size over this period indicate that (1) human evolution does not stop with the appearance of "anatomically modern Homo sapiens," (2) changes in tooth size fluctuate with increases in the efficiency and complexity of cultural systems, and (3) the Early Upper Paleolithic sample should be considered transitional between Wurm II European Neanderthals and later Upper Paleolithic and Mesolithic groups.     

Facilitating play through communication: significance of teeth exposure in the gorilla play face

Primate facial expressions (FEs) likely play an important role in primate society: through facial signals, individuals can potentially send and receive information and may benefit from coordinating their behavior accordingly. Many primates use a relaxed open mouth (ROM) facial display or “play face” (PF) during play behavior, where the mouth is open but teeth are covered. In addition to this conventional PF, however, Western Lowland gorillas (Gorilla gorilla gorilla) also use a full PF where the upper teeth are exposed. As the teeth are similarly exposed in the bared-teeth expression (which is a signal of appeasement, submission and/or affiliation), the full PF may be a blend of the PF and bared-teeth face, and have a different signal function to the PF alone. Focal animal sampling of captive Western Lowland gorillas (N=10) showed that the full PF was more often observed in intense rather than gentle play, and intense play bouts that featured the full PF were longer than those that featured only the PF. Both expressions were associated with an increase in affinitive behavior between sender and receiver postplay, but only the full PF was associated with an increase higher than that of play alone. Overall, the findings suggest that the full PF has an additional role in coordinating and maintaining play, possibly though reducing uncertainty in the receiver and confirming that play is only play.