The 1909 Darwin celebration. Reexamining evolution in the light of Mendel, mutation, and meiosis

In June 1909, scientists and dignitaries from 167 different countries gathered in Cambridge to celebrate the hundredth anniversary of Charles Darwin's birth and the fiftieth anniversary of the publication of Origin of Species. The event was one of the most magnificent commemorations in the annals of science. Delegates gathered within the cloisters of Cambridge University not only to honor the "hero" of evolution but also to reassess the underpinnings of Darwinism at a critical juncture. With the mechanism of natural selection increasingly under attack, evolutionary theory was in disarray. Against this backdrop, biologists weighed the impact of several new developments--the rediscovery of Mendel's laws of heredity, de Vriesian mutation theory, and the linkage of sex-cell division (recently named "meiosis") to the mechanism of heredity. The 1909 Darwin celebration thus represents a significant watershed in the history of modem biology that allows historians to assess the status of evolution prior to the advent of the chromosome theory of genetics.     

Use of a mnemonic technique to teach young children foreign language vocabulary

Children 3 to 6 years of age learned simple Spanish vocabulary items using an adaptation of the keyword method of foreign language vocabulary learning. Using this version of the keyword method, the learner remembered a picture of the translation referent of the vocabulary item interacting with the referent of a concrete English word which sounded like part of the foreign word (the keyword). Children who used the keyword method remembered more vocabulary translations than children who were not instructed in keyword method usage.     

The Origins of Parenting Stress During the Transition to Parenthood: A New Family Model

This paper describes the origins of parenting stress, defined both as tensions in the parent-child relationship and as broader changes in five family domains as men and women make the transition from couple to family life. Despite significant change in their average level of functioning, parents show continuity in their level of adaptation from pregnancy through the first five years of parenthood. Parenting stress emerges from the context of parents' individual and marital adaptation before the child is born. It is possible to identify expectant parents who are at risk for later parenting stress and lower well-being across employment and family domains. Path analyses show that men's and women's prior well-being and their involvement in paid work during pregnancy are associated with higher parenting stress—and lower self-esteem, marital satisfaction, family work satisfaction, and job satisfaction—two years later when their babies are 18months old. Stress in the parent-child relationship at 18 months postpartum compounds preexisting stress in other family domains to reduce well-being in other aspects of family life. Links among parenting stress, parenting quality, and children's adaptation to school lead to suggestions for preventive interventions early in the family life cycle.     

Enrollment in Physical Education Is Associated With Overall Physical Activity in Adolescent Girls

Little is known about population-level contributions of school physical education to overall physical activity (PA) in youth. Because PA levels are lower in girls than boys, it is particularly important that the effects of PE programs in adolescent girls be understood. Thus, the purpose of this study was to determine the association of enrollment in physical education and overall physical activity participation in adolescent girls. A measurement protocol was administered to cross-sectional samples of 8th-, 9th-, and 12th-grade girls participating in a school-based PA intervention study (1998–2003). PA was assessed with the 3-Day Physical Activity Recall. Three-way analyses of variance were performed to compare groups formed on the basis of physical education enrollment. For each grade group of girls, those who were enrolled in physical education reported more moderate-to-vigorous PA and more vigorous PA than nonenrolled girls. When activity in physical education classes was deleted, 8th-and 9th-grade physical education enrollees were not more active than nonenrollees; however, 12th-grade physical education enrollees remained more active than nonenrollees. Girls who were enrolled in physical education were more physically active than nonenrolled girls in all three grade levels. These findings suggest that expanded enrollment in physical education may increase American adolescent girls' PA level.     

Is Visually Guided Reaching in Early Infancy a Myth?

The issue examined was whether infants require sight of their hand when first beginning to reach for, contact, and grasp objects. 7 infants were repeatedly tested between 6 and 25 weeks of age. Each session consisted of 8 trials of objects presented in the light and 8 trials of glowing or sounding objects in complete darkness. Infants first contacted the object in both conditions at comparable ages (mean age for light, 12.3 weeks, and for dark, 11.9 weeks). Infants first grasped the object in the light at 16.0 weeks and in the dark at 14.7 weeks, a nonsignificant difference. Once contact was observed, infants continued to touch and grasp the objects in both light and dark throughout all sessions. Because infants could not see their hand or arm in the dark, their early success in contacting the glowing and sounding objects indicates that proprioceptive cues, not sight of the limb, guided their early reaching. Reaching in the light developed in parallel with reaching in the dark, suggesting that visual guidance of the hand is not necessary to achieve object contact either at the onset of successful reaching or in the succeeding weeks.