The sexual selection of hominin bipedalism

In this article, I advance a novel hypothesis on the evolution of hominin bipedalism. I begin by arguing extensively for how the transition to bipedalism must have been problematic for hominins during the Neogene. Due to this and the fact that no other primate has made the unusual switch to bipedalism, it seems likely that the selection pressure towards bipedalism was unusually strong. With this in mind, I briefly lay out some of the most promising hypotheses on the evolutionary origin of hominin bipedalism and show how most, if not all, fail in the face of the need for an unusually strong selection pressure. For example, some hypotheses maintain that hominins became bipedal so they could use their hands for carrying infants, food, or other valuable objects. But extant apes are able to carry objects in one of their front limbs (while walking with the other three), and thus it does not seem plausible that our hominin ancestors went through the troublesome transition to bipedalism just so they could carry objects a little more efficiently. After I show that past hypotheses are wanting in the face of this challenge, I argue that there is only one selection pressure powerful enough to instigate a strange and problematic evolutionary adaptation like bipedalism, and that is sexual selection. Specifically, from the fact that bipedal locomotion is an important strategy for intimidating others and ascending the dominance hierarchy in extant apes, I argue that for no particular selective reason bipedal locomotion became a signal for high fitness (much as a large and intricate tail became a signal for high fitness for peahens), and this led to the trait being continuously reinforced in spite of all its deleterious fitness consequences

Students' understandings of human organs and organ systems

How do people develop their understanding of what is inside them? This study looks at students' understandings of their internal structure. A cross-sectional approach was used involving a total of 158 students in England from six different age groups (ranging from 4 year-olds to first year undergraduates). Students were given a blank piece of A4-sized paper and asked to draw what they thought was inside themselves. Repeated inspections of the completed drawings allowed us to construct a seven point scale of these representations. Our analysis shows the extent to which student understanding increases with age and the degree to which pupils know more about some organs and organ systems than others. While gender differences in the drawings were generally not large there were some intriguing differences in the ways males and females drew reproductive organs

Seeing the natural world: a tension between pupils’ diverse conceptions as revealed by their visual representations and monolithic science lessons

In this paper we report on drawings of the natural environment produced by a sample of 13-14 year-olds. One of our interests is in the extent to which these young people see the world in the way rewarded in science lessons. With rare exceptions, school science generally assumes that for any scientific issue there is a single valid scientific conception so that alternative conceptions are misconceptions. The drawings reveal a plurality of ways in which the natural environment is portrayed and we conclude that there is scientific as well as other worth in this diversity. We argue that schools need to take account of this diversity; many pupils will not be interested in a single, monolithic depiction of the natural world in their school science lessons

Cultural variation in cognitive flexibility reveals diversity in the development of executive functions

Cognitive flexibility, the adaptation of representations and responses to new task demands, improves dramatically in early childhood. It is unclear, however, whether flexibility is a coherent, unitary cognitive trait, or is an emergent dimension of task-specific performance that varies across populations with divergent experiences. Three-to 5-year-old English-speaking U.S. children and Tswana-speaking South African children completed two distinct language-processing cognitive flexibility tests: the FIM-Animates, a word-learning test, and the 3DCCS, a rule-switching test. U.S. and South African children did not differ in word-learning flexibility but showed similar age-related increases. In contrast, U.S. preschoolers showed an age-related increase in rule-switching flexibility but South African children did not. Verbal recall explained additional variance in both tests but did not modulate the interaction between population sample (i.e., country) and task. We hypothesize that rule-switching flexibility might be more dependent upon particular kinds of cultural experiences, whereas word-learning flexibility is less cross-culturally variable

Toward-1mm depth precision with a solid state full-field range imaging system

Previously, we demonstrated a novel heterodyne based solid-state full-field range-finding imaging system. This system is comprised of modulated LED illumination, a modulated image intensifier, and a digital video camera. A 10 MHz drive is provided with 1 Hz difference between the LEDs and image intensifier. A sequence of images of the resulting beating intensifier output are captured and processed to determine phase and hence distance to the object for each pixel. In a previous publication, we detailed results showing a one-sigma precision of 15 mm to 30 mm (depending on signal strength). Furthermore, we identified the limitations of the system and potential improvements that were expected to result in a range precision in the order of 1 mm. These primarily include increasing the operating frequency and improving optical coupling and sensitivity. In this paper, we report on the implementation of these improvements and the new system characteristics. We also comment on the factors that are important for high precision image ranging and present configuration strategies for best performance. Ranging with sub-millimeter precision is demonstrated by imaging a planar surface and calculating the deviations from a planar fit. The results are also illustrated graphically by imaging a garden gnome

Australia’s Retail Superannuation Fund Industry: Structure, Conduct and Performance

In this analysis of Australiaâs superannuation arrangements it is our conjecture that the structure and conduct of the retail superannuation industry in Australia directly impacts performance, resulting in the delivery of costly funds management products which add minimal value for investors over the long term. In this study, we take the perspective of an investor faced with selecting a retail superannuation fund, and explore the extent to which various differentiating characteristics (such as style, rating and cost) provide insights into fund quality which uses a variety of asset pricing models for the period 1991 through 2003. The results of this study, suggest that investors cannot garner superior risk-adjusted returns through reliance on such characteristics.Superannuation funds, Australia; Performance evaluation

Parents’ Motivations for Enrolling their Children in Recreational Sports

 Extensive literature covers reasons for participation in sports from the perspective of youth athletes. However, athletic involvement starts early and is determined in part by parental support. The purpose of this study was to learn more about parents’ motivations for enrolling their children in sports. A 49-item parent motivational scale of reasons for enrolling child(ren) in sports was created as part of the study first as a pilot and later tested with 84 parent participants who had school-aged children enrolled in recreational sports. An open-ended question on primary reasons why parents enrolled their child in sports was also included in the study. Exploratory factor analysis of the motivational scale indicated a four-component solution for types of reasons parents enrolled their children in sports: 1. Extrinsic/parent-focused; 2. Child growth and development; 3. Social benefits; and 4. Health/well-being.  Parents rated the latter three types of beneficial reasons for enrolling children in sports more highly than extrinsic/parent-focused ones and were more likely to list beneficial than extrinsic reasons in the open-ended question. Scores on several individual motivational items varied by child’s, not parent’s, gender and parent’s marital status. Implications for use of self-determination and expectancy-value theoretical perspectives, understanding parents’ motivations to encourage children’s sports participation while considering family structure and gender of child, and study limitations with ideas for future research are discussed.  &nbsp