Some current ideas about the evolution of the human life history

Journal ArticleHuman life history is characterised by a long juvenile period (weaning to reproductive maturity), and a long post-reproductive lifespan in females. How do we explain the differences between our nearest relatives, the great apes, and ourselves? This chapter summarises some recent attempts to use life history models on data from contemporary hunter-gatherers, and other noncontracepting populations with little access to modern medicine

Hadza scavenging: implications for Plio/Pleistocene Hominid subsistence

Journal ArticleThe frequent association of stone tools and large animal bones in African Plio/Pleistocene archaeological sites has long been taken as evidence of the importance of hunting in early hominid diets. Many now argue that it reflects hominid scavenging, not hunting

Global process and local ecology: how should we explain differences between the Hadza and the !Kung?

Journal ArticleIn this chapter we discuss explanations for the diversity of behavior of contemporary forager populations. Other contributors document variation among southern African savanna Bushman groups, and central African forest Pygmies. We confine ourselves to trying to explain some differences between two savanna groups who have been studied quantitatively, the Hadza and the !Kung. We further confine ourselves to discussing two kinds of explanation that are currently considered to be opposed to one another, behavioral ecology (Smith and Winterhalder 1992), and political economy/historical revisionism as presented to hunter-gatherer researchers by Wilmsen (1989)

Neural stem cells genetically-modified to express neprilysin reduce pathology in Alzheimer transgenic models

INTRODUCTION: Short-term neural stem cell (NSC) transplantation improves cognition in Alzheimer’s disease (AD) transgenic mice by enhancing endogenous synaptic connectivity. However, this approach has no effect on the underlying beta-amyloid (Aβ) and neurofibrillary tangle pathology. Long term efficacy of cell based approaches may therefore require combinatorial approaches. METHODS: To begin to examine this question we genetically-modified NSCs to stably express and secrete the Aβ-degrading enzyme, neprilysin (sNEP). Next, we studied the effects of sNEP expression in vitro by quantifying Aβ-degrading activity, NSC multipotency markers, and Aβ-induced toxicity. To determine whether sNEP-expressing NSCs can also modulate AD-pathogenesis in vivo, control-modified and sNEP-NSCs were transplanted unilaterally into the hippocampus of two independent and well characterized transgenic models of AD: 3xTg-AD and Thy1-APP mice. After three months, stem cell engraftment, neprilysin expression, and AD pathology were examined. RESULTS: Our findings reveal that stem cell-mediated delivery of NEP provides marked and significant reductions in Aβ pathology and increases synaptic density in both 3xTg-AD and Thy1-APP transgenic mice. Remarkably, Aβ plaque loads are reduced not only in the hippocampus and subiculum adjacent to engrafted NSCs, but also within the amygdala and medial septum, areas that receive afferent projections from the engrafted region. CONCLUSIONS: Taken together, our data suggest that genetically-modified NSCs could provide a powerful combinatorial approach to not only enhance synaptic plasticity but to also target and modify underlying Alzheimer’s disease pathology