Bonobos, chimpanzees, gorillas, and orang utans use feature and spatial cues in two spatial memory tasks

Animals commonly use feature and spatial strategies when remembering places of interest such as food sources or hiding places. We conducted three experiments with great apes to investigate strategy preferences and factors that may shape them. In the first experiment, we trained 17 apes to remember 12 different food locations on the floor of their sleeping room. The 12 food locations were associated with one feature cue, so that feature and spatial cues were confounded. In a single test session, we brought the cues into conflict and found that apes, irrespective of species, showed a preference for a feature strategy. In the second experiment, we used a similar procedure and trained 25 apes to remember one food location on a platform in front of them. On average, apes preferred to use a feature strategy but some individuals relied on a spatial strategy. In the final experiment, we investigated whether training might influence strategy preferences. We tested 21 apes in the platform set-up and found that apes used both, feature and spatial strategies irrespective of training. We conclude that apes can use feature and spatial strategies to remember the location of hidden food items, but that task demands (e.g. different numbers of search locations) can influence strategy preferences. We found no evidence, however, for the role of training in shaping these preferences

Imprinting of the Polycomb Group Gene MEDEA Serves as a Ploidy Sensor in Arabidopsis

Balanced maternal and paternal genome contributions are a requirement for successful seed development. Unbalanced contributions often cause seed abortion, a phenomenon that has been termed “triploid block.” Misregulation of imprinted regulatory genes has been proposed to be the underlying cause for abnormalities in growth and structure of the endosperm in seeds with deviating parental contributions. We identified a mutant forming unreduced pollen that enabled us to investigate direct effects of unbalanced parental genome contributions on seed development and to reveal the underlying molecular mechanism of dosage sensitivity. We provide evidence that parent-of-origin–specific expression of the Polycomb group (PcG) gene MEDEA is causally responsible for seed developmental aberrations in Arabidopsis seeds with increased paternal genome contributions. We propose that imprinted expression of PcG genes is an evolutionary conserved mechanism to balance parental genome contributions in embryo nourishing tissues

Teaching: Natural or Cultural?

In this chapter I argue that teaching, as we now understand the term, is historically and cross-culturally very rare. It appears to be unnecessary to transmit culture or to socialize children. Children are, on the other hand, primed by evolution to be avid observers, imitators, players and helpers—roles that reveal the profoundly autonomous and self-directed nature of culture acquisition (Lancy in press a). And yet, teaching is ubiquitous throughout the modern world—at least among the middle to upper class segment of the population. This ubiquity has led numerous scholars to argue for the universality and uniqueness of teaching as a characteristically human behavior. The theme of this chapter is that this proposition is unsustainable. Teaching is largely a result of recent cultural changes and the emergence of modern economies, not evolution