Modifications to the Aesop's Fable Paradigm Change New Caledonian Crow Performances

While humans are able to understand much about causality, it is unclear to what extent non-human animals can do the same. The Aesop''s Fable paradigm requires an animal to drop stones into a water-filled tube to bring a floating food reward within reach. Rook, Eurasian jay, and New Caledonian crow performances are similar to those of children under seven years of age when solving this task. However, we know very little about the cognition underpinning these birds'' performances. Here, we address several limitations of previous Aesop''s Fable studies to gain insight into the causal cognition of New Caledonian crows. Our results provide the first evidence that any non-human animal can solve the U-tube task and can discriminate between water-filled tubes of different volumes. However, our results do not provide support for the hypothesis that these crows can infer the presence of a hidden causal mechanism. They also call into question previous object-discrimination performances. The methodologies outlined here should allow for more powerful comparisons between humans and other animal species and thus help us to determine which aspects of causal cognition are distinct to humans.     

On the Role of VDAC in Apoptosis: Fact and Fiction

Research on VDAC has accelerated as evidence grows of its importance in mitochondrial function and in apoptosis. New investigators entering the field are often confounded by the VDAC literature and its many apparent conflicts and contradictions. This review is an effort to shed light on the situation and identify reliable information from more questionable claims. Our views on the most important controversial issues are as follows: VDAC is only present in the mitochondrial outer membrane. VDAC functions as a monomer. VDAC functions normally with or without Ca²⁺. It does not form channels that mediate the flux of proteins through membranes (peptides and unfolded proteins are excluded from this statement). Closure of VDAC, not VDAC opening, leads to mitochondria outer membrane permeabilization and apoptosis.     

Margaret Mead and Samoa: Coming of Age in Fact and Fiction

Derek Freeman's 1983 critique of Margaret Mead's Coming of Age in Samoa has prompted one of the most heated debates in recent anthropological memory. Yet even Mead's defenders have generally accepted the view that she saw Samoa as a romantic paradise. Here I argue that a careful reading of Coming of Age shows quite a different picture. In my reanalysis, Mead's work emerges as complex and somewhat enigmatic, with facile conclusions standing in contrast to much rich and sensitive ethnography. My goal in this article is to highlight what Mead actually said, pointing up the notable discrepancy between the popular perception and her actual account.     

Transdifferentiation in Animal Cells: Fact or Artifact?

Some specialized animal cells can overtly change from one differentiated phenotype to another through the process of transdifferentiation. In this review article, representative and convincing examples of transdifferentiation in cells of various animals ranging from mammals to coelenterates are presented. Several basic nature of the cellular properties that underly the transdifferentiation process is discussed. Studies are in progress to understand the mechanism of transdifferentiation in terms of gene expression.     

Periods of Nutritional Stress in the Annual Cycles of Endotherms: Fact or Fiction?

An animal's nutritional status depends on (1) nutrient accessibility,(2) nutrient demand, and (3) physiological, metabolic, morphological,and behavioral compensations that avert or minimize discrepancies,if any, between the first two. The main thesis of this essayis that the diversity and potency of such compensatory mechanismshave often been underrated, and hence the frequency and intensityof nutritional stress in free-living animals have often beenexaggerated. This theme is explored in conjunction with an inventoryof the modes of compensation for actual or potential dietarydeficiencies.     

The FlyBar: Administering Alcohol to Flies

Fruit flies (Drosophila melanogaster) are an established model for both alcohol research and circadian biology. Recently, we showed that the circadian clock modulates alcohol sensitivity, but not the formation of tolerance. Here, we describe our protocol in detail. Alcohol is administered to the flies using the FlyBar. In this setup, saturated alcohol vapor is mixed with humidified air in set proportions, and administered to the flies in four tubes simultaneously. Flies are reared under standardized conditions in order to minimize variation between the replicates. Three-day old flies of different genotypes or treatments are used for the experiments, preferably by matching flies of two different time points (e.g., CT 5 and CT 17) making direct comparisons possible. During the experiment, flies are exposed for 1 hr to the pre-determined percentage of alcohol vapor and the number of flies that exhibit the Loss of Righting reflex (LoRR) or sedation are counted every 5 min. The data can be analyzed using three different statistical approaches. The first is to determine the time at which 50% of the flies have lost their righting reflex and use an Analysis of the Variance (ANOVA) to determine whether significant differences exist between time points. The second is to determine the percentage flies that show LoRR after a specified number of minutes, followed by an ANOVA analysis. The last method is to analyze the whole times series using multivariate statistics. The protocol can also be used for non-circadian experiments or comparisons between genotypes.     

Animal Cognition: Function,Mechanisms, Evolution,and Development

The manner in which any animal,including a human,behaves depends on the information it receives from its environment.The capacity to use this information depend...