Monday, July 16, 2018

Necrophilia in crows: Occasional contacts, which take a variety of aggressive and sexual forms, may result from an inability to mediate conflicting stimuli

Occurrence and variability of tactile interactions between wild American crows and dead conspecifics. Kaeli Swift, John M. Marzluff. Philosophical Transactions of the Royal Society B: Biological Sciences, September 5 2018, Volume 373, issue 1754, 10.1098/rstb.2017.0259

Abstract: Observations of some mammals and birds touching their dead provoke questions about the motivation and adaptive value of this potentially risky behaviour. Here, we use controlled experiments to determine if tactile interactions are characteristic of wild American crow responses to dead crows, and what the prevalence and nature of tactile interactions suggests about their motivations. In Experiment 1, we test if food or information acquisition motivates contact by presenting crows with taxidermy-prepared dead crows, and two species crows are known to scavenge: dead pigeons and dead squirrels. In Experiment 2, we test if territoriality motivates tactile interactions by presenting crows with taxidermy crows prepared to look either dead or upright and life-like. In Experiment 1, we find that crows are significantly less likely to make contact but more likely to alarm call and recruit other birds in response to dead crows than to dead pigeons and squirrels. In addition, we find that aggressive and sexual encounters with dead crows are seasonally biased. These findings are inconsistent with feeding or information acquisition-based motivation. In Experiment 2, we find that crows rarely dive-bomb and more often alarm call and recruit other crows to dead than to life-like crows, behaviours inconsistent with responses given to live intruders. Consistent with a danger response hypothesis, our results show that alarm calling and neighbour recruitment occur more frequently in response to dead crows than other stimuli, and that touching dead crows is atypical. Occasional contacts, which take a variety of aggressive and sexual forms, may result from an inability to mediate conflicting stimuli.

Across both experiments, we observed n = 11 attempts to mate with a crow in dead posture (4.7% of N ¼ 234 trials), 90% of which were coupled with scolding and all of which took place before the end of May. Sexual behaviours around dead conspecifics are rare, but not unique to crows. Hetero and homosexual necrophilia have been observed across a wide variety of taxa. Sexual arousal in response to dead conspecifics has been documented in bottle nosed dolphins [4] and humpback whales (Magaptera novaeangliae; [34]). Mating attempts with dead conspecifics have been observed in Richardson's ground squirrel (Citellus richardsoni), mallards (Anas platyrhynchos), sand martins (Riparia riparia) cururu toads (Rhinella steuvax) and great ameivas (Ameiva ameiva; [35.39]). The copulation posture typical of dead birds has been proposed as the releasing factor for such inappropriate attempts to mate, particularly among monomorphic birds [37]. In Experiment 2, however, we show that crows attempted to mate both with a life-like crow in neutral standing posture and a dead crow with the wings tucked close to the body.  These observations call into question the validity of posture as the primary releasing factor for copulation events between crows and dead crows, and warrant further investigation.

Given the prevalence of scolding before, during or immediately following copulation events with dead, but not life-like, crows, alarm induced arousal, rather than reproductive attempts, might better explain copulation with dead crows. Increased sexual behaviour following alarm or excitement has been observed in the zebra finch (Taeniopygia guttata; [40]), vermillion flycatcher (Pyrocephalus rubinus, [41]) and pied avocet (Recuruirostra avosetta; [42]). Following the death of a group member, sexual behaviour occurring outside the breeding season was observed in rhesus macaques [32]. Likewise, we observed mating attempts between presumed pairs following discovery of a dead crow. It is possible in this context that distress induces arousal resulting in copulation attempts between mates if possible, but in the immediate absence of the mate results in displacementmounting.  In rooks (Corvus frugilegus), sexual displays by males sometimes stimulate reverse mounting by females [43]. In our study, females witnessing male precopulatory behaviour prior to mounting the stimulus may be responsible for the two possible instances of reverse mounting.

In addition to the multiple mating attempts with the dead and life-like crows, we also observed one attempted copulation with the dead pigeon. Attempts to mate with live heterospecifics have been observed in a variety of species including seals and non-human primates [44,45]. Although these events are rare enough that determining causal factors remains difficult, restricted access to conspecific females has been commonly observed in these cases. Such information about the crow involved in this case is not known.

Children as young as 4 years old negatively evaluate & sanction free riders. Across six studies, we showed that these tendencies are robust, large in magnitude, tuned to intentional rather than unintentional noncontribution, & generally consistent across third- & first-party cases

In Defense of the Commons: Young Children Negatively Evaluate and Sanction Free Riders. Fan Yang et al. Psychological Science,

Abstract: Human flourishing depends on individuals paying costs to contribute to the common good, but such arrangements are vulnerable to free riding, in which individuals benefit from others’ contributions without paying costs themselves. Systems of tracking and sanctioning free riders can stabilize cooperation, but the origin of such tendencies is not well understood. Here, we provide evidence that children as young as 4 years old negatively evaluate and sanction free riders. Across six studies, we showed that these tendencies are robust, large in magnitude, tuned to intentional rather than unintentional noncontribution, and generally consistent across third- and first-party cases. Further, these effects cannot be accounted for by factors that frequently co-occur with free riding, such as nonconforming behaviors or the costs that free riding imposes on the group. Our findings demonstrate that from early in life, children both hold and enforce a normative expectation that individuals are intrinsically obligated to contribute to the common good.

Keywords: free riding, common good, norm enforcement, moral development, cooperation, open data, open materials, preregistered

Prestigious institutions had on average 65% higher grant application success rates & 50% larger award sizes, whereas less-prestigious institutions produced 65% more publications & had a 35% higher citation impact per dollar of funding

High cost of bias: Diminishing marginal returns on NIH grant funding to institutions. Wayne P. Wahls. bioRxiv,

Abstract: Scientific output is not a linear function of amounts of federal grant support to individual investigators. As funding per investigator increases beyond a certain point, productivity decreases. This study reports that such diminishing marginal returns also apply for National Institutes of Health (NIH) research project grant funding to institutions. Analyses of data (2006-2015) for a representative cross-section of institutions, whose amounts of funding ranged from $3 million to $440 million per year, revealed robust inverse correlations between funding (per institution, per award, per investigator) and scientific output (publication productivity and citation impact productivity). Interestingly, prestigious institutions had on average 65% higher grant application success rates and 50% larger award sizes, whereas less-prestigious institutions produced 65% more publications and had a 35% higher citation impact per dollar of funding. These findings suggest that implicit biases and social prestige mechanisms (e.g., the Matthew effect) have a powerful impact on where NIH grant dollars go and the net return on taxpayers investments. They support evidence-based changes in funding policy geared towards a more equitable, more diverse and more productive distribution of federal support for scientific research. Success rate/productivity metrics developed for this study provide an impartial, empirically based mechanism to do so.

The lure of death: suicide and human evolution

Humphrey N. 2018 The lure of death: suicide and human evolution. Phil. Trans. R. Soc. B 373: 20170269.

Suicide used to be called self-murder, felo de se. In an evolutionary context, the term murder is not inappropriate. Human beings have always been murderers, killers of other living beings. First, of course, killers of animal prey for meat, but also killers of other men and women. While not every ancient human would have had first-hand experience of assassination, everyone would have known and talked about it. Then, at some point, the idea must have dawned. Here’s how the psychiatrist, Erwin Stengel has put it: ‘At some stage of evolution man must have discovered that he can kill not only animals and fellow-men but also himself. It can be assumed that life has never since been the same to him’ [1, p. 37].

The purpose of this paper is to consider just how radically life changed. I argue that the human mind must have had to evolve to a critical level of sophistication before anyone could arrive at the idea that ‘I can kill myself’. However, from then on, suicide would never have been far from people’s thoughts. When times were hard, some individuals would have been bound to see death as an attractive option. Yet killing themselves would usually—if not always—have been a maladaptive act. I explore how this played out historically, and what remedies, if any, were available.


But, now, to go deeper: when you think ‘I can kill myself’, who is this ‘self’ and what do you imagine will result from ‘killing’ it? Again, Stengel implies that early humans would have understood the inevitable consequences of self-killing from observing the killing of others. Bodily death, however caused, has effects that anyone can see and take on board. There’s the obvious bodily decay. But the most salient change is in the dead person’s role as an actor in the physical or social world. They will not be coming back. This is a fact of death that non-human animals with complex social lives can also understand up to a point. Frans de Waal describes how, when a group of chimpanzees in the Arnhem Zoo were shown a video film of the alpha-male, Nickie, who had died by drowning 2 years earlier, his erstwhile rivals panicked as if they had seen a ghost [2, p. 214]. By applying this to your own case, you would realize that you yourself once dead will no longer participate directly in the lives of others.

But we must go deeper still. For there is, of course, another meaning of ‘self’, and hence, the probability that self-killingwill have a still more significant result. When your body dies, what happens to your mind? Once you are no longer an actor in the public realm, can you no longer be a thinker or feeler in the private one? This is not of course something you or anyone else can discover from direct observation. But it is perhaps something you can deduce from circumstantial evidence. As a human, with a ‘theory of mind,’ you expect to be able to infer another person’s mental state from their outward behaviour. When, now, you observe that an individual’s body no longer behaves in any way at all—it neither acts spontaneously nor reacts to your probes—you have very good reason to suppose there is no longer anyone at home inside. True, absence of evidence is not entirely reliable as evidence of absence. But, in fact, you yourself have had plenty of direct experience of your own mind going absent at a time of pseudo-death. When you fall asleep, and your body becomes motionless and unresponsive, you know for a fact that your mind temporarily vanishes. You may remember how as a child you cried yourself to sleep and found blessed relief in the ensuing oblivion.