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Five years ago, CWA reported on the discovery of the oldest rock art found in North Africa (CWA 24). Dirk Huyge and his team have been back to Egypt to re-examine the site: it seems not only are the petroglyphs even older than first thought, they may show possible contact with Europe.
Rates of participation in organ donation programs are known to be powerfully influenced by the relevant default policy in effect (”opt-in” vs. “opt-out”). Three studies provide evidence that this difference in participation may occur in part because the requirement to opt-in or opt-out results in large differences in the meaning that individuals attach to participation. American participants in Study 1 rated participation as a significantly more substantial action when agreement was purportedly obtained under opt-in rather than opt-out conditions, and nonagreement as a greater abrogation of responsibility when that decision was made under opt-out rather than under opt-in conditions. Study 2 replicated these findings with respondents who live in Germany, which employs an opt-in donation policy, and in Austria, which has an opt-out policy. Study 3 required American participants to rate various actions that differ in the effort and self-sacrifice they demand. As predicted, the placement of organ donation on the resulting multidimensional scaling dimension differed significantly depending on whether it purportedly was made in an opt-in country (where it was considered roughly akin to giving away half of one's wealth to charity upon one's death) or an opt-out country (where it fell between letting others get ahead of one in line and volunteering some time to help the poor).We discuss the relationship between this change of meaning account and two other mechanisms-behavioral inertia and implicit norms-that we believe underlie the default effect in decision making and other effects of policies designed to influence decision-makers.
default options | opt-in vs. opt-out | subjective meaning | construal
Schmittner et al. (Reports, 9 December 2011, p. 1385) report a new, low estimate of equilibrium climate sensitivity based on a comparison of Last Glacial Maximum climate model simulations and paleoproxy data. Here, we show that exclusion of questionable comparison points and constructive changes to model design are both likely capable of altering the most probable value of equilibrium climate sensitivity suggested in Schmittner et al.
Andreas Schmittner, Nathan M. Urban, Jeremy D. Shakun, Natalie M. Mahowald, Peter U. Clark, Patrick J. Bartlein, Alan C. Mix & Antoni Rosell-Melé
The removal of data by Fyke and Eby is mostly unjustified, and their statistics are oversimplified, but the suggestion that structural model uncertainty—in particular, the atmospheric heat flux formulation—may have led to underestimation of equilibrium climate sensitivity for a doubling of atmospheric carbon dioxide concentrations in our 2011 paper may have merit and should be quantified in future studies.
Many written forms required by businesses and governments rely on honest reporting. Proof of honest intent is typically provided through signature at the end of, e.g., tax returns or insurance policy forms. Still, people sometimes cheat to advance their financial self-interests—at great costs to society. We test an easy-to-implement method to discourage dishonesty: signing at the beginning rather than at the end of a self-report, thereby reversing the order of the current practice. Using laboratory and field experiments, we find that signing before—rather than after—the opportunity to cheat makes ethics salient when they are needed most and significantly reduces dishonesty.
morality | nudge | policy-making | fraud
The classic anthropological hypothesis known as the “obstetrical dilemma” is a well-known explanation for human altriciality, a condition that has significant implications for human social and behavioral evolution. The hypothesis holds that antagonistic selection for a large neonatal brain and a narrow, bipedal-adapted birth canal poses a problem for childbirth; the hominin “solution” is to truncate gestation, resulting in an altricial neonate. This explanation for human altriciality based on pelvic constraints persists despite data linking human life history to that of other species. Here, we present evidence that challenges the importance of pelvic morphology and mechanics in the evolution of human gestation and altriciality. Instead, our analyses suggest that limits to maternal metabolism are the primary constraints on human gestation length and fetal growth. Although pelvic remodeling and encephalization during hominin evolution contributed to the present parturitional difficulty, there is little evidence that pelvic constraints have altered the timing of birth.
bipedalism | EGG hypothesis | energetics | metabolic crossover hypothesis | pregnancy
The debate about the origins of human prosociality has focused on the presence or absence of similar tendencies in other species, and, recently, attention has turned to the underlying mechanisms. We investigated whether direct reciprocity could promote prosocial behavior in brown capuchin monkeys (Cebus apella). Twelve capuchins tested in pairs could choose between two tokens, with one being “prosocial” in that it rewarded both individuals (i.e., 1/1), and the other being “selfish” in that it rewarded the chooser only (i.e., 1/0). Each monkey's choices with a familiar partner from their own group was compared with choices when paired with a partner from a different group. Capuchins were spontaneously prosocial, selecting the prosocial option at the same rate regardless of whether they were paired with an in-group or out-group partner. This indicates that interaction outside of the experimental setting played no role. When the paradigm was changed, such that both partners alternated making choices, prosocial preference significantly increased, leading to mutualistic payoffs. As no contingency could be detected between an individual's choice and their partner's previous choice, and choices occurred in rapid succession, reciprocity seemed of a relatively vague nature akin to mutualism. Having the partner receive a better reward than the chooser (i.e., 1/2) during the alternating condition increased the payoffs of mutual prosociality, and prosocial choice increased accordingly. The outcome of several controls made it hard to explain these results on the basis of reward distribution or learned preferences, and rather suggested that joint action promotes prosociality, resulting in so-called attitudinal reciprocity.
cooperation | tit-for-tat | inequity | mirroring
Reuben's position in the genealogies of the tribes of Israel suggests that once Reuben played a major role in Israelite society, whether political or (more likely) religious. Evidently Reuben's preeminence was early in tribal history, for the evidence is clear that Reuben as a tribal entity with a fixed territory disappeared in the course of the eleventh Century B.C.E.
A remarkable series of traditional events are laid in the „allotted“ territory of Reuben north of the Arnon, notably events in the „valley opposite Bet Pe'or“ between the mountain ridges of Mount Pe'or and Mount (Pisgah-)Nebo: the lawgiving and covenant making of Moses of Deuteronomic tradition, the burial of Moses, the affair of Ba'l Pe'or, and certain of the oracles of Balaam. Evidence is reviewed also pointing to existence of Reubenite (and perhaps Gadite) shrines at the city of Nebo and at Gilgal.
The origin and motivation of the traditions are sought by relating them to other early stories of strife reflecting rivalry between priestly houses, one tracing its lineage to Moses (the Levites) and one to Aaron.
Finally this priestly lore is compared with historical and archaeological data, especially that from Transjordan and Midian (the northern Hijaz), and a new formulation of the Midianite hypothesis is sketched.
The lack of early Iron Age burials in the central highlands is a known phenomenon (e.g., Tappy 1995: 65-66; Ilan 1997: 220; Barkay 1994: 160, n. 211), which, surprisingly, has received little attention in the archaeological literature. The issue was recently addressed by Raz Kletter (2002), who argues that the lack of observable Iron I burials in the highlands is a unique reality, since burials from other periods—including the Late Bronze Age and later phases of the Iron Age—were found in the same region and that contemporaneous Iron Age I burials were found in other parts of the Land of Israel. Thus, the lack (or extreme rarity) of Iron Age I burials in the highlands cannot be attributed to an expected differentiation between highlands and lowlands, nor is it generally typical of the Iron Age I\@. Since the phenomenon of the lack of burials is unique to the Iron Age I highland society, it requires a systematic explanation. The present article evaluates the explanations proposed by Kletter for the phenomenon and suggests that the explanation lies elsewhere, in the socio-ideological realm.
The dichotomy between early Homoand Paranthropusis justified partly on morphology1,2. In terms of diet, it has been suggested that early Homo was a generalist but that Paranthropus was a specialist3. However, this model is challenged and the issue of the resources used by Australopithecus, the presumed common ancestor, is still unclear. Laser ablation profiles of strontium/calcium, barium/ calcium and strontium isotope ratios in tooth enamel are a means to decipher intra-individual diet and habitat changes. Here we show that the home range area was of similar size for species of the three hominin genera but that the dietary breadth was much higher in Australopithecus africanus than in Paranthropus robustus and early Homo. We also confirm that P. robustus relied more on plant-based foodstuffs than early Homo. A South African scenario is emerging in which the broad ecological niche of Australopithecus became split, and was then occupied by Paranthropus and early Homo, both consuming a lower diversity of foods than Australopithecus.
Greenland ice cores reveal that mean annual temperatures during the Younger Dryas (YD) cold interval-about 12.9 to 11.7 thousand years ago (ka)-and the 150-year-long cold reversal that occurred 8.2 thousand years ago were 15° and 3° to 4°C colder than today, respectively. Reconstructing ice-sheet response to these climate perturbations can help evaluate ice-sheet sensitivity to climate change. Here, we report the widespread advance of Laurentide Ice Sheet outlet glaciers and independent mountain glaciers on Baffin Island, Arctic Canada, in response to the 8.2-ka event and show that mountain glaciers during the 8.2-ka event were larger than their YD predecessors. In contrast to the wintertime bias of YD cooling, we suggest that cooling during the 8.2-ka event was more evenly distributed across the seasons.
Paul Ormerod assesses a Bayesian take on predicting everything from poker games to climate change.
The Signal and the Noise: Why So Many Predictions Fail – but Some Don't. Nate Silver. Penguin: 2012. 352 pp. $ 27.95
A serious problem with many forecasting models is that they try to explain too much, and end up `explaining' the noise. Silver documents this little-known but fundamental problem of `overfitting' in clear terms.
Silver discusses the poor record of economic forecasting at length, and is correct in stressing the importance of understanding the data, rather than just pouring it into a statistical package and pressing the button. He does not, however, make clear how a Bayesian approach could have predicted the financial crisis.
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