Abstract Theories on evolution of cooperation assume that interacting individuals can change their strategies under different expected payoffs and cultural contexts. The willingness to invest resources into partners and to cooperate may therefore vary in collectivistic Eastern Asia as opposed to more individualistic Western countries partly because of cultural differences. An experiment was implemented examining the willingness of young Chinese subjects to mitigate the consequences of climate change in a country severely affected by air pollution. Following a design already implemented in Germany (Jacquet et al. 2013 Nat Clim Change), we set up a public goods game in which groups of six students had to reach a minimum investment threshold to be able to save funds for a reforestation project to curb climate change. Differently from the German model in which none of the groups managed to reach the threshold, five out of eight Chinese groups cooperate successfully to reach the reforestation goal. We attribute to cultural differences of individualism and collectivism the main explanation for these different results. In China, in fact, collectivistic values allow for the emergence of this environmentally driven cooperation.
COVID-19 escalated into a pandemic posing several humanitarian as well as scientific challenges. We here investigated the geographical character of the early spread of the infection and correlated it with several annual satellite and ground indexes of air quality in China, the United States, Italy, Iran, France, Spain, Germany, and the United Kingdom. The time of the analysis corresponded with the end of the first wave infection in China, namely June 2020. We found more viral infections in those areas afflicted by high PM 2.5 and nitrogen dioxide values. Higher mortality was also correlated with relatively poor air quality. In Italy, the correspondence between the Po Valley pollution and SARS-CoV-2 infections and induced mortality was the starkest, originating right in the most polluted European area. Spain and Germany did not present a noticeable gradient of pollution levels causing non-significant correlations. Densely populated areas were often hotspots of lower air quality levels but were not always correlated with a higher viral incidence. Air pollution has long been recognised as a high risk factor for several respiratory-related diseases and conditions, and it now appears to be a risk factor for COVID-19 as well. As such, air pollution should always be included as a factor for the study of airborne epidemics and further included in public health policies.
Collective punishment and reward are usually regarded as two potential mechanisms to explain the evolution of cooperation. Both scenarios, however, seem problematic to understand cooperative behavior, because they can raise the second-order free-rider problem and many organisms are not able to discriminate less cooperating individuals. Even though they have been proved to increase cooperation, there has been a debate about which one being more effective. To address this issue, we resort to the N-player evolutionary snowdrift game (NESG), where a collective punishment/reward mechanism is added by allowing some players to display punishment/reward towards all remaining players. By means of numerous simulations and analyses, we find that collective punishment is more effective in promoting cooperation for a relatively high initial frequency of cooperation or for a relatively small group. When the intensity of punishment exceeds a certain threshold, a stable state of full cooperation emerges for both small and large groups. In contrast, such state does not appear for large groups playing a NESG with reward mechanism. In the case of mutualistic interactions, finally, our results show the new payoff with collective punishment/reward can lead to the coexistence of cooperators and defectors when discrimination between these two is not possible.
Abstract We investigated the geographical character of the COVID-19 infection in China and correlated it with satellite- and ground-based measurements of air quality. Controlling for population size, we found more viral infections in those areas afflicted by high Carbon Monoxide, formaldehyde, PM 2.5, and Nitrogen Dioxide values. Higher mortality was also correlated with relatively poor air quality. Air pollution appears to be a risk factor for the incidence of this disease, similar to smoking. This suggests the detrimental impact of air pollution in these types of respiratory epidemics. Short summary There is a significant correlation between air pollution and COVID-19 spread and mortality in China. The correlation stands at a second-order administration level, after controlling for varying population densities and removing Wuhan and Hubei from the dataset. Living in an area with low air quality is a risk factor for becoming infected and dying from this new form of coronavirus.
SummaryThe correlation for diastolic and systolic blood pressure was studied in two samples of quartets each consisting of two pairs. The first sample comprised pairs of sisters and their husbands, and the second sample was comprised of brothers and their wives. All siblings were between 30 and 55 years of age and had been married for at least 5 years. It was found that unrelated men married to sisters had a significant correlation in both diastolic (r = 0·28) and systolic (r = 0·41) pressure. For systolic blood pressure, the correlation between pairs of unrelated men married to sisters was significantly larger than the homologous correlation existing in pairs of brothers married to unrelated women. The correlations of systolic and diastolic pressure in sisters were significantly smaller than the same correlations measured in the wives of brothers. The correlations in height for men, used as an internal control to compare marital and genetic effects, were unaffected by marriage, as expected. The correlations in height for pairs of sisters, however, were no larger than those observed in pairs of unrelated women married to brothers. It was concluded that in adult married men and women of the Ferrara population, aged 30 to 55 years, the influence of genetic factors on blood pressure is less important than the influence of cultural factors.
Experimental evidence with humans and with other primates suggests a preference for interacting with higher-status individuals. For two years we studied wild vervet monkeys. In our treatment phase, some individuals are granted an advantaged role in cooperation to obtain food. Relative to an earlier, control phase, advantaged individuals receive more socially positive behaviors, while “alpha” (highest rank) individuals receive fewer. The increase is focused on lower-ranking advantaged individuals. Alpha individuals become more aggressive, but less influential. Overall, our results support a "signaling" rather than a "preference" hypothesis for how status affects behavior.
The study of stress in captive animals maintained in zoos allows to consider elements that play a main role for the welfare of these species. Among these elements there are the zoo visitors, recently found in the scientific literature as negatively influencing the animals especially when these are primates. At Chester Zoo (UK), a group of six mandrills was investigated after having shown signs of stereotypical behaviour comprised of hair plucking. Through the application of ethology, notably the procedure of all-animal scan sampling, a series of variables was collected. From the data it was tested whether the public's density and the noise produced were responsible for the occurrence of visitor-directed aggression and stereotypies. These data were statistically analysed through mixed effects linear models. This statistical treatment provides a powerful way of testing of data with a degree of interdependency (such as scan samples of a particular individual). Such data are often yielded in studies with low numbers of individuals, as is often the case under captive conditions. The results collected from the zoo visitors found that they used to stay for longer in proximity of the enclosure producing a louder noise when the animals were found in the in-door enclosure and in proximity of the glass window dividing the public. The analysis of the animal behaviour showed that a correlation exists between the visitors’ density and noise and the occurrence of aggressive related displays towards the public by the animals. The visitors' density was also found to be responsible for the higher occurrence of stereotypical bouts of hair plucking. It was hypothesised that the latter was an indirect relationship and resulted from the fact that aggressive behaviours towards visitors did not have the effect anticipated by the mandrills leading to frustration and subsequent hair plucking.
Investigating hierarchical class segregation and the use of punishment applied downward in a hierarchy acts as a key aspect to ascertain how dominant and subordinate partners cooperate to achieve mutual profit. In countries with an uneven wealth distribution, this mutual profit may be reduced, especially for the lower socioeconomic classes. In this experiment, we implemented an Iterated Prisoner’s Dilemma Game in one such country with a starkly high Gini index, China. We split relatively richer and poorer subjects into separate classes and gave only one the authority to punish the other. When rich subjects could unidirectionally punish poor subjects (as in a segregated society), rich subjects decreased their cooperation effort while punishing poor subjects. When rich and poor subjects, instead, could punish each other in random combinations (as in an integrated society) they decreased defections so they could punish more. In the segregated society model, the punishing classes earned twice as much as the non-punishers. Conversely, in the integrated society model, weak differences in earnings were found, leading to a decrease in inequality. An Agent Based simulation confirmed these results when the interacting agents became thousands rather than the over three hundred human participants. From our research, we conclude that, especially in developing economies, stimulating the wealthier and poorer individuals towards a socioeconomic integration of their cooperative exchanges may ultimately lead to a redistribution of wealth.
Cooperation theories assume that interacting individuals can change their strategies under different expected payoffs, depending on their social status or social situations. When looking at sex differences in cooperation, the existing studies have found that the genders cooperate at similar frequencies. However, the majority of the data originate within Western human societies. In this paper, we explore whether there are gender differences in cooperation in China. An Iterated Prisoner's Dilemma game with a punishment option was used to gather data about Southwest Chinese subjects in a culture in which men have a hierarchical advantage over women. Results indicate that men invested into partners significantly more than women did (34% ♂ vs. 24% ♀) while women, in turn, were more likely to defect (65% ♀ vs. 50% ♂). In this region, women have customarily held less economic power and they are used to obtain a payoff typically lower than men. We suggest that the women's willingness to invest in cooperation has decreased throughout evolutionary time, providing us with an illustration of a culturally-driven shift towards a disparity in gender cooperation interests.
Explaining parasite virulence is a great challenge for evolutionary biology. Intuitively, parasites that depend on their hosts for their survival should be benign to their hosts, yet many parasites cause harm. One explanation for this is that within-host competition favors virulence, with more virulent strains having a competitive advantage in genetically diverse infections. This idea, which is well supported in theory, remains untested empirically. Here we provide evidence that within-host competition does indeed select for high parasite virulence. We examine the rodent malaria Plasmodium chabaudi in laboratory mice, a parasite-host system in which virulence can be easily monitored and competing strains quantified by using strain-specific real-time PCR. As predicted, we found a strong relationship between parasite virulence and competitive ability, so that more virulent strains have a competitive advantage in mixed-strain infections. In transmission experiments, we found that the strain composition of the parasite populations in mosquitoes was directly correlated with the composition of the blood-stage parasite population. Thus, the outcome of within-host competition determined relative transmission success. Our results imply that within-host competition is a major factor driving the evolution of virulence and can explain why many parasites harm their hosts.
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