Previous research has produced inconsistent findings regarding the role of altruism in mating success; this study sought to test whether altruism (charity/volunteer work) relates to number of offspring

Allen, M. S., Robson, D. A., Mishra, M., & Laborde, S. (2023). A prospective and retrospective 10-year study of altruism and reproductive success. Evolutionary Behavioral Sciences, Jan 2023. https://doi.org/10.1037/ebs0000320

Abstract: Previous research has produced inconsistent findings regarding the role of altruism in mating success. This study sought to test whether altruism (charity/volunteer work) relates to number of offspring. A nationally representative sample of Australian adults was separated into those unlikely to have more children (n = 4,296; age ≥ 45 [women], age ≥ 55 [men], Mage = 68.9 ± 11.0 years) and those likely to have more children (n = 4,724; age range = 18–44 [women], 18–54 [men], Mage = 32.8 ± 10.5 years). Measures of altruism and number of children were taken at baseline and 10 years later. In the retrospective analysis of older adults, there was a very small effect size in the predicted direction, indicating that more altruistic adults had more children. In the prospective analysis of younger adults, higher levels of altruism related to a greater number of total children 10 years later, as well as a greater number of children conceived during those 10 years. Increases in altruism over 10 years also related to a greater number of total children and a greater number of children conceived during those 10 years. Effect sizes were small to very small in all instances. There were no sex moderation effects and analyses controlled for personality, medical difficulties in childbearing, and sociodemographic factors. These findings provide evidence that altruism has a role in reproductive success, and indicate that inconsistent findings in previous research might simply reflect the small (real-world) effect size. 

Impact Statement: This research has demonstrated that Australian adults who do more charity or volunteer work tend to have more children. This effect was observed in men and women, as well as both younger and older adults. The study indicates that taking part in more charity or volunteer work might be a useful approach to developing successful relationships and long-term life satisfaction.

Revisiting the Connection Between State Medicaid Expansions and Adult Mortality: These findings imply that evidence that pre-ACA Medicaid expansions to adults saved lives is not as clear as previously suggested

Revisiting the Connection Between State Medicaid Expansions and Adult Mortality. Charles J. Courtemanche, Jordan W. Jones, Antonios M. Koumpias & Daniela Zapata, NBER Working Paper 30818, January 2023. DOI 10.3386/w30818

Abstract: This paper examines the impact of Medicaid expansions to parents and childless adults on adult mortality. Specifically, we evaluate the long-run effects of eight state Medicaid expansions from 1994 through 2005 on all-cause, healthcare-amenable, non-healthcare-amenable, and HIV-related mortality rates using state-level data. We utilize the synthetic control method to estimate effects for each treated state separately and the generalized synthetic control method to estimate average effects across all treated states. Using a 5% significance level, we find no evidence that Medicaid expansions affect any of the outcomes in any of the treated states or all of them combined. Moreover, there is no clear pattern in the signs of the estimated treatment effects. These findings imply that evidence that pre-ACA Medicaid expansions to adults saved lives is not as clear as previously suggested.

Discussion

Currently, there is significant data on self-awareness in social animals, but little information on solitary species (Ma et al., 2015). Although all animals that have passed the MSR are all social, sociality does not automatically suggest that animals are self-aware. Some social animals fail to demonstrate self-recognition. To confirm any hypothesis that compares social and solitary animals and their capacity for self-awareness, additional research must be conducted on MSR in solitary species. This paper recommends monitor lizards (Varanidae) for future MSR testing because they are highly solitary but also very intelligent (Pianka and King, 2004; Northcutt, 2013; Güntürkün et al., 2020; Howard and Freeman, 2022). In particular, the Komodo dragon (Varanus komodoensis) is an attractive candidate. They live solitarily and only occasionally congregate at large carcasses (MacLean, 1978). Less is known about the cognitive ability of Komodo dragons, so a self-recognition test would also shed light on this aspect of study.

The hypothesis presented in this paper also serves as preliminary support for a more comprehensive meta-analysis. A future study quantifying sociality on an ordinal or numeric scale instead of a binary social versus non-social categorization is highly recommended. This helps mitigate the lack of research in solitary species as using graded sociality allows for more precise comparisons within social species (for which information on self-recognition is abundant). For example, it is possible that a highly social animal like the Indian house crow is more capable of self-recognition than a semi-social animal like Clark’s nutcracker. This paper recommends starting the meta-analysis with corvids because the social behavior of species within the same family is more comparable. Corvids display varying levels of sociality and numerous corvid species have already been tested for self-recognition. Subsequent studies can quantify variables such as group size and association level for drastically different species, expanding toward a comprehensive scale including all the animals covered in this study.

Many uncertainties remain in the study of animal self-awareness. The mark test itself remains a debatable measure of self-awareness, with the major question: does failing the MSR test mean a lack of self-awareness? It is possible that some self-aware animals simply do not care about the mark but do possess awareness of their private mental thoughts and an understanding of self. As shown in tests with garter snakes, dogs, and octopuses, the MSR test is subject to sensory limitations, creating a possible bias against animals that do not use vision as their primary sense. Failing the visual MSR does not necessarily mean the species cannot self-recognize. Additionally, as is the case with the gorillas and rhesus macaques, it is unknown if trained self-directed behavior necessarily means natural self-recognition. Moreover, Gallup and Anderson’s (2019) review concludes that differences in self-awareness in different animals may be qualitative rather than quantitative. Thus, developing more objective and reliable self-recognition tests, perhaps designed individually for one species or a group of similar species, remains a future challenge.

Another area of future research is whether self-recognizing, non-human animals can know their internal mental states such as emotions. A basic level of self-awareness is confirmed to be present in non-human animals that conclusively pass the mirror test, but it is unknown if this can be extended to include their knowledge of internal thoughts and emotions.

A basic level of self-knowledge is guaranteed in animals that pass the mirror test, but it is unknown if they possess advanced understanding of private mental states. Despite uncertainties in the methodology of determining self-awareness and a scarcity of information on solitary species, the existing data appears firm in the pattern of social animals being more likely to be self-aware than non-social ones because no solitary species has shown self-recognition. Among the species analyzed in this article, the conclusively self-aware animals were social to some degree, with humans and chimpanzees being highly social and orangutans being semi-social. Other animals exhibiting strongly suggestive signs of self-awareness were also highly social. These are bonobos, bottlenose dolphins, and the bluestreak cleaner wrasse. Certain species showed signs of MSR in individual studies or after training, but the research lacks independent verification by additional studies to be considered strongly suggestive of self-awareness. Examples include the orca, Eurasian magpie, Asian elephant, ant, western gorilla, pigeon, rhesus macaque, and garter snake. The three solitary species, octopus, panda, and Malayan sun bear, analyzed in this paper failed to demonstrate self-recognition. Several social animals also failed to demonstrate self-recognition, such as New Caledonian crows, the gray parrot, and sea lions, although this does not affect the comparison with solitary species. This hypothesis is strengthened by the social intelligence hypothesis, which suggests that social animals are more likely to boast greater cognitive abilities than solitary species due to more opportunities for cognitive challenge in complex social environments. Given the existing literature, this article proposes social animals are more likely to be self-aware than solitary ones.

This paper found that only social animals have demonstrated self-awareness while no solitary species has ever shown this capability

Sociality and self-awareness in animals. Yanyu Lei. Front. Psychol., January 9 2023. https://doi.org/10.3389/fpsyg.2022.1065638

Abstract: Recognizing one’s mirror reflection as oneself appears to be a simple task, but beyond humans, very few animals have consistently demonstrated this capability. Mirror self-recognition is indicative of self-awareness, which is one’s capacity for self-directed knowledge. This Perspective reviews literature from the past 50 years on animal self-recognition and evaluates 20 different species. The goal was to determine a common characteristic shared by all self-aware animals that allow for this advanced cognitive capability. This paper found that only social animals have demonstrated self-awareness while no solitary species has ever shown this capability. This is supported by the social intelligence hypothesis, which posits that social animals are more cognitively sophisticated than solitary ones because their brains evolved to process the more complex social environment around them. Given the available information, this article proposes that social animals are more likely to be self-aware than solitary species.