Immune cell composition varies by age, sex and exposure to social adversity in free-ranging Rhesus Macaques.

Increasing age is associated with dysregulated immune function and increased inflammation-patterns that are also observed in individuals exposed to chronic social adversity. Yet we still know little about how social adversity impacts the immune system and how it might promote age-related diseases. Here, we investigated how immune cell diversity varied with age, sex and social adversity (operationalized as low social status) in free-ranging rhesus macaques.

The biology of aging in a social world: Insights from free-ranging rhesus macaques.

Social adversity can increase the age-associated risk of disease and death, yet the biological mechanisms that link social adversities to aging remain poorly understood. Long-term naturalistic studies of nonhuman animals are crucial for integrating observations of social behavior throughout an individual's life with detailed anatomical, physiological, and molecular measurements. Here, we synthesize the body of research from one such naturalistic study system, Cayo Santiago, which is home to the world's longest continuously monitored free-ranging population of rhesus macaques (Macaca mulatta).

Urinary cytokine measurements do not reflect surgery-induced inflammation in rhesus macaques.

Measurement of the health and disease status of free-ranging primates is often limited by a lack of available biomarkers of immune activation and inflammation that can be applied noninvasively via the measurement of urine or fecal samples. Here, we evaluate the potential usefulness of noninvasive urinary measurements of a number of cytokines, chemokines, and other markers of inflammation and infection. We took advantage of surgery-associated inflammation in seven captive rhesus macaques, collecting urine samples before and after the medical interventions.

Greater variability in rhesus macaque () endocranial volume among males than females.

The greater male variability (GMV) hypothesis proposes that traits are more variable among males than females, and is supported by numerous empirical studies. Interestingly, GMV is also observed for human brain size and internal brain structure, a pattern which may have implications for sex-biased neurological and psychiatric conditions. A better understanding of neuroanatomical variability in non-human primates may illuminate whether certain species are appropriate models for these conditions.

The rhesus macaque as a success story of the Anthropocene.

Of all the non-human primate species studied by researchers, the rhesus macaque () is likely the most widely used across biological disciplines. Rhesus macaques have thrived during the Anthropocene and now have the largest natural range of any non-human primate. They are highly social, exhibit marked genetic diversity, and display remarkable niche flexibility (which allows them to live in a range of habitats and survive on a variety of diets).

Aging and Senescence across Reproductive Traits and Survival in Superb Fairy-Wrens ().

AbstractWhy do senescence rates of fitness-related traits often vary dramatically? By considering the full aging trajectories of multiple traits, we can better understand how a species' life history shapes the evolution of senescence within a population. Here, we examined age-related changes in sex-specific survival, reproduction, and several components of reproduction using a long-term study of a cooperatively breeding songbird, the superb fairy-wren (). We compared aging patterns between traits by estimating standardized rates of maturation, age of onset of senescence, and rates of senescence while controlling for confounding factors reflecting individual variability in life history.

Do the ages of parents or helpers affect offspring fitness in a cooperatively breeding bird?

Age-related changes in parental phenotypes or genotypes can impact offspring fitness, but separating germline from nongermline transgenerational effects of ageing is difficult for wild populations. Further, in cooperatively breeding species, in addition to parental ages, the age of 'helpers' attending offspring may also affect juvenile performance. Using a 30-year study of a cooperative breeder with very high rates of extra-pair paternity, the superb fairy-wren (Malurus cyaneus), we investigated the effects of maternal, paternal and helper ages on three measures of offspring performance: nestling weight, juvenile survival to independence and recruitment to the breeding population.

Digest: Indirect genetic effects of males on female reproductive traits in the wild.

The indirect genetic effects of fathers on the expression and evolution of female reproductive traits in the wild is not well understood. In a wild population of great tits (Parus major), Evans et al. estimated the genetic and nongenetic effects of male mates on two female reproductive traits, lay date and clutch size.

Ageing with a silver-spoon: A meta-analysis of the effect of developmental environment on senescence.

What determines variation between individuals in how they senesce, and are environmental conditions experienced during development relevant to late-life performance? We report a meta-analysis of studies of wild populations to determine how the quality of the environment experienced during development affects rates of survival and reproductive senescence. From studies of 14 bird or mammal species, we calculated effect sizes for the interaction between the effects of environmental quality during development and age in predicting survival ( = 18) or reproduction ( = 30) over time in late life. We found no evidence that developmental environment affected rates of survival senescence (β = -1.