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Long-Term Perspectives on Ecology and Life History in the Amboseli Baboons

Synopsis of the Project

            The Amboseli Baboon Research Project is a long-term continuous longitudinal study that was started in 1971 to gather data on the behavior of Amboseli baboons. Behaviors are studied at the population, group, and individual level. The scope included studying other aspects such as genetics, ecology, demography, hybridization, endocrinology, nutrition, and social behavior of the baboons (Archie, 2020).

Explanation of the Goal of the Study

            The Amboseli Baboon Research Project had two major goals: to determine the dominant drivers of gut microbiome dynamic in wild baboon populations and to determine the behavioral and developmental consequences of early life adversity (Archie, 2020).

The Rationale behind the Study

            Bacterial microbiome in the gut of baboons are characterized by about 30 phyla that are highly dynamic in nature with important functions such as digestion of food, synthesis of essential vitamins and mineral salts, and development of resistance mechanism against pathogens (Archie, 2020). Wide diversity of gut microbiome is associated with benefits such as increased production of short chain fatty acids, increased production of antioxidants, improved lipid metabolism, low gut inflammation, increased insulin sensitivity, and reduced risk of some infections (Valdes et al., 2018). Some of these bacterial compete with each other, whereas other cooperate in nature resulting on gut microbiome diversity (Archie, 2020). Therefore, it is important to understand the organizing principles that drive microbiome biodiversity since they are essential for supporting life of the host. On the other hand, it was important to examine behavioral and developmental consequences for early life adversity since they may have downstream negative consequences such as shortened life-span and poor health outcomes (Archie, 2020).

An Outline of the Methods Used

            The research collected time series data on the baboon gut microbiome in 17,277 fecal samples from 602 baboons over a period of 14 years. The methods that were used to study microbiome diversity and change over time included 16S gene sequencing and DADA2 pipeline.  Physical observations were made so as to study the consequences of early life adversity on individual baboons. Some of the sources of adversity included resources, family structure and maternal social environment (Archie, 2020).  Resource parameters that were studied included large social group size and drought in the first year of life. Family structure parameters included presence of a competing younger sibling and maternal death. Maternal social environment aspects that were studied included maternal social isolation (n=189 females) and low maternal social rank (n=189 females) (Archie, 2020).

Description of the Results

            One of the key findings is that baboon gut microbiome tend to change in synchrony across different annual seasonal cycles. The rationale for this is that there is change of food types, water drinking sources, and availability of food through various seasons. It was also found that 97% of the gut microbial taxonomic-abundances are significantly heritable. The average heritability of the microbial abundances was approximately 6% (Archie, 2020). It was also established that microbiome dynamics are idiosyncratic to the individual hosts, regardless of the fact the individuals were living in the same environment. These idiosyncrasies could be explained, in part, by different host control mechanisms, which are linked to the genotype of a given host. Idiosyncrasies at the host level may lead to challenges for microbiome interventions (Archie, 2020). Gut microbiome has measurable impact on the stress influence, brain function, social behavior, depressive symptoms, and anxiety (Johnson, 2020).

            On the study of consequences of adversity on behavior and development, it was established that median life span without adversity was 22 years and 9 years with adversity.  Another finding was that lifespan tends to explain 83% of the variation in lifetime reproductive success. It was also found that lifespan is a dominant determinant of fitness, but not the pace and the timing of reproduction. In addition, early life adversity was associated with increased secretion of glucocorticoid hormones, depicting increased susceptibility to stress (Archie, 2020). Acute stress is associated with release of glucocorticoids and norepinephrine. These stress hormones may lead to development and consolidation of long-lasting memories (Osborne, Pearson-Leary, & McNay, 2015).

Significance of the Results

            Diversity of the gut microbiome in an individual is determined by genetics as well as the environment in which one lives in. Besides, microbial variation is unique to individuals and there is no fit-all microbial therapy for all individuals living in a given environment. Another significant finding is that adversity may lead to a shortened lifespan and does not confer reproductive advantage to an individual. Besides, early life adversity can have significant impact on an individual’s stress response (Archie, 2020).

Future Research Recommendations

            Future studies should study whether there is similar microbiome diversity in the gut of humans, and whether there is synchrony or idiosynchrony in gut diversity of human beings who live in a certain defined environment. Besides, the effect of early life adversity on the lives of human beings should also be established in the future studies.