Molecular sequence variation at a locus informs about the evolutionary history of the sample and past population size dynamics. The Kingman coalescent is used in a generative model of molecular sequence variation to infer evolutionary parameters. However, it is well understood that inference under this model does not scale well with sample size. Here, we build on recent work based on a lower resolution coalescent process, the Tajima coalescent, to model longitudinal samples. While the Kingman coalescent models the ancestry of labeled individuals, we model the ancestry of individuals labeled by their sampling time. We propose a new inference scheme for the reconstruction of effective population size trajectories based on this model and the infinite-sites mutation model. Modeling of longitudinal samples is necessary for applications (e.g., ancient DNA and RNA from rapidly evolving pathogens like viruses) and statistically desirable (variance reduction and parameter identifiability). We propose an efficient algorithm to calculate the likelihood and employ a Bayesian nonparametric procedure to infer the population size trajectory. We provide a new MCMC sampler to explore the space of heterochronous Tajima’s genealogies and model parameters. We compare our procedure with state-of-the-art methodologies in simulations and an application to ancient bison DNA sequences. Supplementary materials for this article are available online including a standardized description of the materials available for reproducing the work.

Much anthropological scholarship on war—particularly “civil war”—focuses on violence perpetrated between organized political groups within the confines of a national space. In contrast, this article examines how “internal armed conflict” manifests across international borders, irrupting as interpersonal violence in spaces that are supposedly external to war. More specifically, I demonstrate how “the Colombian armed conflict” unfolds between refugees and their persecutors in Quito, Ecuador, through fleeting encounters based upon processes of life-threatening recognition. These everyday encounters constitute “intimate war,” a relational condition of world-making involving terrifying social attachments—threatening verbal and physical gestures and cues—between “strangers,” or people who are not necessarily familiar with each other. In this context, refugees enact strategies of evasion to avoid detection by their persecutors, such as bus hopping, visually scanning their surroundings, and avoiding other Colombians. Terrifying encounters across borders, and refugees’ strategies to avoid them, unsettle normative assumptions about the desirability of recognition, where and how war happens, and what constitutes escape.