Most relapsing fever bacteria that infect humans are spread by ticks, but Borrelia recurrentis is unique in being transmitted between humans via body lice. Now, new genomic evidence from ancient British remains suggests that B. recurrentis diverged from its tick-borne relatives and began adapting to transmission by lice between 6000 and 4000 years ago – coinciding with the widespread use of wool textiles by humans. The findings underscore how ancient DNA can illuminate the origins and evolution of infectious diseases and how pathogens like B. recurrentis have been shaped by human social transformations. Several pathogenic bacterial species that once relied on ticks for transmission have independently evolved to use lice as vectors instead, including B. recurrentis. B. recurrentis has no known animal reservoir. Moreover, this louse-adapted pathogen tends to show higher virulence compared to its tick-borne relatives, suggesting a process of specialization. However, the precise timeline and genetic mechanisms behind its adaptation to lice and its increased virulence in humans remain uncertain.

Using advanced ancient DNA techniques optimized for degraded genetic material, Pooja Swali and colleagues recovered and analyzed four ancient B. recurrentis genomes from human remains in Britain, dating from roughly 2300 to 600 years ago. Through phylogenetic and pan-genome analysis, Swali et al. estimate that B. recurrentis diverged from its closest relative, B. duttonii, approximately 4700 – 5600 years ago. This period coincided with shifts in human behavior during the Neolithic-Bronze Age transition, such as the rise of sedentary lifestyles, the advent of wool textiles, and densely populated settlements. According to the authors, these changes may have facilitated the adaptation of B. recurrentis to the human body louse and also promoted genome reduction and host specialization. Over time, B. recurrentis underwent substantial genome reductions, particularly in plasmid-encoded genes. These genetic changes were accompanied by gains and losses of surface proteins that help the bacterium evade the host immune system.

Women living in neighborhoods with high vulnerability had a higher risk of earlier natural menopause onset, primarily due to socioeconomic status and household conditions.

No significant association was found between neighborhood disadvantage and the severity of menopause symptoms.

A new study from researchers at Aarhus University and Aarhus University Hospital found no increased risk of neurodevelopmental disorders in children whose fathers were treated with valproate during spermatogenesis. The results have just been published in JAMA Network Open and cast new light on the European Medicines Agency’s (EMA's) recent recommendation for precautionary measures.

Birth rates are declining worldwide, while dog parenting practices are gaining popularity. What does this growing “furry children” trend reveal about our societies? Researchers from Eötvös Loránd University suggest that, while dogs do not actually replace children, they may, in some cases, offer an opportunity to fulfil a nurturing drive similar to parenting, but with fewer demands than raising biological offspring. Their review, published in European Psychologist, also examines how the shifting roles of dogs within modern family structures are influenced by individual circumstances, but also by cultural norms.