Functional diversity of microbial ecologies estimated from ancient human coprolites and dental calculus.

Human microbiome studies are increasingly incorporating macroecological approaches, such as community assembly, network analysis and functional redundancy to more fully characterize the microbiome. Such analyses have not been applied to ancient human microbiomes, preventing insights into human microbiome evolution. We address this issue by analysing published ancient microbiome datasets: coprolites from Rio Zape (n = 7; 700 CE Mexico) and historic dental calculus (n = 44; 1770-1855 CE, UK), as well as two novel dental calculus datasets: Maya (n = 7; 170 BCE-885 CE, Belize) and Nuragic Sardinians (n = 11; 1400-850 BCE, Italy). Periodontitis-associated bacteria (Treponema denticola, Fusobacterium nucleatum and Eubacterium saphenum) were identified as keystone taxa in the dental calculus datasets. Coprolite keystone taxa included known short-chain fatty acid producers (Eubacterium biforme, Phascolarctobacterium succinatutens) and potentially disease-associated bacteria (Escherichia, Brachyspira). Overlap in ecological profiles between ancient and modern microbiomes was indicated by similarity in functional response diversity profiles between contemporary hunter-gatherers and ancient coprolites, as well as parallels between ancient Maya, historic UK, and modern Spanish dental calculus; however, the ancient Nuragic dental calculus shows a distinct ecological structure. We detected key ecological signatures from ancient microbiome data, paving the way to expand understanding of human microbiome evolution. This article is part of the theme issue 'Insights into health and disease from ancient biomolecules'.

Charcot in the ICU: functional tetraplegia after surgery.

Functional neurological disorder is a condition in which a patient has physical findings that are not compatible with anatomical boundaries, have no structural substrate and are not representable of an established disease. General anaesthesia and surgery have been previously reported as precipitating factors for functional disorders and mostly involve dissociative (non-epileptic) seizures. We report a patient with no psychiatric history or prior abnormal examination who developed sudden onset functional tetraplegia and sensory disturbances immediately after elective surgery, and who was subsequently discharged home several days later after nearly complete resolution of neurologic deficits. We highlight the features of this syndrome, including its unique postoperative presentation, unusual resolution and absence of any identifiable psycho-dynamic mechanism. We also introduce the tripod sign as a useful clinical tool in identifying functional tetraplegia.

High and Mighty: Implicit Associations between Space and Social Status.

Figurative language and our perceptuo-motor experiences frequently associate social status with physical space. In three experiments we examine the source and extent of these associations by testing whether people implicitly associate abstract social status indicators with concrete representations of spatial topography (level versus mountainous land) and relatively abstract representations of cardinal direction (south and north). Experiment 1 demonstrates speeded performance during an implicit association test (Greenwald et al., 1998) when average social status is paired with level topography and high status with mountainous topography. Experiments 2 and 3 demonstrate a similar effect but with relatively abstract representations of cardinal direction (south and north), with speeded performance when average and powerful social status are paired with south and north coordinate space, respectively. Abstract concepts of social status are perceived and understood in an inherently spatial world, resulting in powerful associations between abstract social concepts and concrete and abstract notions of physical axes. These associations may prove influential in guiding daily judgments and actions.