Is a downwards head tilt a cross-cultural signal of dominance? Evidence for a universal visual illusion

The present pre-registered research provides the first evidence that a downwards head tilt is sufficient to communicate dominance from a neutral facial expression among the Mayangna, members of an unindustrialized, small-scale traditional society in Nicaragua who have had minimal exposure to North American culture. Consistent with the Action Unit imposter effect observed in North American populations (Witkower and Tracy in Psychol Sci 30:893–906, 2019), changes to the appearance of the upper face caused by a downwards head tilt were sufficient to elicit perceptions of dominance among this population. Given that the Mayangna are unlikely to associate a downwards head tilt or related apparent facial changes with dominance as a result of cross-cultural learning, the present results suggest that perceptions of dominance formed from a downwards head tilt, and the visual illusion shaping these perceptions, are a widely generalizable, and possibly universal, feature of human psychology.

Scum of the Earth: A Hypothesis for Prebiotic Multi-Compartmentalised Environments

Compartmentalisation by bioenergetic membranes is a universal feature of life. The eventual compartmentalisation of prebiotic systems is therefore often argued to comprise a key step during the origin of life. Compartments may have been active participants in prebiotic chemistry, concentrating and spatially organising key reactants. However, most prebiotically plausible compartments are leaky or unstable, limiting their utility. Here, we develop a new hypothesis for an origin of life environment that capitalises upon, and mitigates the limitations of, prebiotic compartments: multi-compartmentalised layers in the near surface environment—a ’scum’. Scum-type environments benefit from many of the same ensemble-based advantages as microbial biofilms. In particular, scum layers mediate diffusion with the wider environments, favouring preservation and sharing of early informational molecules, along with the selective concentration of compatible prebiotic compounds. Biofilms are among the earliest traces imprinted by life in the rock record: we contend that prebiotic equivalents of these environments deserve future experimental investigation.

Scum of the Earth: a hypothesis for prebiotic multi-compartmentalised environments}

Compartmentalisation by bioenergetic membranes is a universal feature of life. The eventual compartmentalisation of prebiotic systems is therefore often argued to comprise a key step during the origin of life. Compartments may have been active participants in prebiotic chemistry, concentrating and spatially organising key reactants. However, most prebiotically plausible compartments are leaky or unstable, limiting their utility. Here, we develop a new hypothesis for an origin of life environment, that capitalises upon, and mitigates the limitations of, prebiotic compartments: multi-compartmentalised layers in the near surface environment --- a 'scum'. Scum-type environments benefit from many of the same ensemble-based advantages as microbial biofilms. In particular, scum layers mediate diffusion with the wider environment, favouring preservation and sharing of early informational molecules, along with the selective concentration of compatible prebiotic compounds. Biofilms are among the earliest traces imprinted by life in the rock record: we contend that prebiotic equivalents of these environments deserve future experimental investigation.

The art of translation and artificial intelligence

The cognitive process and one of its most difficult aspects – translation into different languages - is an obstacle to creating a perfect Artificial Intelligence, because translation is not limited to formulas. The accuracy of the terminology and the lack of ambiguity of the word are the purposes of artificial intelligence while limiting the development of linguistic thinking. The transhumanism involves the improvement of the man, as an unfinished link of evolution, based on his connection with technological elements. From the author`s point of view, the “man-machine” interaction offers a dubious advantage for the human civilization and the planetary ecological system. This is, first of all, anachronistic and its main goal is singularity, i.e., the management of intellectual energy within the strict framework of technology. The article schematically provides the explicit sequence of the translation process. Based on relevant examples, the author demonstrates the difference between mental operations of Artificial Intelligence and those of the man in the translation process. According to the author, translation is a universal feature of human thought, while the process of translating the thought into the speech form is due to biological-genetic, emotional, socio-historical memory and experience, as well as the possibility of the individual translation of the thought into the mother tongue and into any other language. Moreover, translation is one of the strongest survival qualities of homo sapiens.

English-Speaking Adults' Labeling of Child- and Adult-Directed Speech Across Languages and Its Relationship to Perception of Affect

Child-directed speech, as a specialized form of speech directed toward young children, has been found across numerous languages around the world and has been suggested as a universal feature of human experience. However, variation in its implementation and the extent to which it is culturally supported has called its universality into question. Child-directed speech has also been posited to be associated with expression of positive affect or “happy talk.” Here, we examined Canadian English-speaking adults' ability to discriminate child-directed from adult-directed speech samples from two dissimilar language/cultural communities; an urban Farsi-speaking population, and a rural, horticulturalist Tseltal Mayan speaking community. We also examined the relationship between participants' addressee classification and ratings of positive affect. Naive raters could successfully classify CDS in Farsi, but only trained raters were successful with the Tseltal Mayan sample. Associations with some affective ratings were found for the Farsi samples, but not reliably for happy speech. These findings point to a complex relationship between perception of affect and CDS, and context-specific effects on the ability to classify CDS across languages.

Disciplines in the Scientonomic Ontology

The role of categories of knowledge, or disciplines, in science has not previously been explored in scientonomy. While disciplinary communities devoted to the production of knowledge are a modern phenomenon, the practice of dividing knowledge into categories is a universal feature of science. Although at any moment of time, many questions and theories can be part of a given discipline, not all of these are essential to the discipline. We show that two components are essential to a discipline: the discipline’s core questions as well as the discipline’s delineating theory, a second-order theory that identifies these questions as essential to the discipline. If the questions of one discipline are a proper subset of the questions of another discipline, the former discipline is a subdiscipline of the latter. Since a discipline is a complex entity consisting of questions and a theory, epistemic agents can take epistemic stances towards disciplines. A discipline is said to be accepted if its core questions and its delineating theory are all accepted. To illustrate the applicability of these new concepts, the transition from physical to biological anthropology is discussed.

Myosin Light Chain Kinase driven myosin II turnover regulates actin cortex contractility during mitosis

Force generation by the molecular motor myosin II (MII) at the actin cortex is a universal feature of animal cells. Despite its central role in driving cell shape changes, the mechanisms underlying MII regulation at the actin cortex remain incompletely understood. Here we show that Myosin Light Chain Kinase (MLCK) promotes MII turnover at the mitotic cortex. Inhibition of MLCK resulted in an alteration of the relative levels of phosphorylated Regulatory Light Chain (RLC), with MLCK preferentially creating a short-lived pRLC species and Rho associated kinase (ROCK) preferentially creating a stable ppRLC species during metaphase. Slower turnover of MII and altered RLC homeostasis upon MLCK inhibition correlated with increased cortex tension, driving increased membrane bleb initiation and growth, but reduced bleb retraction during mitosis. Taken together, we show that ROCK and MLCK play distinct roles at the actin cortex during mitosis; ROCK activity is required for recruitment of MII to the cortex, while MLCK activity promotes MII turnover. Our findings support the growing evidence that MII turnover is an essential dynamic process influencing the mechanical output of the actin cortex. [Media: see text]

Unconventional conservation reveals structure-function relationships in the synaptonemal complex

Functional requirements constrain protein evolution, commonly manifesting in conserved primary amino acid sequence. Here, we extend this idea to secondary structural features by tracking their conservation in essential meiotic proteins with highly diverged sequences. The synaptonemal complex (SC) aligns parental chromosome pairs and regulates exchanges between them. In electron micrographs of meiocytes from all eukaryotic clades, the SC appears as a ~100 nm-wide ladder-like structure with regular striations. Despite the conserved ultrastructure and functions, the proteins that make up the SC are highly divergent in sequence. Here we found that, within the Caenorhabditis genus, SC proteins are significantly more diverged than other proteins. However, SC proteins have highly conserved protein length and coiled-coil domain structure. The same unconventional conservation signature holds true for SC proteins in Drosophila and mammals, suggesting it could be a universal feature of SC proteins. We used this evolutionary signature to identify a novel SC protein in the nematode Pristionchus pacificus, Ppa-SYP-1, which has no significant homology to any protein outside of Pristionchus. Our work suggests that the length and relative arrangement of coiled-coils play a key role in the structure and function of the SC. Furthermore, our analysis implies that expanding sequence analysis beyond measures of per-site identity or similarity can enhance our understanding of protein evolution and function.

Early constipation predicts faster dementia onset in Parkinson’s disease

Constipation is a common but not a universal feature in early PD, suggesting that gut involvement is heterogeneous and may be part of a distinct PD subtype with prognostic implications. We analysed data from the Parkinson’s Incidence Cohorts Collaboration, composed of incident community-based cohorts of PD patients assessed longitudinally over 8 years. Constipation was assessed with the MDS-UPDRS constipation item or a comparable categorical scale. Primary PD outcomes of interest were dementia, postural instability and death. PD patients were stratified according to constipation severity at diagnosis: none (n = 313, 67.3%), minor (n = 97, 20.9%) and major (n = 55, 11.8%). Clinical progression to all three outcomes was more rapid in those with more severe constipation at baseline (Kaplan–Meier survival analysis). Cox regression analysis, adjusting for relevant confounders, confirmed a significant relationship between constipation severity and progression to dementia, but not postural instability or death. Early constipation may predict an accelerated progression of neurodegenerative pathology.

Explosive fragmentation of Prince Rupert’s drops leads to well-defined fragment sizes

Anyone who has ever broken a dish or a glass knows that the resulting fragments range from roughly the size of the object all the way down to indiscernibly small pieces: typical fragment size distributions of broken brittle materials follow a power law, and therefore lack a characteristic length scale. The origin of this power-law behavior is still unclear, especially why it is such an universal feature. Here we study the explosive fragmentation of glass Prince Rupert’s drops, and uncover a fundamentally different breakup mechanism. The Prince Rupert’s drops explode due to their large internal stresses resulting in an exponential fragment size distribution with a well-defined fragment size. We demonstrate that generically two distinct breakup processes exist, random and hierarchical, that allows us to fully explain why fragment size distributions are power-law in most cases but exponential in others. We show experimentally that one can even break the same material in different ways to obtain either random or hierarchical breakup, giving exponential and power-law distributed fragment sizes respectively. That a random breakup process leads to well-defined fragment sizes is surprising and is potentially useful to control fragmentation of brittle solids.