Reciprocal altruism may have evolved by accident

The most accepted explanation for the evolution of reciprocal altruism is based on cooperative reciprocators engaged in intertemporal choice. Here, we parsimoniously dismiss this narrative and suggest a new hypothesis based on random encounters of selfish individuals that result in theft. Theft can coexist with passive reactions on the victims, as it does not jeopardize survival and reproduction in times of abundance. As a result, offspring with psychological adaptations of not reacting to theft can become reliable reciprocators amid scarcity.

Stem embolism vulnerability curve depends on methods used: is there a fifth mechanism of cavitation?

A long-established ecological paradigm predicts a functional relationship determining vulnerability to cavitation: vulnerability increases with vessel hydraulic efficiency and vessel diameter. Even within a species, big vessels cavitate before small ones. Some centrifuge methods for measuring vulnerability are prone to artifacts due to nano-particles seeding early embolism, as the particles are drawn into vessels during measurements. Both the Sperry and Cochard rotors are prone to early cavitation due to nano-particles drawn into long and wide vessels in Robinia pseudoacacia and Quercus acutissima, whereas extraction centrifuge methods produce vulnerability curves more resistant to cavitation. Sufficient nano-particles pass through the stems to seed early embolism in all rotor designs. For several years, people have thought that early embolism is induced by nano-particles present in laboratory water. One new hypothesis is that the origin of nano-particles is from cut-open living cells but a much bigger study including many species is required to confirm this idea. This paper confirms the hypothesis in comparisons between short-vesselled Acer, and long-vesselled Robinia, and Quercus. Our new results and a review of old results justifies bigger study. Hypothetical nano-particles might explain why different methods for measuring vulnerability curves cause different T50 = tensions causing 50% loss of hydraulic conductivity. Hence the hypothesis for future research should be that the open-vessel artifact is consistent with 'long' vessels surrounded by cut open living cells.

Low vision impairs implicit sensorimotor adaptation in response to small errors, but not large errors

Successful goal-directed actions require constant fine-tuning in response to errors introduced by changes in the body and environment. This implicit adaptive process has been assumed to operate in a statistically optimal fashion, reducing its sensitivity to errors when sensory uncertainty is high. However, recent work has shown that visual uncertainty attenuates implicit adaptation for small errors, but not large errors, a result that is at odds with an optimal integration hypothesis. This error size interaction has motivated a new hypothesis that sensory uncertainty impacts the distribution of the perceived error locations but not the system's sensitivity to errors. To examine these competing hypotheses, previous studies have experimentally manipulated uncertainty. But it is unknown which hypothesis best describes motor adaptation to sensory uncertainty experienced during daily life. To address this question, we recruited individuals with low vision due to diverse clinical conditions impacting visual uncertainty and matched controls. The groups were tested on visuomotor tasks designed to isolate implicit adaptation and maintain tight control over the error size. In two experiments, low vision was associated with attenuated implicit adaptation only for small errors, but not for large errors. Taken together with prior work in which visual uncertainty was experimentally manipulated, these results support the notion that increasing sensory uncertainty increases the likelihood that errors are mis-localized but does not affect error sensitivity, offering a novel account for the motor learning deficits seen in low vision.

Evolution of Homosexuality in the Human Males: Improved Mixed-Team Performance Hypothesis

Male homosexual preference (MHP) is present in many human societies, making up a small but significant cohort. Because homosexual mate preferences are associated with lower fecundity, many evolutionary explanations have been advanced to account for the persistence of this trait. After reviewing a number of these hypotheses and finding room for additional explanations, we propose a new hypothesis that depends on the observed greater empathy and reduced hostility of men who express MHP. This gives them a central role in the performance of groups or teams (all male and mixed) where cooperation and intra-team coherence are at a premium. In this view, teams that contain men with MHP will outcompete teams without such men, other variables being similar. The links between personality traits and team performance do not require homosexual activity within the group. The hypothesis is supported by observations of the personality traits associated with MHP, such as increased agreeableness, which is linked to the literature on team cohesion and performance in sports and other kinds of teams and groups. This novel hypothesis could be examined through direct study of team performance. The proposed hypothesis may also have relevance to better performance among the diverse teams whose efficient performance is so important in modern society.

Killing Politics Softly

Early propaganda studies in authoritarian countries argue that state media works to legitimize the regime through indoctrination and persuasion. However, recent scholarship shows that citizens in authoritarian countries—in states like China, Syria, Russia, and Kazakhstan—can be unconvinced by state propaganda. How, then, does the way in which citizens experience unconvincing propaganda shape their political beliefs? How might unpersuasive propaganda contribute to authoritarian stability? Given the lack of alternative theories of propaganda, this article proposes a new hypothesis based on a reception study that interviewed 24 Russian citizens from Krasnoiarsk Krai after they watched items from Russian state television. The article theorizes that unconvincing state propaganda in Russia can reinforce a preexisting cynical attitude toward politics—an attitude that makes the collective action necessary for bottom-up reform hard to contemplate, let alone organize in an authoritarian context.

Chemical hardness-driven interpretable machine learning approach for rapid search of photocatalysts

Strategies combining high-throughput (HT) and machine learning (ML) to accelerate the discovery of promising new materials have garnered immense attention in recent years. The knowledge of new guiding principles is usually scarce in such studies, essentially due to the ‘black-box’ nature of the ML models. Therefore, we devised an intuitive method of interpreting such opaque ML models through SHapley Additive exPlanations (SHAP) values and coupling them with the HT approach for finding efficient 2D water-splitting photocatalysts. We developed a new database of 3099 2D materials consisting of metals connected to six ligands in an octahedral geometry, termed as 2DO (octahedral 2D materials) database. The ML models were constructed using a combination of composition and chemical hardness-based features to gain insights into the thermodynamic and overall stabilities. Most importantly, it distinguished the target properties of the isocompositional 2DO materials differing in bond connectivities by combining the advantages of both elemental and structural features. The interpretable ML regression, classification, and data analysis lead to a new hypothesis that the highly stable 2DO materials follow the HSAB principle. The most stable 2DO materials were further screened based on suitable band gaps within the visible region and band alignments with respect to standard redox potentials using the GW method, resulting in 21 potential candidates. Moreover, HfSe2 and ZrSe2 were found to have high solar-to-hydrogen efficiencies reaching their theoretical limits. The proposed methodology will enable materials scientists and engineers to formulate predictive models, which will be accurate, physically interpretable, transferable, and computationally tractable.

Reducing the Number of Measuring Points of the LED-Based Colorimetric Probe

In this paper, reducing the number of necessary measuring points for estimating a reflected electromagnetic spectrum of a printed color patch is presented. In our previous work, a machine learning-based method was proven to be superior to Cubic Hermite interpolation in estimating spectrum based on six measured values. Now, the new hypothesis is that the number of measuring points could be decreased without the significant loss of the spectrum estimation. The ECI2002 test chart was used to create the dataset, which was further divided into training and test subset. For all the colors on the test chart, the measurements were performed on printed patches with the device proposed in our previous work, as well as with the commercial spectrophotometer X-Rite i1 Publish Pro2, which were then used as the ground truth, or reference values. The Artificial Neural Networks were trained to estimate spectrums based on measurements acquired with our device. The results proved satisfactory even when the number of measuring points is reduced from six to three.

Fitness benefits of dietary restriction

Dietary restriction (DR) improves survival across a wide range of taxa yet remains poorly understood. The key unresolved question is whether this evolutionarily conserved response to temporary lack of food is adaptive. Recent work suggests that early-life DR reduces survival and reproduction when nutrients subsequently become plentiful, thereby challenging adaptive explanations. A new hypothesis maintains that increased survival under DR results from reduced costs of overfeeding. We tested the adaptive value of DR response in an outbred population of Drosophila melanogaster fruit flies. We found that DR females did not suffer from reduced survival upon subsequent re-feeding and had increased reproduction and mating success compared to their continuously fully fed (FF) counterparts. The increase in post-DR reproductive performance was of sufficient magnitude that females experiencing early-life DR had the same total fecundity as continuously FF individuals. Our results suggest that the DR response is adaptive and increases fitness when temporary food shortages cease.