86,560 research outputs found
Encounters with archaic hominins
No full textThe presence of Neanderthal DNA fragments in the genomes of modern humans from Europe and East Asia indicates multiple episodes of interbreeding between Neanderthals and the ancestors of both populations. © 2018, Springer Nature Limited
The complexity of understanding others as the evolutionary origin of empathy and emotional contagion
Full text linkContagious yawning, emotional contagion and empathy are characterized by the activation of similar neurophysiological states or responses in an observed individual and an observer. For example, it is hard to keep one’s mouth closed when imagining someone yawning, or not feeling distressed while observing other individuals perceiving pain. The evolutionary origin of these widespread phenomena is unclear, since a direct benefit is not always apparent. We explore a game theoretical model for the evolution of mind-reading strategies, used to predict and respond to others’ behavior. In particular we explore the evolutionary scenarios favoring simulative strategies, which recruit overlapping neural circuits when performing as well as when observing a specific behavior. We show that these mechanisms are advantageous in complex environments, by allowing an observer to use information about its own behavior to interpret that of others. However, without inhibition of the recruited neural circuits, the observer would perform the corresponding downstream action, rather than produce the appropriate social response. We identify evolutionary trade-offs that could hinder this inhibition, leading to emotional contagion as a by-product of mind-reading. The interaction of this model with kinship is complex. We show that empathy likely evolved in a scenario where kin- and other indirect benefits co-opt strategies originally evolved for mind-reading, and that this model explains observed patterns of emotional contagion with kin or group members. © 2019, The Author(s)
Selective strolls: Fixation and extinction in diploids are slower for weakly selected mutations than for neutral ones
No full textIn finite populations, an allele disappears or reaches fixation due to two main forces, selection and drift. Selection is generally thought to accelerate the process: a selected mutation will reach fixation faster than a neutral one, and a disadvantageous one will quickly disappear from the population. We show that even in simple diploid populations, this is often not true. Dominance and recessivity unexpectedly slow down the evolutionary process for weakly selected alleles. In particular, slightly advantageous dominant and mildly deleterious recessive mutations reach fixation slightly more slowly than neutral ones (at most 5%). This phenomenon determines genetic signatures opposite to those expected under strong selection, such as increased instead of decreased genetic diversity around the selected site. Furthermore, we characterize a new phenomenon: mildly deleterious recessive alleles, thought to represent a wide fraction of newly arising mutations, on average survive in a population slightly longer than neutral ones, before getting lost. Consequently, these mutations are on average slightly older than neutral ones, in contrast with previous expectations. Furthermore, they slightly increase the amount of weakly deleterious polymorphisms, as a consequence of the longer unconditional sojourn times compared to neutral mutations. © 2015 by the Genetics Society of America
Better support for a small effective population size of Neandertals and a long shared history of Neandertals and Denisovans
No full textNational Academy of Science
Cognitive Twists: The Coevolution of Learning and Genes in Human Cognition
No full textIn this paper, we propose the expression cognitive twists for cognitive mechanisms that result from the coevolution of genes and learning. Evidence is available that at least some cultural learning mechanisms, such as imitation and language, have evolved genetically under the pressure produced by culture, even though they are mostly acquired through domain-general learning during development. Although the existence of these mechanisms is consistent with evolutionary theory, their importance has not been sufficiently emphasized by mind-centered accounts of human cognitive evolution, namely evolutionary psychology and cultural evolutionary psychology. We provide concrete examples of cognitive twists, such as vocal imitation. Genetic changes in action-perception matching circuits suggest that human imitation and perhaps language are cognitive twists, namely plastic, learnable, yet genetically evolved cognitive mechanisms. We conclude that cognitive twists depict plausible evolutionary scenarios for the evolution of cognition in Homo sapiens
Cognitive Twists: The Coevolution of Learning and Genes in Human Cognition
No full textIn this paper, we propose the expression cognitive twists for cognitive mechanisms that result from the coevolution of genes and learning. Evidence is available that at least some cultural learning mechanisms, such as imitation and language, have evolved genetically under the pressure produced by culture, even though they are mostly acquired through domain-general learning during development. Although the existence of these mechanisms is consistent with evolutionary theory, their importance has not been sufficiently emphasized by mind-centered accounts of human cognitive evolution, namely evolutionary psychology and cultural evolutionary psychology. We provide concrete examples of cognitive twists, such as vocal imitation. Genetic changes in action-perception matching circuits suggest that human imitation and perhaps language are cognitive twists, namely plastic, learnable, yet genetically evolved cognitive mechanisms. We conclude that cognitive twists depict plausible evolutionary scenarios for the evolution of cognition in Homo sapiens
On the fitness of informative cues in complex environments
No full textTo be able to deal with uncertainty is of primary importance to all organisms. When cues provide information about the state of the environment, organisms can use them to respond flexibly. Thus information can provide fitness advantages. Without environmental cues, an organism can reduce the risks of environmental uncertainty by hedging its bets across different scenarios. Risk mitigation is then possible by adopting a life-history of bet-hedging, either randomly switching between phenotypes (diversifying bet-hedging) or adopting intermediate phenotypes (conservative bet-hedging). Hence, understanding patterns of bet-hedging is necessary in order to quantify the fitness benefit of environmental cues, since it provides a baseline fitness in the absence of informative cues. Quantifying fitness benefits in terms of mutual information reveals deep connections between Darwinian evolution and information theory. However, physiological constraints or complex ecological scenarios often lead to the number of environmental states to exceed that of potential phenotypes, or a single intermediate phenotype is adopted, as in the case of conservative bet-hedging. Incorporating these biological complexities, we generalise the relationship between information theory and Darwinian fitness. Sophisticated bet-hedging strategies combining diversifying and conservative bet-hedging - can then evolve. We show that, counterintuitively, environmental complexity can reduce, rather than increase, the number of phenotypes that an organism can adopt. In conclusion, we develop an information-theoretic extensible approach for investigating and quantifying fitness in ecological studies
Cognitive twists: the coevolution of learning and genes in Human Cognition
No full textIn this paper, we propose the expression cognitive twists for cognitive mechanisms that result from the coevolution of genes and learning. Evidence is available that at least some cultural learning mechanisms, such as imitation and language, have evolved genetically under the pressure produced by culture, even though they are mostly acquired through domain-general learning during development. Although the existence of these mechanisms is consistent with evolutionary theory, their importance has not been sufficiently emphasized by mind-centered accounts of human cognitive evolution, namely evolutionary psychology and cultural evolutionary psychology. We provide concrete examples of cognitive twists, such as vocal imitation. Genetic changes in action-perception matching circuits suggest that human imitation and perhaps language are cognitive twists, namely plastic, learnable, yet genetically evolved cognitive mechanisms. We conclude that cognitive twists depict plausible evolutionary scenarios for the evolution of cognition in Homo sapiens.1 Evolutionary Accounts of the Human Mind 2 Cognitive Gadgets Beats Instincts 3 Cognitive Gadgets in Evolutionary Theory 4 Cognitive Twist: a Category Proposal 5 Criteria for Cognitive Twists: the Case for Action‑Perception Matching 5.1 Evidence of Function 5.2 Evolutionary Changes 5.3 Theoretical Models 6 Imitation as a Cognitive Twist 7 Conclusion 7.1 Box 1. The Mirror Neuron Systems for Actions and Emotion
Population Dynamics and Structural Effects at Short and Long Range Support the Hypothesis of the Selective Advantage of the G614 SARS-CoV-2 Spike Variant
Full text linkSARS-CoV-2 epidemics quickly propagated worldwide, sorting virus genomic variants in newly established propagules of infections. Stochasticity in transmission within and between countries or an actual selective advantage could explain the global high frequency reached by some genomic variants. Using statistical analyses, demographic reconstructions, and molecular dynamics simulations, we show that the globally invasive G614 spike variant 1) underwent a significant demographic expansion in most countries explained neither by stochastic effects nor by overrepresentation in clinical samples, 2) increases the spike S1/S2 furin-like site conformational plasticity (short-range effect), and 3) modifies the internal motion of the receptor-binding domain affecting its cross-connection with other functional domains (long-range effect). Our results support the hypothesis of a selective advantage at the basis of the spread of the G614 variant, which we suggest may be due to structural modification of the spike protein at the S1/S2 proteolytic site, and provide structural information to guide the design of variant-specific drugs
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