Baldwin Effect Research Articles

Phase Transitions in the Evolution Model with Phenotypic Variation via Learning

The Baldwin effect describes how phenotypic variations such as the learned behaviors among clones (individuals with identical genes, i.e., isogenic individuals) can generally affect the course of evolution. We investigate the effects of phenotypic variation via learning on the evolutionary dynamics of a population. In a population, we assume the individuals to be haploid with two genotypes: one genotype shows phenotypic variation via learning and the other does not. We use an individual-based Moran model in which the evolutionary dynamics is formulated in terms of a master equation and is approximated as the Fokker-Planck equation (FPE) and the coupled nonlinear stochastic differential equations (SDEs) with multiplicative noise. In the infinite population limit, we analyze the deterministic part of the SDEs to obtain the fixed points and determine the stability of each fixed point. We find discrete phase transitions in the population distribution when the set of probabilities of reproducing the fitter and the unfit isogenic individuals is equal to the set of critical values determined by the stability of the fixed points. We also carry out numerical simulations in the form of the Gillespie algorithm and find that the results of the simulations are consistent with the analytic predictions.

Ancel (2000) on the Baldwin effect

Ancel (2000) on the Baldwin effect

How learning can change the course of evolution.

The interaction between phenotypic plasticity, e.g. learning, and evolution is an important topic both in Evolutionary Biology and Machine Learning. The evolution of learning is commonly studied in Evolutionary Biology, while the use of an evolutionary process to improve learning is of interest to the field of Machine Learning. This paper takes a different point of view by studying the effect of learning on the evolutionary process, the so-called Baldwin effect. A well-studied result in the literature about the Baldwin effect is that learning affects the speed of convergence of the evolutionary process towards some genetic configuration, which corresponds to the environment-induced plastic response. This paper demonstrates that learning can change the outcome of evolution, i.e., lead to a genetic configuration that does not correspond to the plastic response. Results are obtained both analytically and experimentally by means of an agent-based model of a foraging task, in an environment where the distribution of resources follows seasonal cycles and the foraging success on different resource types is conditioned by trade-offs that can be evolved and learned. This paper attempts to answer a question that has been overlooked: whether learning has an effect on what genotypic traits are evolved, i.e. the selection of a trait that enables a plastic response changes the selection pressure on a different trait, in what could be described as co-evolution between different traits in the same genome.

Effects of individual and social learning on the evolution of co-creative linguistic communication

The effects of learning have been regarded as important factors of the evolutionary process of human linguistic abilities. Our purpose is, by use of computer simulations, to examine the effects of individual and social learning on the evolution of cognitive (e.g., building language hierarchy) and communicative (e.g., intention sharing) abilities of language based on the interplay between biological and cultural evolution of language. In particular, we focus on a co-creative aspect of linguistic communication, which is a synergy of both cognitive and communicative aspects of language. Our simulation results show that roles of individual and social learning can work together and contribute to the evolution of co-creative aspect of linguistic abilities. It is also implied that the stable evolutionary process of cognitive abilities is based on repeated occurrences of the Baldwin effect, and dynamic and less assimilated evolution of communicative traits can work together, contributing to the co-creative communication.

The Spectroscopic Signature of Variability in High-redshift Quasars

Abstract Using 16,421 spectra from a sample of 340 quasars (1.62 < z < 3.30) from the Sloan Digital Sky Survey (SDSS) Reverberation Mapping Project, we present an analysis of quasar spectral variability. We confirm the intrinsic Baldwin effect (BE) and brighter-means-bluer trends in which emission line strength and color are associated with changes in luminosity. We then create a composite differential spectrum that captures the wavelength dependence of quasar variability as a function of change in luminosity. When using a bandpass around 1740 Å to describe the luminosity, the differential spectrum follows a power law at longer wavelengths that breaks blueward of 1700 Å. However, the shape of the differential spectrum, the location of the power-law break, and the slope of the intrinsic BE all vary with the choice of bandpass used to define the change in quasar luminosity. We propose that the observed behavior can be explained by inhomogeneous accretion or slim accretion disk models where delays in the reprocessing of incident light on the accretion disk cause local deviations in temperature from the thin-disk model. Finally, we quantify the effects on cosmology studies that are due to the variations in the quasar spectrum in the Lyα forest wavelength range. Using the observed spectroscopic signatures to predict the quasar continuum over the interval 1040 < λ < 1200 Å, we find that the derived spectral templates can reduce the uncertainty of the Lyα forest continuum level in individual epochs from 17.2% to 7.7%, near the level where systematic errors in SDSS flux calibration are expected to dominate.

Construction of Fused Oxabicyclic Scaffolds from Glycals and Styrenes via One-Pot Domino Transformations.

Triflic acid catalyzed cascade stereoselective reaction of glycals with styrenes delivers complex oxabicyclic scaffolds such as cis-oxadecalins or cis-cyclopentanofurans simply by tweaking the solvent. In the presence of participating solvents like benzene/toluene, cascade Ferrier C-glycosylation and double Friedel-Crafts reaction leads to densely chiral benzo-fused oxadecalins, whereas in DCM, an unprecedented ring-opening, ring-closing sequence generated cis-cyclopentanofurans. An attempt has been made to explain the above cascade sequences via intermediate trapping, kinetic experiments, and Baldwin's rules.

Facultative parasites as evolutionary stepping-stones towards parasitic lifestyles.

Parasites and parasitic lifestyles have evolved from free-living organisms multiple times. How such a key evolutionary transition occurred remains puzzling. Facultative parasites represent potential transitional states between free-living and fully parasitic lifestyles because they can be either free-living or parasitic depending on environmental conditions. We suggest that facultative parasites with phenotypically plastic life-history strategies may serve as evolutionary stepping-stones towards obligate parasitism. Pre-adaptations provide a starting point for the transition towards opportunistic or facultative parasitism, but what evolutionary mechanism underlies the transition from facultative to obligate parasitism? In this Opinion Piece, we outline how facultative parasites could evolve towards obligate parasites via genetic assimilation, either alone or in combination with the Baldwin effect. We further describe the key predictions stemming from each of these evolutionary pathways. The importance of genetic assimilation in evolution has been hotly debated. Studies on facultative parasites may not only provide key insights regarding the evolution of parasitism, but also provide ideal systems in which to test evolutionary theory on genetic accommodation.

5-Endo-dig cyclizations in organic syntheses.

The favorability of ring closure reactions as per Baldwin rules has gained immense importance recently. This is evident from the current literature such as research articles, reviews, and books that have been published in this area. This review covers the recent applications of 5-endo-dig cyclization in organic synthesis focusing in the last two decades. A variety of 5-membered heterocycles as well as carbocycles could be synthesized via 5-endo-dig cyclization reactions. The important applications of 5-endo-dig cyclization in organic synthesis covering different aspects have been summarized in this review.

Computational Complexity as an Ultimate Constraint on Evolution.

Experiments show that evolutionary fitness landscapes can have a rich combinatorial structure due to epistasis. For some landscapes, this structure can produce a computational constraint that prevents evolution from finding local fitness optima-thus overturning the traditional assumption that local fitness peaks can always be reached quickly if no other evolutionary forces challenge natural selection. Here, I introduce a distinction between easy landscapes of traditional theory where local fitness peaks can be found in a moderate number of steps, and hard landscapes where finding local optima requires an infeasible amount of time. Hard examples exist even among landscapes with no reciprocal sign epistasis; on these semismooth fitness landscapes, strong selection weak mutation dynamics cannot find the unique peak in polynomial time. More generally, on hard rugged fitness landscapes that include reciprocal sign epistasis, no evolutionary dynamics-even ones that do not follow adaptive paths-can find a local fitness optimum quickly. Moreover, on hard landscapes, the fitness advantage of nearby mutants cannot drop off exponentially fast but has to follow a power-law that long-term evolution experiments have associated with unbounded growth in fitness. Thus, the constraint of computational complexity enables open-ended evolution on finite landscapes. Knowing this constraint allows us to use the tools of theoretical computer science and combinatorial optimization to characterize the fitness landscapes that we expect to see in nature. I present candidates for hard landscapes at scales from single genes, to microbes, to complex organisms with costly learning (Baldwin effect) or maintained cooperation (Hankshaw effect). Just how ubiquitous hard landscapes (and the corresponding ultimate constraint on evolution) are in nature becomes an open empirical question.

A receding torus model for the Iwasawa–Taniguchi effect for Compton-thick AGN

Recently, Boorman et al. (2018) reported on the discovery of the Iwasawa-Taniguchi (I-T) effect (a.k.a. X-ray Baldwin effect) for Compton-thick AGN. They measured a decrease of the 6.4 keV iron line equivalent width with the 12mu luminosity, assumed as a proxy for the intrinsic X-ray luminosity, which in Compton-thick AGN is not directly observable. One of the most popular explanations of the classic I-T effect is the so-called receding torus model, i.e. the decrease of the covering factor of the molecular `torus' with X-ray luminosity. In this paper we show that an I-T effect for Compton-thick AGN is indeed expected in the receding torus model, assuming that the torus is funnelling the primary X-ray luminosity which is then scattered in a `hot mirror'. We found that the observed relation is well reproduced provided that the typical column density of the `hot mirror' is about 7.5x10^{22} cm^{-2}.

An effective application of 3D cloud printing service quality evaluation in BM‐MOPSO

SummaryAddressing service control factors, rapid manufacturing environment change, difficulty of resource allocation evaluation, resource optimization of 3D cloud printing service in a cloud manufacturing environment, and other characteristics, this paper proposes an evaluation indicator system of innovative new product development 3D printing order task execution. The evaluation indicator has eight dimensional components, including Time (T), Quality of Service (Q), Matching (Mat), Reliability (R), Flexibility (Flex), Cost (C), Fault tolerance (Ft), and Satisfaction (Sa). It constructs a type of optimal selection model based on a Multi‐Agent 3D Cloud Printing Service Quality Evaluation and a framework of cloud service evaluation of an AHP‐TOPSIS evaluation model based on Pareto optimization, and it designs an algorithm involving hybrid multi‐objective particle swarm optimization (PSO) based on the Baldwin Effect Model. In addition, this paper verifies the effectiveness of the algorithm through an example and offers a case study designed to test its feasibility and effectiveness.

How morphological development can guide evolution

Organisms result from adaptive processes interacting across different time scales. One such interaction is that between development and evolution. Models have shown that development sweeps over several traits in a single agent, sometimes exposing promising static traits. Subsequent evolution can then canalize these rare traits. Thus, development can, under the right conditions, increase evolvability. Here, we report on a previously unknown phenomenon when embodied agents are allowed to develop and evolve: Evolution discovers body plans robust to control changes, these body plans become genetically assimilated, yet controllers for these agents are not assimilated. This allows evolution to continue climbing fitness gradients by tinkering with the developmental programs for controllers within these permissive body plans. This exposes a previously unknown detail about the Baldwin effect: instead of all useful traits becoming genetically assimilated, only traits that render the agent robust to changes in other traits become assimilated. We refer to this as differential canalization. This finding also has implications for the evolutionary design of artificial and embodied agents such as robots: robots robust to internal changes in their controllers may also be robust to external changes in their environment, such as transferal from simulation to reality or deployment in novel environments.

Information Theory, Developmental Psychology, and the Baldwin Effect.

As part of the extended evolutionary synthesis, there has recently been a new emphasis on the effects of biological development on genetic inheritance and variation. The exciting new directions taken by those in the community have by a pre-history filled with related ideas that were never given a rigorous foundation or combined coherently. Part of the historical background of the extended synthesis is the work of James Mark Baldwin on his so-called “Baldwin Effect.” Many variant re-interpretations of his work obscure the original meaning of the Baldwin Effect. This paper emphasizes a new approach to the Baldwin Effect, focusing on his work in developmental psychology and how that would impact evolution. We propose a novel population genetics model of the Baldwin Effect. First, the impact of a kind of learning process motivated by motor babbling, in the developmental psychology literature, on evolution; second, that Information-theoretic phenotype reshaping speeds up evolution compared to populations without this kind of learning. The basic idea behind the model is to allow the organism to apply abstraction to his initial phenotype to situate it within one of a few different classes of phenotypes in the local neighborhood of a fitness maximum. The reshaping of the phenotype space thereby allows the organism to reach a nearby fitness maximum. By so doing, valleys in the fitness landscape are leveled out, making a rugged fitness landscape into a set of mesas and plateaus with increasing height. Using this model we can show the first sizeable speed-up for the Baldwin Effect compared to ordinary population genetics. We also introduce an information-theoretic foundation for the Baldwin Effect, which may be of independent interest.

An Iwasawa–Taniguchi effect for Compton-thick active galactic nuclei

We present the first study of an Iwasawa-Taniguchi/X-ray Baldwin effect for Compton-thick active galactic nuclei (AGN). We report a statistically significant anti-correlation between the rest-frame equivalent width (EW) of the narrow core of the neutral Fe K$\alpha$ fluorescence emission line, ubiquitously observed in the reflection spectra of obscured AGN, and the mid-infrared 12$\,\mu$m continuum luminosity (taken as a proxy for the bolometric AGN luminosity). Our sample consists of 72 Compton-thick AGN selected from pointed and deep-field observations covering a redshift range of $z\sim0.0014-3.7$. We employ a Monte Carlo-based fitting method, which returns a Spearman's Rank correlation coefficient of $\rho=-0.28\pm0.12$, significant to 98.7% confidence. The best fit found is ${\rm log}({\rm EW}_{{\rm Fe\,K}\alpha})\,\propto\,-0.08\pm0.04\,{\rm log}(L_{12\,\mu{\rm m}})$, which is consistent with multiple studies of the X-ray Baldwin effect for unobscured and mildly obscured AGN. This is an unexpected result, as the Fe K$\alpha$ line is conventionally thought to originate from the same region as the underlying reflection continuum, which together constitute the reflection spectrum. We discuss the implications this could have if confirmed on larger samples, including a systematic underestimation of the line of sight X-ray obscuring column density and hence the intrinsic luminosities and growth rates for the most luminous AGN.

Baldwin effect and Lamarckian evolution in a memetic algorithm for Euclidean Steiner tree problem

The study is concerned with the Baldwin effect and Lamarckian evolution in a memetic algorithm for Euclidean Steiner tree problem (ESTP). The main aim is to examine the importance of the proposed local search procedures for the ability of the algorithm to find solutions to ESTP. Two local search procedures are proposed as a part of an evolutionary algorithm for ESTP, and the effect of their use is carefully analyzed. The correction procedure modifies the given chromosome so that it satisfies the degree and angle conditions in ESTP. The improvement procedure actively adds new Steiner points to the evaluated solution. The modified solutions are accepted with varying probability, leading to a spectrum of algorithms with a Baldwin effect on one end and Lamarckian evolution on the other. The results are carefully analyzed using proper statistical procedures (Friedman test and post-hoc procedures). To further check the ability of the proposed algorithm to find the optimal or near optimal solutions, results for problems from OR-Lib are provided.

A long-range tautomeric effect on a new Schiff isoniazid analogue, evidenced by NMR study and X-ray crystallography

Isoniazid analogues were cyclized through acid catalysis by closing a THF ring, as favoured by Baldwin's rules (5-exo-trig).

The Evolution of Sex through the Baldwin Effect.

This article suggests that the fundamental haploid-diploid cycle of eukaryotic sex exploits a rudimentary form of the Baldwin effect. With this explanation for the basic cycle, the other associated phenomena can be explained as evolution tuning the amount and frequency of learning experienced by an organism. Using the well-known NK model of fitness landscapes, it is shown that varying landscape ruggedness varies the benefit of the haploid-diploid cycle, whether based upon endomitosis or syngamy. The utility of pre-meiotic doubling and recombination during the cycle are also shown to vary with landscape ruggedness. This view is suggested as underpinning, rather than contradicting, many existing explanations for sex.

The Role of the Baldwin Effect in the Evolution of Human Musicality.

From the biological perspective human musicality is the term referred to as a set of abilities which enable the recognition and production of music. Since music is a complex phenomenon which consists of features that represent different stages of the evolution of human auditory abilities, the question concerning the evolutionary origin of music must focus mainly on music specific properties and their possible biological function or functions. What usually differentiates music from other forms of human sound expressions is a syntactically organized structure based on pitch classes and rhythmic units measured in reference to musical pulse. This structure is an auditory (not acoustical) phenomenon, meaning that it is a human-specific interpretation of sounds achieved thanks to certain characteristics of the nervous system. There is historical and cross-cultural diversity of this structure which indicates that learning is an important part of the development of human musicality. However, the fact that there is no culture without music, the syntax of which is implicitly learned and easily recognizable, suggests that human musicality may be an adaptive phenomenon. If the use of syntactically organized structure as a communicative phenomenon were adaptive it would be only in circumstances in which this structure is recognizable by more than one individual. Therefore, there is a problem to explain the adaptive value of an ability to recognize a syntactically organized structure that appeared accidentally as the result of mutation or recombination in an environment without a syntactically organized structure. The possible solution could be explained by the Baldwin effect in which a culturally invented trait is transformed into an instinctive trait by the means of natural selection. It is proposed that in the beginning musical structure was invented and learned thanks to neural plasticity. Because structurally organized music appeared adaptive (phenotypic adaptation) e.g., as a tool of social consolidation, our predecessors started to spend a lot of time and energy on music. In such circumstances, accidentally one individual was born with the genetically controlled development of new neural circuitry which allowed him or her to learn music faster and with less energy use.

The revival of the Baldwin effect

The idea that a genetically fixed behavior evolved from the once differential learning ability of individuals that performed the behavior is known as the Baldwin effect. A highly influential paper [Hinton G.E., Nowlan S.J., 1987. How learning can guide evolution. Complex Syst. 1, 495-502] claimed that this effect can be observed in silico, but here we argue that what was actually shown is that the learning ability is easily selected for. Then we demonstrate the Baldwin effect to happen in the in silico scenario by estimating the probability and waiting times for the learned behavior to become innate. Depending on parameter values, we find that learning can increase the chance of fixation of the learned behavior by several orders of magnitude compared with the non-learning situation.

Quasar Rain: The Broad Emission Line Region as Condensations in the Warm Accretion Disk Wind

Abstract The origin of the broad emission line region (BELR) in quasars and active galactic nuclei is still unclear. I propose that condensations form in the warm, radiation-pressure-driven, accretion disk wind of quasars creating the BEL clouds and uniting them with the other two manifestations of cool (∼104 K) gas in quasars, the low ionization phase of the warm absorbers (WAs) and the clouds causing X-ray eclipses. The cool clouds will condense quickly (days to years), before the WA outflows reach escape velocity (which takes months to centuries). Cool clouds form in equilibrium with the warm phase of the wind because the rapidly varying X-ray quasar continuum changes the force multiplier, causing pressure waves to move gas into stable locations in pressure–temperature space. The narrow range of two-phase equilibrium densities may explain the (luminosity) scaling of the BELR size, while the scaling of cloud formation timescales could produce the Baldwin effect. These dense clouds have force multipliers of order unity and so cannot be accelerated to escape velocity. They fall back on a dynamical timescale (months to centuries), producing an inflow that rains down toward the central black hole. As they soon move at Mach ∼10–100 with respect to the WA outflow, these “raindrops” will be rapidly destroyed within months. This rain of clouds may produce the elliptical BELR orbits implied by velocity-resolved reverberation mapping in some objects and can explain the opening angle and destruction timescale of the narrow “cometary” tails of the clouds seen in X-ray eclipse observations. Some consequences and challenges of this “quasar rain” model are presented, along with several avenues for theoretical investigation.