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PubMed2006

An evolutionary concept of polycystic ovarian disease: does evolution favour reproductive success over survival?

Polycystic ovarian disease (PCOD) is currently considered as possibly the most frequent cause of female infertility. It is also closely associated with syndrome XX, which, in turn, is closely linked with premature and excessive mortality. Considering these adverse effects on reproductive success and human survival, the evolutionary survival of PCOD, itself considered by many to be a genetically transmitted condition, would, on first glance, appear surprising, since evolution usually discriminates against both of these traits. However, an analysis of some recently reported characteristics of the condition calls for the reconsideration of PCOD as a condition which, from an evolutionary viewpoint, favours decreased reproductive success. Indeed, the reported observations that patients with PCOD will resume spontaneous ovulation with even relatively minor weight loss, and experience later menopause than controls, suggests exactly the opposite. Under an evolutionary concept, PCOD can thus be seen as a 'fertility storage condition' which in fact favours human reproductive success and allows the human species to maintain fertility even during adverse environmental circumstances, such as famines.

Anovulation↗
PubMed1998

Heterochrony and allometry: the analysis of evolutionary change in ontogeny.

The connection between development and evolution has become the focus of an increasing amount of research in recent years, and heterochrony has long been a key concept in this relation. Heterochrony is defined as evolutionary change in rates and timing of developmental processes; the dimension of time is therefore an essential part in studies of heterochrony. Over the past two decades, evolutionary biologists have used several methodological frameworks to analyse heterochrony, which differ substantially in the way they characterize evolutionary changes in ontogenies and in the resulting classification, although they mostly use the same terms. This review examines how these methods compare ancestral and descendant ontogenies, emphasizing their differences and the potential for contradictory results from analyses using different frameworks. One of the two principal methods uses a clock as a graphical display for comparisons of size, shape and age at a particular ontogenic stage, whereas the other characterizes a developmental process by its time of onset, rate, and time of cessation. The literature on human heterochrony provides particularly clear examples of how these differences produce apparent contradictions when applied to the same problem. Developmental biologists recently have extended the concept of heterochrony to the earliest stages of development and have applied it at the cellular and molecular scale. This extension brought considerations of developmental mechanisms and genetics into the study of heterochrony, which previously was based primarily on phenomenological characterizations of morphological change in ontogeny. Allometry is the pattern of covariation among several morphological traits or between measures of size and shape; unlike heterochrony, allometry does not deal with time explicitly. Two main approaches to the study of allometry are distinguished, which differ in the way they characterize organismal form. One approach defines shape as proportions among measurements, based on considerations of geometric similarity, whereas the other focuses on the covariation among measurements in ontogeny and evolution. Both are related conceptually and through the use of similar algebra. In addition, there are close connections between heterochrony and changes in allometric growth trajectories, although there is no one-to-one correspondence. These relationships and outline links between different analytical frameworks are discussed.

Animals↗
PubMed1992

The paranasal sinuses and other enigmas: an aquatic evolutionary theory.

The functional role of the paranasal sinuses in man has long been in dispute and as yet no satisfactory explanation has been offered for these 'unwanted' spaces. An answer may be found by study of the comparative evolutionary development of the sinuses in man and other higher primates. Several unique physical characteristics of man not seen elsewhere in the ape family, or indeed in other terrestrial mammals, including some relating to the upper aerodigestive tract, are not satisfactorily explained by the traditionally held theory of evolutionary development of early man directly from the arboreal ape. It is argued that these developmental differences are much more logically explained by a period of aquatic adaptation at a crucial period in the evolution of pre-hominid man. A new theory is proposed which might explain the importance of the sinus air cavities as buoyancy aids for protection of the upper airway tract in such an aquatic environment. Further evidence is offered relating to a pathological condition of the external ear canal which supports this theory that man at some stage in his early development acquired an affinity for an aquatic environment. Explanation of these unique hominid characteristics in terms of an aquatic evolutionary theory may help to resolve some of the enigmatic inconsistencies between man and other higher primates, and may account for man's eventual emergence as the dominant extant species, and perhaps an explanation for the 'missing link'.

Animals↗
PubMed2006

Resolving the paradox of common, harmful, heritable mental disorders: which evolutionary genetic models work best?

Given that natural selection is so powerful at optimizing complex adaptations, why does it seem unable to eliminate genes (susceptibility alleles) that predispose to common, harmful, heritable mental disorders, such as schizophrenia or bipolar disorder? We assess three leading explanations for this apparent paradox from evolutionary genetic theory: (1) ancestral neutrality (susceptibility alleles were not harmful among ancestors), (2) balancing selection (susceptibility alleles sometimes increased fitness), and (3) polygenic mutation-selection balance (mental disorders reflect the inevitable mutational load on the thousands of genes underlying human behavior). The first two explanations are commonly assumed in psychiatric genetics and Darwinian psychiatry, while mutation-selection has often been discounted. All three models can explain persistent genetic variance in some traits under some conditions, but the first two have serious problems in explaining human mental disorders. Ancestral neutrality fails to explain low mental disorder frequencies and requires implausibly small selection coefficients against mental disorders given the data on the reproductive costs and impairment of mental disorders. Balancing selection (including spatio-temporal variation in selection, heterozygote advantage, antagonistic pleiotropy, and frequency-dependent selection) tends to favor environmentally contingent adaptations (which would show no heritability) or high-frequency alleles (which psychiatric genetics would have already found). Only polygenic mutation-selection balance seems consistent with the data on mental disorder prevalence rates, fitness costs, the likely rarity of susceptibility alleles, and the increased risks of mental disorders with brain trauma, inbreeding, and paternal age. This evolutionary genetic framework for mental disorders has wide-ranging implications for psychology, psychiatry, behavior genetics, molecular genetics, and evolutionary approaches to studying human behavior.

Adaptation, Physiological↗
PubMed2005

Shared promiscuous activities and evolutionary features in various members of the amidohydrolase superfamily.

The amidohydrolase superfamily comprises hundreds of hydrolytic enzymes of the (beta/alpha)8 barrel fold with mono- or binuclear active-site metal centers, and a diverse spectrum of substrates and reactions. Promiscuous activities, or cross-reactivities, between different members of the same superfamily may provide important hints regarding evolutionary and mechanistic relationships. We examined three members: dihydroorotase (DHO), phosphotriesterase (PTE), and PTE-homology protein (PHP). Of particular interest are PTE, which is thought to have evolved within the last several decades, and PHP, an amidohydrolase superfamily member of unknown function, and the closest known homologue of PTE. We found a diverse and partially overlapping pattern of promiscuous activities in these enzymes, including a significant lactonase activity in PTE, esterase activities in both PTE and PHP, and a weak PTE activity in DHO. Directed evolution was applied to improve the promiscuous esterase activities of PTE and PHP. Remarkably, the most recurrent mutation increasing esterase activity in PTE, or PHP, maps to the same location in their superposed 3D structures. The evolved variants also exhibit newly acquired promiscuous activities that were not selected for, including very weak, yet measurable, paraoxonase activity in PHP. Our results illustrate the mechanistic, structural, and evolutionary links between these enzymes, and highlight the importance of studying laboratory evolution intermediates that might resemble node intermediates along the evolutionary pathways leading to the divergence of enzyme superfamilies.

Amidohydrolases↗
PubMed2001

The executive functions and self-regulation: an evolutionary neuropsychological perspective.

Neuropsychology has customarily taken a molecular and myopic view of executive functioning, concentrating largely on those proximal processes of which it may be comprised. Although commendable as a starting point, such an approach can never answer the question, "Why executive functioning?" The present paper encourages neuropsychologists to contemplate the longer-term, functional nature of the executive functions (EFs), using an evolutionary perspective. For purely illustrative purposes, a previously developed model of the EFs is briefly presented and is then examined from an evolutionary perspective. That model views the EFs as forms of behavior-to-the-self that evolved from overt (public) to covert (private) responses as a means of self-regulation. That was necessary given the interpersonal competition that arises within this group-living species. The EFs serve to shift the control of behavior from the immediate context, social others, and the temporal now to self-regulation by internal representations regarding the hypothetical social future. The EFs seem to meet the requirements of a biological adaptation, being an improbable complex design for a purpose that exists universally in humans. Discovering the adaptive problems that the EFs evolved to solve offers an invaluable research agenda for neuropsychology lest that agenda be resolved first by other scientific disciplines. Some adaptive problems that the EFs may have evolved to solve are then considered, among them being social exchange (reciprocal altruism or selfish cooperation), imitation and vicarious learning as types of experiential theft, mimetic skill (private behavioral rehearsal) and gestural communication, and social self-defense against such theft and interpersonal manipulation. Although clearly speculative at the moment, these proposals demonstrate the merit of considering the larger adaptive problems that the EFs evolved to solve. Taking the evolutionary stance toward the EFs would achieve not only greater insight into their nature, but also into their assessment and into those larger adaptive capacities that may be diminished through injury or developmental impairment toward that system.

Adaptation, Psychological↗
PubMed2001

On the relative importance of haplodiploidy, assortative mating and social synergy on the evolutionary emergence of social behavior.

Advances in multiagent simulation techniques make it possible to study more realistic dynamics of complex systems and allow evolutionary theories to be tested. Here I use simulations to assess the relative importance of reproductive systems (haplodiploidy vs. diploidy), mate selection (assortative mating vs. random mating) and social economics (pay-off matrices of evolutionary games) in the evolutionary dynamics leading to the emergence of social cooperation in the provision of parental care. The simulations confirm that haplo-diploid organisms and organisms mating assortatively have a higher probability for fixing alleles and require less favorable conditions for their fixation, than diploids or organisms mating randomly. The simulations showed that social behavior was most likely to emerge a) when the cost for parental investment was much lower than the benefits to the offspring, b) when cooperation improved synergistically the fitness of offspring compared to the corresponding egoistic behavior and c) when alleles coding for altruistic or social behavior could be rapidly fixed in the population, thanks to mechanisms such as haplo-diploidy and/or assortative mating. Cooperative social behavior always appeared if sociality conferred much higher fitness gains compared to non cooperative alternatives suggesting that the most important factors for the emergence and maintenance of social behavior are those based on energetic or efficiency considerations. The simulations, in congruence with the scant experimental evidence available, suggest that economic considerations rather than genetic ones are critical in explaining the emergence and maintenance of sociality.

Animals↗
PubMed2001

Lectin and lectin-related proteins in lima bean (Phaseolus lunatus L.) seeds: biochemical and evolutionary studies.

Lectin-related polypeptides are a class of defence proteins found in seeds of Phaseolus species. In Lima bean (P. lunatus), these proteins and their genes have been well characterized in the Andean morphotype, which represents one of the two gene pools of this species. To study the molecular evolution of the lectin family in Lima bean we characterized the polypeptides belonging to this multigene family and cloned the genes belonging to the Mesoamerican gene pool. The latter gene pool contains components similar to those of the Andean pool, namely: an amylase inhibitor-like (AIL), an arcelin-like (ARL) lectin and the less abundant Lima bean lectin (LBL). These proteins originate from an ancestor gene of the lectin type which duplicated to yield the lectin gene and the progenitor of ARL and AIL. In this species. ARL represents an evolutionary intermediate form that precedes AIL. Phylogenetic analysis supports an Andean origin for Lima bean. The molecular evolutionary studies were extended to the genes of common bean and demonstrated that true lectin genes and the ancestor of lectin-related genes are the result of a duplication event that occurred before speciation. Lima and common bean followed different evolutionary pathways and in the latter species a second duplication event occurred that gave rise, in Mesoamerican wild genotypes, to arcelin genes.

Amino Acid Sequence↗
PubMed2002

Evolutionary relationships of flying foxes (genus Pteropus) in the Philippines inferred from DNA sequences of cytochrome b gene.

Six flying fox species, genus Pteropus (four from the Philippines) were investigated using complete cytochrome b gene sequences (1140 bp) to infer their evolutionary relationships. The DNA sequences generated via polymerase chain reaction were analyzed using the neighbor-joining, parsimony, and maximum likelihood methods. We estimated that the first evolutionary event among these Pteropus species occurred approximately 13.90 +/- 1.49 MYA. Within this short period of evolutionary time we further hypothesized that the ancestors of the flying foxes found in the Philippines experienced a subsequent diversification forming two clusters in the topology. The first cluster is composed of P. pumilus (Philippine endemic), P. speciosus (restricted in western Mindanao) with P. scapulatus, while the second one comprised P. vampyrus and P. dasymallus species based on the analysis from first and second codon positions. Consistently, all phylogenetic analyses divulged close association of P. dasymallus with P. vampyrus contradicting the previous report categorizing P. dasymallus under subniger species group with P. pumilus. P. speciosus, and P. hypomelanus. The Philippine endemic species (P. pumilus) is closely linked with P. speciosus. The representative samples of P. vampyrus showed a large genetic distance of 1.87%. The large genetic distance between P. dasymallus and P. hypomelanus, P. pumilus and P. speciosus denotes a distinct species group.

Animals↗
PubMed1997

Comparative mapping of Xp22 genes in hominoids--evolutionary linear instability of their Y homologues.

Several genes located within or proximal to the human PAR in Xp22 have homologues on the Y chromosome and escape, or partly escape, inactivation. To study the evolution of Xp22 genes and their Y homologues, we applied multicolour fluorescence in situ hybridization (FISH) to comparatively map DNA probes for the genes ANT3, XG, ARSD, ARSE (CDPX), PRK, STS, KAL and AMEL to prometaphase chromosomes of the human species and hominoid apes. We demonstrate that the genes residing proximal to the PAR have a highly conserved order on the higher primate X chromosomes but show considerable rearrangements on the Y chromosomes of hominoids. These rearrangements cannot be traced back to a simple model involving only a single or a few evolutionary events. The linear instability of the Y chromosomes gives some insight into the evolutionary isolation of large parts of the Y chromosomes and thus might reflect the isolated evolutionary history of the primate species over millions of years.

Animals↗
PubMed2003

From the stress theory of aging to energetic and evolutionary expectations for longevity.

Stress targets energy carriers. Genes for stress resistance are selected that convey high metabolic efficiency enabling adaptation to the energetically restrictive and hence stressful environments of natural populations. Data from experimental organisms and from humans are consistent with a primary role for stress resistance underlying life span, which provides a hitherto neglected procedure for assaying longevity in natural populations. Taking into account the metabolic consequences of stressful environments, the free-radical theory of aging becomes a general stress theory of aging. A recent derivative, the deprivation-syndrome theory of aging, highlights resource and hence energy shortages. Energy balances under the stress theory of aging are primary for an understanding of the evolutionary limits of longevity of organisms in their habitats. In contrast, well-nourished humans of the modern era, and laboratory, domesticated and island populations are exposed to more benign conditions which appear to provide the background for other evolutionary theories of aging, especially the mutation accumulation and antagonistic pleiotropy theories. In modern human populations where selection for stress resistance is relaxed compared with earlier harsher conditions, substantial future evolutionary extensions to maximum life span may be difficult to attain because of the mutation accumulation process. However there is an urgent need for comparative empirical studies of life-history traits including longevity under benign and harsh environments.

Aging↗
PubMed1999

Evolutionary relationships between HLA-B alleles as indicated by an analysis of intron sequences.

The HLA-B locus is the most polymorphic of the class I genes encoded within the human major histocompatibility complex. This polymorphism is mainly located in exons 2 and 3, which code for the molecule's alpha1 and alpha2 domains and includes the antigenic peptide binding site. However, information about adjacent non-coding regions (introns 1 and 2) has not been extensively reported but could be very important in establishing an understanding of the evolutionary mechanisms involved in the polymorphism generation of HLA-B and the Mhc loci. In the present work, introns 1 and 2 of 14 HLA-B alleles are studied and their significance is discussed; 10 have been sequenced in our own laboratory and the other 4 have been previously reported by others. Different serological families share the complete intron 1 sequence; at this region, 12 out of 14 HLA-B alleles could be included in four groups with the same intron 1 sequence: a) B*0702, B*4201, B*4801; b) B*27052, B*4002, B*4011; c) B*40012, B*4101, including B*4501, B*5001 (these latter two alleles have specific characteristics in both introns 1 and 2, which may reflect a common evolutionary pathway); and d) B*44031, B*44032. The other alleles, B*1402, and B*1801, do not have identical intron 1 sequences compared to any of the described groups, but share many similarities with them. The B*1801 evolutionary pathway seems to be very specific since it branches separately from other alleles both in intron 1 and intron 2 dendrograms. On the other hand, HLA-B allelic group distribution and similarities according to intron 1 sequences were not confirmed when using intron 2, especially in the cases of B*4002, B*4101 and B*4801. This would suggest that both point mutations fixed by genetic drift and gene conversion events are involved in HLA-B diversification. The latter events could be supported by the strong homology between intron 1 and, to a lesser extent, intron 2, and also the CG content within them. Finally, the precise knowledge of these non-coding regions could be important for developing DNA base typing strategies for the HLA-B alleles.

Alleles↗
PubMed1996

Sex differences in social behavior. Are the social role and evolutionary explanations compatible?

The competing claims of two explanations of sex differences in social behavior, social role theory, and evolutionary psychology are examined. The origin and scope of research on sex differences in social behavior are outlined, and the application of social role theory is discussed. Research that is based on modern sexual selection theory is described, and whether its findings can be explained by social role theory is considered. Findings associated with social role theory are weighed against evolutionary explanations. It is concluded that evolutionary theory accounts much better for the overall pattern of sex differences and for their origins. A coevolutionary approach is proposed to explain cross-cultural consistency in socialization patterns.

Female↗
PubMed2003

Evolutionary psychology from a developmental systems perspective: comment on Lickliter and Honeycutt (2003).

Although agreeing with R. Lickliter and H. Honeycutt (2003) that evolutionary psychology lacks and should adopt a coherent developmental model to explain how evolved mechanisms become expressed in phenotypes, it is argued that adhering to the principles of developmental systems theory, despite enhancing evolutionary psychology, would not change appreciably its basic focus. The concepts of innateness and modularity, what is inherited and what evolves, as well as the possible role of developmental plasticity in the evolution of human cognition are discussed. It is proposed that evolutionary psychology can incorporate the developmental systems perspective into its theorizing, with the end result being a science that more closely reflects human nature.

Biological Evolution↗
PubMed2003

Developmental dynamics and contemporary evolutionary psychology: status quo or irreconcilable views? Reply to Bjorklund (2003), Krebs (2003), Buss and Reeve (2003), Crawford (2003), and Tooby et Al. (2003).

The authors address commentaries by D. F. Bjorklund (2003); D. M. Buss and H. K. Reeve (2003); C. B. Crawford (2003); D. L. Krebs (2003); and J. Tooby, L. Cosmides, and H. C. Barrett (2003) on their analysis of the underlying assumptions of contemporary evolutionary psychology (R. Lickliter & H. Honeycutt, 2003). The authors argue that evolutionary psychology currently offers no coherent framework for how to integrate genetic, environmental, and experiential factors into a theory of behavioral or cognitive phenotypes. The authors propose that this absence is due to a lack of developmental analysis in the major works of evolutionary psychology, resulting in an almost exclusive focus on adaptationist accounts of evolution by natural selection rather than a more broad-based focus on the process and products of evolution by epigenetic developmental dynamics.

Adaptation, Physiological↗
PubMed2002

Developmental-behavioral initiation of evolutionary change.

The traditional approach to evolutionary psychology relies entirely on natural selection as the cause of the evolution of adaptations. Exclusive reliance on natural selection overlooks the fact that changes in development are a necessary prerequisite for evolutionary change. These developmental changes provide the material for natural selection to work on. In the neo-Darwinian scenario, the mechanisms of evolution are mutation or genetic recombination, selection, migration, and eventual reproductive isolation. In the spirit of evolutionary pluralism, the author describes a different 3-stage scenario in which migration (the invasion of new niches or habitats) may occur without mutation or genetic recombination and selection first initiating a change in genes or gene frequencies.

Adaptation, Physiological↗
PubMed2006

Comparative evolutionary psychology of sperm competition.

A comparative evolutionary psychological perspective predicts that species that recurrently faced similar adaptive problems may have evolved similar psychological mechanisms to solve these problems. Sperm competition provides an arena in which to assess the heuristic value of such a comparative evolutionary perspective. The sperm competition that results from female infidelity and polyandry presents a similar class of adaptive problems for individuals across many species. The authors first describe mechanisms of sperm competition in insects and in birds. They suggest that the adaptive problems and evolved solutions in these species provide insight into human anatomy, physiology, psychology, and behavior. The authors then review recent theoretical and empirical arguments for the existence of sperm competition in humans and discuss proposed adaptations in humans that have analogs in insects or birds. The authors conclude by highlighting the heuristic value of a comparative evolutionary psychological approach in this field.

Animals↗
PubMed1979

Evolutionary change in the insulin receptors of hystricomorph rodents.

INSULIN receptors have been thought to have remained unaltered despite evolutionary changes in the hormone(1). Because insulins from hystricomorph rodents are known to be highly substituted compared with other mammalian insulins, we decided to investigate the insulin receptor of some hystricomorphs to determine whether evolutionary change had occurred within the receptor itself. Here we present the first evidence that hystricomorph rodent insulin receptors have undergone evolutionary change.

Journal Article↗