Biological Theory

Toward a Macroevolutionary Theory of Human Evolution: The Social Protocell Abstract Despite remarkable empirical and methodological advances, our theoretical understanding of the evolutionary processes that made us human remains fragmented and contentious. Here, we make the radical proposition that the cultural communities within which Homo emerged may be understood as a novel exotic form of organism. The argument begins from a deep congruence between robust features of Pan community life cycles and protocell models of the origins of life. We argue that if a cultural tradition, meeting certain requirements, arises in the context of such a "social protocell," the outcome will be an evolutionary transition in individuality whereby traditions and hominins coalesce into a macroscopic bio-socio-technical system, with an organismal organization that is culturally inherited through irreversible fission events on the community level. We refer to the resulting hypothetical evolutionary individual as a "sociont." The social protocell provides a preadapted source of alignment of fitness interests that addresses a number of open questions about the origins of shared adaptive cultural organization, and the derived genetic (and highly unusual) adaptations that support them. Also, social cooperation between hominins is no longer in exclusive focus since cooperation among traditions becomes salient in this model. This provides novel avenues for explanation. We go on to hypothesize that the fate of the hominin in such a setting would be mutualistic coadaptation into a part-whole relation with the sociont, and we propose that the unusual suite of derived features in Homo is consistent with this hypothesis.

Mating Markets: A Naturally Selected Sex Allocation Theory of Sexual Selection Abstract This article utilizes three premises. (1) There are commonly ecologically oriented, naturally selected specialized differences in frequency and/or quality as well as sexually selected differences between the sexes. (2) Sex in the sense of coming together and going apart (syngamy and meiosis in haploids) or going apart and coming together (meiosis and syngamy in diploids) is trade in these naturally selected differences, i.e., there is a mating market in sexual species. (3) While such trade is beneficial to the population as a whole, sexual competition and selection is conflict over the profits of that trade and can be detrimental to the population as a whole. These premises yield a naturally selected sex allocation theory of the possible directions and forms of sexual selection, i.e., one that includes costs as well as frequencies. This can explain conventional sex roles, the sex-role reversed, inter- as well as intrasexual selection, and passive as well as active choice. Any of these alternatives may be over mates, over gametes, or both. A hypothetical example based on density dependence relative to resources is provided, one that suggests that centrioles may be a cytoplasmic resource in males in multicellular animals, and which are the target of active choice and the mechanism of manipulation in passive female choice. As a whole, the approach yields a truly general theory of sexual selection, provides an alternative to the mechanism for Fisher's principle, and gives a theoretical explanation for Mayr's biological species definition.

Social-Ecological Theory of Maximization: Basic Concepts and Two Initial Models Abstract Efforts have been dedicated to the understanding of social-ecological systems, an important focus in ethnobiological studies. In particular, ethnobiological investigations have found evidence and tested hypotheses over the last 30 years on the interactions between human groups and their environments, generating the need to formulate a theory for such systems. In this article, we propose the social-ecological theory of maximization to explain the construction and functioning of these systems over time, encompassing hypotheses and evidence from previous ethnobiological studies. In proposing the theory, we present definitions and two conceptual models, an environmental maximization model and a redundancy generation model. The first model seeks to address biota selection and its use by human populations. The second emphasizes how the system organizes itself from the elements that were incorporated into it. Furthermore, we provide the theoretical scenario of plant selection and use from an evolutionary perspective, which explicitly integrates the phylogenetic relationships of plants (or other living resources) and human beings.

Why is There No Successful Whole Brain Simulation (Yet)? Abstract With the advent of powerful parallel computers, efforts have commenced to simulate complete mammalian brains. However, so far none of these efforts has produced outcomes close to explaining even the behavioral complexities of animals. In this article, we suggest four challenges that ground this shortcoming. First, we discuss the connection between hypothesis testing and simulations. Typically, efforts to simulate complete mammalian brains lack a clear hypothesis. Second, we treat complications related to a lack of parameter constraints for large-scale simulations. To demonstrate the severity of this issue, we review work on two small-scale neural systems, the crustacean stomatogastric ganglion and the Caenorhabditis elegans nervous system. Both of these small nervous systems are very thoroughly, but not completely understood, mainly due to issues with variable and plastic parameters. Third, we discuss the hierarchical structure of neural systems as a principled obstacle to whole-brain simulations. Different organizational levels imply qualitative differences not only in structure, but in choice and appropriateness of investigative technique and perspective. The challenge of reconciling different levels also undergirds the challenge of simulating and hypothesis testing, as modeling a system is not the same thing as simulating it. Fourth, we point out that animal brains are information processing systems tailored very specifically for the ecological niches the respective animals live in.

The Role of Assessor Teaching in Human Culture Abstract According to the dual inheritance theory, cultural learning in our species is a biased and highly efficient process of transmitting cultural traits. Here we define a model of cultural learning where social learning is integrated as a complementary element that facilitates the discovery of a specific behavior by an apprentice, and not as a mechanism that works in opposition to individual learning. In that context, we propose that the emergence of the ability to approve or disapprove of offspring behavior, orienting their learning (a process we call assessor teaching), transformed primate social learning into a cultural transmission system, like that which characterizes our species. Assessor teaching facilitates the replication and/or reconstruction of behaviors that are difficult to imitate and helps to determine which behaviors should be imitated. We also explore the form in which assessor teaching has conditioned the evolution of our abilities to develop cultures in the hominin line, converting us into individuals equipped with what we call a suadens psychology. Our main point is to defend the hypothesis that suadens psychology determines the stability and dynamics that affect the trajectories of many cultural characters. We compare our proposal with other theories about cultural evolution, specifically with dual inheritance theory and cultural attraction theory.

Multicellular Individuality: The Case of Bacteria Abstract Recent attention to complex group-level behavior amongst bacteria has led some to conceive of multicellular clusters of bacteria as individuals. In this article, I assess these recent claims by first drawing a distinction between two concepts of individuality: physiological and evolutionary. I then survey cases that are representative of three different modes of growth: myxobacteria (surface-attached agglomerative growth), Bacillus subtilis(agglomerative growth not attached to a surface), and cyanobacteria (filamentous growth). A closer look at these cases indicates that multicellular individuality among bacteria is remarkably complex. Physiologically, the three cases of multicellular clusters do not form physiological individuals. But matters are different when it comes to evolutionary individuality; although multicellular clusters that grow by agglomeration are not highly individuated, filament-forming groups achieve a relatively high degree of individuality. I also suggest that debates about bacterial multicellular individuality may have been obscured by a failure to see that selection on highly individuated groups is by no means the only mechanism to bring about the complex group-level behaviors that have led some to view bacteria as multicellular individuals.

Are Verbal-Narrative Models More Suitable than Mathematical Models as Information Processing Devices for Some Behavioral (Biosemiotic) Problems? Abstract This article argues that many, if not most, behavior descriptions and sequencing are in essence an interpretation of signs, and are evaluated as sequences of signs by researchers. Thus, narrative analysis, as developed by Barthes and others, seems best suited to be used in behavioral/biosemiotic studies rather than mathematical modeling, and is very similar to some classic ethology methods. As our brain interprets behaviors as signs and attributes meaning to them, narrative analysis seems more suitable than mathematical modeling to describe and study behavior. Mathematical models are, on many occasions, extremely reductionist and simplifying because of computational and/or numerical representation limitations that lead to errors and straitjacketing interpretations of reality. Since actual animals (and our analysis of their behavior) are not as optimal in real life as our mathematical models, here it is proposed that we should consider logical/verbal models and semantic interpretations as equally or even better suited for behavioral analysis, and refrain from enforcing mathematical modeling as the only (right) way to study and understand biological problems, especially those of a behavioral and biosemiotic nature.

Criteria for Holobionts from Community Genetics Abstract We address the controversy in the literature concerning the definition of holobionts and the apparent constraints on their evolution using concepts from community population genetics. The genetics of holobionts, consisting of a host and diverse microbial symbionts, has been neglected in many discussions of the topic, and, where it has been discussed, a gene-centric, species-centric view, based in genomic conflict, has been predominant. Because coevolution takes place between traits or genes in two or more species and not, strictly speaking, between species, it may affect some traits but not others in either host or symbiont. Moreover, when interacting species pairs are embedded in a larger community, indirect ecological effects can alter the expected pairwise dynamics. Mode of symbiont transmission and the degree of host inbreeding both affect the extent of microbial mixing across host lineages and thereby the degree to which selection on one trait of either partner affects other aspects of a holobiont phenotype. We discuss several potential defining criteria for holobionts using community genetics and population genetics models, suggesting their application and limitations. Using community genetics models, we show how conflict between genomes can be self-limiting, while cooperation and mutualism tend to be self-accelerating. It is likely that this bias in the evolutionary dynamics of interaction between hosts and symbionts is an important feature of holobionts. This bias in the evolutionary dynamic could contribute to explaining the absence of cheaters from natural mutualisms, although cheaters are predicted by gene-centered conflict theory to cause the evolutionary instability of mutualisms. Additionally, it may help explain the more frequent origin of mutualisms from parasitic than from free-living systems, an evolutionary trajectory opposite to that predicted by genome conflict theory.

Reflections on a Biometrics of Organismal Form Abstract Back in 1987 the physicist/theoretical biologist Walter Elsasser reviewed a range of philosophical issues at the foundation of organismal biology above the molecular level. Two of these are particularly relevant to quantifications of form: the concept of ordered heterogeneity and the principle of nonstructural memory, the truism that typically the forms of organisms substantially resemble the forms of their ancestors. This essay attempts to weave Elsasser's principles together with morphometrics (the biometrics of organismal form) for one prominent data type, the representation of animal forms by positions of landmark points. I introduce a new spectrum of pattern descriptors of the shape variation of landmark configurations, ranging from the most homogeneous (uniform shears) through growth gradients and focal features to a model of totally disordered heterogeneity incompatible with the rhetoric of functional explanation. An investigation may end up reporting its findings by one of these descriptors or by several. These descriptors all derive from one shared diagrammatic device: a log–log plot of sample variance against one standard formalism of today's geometric morphometrics, the bending energies of the principal warps that represent all the scales of variability around the sample average shape. The new descriptors, which I demonstrate over a variety of contemporary morphometric examples, may help build the bridge we urgently need between the arithmetic of today's burgeoning image-based data resources and the rhetoric of biological explanations aligned with the principles of Elsasser along with an even earlier philosopher of biology, the Viennese visionary Hans Przibram.

How Did Language Evolve? Some Reflections on the Language Parasite Debate Abstract The language parasite approach (LPA) refers to the view that language, like a parasite, is an adaptive system that evolves to fit its human hosts. Supported by recent computer simulations, LPA proponents claim that the reason that humans can use languages with ease is not because we have evolved with genetically specified linguistic instincts but because languages have adapted to the preexisting brain structures of humans. This article examines the LPA. It argues that, while the LPA has advantages over its rival, Chomskyan nativism, there are additional factors that may limit linguistic variety that have yet to be identified by its insightful proponents. This article suggests abandoning the search for a decisive cause of language capacity and argues that language evolution is more likely to arise from balancing multiple engineering constraints.

Alexandros Sfakianakis
Anapafseos 5 . Agios Nikolaos
Crete.Greece.72100
2841026182

6948891480

alsfakia@gmail.com