Issues related to mineralized tissue biology in human evolutionary research

This comunication has two primary aims concerned with mineralized tissue biology (e.g. hard tissue biology of bone and tooth) research in human evolutionary studies: First, to introduce the literature and the methods (at the time of this symposium) so that one has an idea of the nature of this research and where one can go for details of the methodologies, etc; Second — and of primary concern here — to discuss issues that have come to light as a result of these studies mainly because of its recent beginnings as a subfield within paleoanthropology. Issues related to skeletal studies include; 1) whether different cortical surface pattens and bone tissue types influence the appearance and interpretation of bone growth activity states; 2) if SEM analyses of cortical surfaces in fossil hominids allow one to construct meaningful representations of remodeling patterns; 3) whether these representations can be used in phylogenetic arguments; and 4) how intraspecific variability would affect these issues. Issues related to dental studies include: 1) the relationship between the rate and pattern of eraly hominid dental development; 2) experimental support for the calibration of eraly hominid dental developmental rates; and 3) whether replica techniques are suitable for microanatomical studies of these sorts.     

Iconometrographics in evolutionary biology

The essential dialogue between Apollinian and Dionysiac poles required for the advance of music and art was likened to the scientific debate between «justifiers» and «innovators». The use of ratios and simple algorithms was indicted as being retrogressive in terms of modern microcomputer technology and iconometrographic models. Three examples were used to illustrate the approach in the resolution of complex data sets comparing samples: (1) 45,XO with a 46,XY controls, (2) sexual dimorphism in young adults and (3) Black and White Olympic athletes. The iconometrographic approach was proposed as a primary orientation in human biology, particularly in secular trend studies concerned with the recognition and assessment of complex evolutionary trends.     

Explanatory pluralism in evolutionary biology

The ontological dependence of one domain on another is compatible with the explanatory autonomy of the less basic domain. That autonomy results from the fact that the relationship between two domains can be very complex. In this paper I distinguish two different types of complexity, two ways the relationship between domains can fail to be transparent, both of which are relevant to evolutionary biology. Sometimes high level explanations preserve a certain type of causal or counterfactual information which would be lost at the lower level; I argue that this is central to the proper understanding of the adaptationist program. Sometimes high level kinds are multiply realised by lower level kinds: I argue that this is central to the understanding of macroevolution.     

Methodological problems in evolutionary biology

One of the major criticisms of optimal foraging theory (OFT) is that it is not testable. In discussions of this criticism opposing parties have confused methodological concepts and used meaningless biological concepts. In this paper we discuss such misunderstandings and show that OFr has an empirically testable, and even well-confirmed, general core theory. One of our main conclusions is that specific model testing should not be aimed at proving optimality, but rather at identifying the context in which certain types of behaviour are optimal. To do this, it is necessary to be aware of the assumptions made in testing a model. The assumptions that are explicitly stated in the literature up to now do not completely cover the actual assumptions made in testing OFT models in practice. We present a more comprehensive set of assumptions. Although all the assumptions play a role in testing models, they are not of equal status. Crucial assumptions concern constraints and the relation between fitness and currency. Therefore, it is essential to make such assumptions testable in practice. We show that a more explicit relationship between OFT modelling and evolutionary theory can help with this. Specifically, phylogeny reconstruction and population dynamic modelling can and should be used to formulate assumptions concerning constraints and currencies.     

Phylogenetic thinking in the modern biology

Any research activity is conducted within the framework of a cognitive situation which is defined by certain basic assumptions about ontology of the portion of the objective world under investigation. From the standpoint of the non-classical scientific epistemology, a part of that situation is constituted by personal knowledge which is formed by a set of thinking (cognitive) styles. The scholastic thinking existing in taxonomy and phylogenetics is considered as an example showing unavoidability of such styles in the natural history knowledge. It is initially rooted in the antic, mythological by its essence, persuasion of isomorphism between movements of the objective reality and of the mind. The instrumentalism entailed by scholastic thinking is based on the mythologeme according to which the "right method" par excellence can lead to the "right knowledge". That is why any disputes between different numerical methods of phylogenetic reconstructions are vain: their validity could be assessed not formally but within particular cognitive situations formed by particular basic models of the phylogenesis. Phylogenetic thinking is of the key importance in evolutionary biology and has great impact on various fields of biology based on it. It is pretty mythological because of non-observability of the phylogenesis: the latter is rather "thinked-in" in the objective world then is induced from the observed facts. It constitutes a part of the evolutionary thinking considering mainly macroevolutionary trends and stressing the initial causes in the structure of causal relations in the analyses of the diversity of organisms. The "tree thinking" of O'Hara is its rough operational equivalent. Relation between phylogenetic thinking and some other styles are considered, which are population, phenetic, typological, and epigenetic ("developmental" of O'Hara). Phylogenetic thinking makes it obliged inclusion of the initial causes in the explanatory models which underlie adaptive and functional peculiarities of organisms, as well as of the entire structure of the biodiversity. It manifests itself in such kind of models through uncovering the phylogenetic signal. This thinking style has great effect on understanding of the ontology of taxa and acknowledges the objective status of the phylogenetic pattern. It is intrinsically included in the argumentation schemes of constructional morphology, comparative phylogenetics. The central metaphor of the phylogenetics is the Tree of Life. Emagination of its unity and uniquiness is of naturphilosophical nature. From the contemporary epistemological standpoint, it should be considered as a generalization upon partial hypotheses of evolution of particular structures each corresponding to certain consideration aspect of the global phylogenesis. Acknowledging of multi-aspectness of the phylogenesis constitutes one of the important points of modern phylogenetic thinking. As different semogeneses are incompletely congruent, the Tree of Life is less certain than each of the initial hypotheses. Any attempt to make it more resolved would lead to its reduction to any of the particular semogenetic scheme (i.e. to a "gene tree") or to its "decay" into several trees each corresponding to a particular consideration aspect of the global Tree.     

Phylogeny and evolutionary biology

The phylogenetic system of Hennig, which was designed for classification of synchronous organisms, has only been adapted secondarily to total reconstruction of phylogeny. All fields of fundamental biology are related to the development of evolutionary theory. A better understanding of the origin of life requires new concepts of the historical geology of prebiological environment and new concepts of molecular genetics and biochemistry concerning ribonucleic acids as the initial units for the origin of life.     

The evolutionary biology of sex

In 1861, Charles Darwin wrote "We do not even in the least know the final cause of sexuality; why new beings should be produced by the union of the two sexual elements, instead of by a process of parthenogenesis". It was hardly possible to begin to answer this question at that time, in view of the contemporary lack of knowledge of genetics and cell biology. Since then, research into the cellular basis of reproduction has shown that sexual reproduction is the norm for the majority of eukaryotes, with huge consequences for their biology. The evolution of sex and some of its consequences are the subject of the series of reviews, and a Primer, in this special issue of Current Biology.     

Yeasts as models in evolutionary biology

A report of the workshop 'Evolutionary and Environmental Genomics of Yeasts', Heidelberg, Germany, 1-5 October 2008.     

Considering evolutionary processes in conservation biology

Conservation biologists assign population distinctiveness by classifying populations as evolutionarily significant units (ESUs). Historically, this classification has included ecological and genetic data. However, recent ESU concepts, coupled with increasing availability of data on neutral genetic variation, have led to criteria based exclusively on molecular phylogenies. We argue that the earlier definitions of ESUs, which incorporated ecological data and genetic variation of adaptive significance, are more relevant for conservation. Furthermore, this dichotomous summary (ESU or not) of a continuum of population differentiation is not adequate for determining appropriate management actions. We argue for a broader categorization of population distinctiveness based on concepts of ecological and genetic exchangeability (sensu Templeton).