From Phenotype to Genotype And Back Again

2019 ◽  
Author(s):  
J. Richtsmeier ◽  
K.M. Lesciotto
Keyword(s):  
Human Evolution ◽  
Evolutionary Change ◽  
Cranial Morphology ◽  
Phenotypic Trait ◽  
Critical Feature ◽  
Developmental Mechanism ◽  
Experimental Approaches ◽  
Physical Forces ◽  
Collaborative Efforts ◽  
Current Emphasis

Traditionally, anthropologists study evolutionary change throughmorphological analysis of fossils and comparative primate data. For the analysis of the genotypephenotype continuum, the current emphasis on genes is misplaced because genes don’t make structure. Developmental processes make structure through the activity of cells that use instructions specified by genes. A critical mechanism underlying any phenotypic trait is the genetically guided change in developmental events that produce the trait. But even when a developmental mechanism is identified, the links between genetically guided instructions and phenotypic outcome are lengthy, complicated, flexible, and sensitive to physical forces of functioning organs. We use the study of craniofacial phenotypes of craniosynostosis (premature closure of sutures) to demonstrate how patterns produced by the covariation of cranial traits cannot always reveal mechanism. Next we turn to encephalization, a critical feature of human evolution that covaries with cranial phenotypes, and show how experimental approaches can be used to analyze mechanism underlying this well-documented pattern in human evolution. With the realization that no single line of evidence can explain the dramatic changes in cranial morphology that characterize human evolution come fundamental changes in the way we conduct anthropological inquiry - collaborative efforts from scientists with diverse expertise will continue to push the field forward.

The development of ideas on the role of glucose in regulating milk secretion

1993 ◽  
Vol 44 (3) ◽  
pp. 509 ◽  
Author(s):  
TB Mepham
Keyword(s):  
Animal Studies ◽  
Research Programme ◽  
Mammary Tissue ◽  
Milk Secretion ◽  
Research Programmes ◽  
Experimental Approaches ◽  
Mammary Metabolism ◽  
Glucose Supply ◽  
Current Emphasis

The author has reviewed the development of theories, over the last century, on the role of glucose in mammary metabolism, focusing on three overlapping issues, via. the extent of glucose utilization by mammary tissue, the synthesis of lactose, and the way in which glucose supply controls secretion of the aqueous phase of milk. In the first half of the century, deficiencies in technique produced several misleading results, and later progress resulted largely from methodological advances. Methodology has also been important in shaping research programmes, as is evident in the current emphasis on techniques of molecular biology. However, the review indicates the importance of employing a combination of experimental approaches, including whole-animal studies. Through the adoption of such approaches, it is now appreciated that glucose plays a key role in regulating lactation. It is suggested that developments over the last 30 years, which have led to formulation of an apparently resilient theory of milk secretion, conform to the notion of a 'progressive research programme' built on a 'positive heuristic', as proposed by the philosopher of science, I. Lakatos.

Heterotopy

2003 ◽  
Author(s):  
Mary Jane West-Eberhard
Keyword(s):  
Germ Cells ◽  
Spatial Organization ◽  
Primordial Germ Cells ◽  
Evolutionary Change ◽  
Phenotypic Trait ◽  
Spatial Patterning ◽  
General Body ◽  
Broad Definition ◽  
Adult Leaf ◽  
Definition Of

Heterotopy is the spatial analogue of heterochrony: it is evolutionary change in the site of expression of a phenotypic trait. Gould (1977) attributes the word “heterotopy” to Haeckel, who used it in a more specialized way, to mean evolutionary change in the germ layer from which an organ differentiates. Wray and McClay (1989, p. 810) list several examples of heterotopy, including the origin of muscles in tetrapod forelimbs from different somites, the origin of vertebrate primordial germ cells from different germ layers, and homeotic “heterotopic” mutations that transfer appendages from one body segment to another. A broad definition of heterotopy extends the concept to include spatial patterning, not only transposition from one location to another, but spatial organization of quantitative processes such as growth (Zellditch et al., 1992) or the location of precursors during the development of homologous traits (Wray and McClay, 1988, p. 313). As in other categorizations of transitions, heterotopies could as well be classified in other ways, such as duplication. Severtzoff signaled a general relationship between heterochrony and heterotopy when he wrote that “heterochrony in development is a means of topographic coordination; i.e., new adaptation of the parts to each other.” Many morphological heterochronies in plants produce heterotopic change, since the morphological ontogeny of a plant is recorded in its adult architecture. Thus, changes in timing of expression of juvenile and adult leaf forms result in heterotopic change in architecture of the mature plant, with the juvenile leaves appearing high on the stem, rather than only basally as before. A clear and oft-described example of environmentally mediated heterotopic change was demonstrated in early experiments on melanization in the Himalayan rabbit (Sturtevant, 1913; Iljin, 1927; Iljin and Iljin, 1930; see discussions in Schmalhausen, 1949 [1986]; Huxley, 1942; Levinton, 1988). In the Himalayan rabbit, as in the Siamese cat, pigment normally develops only in the extremities, where skin temperature is below the general body temperature. Individuals raised at temperatures above 30°C develop white extremities.

scholarly journals Change at the Museum - The Knowledge Production of Human Evolution

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Simon Ceder
Keyword(s):  
Human Evolution ◽  
Knowledge Production ◽  
Evolutionary Change ◽  
Individual Species ◽  
Natural History Museums ◽  
Relational Approach ◽  
History Museums ◽  
The Individual ◽  
Inherent Quality

Museums today play an important role as a space for learning about science and the world. For this article, the phenomenon of human evolution is explored as an example of knowledge production about change. Empirical materials on exhibitions of human evolution were collected from visits to 25 historical and natural history museums. The empirical materials are analyzed together with a posthuman version of evolutionary theory, with a focus on aspects of change. This is based on a post-anthropocentric and relational approach to human evolution and change. The analysis shows that (i) museums face an anthropocentric tension, (ii) evolutionary change is seen as both an inherent quality of the individual species and as an entanglement of humans and the natural environment, (iii) the notion of ‘the first human’ produces various and contentious versions of knowledges about evolutionary change.

Settlement, Society and Cognition in Human Evolution

2015 ◽  
Author(s):  
Fiona Coward ◽  
Robert Hosfield ◽  
Matt Pope ◽  
Francis Wenban-Smith
Keyword(s):  
Human Evolution

Learned Placebo Effects in the Immune System

2014 ◽  
Vol 222 (3) ◽  
pp. 148-153 ◽  
Author(s):  
Sabine Vits ◽  
Manfred Schedlowski
Keyword(s):  
Nervous System ◽  
Immune System ◽  
Associative Learning ◽  
Placebo Response ◽  
Immunosuppressive Drug ◽  
Immune Functions ◽  
Placebo Effects ◽  
New Therapeutic Approaches ◽  
Biological Variables ◽  
Experimental Approaches

Associative learning processes are one of the major neuropsychological mechanisms steering the placebo response in different physiological systems and end organ functions. Learned placebo effects on immune functions are based on the bidirectional communication between the central nervous system (CNS) and the peripheral immune system. Based on this “hardware,” experimental evidence in animals and humans showed that humoral and cellular immune functions can be affected by behavioral conditioning processes. We will first highlight and summarize data documenting the variety of experimental approaches conditioning protocols employed, affecting different immunological functions by associative learning. Taking a well-established paradigm employing a conditioned taste aversion model in rats with the immunosuppressive drug cyclosporine A (CsA) as an unconditioned stimulus (US) as an example, we will then summarize the efferent and afferent communication pathways as well as central processes activated during a learned immunosuppression. In addition, the potential clinical relevance of learned placebo effects on the outcome of immune-related diseases has been demonstrated in a number of different clinical conditions in rodents. More importantly, the learned immunosuppression is not restricted to experimental animals but can be also induced in humans. These data so far show that (i) behavioral conditioned immunosuppression is not limited to a single event but can be reproduced over time, (ii) immunosuppression cannot be induced by mere expectation, (iii) psychological and biological variables can be identified as predictors for this learned immunosuppression. Together with experimental approaches employing a placebo-controlled dose reduction these data provide a basis for new therapeutic approaches to the treatment of diseases where a suppression of immune functions is required via modulation of nervous system-immune system communication by learned placebo effects.

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