Evolution

בניגוד לעמדת הניאו-דרוויניזם, שמייצגה הבולט הוא ריצ'רד דוקינס, נלחמה לין מרגוליס עשרות שנים על עמדתה, לפיה לא הגן האנוכי, שמחכה למוטציות מקריות, שיתאימו אותו לסביבה, הוא הכוח המרכזי המניע את האבולוציה, אלא סימביוזות ואינטראקציות בין גנומים, בין תאים, בין אורגניזמים, ובין אלמנטים רבים בעולם ועל פני כדור הארץ, ה"מדברים" ביניהם, משתפים פעולה ומשתנים - הם הכוח החזק המניע את האבולוציה. המחקר השופע לאחרונה עוד ועוד ממצאים על גודלה, איכותה, כוחה, השפעתה, של אוכלוסיית חיידקי המעיים של האדם, מעניק תמיכה גדולה בעמדתה של לין מרגוליס. אף אחד הוא לא לבד ולא אנוכי. כל אחד מאיתנו הוא מושבה של טריליונים על טריליונים תאים שונים ומגוונים, שלכל אחד מהם גנום שונה, והתוצרת שהם מפיקים בשיתוף פעולה ובסימביוזה - הם הכוח המניע את חיי הפרט ואת האבולוציה .                                                    ם

This paper presents an analysis of 56 variants of European and North American examples of the so-called Polyphemus tale (international tale type ATU 1137) using phylogenetic software according to 190 traits. Discussion addresses a number of points of comparative methodology while considering the historical implications of a relationship between different versions of this tale type recorded in diverse cultures.

There are two opposite paradigms to explain aging, here precisely defined as “age-related progressive mortality increase, i.e. fitness decline, in the wild”. The first maintains that natural selection is unable to maintain fitness as age increases. The second asserts that, in particular ecological conditions, natural selection favors specific mechanisms for limiting the lifespan. The predictions derived from the two paradigms are quite different and often opposing. A series of empirical data and certain theoretical considerations (non-universality of aging; great inter-specific variation of aging rates; effects of caloric restriction on lifespan; damage of aging for the senescing individual but its advantage in terms of supra-individual selection; existence of fitness decline in the wild; proportion of deaths due to intrinsic mortality inversely related to extrinsic mortality, when various species are compared; impossibility of explaining the age-related fitness decline as a consequence of genes that are harmful at a certain age; age-related progressive decline of cell turnover capacities; on/off cell senescence; gradual cell senescence) are compared with the predictions of the two paradigms and their compatibility with each paradigm is considered. The result is that the above-mentioned empirical data and theoretical considerations strongly contradict and falsify in many ways all theories belonging to the first paradigm. On the contrary, they are consistent or compatible with the predictions of the second paradigm.

Aging, here precisely defined as “age-related progressive mortality increase in wild conditions”, is currently justified as a side effect of insufficient natural selection at older ages and of prevailing contrary physiological requirements. An opposite paradigm explains aging as a particular type of phenoptosis, a large and well known category of phenomena where an individual sacrifices itself/himself, or close relatives, by effect of supra-individual natural selection.
The two opposing paradigms implicate very different predictions. Evidence and some theoretical arguments are weighed in their agreement and compatibility with the two paradigms: variability of aging rates among species of the same phylum; existence of many species with no detectable senescence; impossibility of justifying aging as an effect of many genes harmful at older ages; lifespan increase, or at least non-decrease, by effect of calorie restriction; aging existence in the wild; aging advantage in terms of supra-individual selection; inverse relation between extrinsic mortality and proportion of deaths caused by aging, in the comparison among species; on/off and gradual cell senescence; age-related decline of cell turnover.
The above said data and arguments are totally consistent with the interpretation of aging as a phenoptotic phenomenon, i.e. something moulded by natural selection and genetically determined and modulated, and in complete contrast with the opposite paradigm.
Aging interpretation as a physiological phenomenon, and not as inevitable and inescapable result of several harmful factors, is very important for the future of gerontology because it makes much more likely the prospect of the full control of this phenomenon.

There are two opposite interpretations, or paradigms, about aging causes: 1) insufficient natural selection against heterogeneous damages; 2) a genetic program favoured by natural selection for its supra-individual advantage. Within the second paradigm, it is possible a careful and consistent description of aging process based on clear evidence.
All cells of our body are in massive continuous turnover, with an overall substitution rate of about 690,000 cells per second. Cells without turnover, as the neurons, for their vitality depend strictly from other cells with active turnover.
This turnover is restrained by cell duplication limits determined by sophisticated regulations of telomere-telomerase system.
Moreover, cell functionality is limited by the activation of cell senescence program (with a probability related to telomere shortening) and by the gradual repression of subtelomeric DNA (in direct relation with telomere shortening).
An old tissue or organ is characterized by an atrophic syndrome: a) reduced number of cells; b) slowed down cell turnover by reduced stem cell replication; c) replacement of the missing differentiated cells with other cells; d) hypertrophy of the remaining differentiated cells; e) altered transcriptome of cells with shortened telomeres or in senescent state; f) alterations of the extracellular matrix and of the cells depending on senescent or died cells; g) cancer vulnerability as a consequence of shortened telomere-induced unstableness.
The possibility of this description of aging process is a pivotal element in support of the programmed aging paradigm and against aging interpreted as a ineluctable degenerative process.

There is then a natural, interconnected, and crucial water cycle upon which all life on earth depends.  Humans have always required a dependable water supply to survive and thrive.  As we have grown in numbers and in concentration; as we have built and infiltrated among, and at times, in opposition to other life forms, we have created future health challenges that must now be addressed.  To do so, each of us must better understand the nature of water, and its relations to weather, ecosystems, agriculture, industry, urban planning, sanitary systems, and value of Integrated Water Resource Management (IWRM).

This was the tentative final version of a syllabus that I used in my Fall 2015 course at Leiden University, provocatively named after the 1999 text by Sterelny and Griffiths: Sex and Death. The subtitle of my course is more reflective of our actual work: Our primary focus was on the implications of the Darwinian Revolution and biological evolution for philosophical and biological as well as ethical, moral, social, and political issues.