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Posts tagged evidence for evolution
The Four Horsemen – Dawkins, Dennett, Harris and Hitchens
Feb 22nd
Richard Dawkins, Daniel Dennett, Sam Harris and Christopher Hitchens having a thorough discussion on Science and Religion. Enjoy!
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Explaining Evolution (The Evidence) – The Lizards from Pod Mrcaru (Part 3)
Feb 20th
Explication – The Why and How
A well-known law in physics and with widespread applicability in almost all sciences says: “In a closed system the total energy of the system remains constant”. This law also remains valid in the study of natural processes and can be translated, for it being a more enlightening tool, to: “In a closed biological system, any benefit, any adaptive adjustment that confers to a biological organism a certain advantage/adaptation in the natural environment, does not manifest itself on the organism without the latter not paying a price for that favor”. We will use the rule above, dear friends, to see how mother nature makes exchange, negotiates with each living organism a wide range of benefits that may have various useful properties one of that being that it may represent the ticket to survival.
“What-if?” Is a question we should learn to ask ourselves more often if we want to understand the structure of biological phenomena, a tool that will help us to transcend time and repeat as many times as required the film of events that helps us visualize the causes, effects and logic nature takes decisions on. What if, 36 years ago, instead of Pod Mrčaru we chose another islet much larger in size but equally uninhabited by terrestrial predators and with the same physiological and micro-climatic conformation . And what would happen if, instead of putting on the island only five pairs of Podarcis Sicula, approximately similar in characteristics, we would put not five, but hundreds, thousands, tens of thousands of lizards from this species that, before landing then on the island, in our super-technological laboratory, we would equip them with various physiological,cognitive and behavioral features, that would make each individual unique, unmistakable?
Obviously that from the feature sets each lizard will acquire, though unmistakable, those sets will be more or less similar to the feature sets of other lizards. So we will have a population of specimens that in some respects will resemble more or less each-other. For example, some specimens will have longer legs, others shorter, some will have a more aggressive behavior, others a more fluent and peaceful one, some will sprint twice as more than the average population, others less, of course, all these new talents being added to the lizards by our genetic engineers. And now imagine that we make a contest, namely, from the 100,000 say lizards introduced to the island, the first 100 that will gather the most resources (that will consume the most food) and manage to copulate(have sex) the most amount of times, all with a minimum of energy expense, within 24 hours as long as we conventionally choose the time of the competition, will be spared from extermination and will be left on the island by researchers, while the rest will be used as food by the same scientists.
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Explaining Evolution (The Evidence) – The Lizards from Pod Mrcaru (Part 2)
Feb 19th
Divergent evolution due to different sources of plant food resources
The experimental results show significant differences in head morphology between the populations of lizards from the two islets; the heads of the Pod Mrčaru lizards (male, female, juvenile) are significantly higher, wider and longer than the heads of the Pod Kopište ones (Fig. 5), so consequently they have a greater bite force, force required for effectively chewing leaves.
Dissections performed on lizards show that specimens with enlarged heads have a diet that consists of many more plants than those with smaller heads. Stomach analysis shows significant differences between seasonal diets of the lizards from the Pod Mrčaru islet, which consists of 34% plants during spring and 61% plants during summer from the total vegetable food consumption.
Clarifying is the fact that the lizards on Pod Kopište have a quantity of food consumption that is 4% during spring and 7% during summer, and there were no differences between diets depending on the season (Fig. 6). Moreover, about 50% of consumed plants (leaves and stems) of lizards from Pod Mrčaru have an elevated content of cellulose which explains the dramatic evolution
The purpose of these valves is to slow down the passage of food through the intestine and to provide the chambers of fermentation, which contain symbiotic micro-organisms, sufficient time to convert cellulose into volatile fatty acids that can then be easily processed by the digestive system. Again, surprisingly, nematode worms capable to do this type of processing were found in significant numbers at the end of the digestive tract of lizards from Pod Mrčaru, but was not present in specimens from the Pod Kopište islet.
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Explaining Evolution (The Evidence)- The Lizards from Pod Mrcaru (Part 1)
Feb 18th
Introduction
Theories, Models, systematizations, these mental constructs that enable us to understand the ontology, the laws by which nature governs itself does not elude any scientific knowledge department, especially the vast universe of bio-entities which in their programmed, nihilistic, ruthless dance they offer a show that demands an explanation. Paradoxically, these complex phenomena of the universe we live in have the gift to be explained by theories that are much easier to understand than other theories explaining more simplistic phenomena; gravitational attraction, the curving of space-time, interactions between subatomic particles are some of this manifestations reflecting the structure of reality that unfortunately require extensive knowledge of mathematics, physics, etc., tools inaccessible to the average individual.
Charles Robert Darwin
