The emotion of disgust evolved initially to optimize responses to the omnivore's dilemma. Individuals who had a properly calibrated sense of disgust were able to consume more calories than their overly disgustable cousins while consuming fewer dangerous microbes than their insufficiently disgustable cousins.
Jonathan HaidtMots clés evolution omnivore disgust
...a large segment of our population appears to have moved, in its cultural beliefs, to the use of an "ideal" measuring implement, based particularly on the individual's self-assessment of what "one's life should be like," e.g., essentially symptom free. This has moved us radically away from the reality of the human condition in which most of us have some nagging physical and mental symptoms for much of our lives. If one looks at history, developing countries, the poor, or soldiers (engaged in a highly stressful, physically and psychologically demanding and always potentially dangerous profession), this reality is clear. One recognizes that such culturally espoused ideal states of health are at best illusory. Life is filled with traumas, fears, apprehensions, hunger, aches, pains, illnesses, failures, unfulfilling work, and memories of pain. It is balanced by moments of happiness and pleasure, memories of positive events, doing one's duty, and enduring. The evolutionary history of our species is one in which those individuals who have survived to continue the human line have done so in the face of extreme violence, hunger, drought, flood, diseases, and war.
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For Man to tell how human life began is hard; for who himself beginning knew?
John MiltonMots clés evolution cosmology origins
To understand Darwin's work, you have to distinguish between his theory of descent and his theory of natural selection. THe full name of the first is the theory of descent with modification. Some call it the fact of evolution, and some call it the doctrine of evolution.
Lee SpetnerMots clés evolution darwin intelligent-design neo-darwinism random-mutation select-mutation
Life is so diversified that to any statement I could make about living organisms there are exceptions. Because of the many exceptions, I should qualify everything I say with hedging phrases such as 'generally,' 'usually,' and 'almost always' But I'm afraid the constant repetition of these hedges will slow me down and bore you. So let's make a pact now that I forego the hedging phrases and you are to understand that almost all my statements may have rare exceptions.
Lee SpetnerMots clés evolution neo-darwinism cell-mutation
Verbal arguments should always be suspect.
Lee SpetnerMots clés evolution neo-darwinism random-mutation biological-variability chance-mutation
Dawkins mentioned two mechanisms: the theory of the ‘primeval soup’ and the Cairns-Smith theory. He discussed the latter in some detail. Since no one has computed, for either theory, the chances of the events occurring, Dawkins could not tell us what those chances are. The mechanisms of both theories, however, have every appearance of being very improbably – even to the point of being impossible.
Lee SpetnerMots clés evolution dawkins random-mutation biogenesis cairns-smith-theory primeval-soup
There is another kind of variation that does not involve the genome at all, and is therefore not heritable. Yet it can produce what looks like evolution. Indeed, the results look so much like evolution that for all we know some of the best examples of evolution may be due to this nonheritable kind of variation. [It] has been observed, is well known, and is well documented.
Lee SpetnerMots clés evolution faux-evolution nonheritable-variation
I am suggesting here that organisms have a built-I capability of adapting to their environment. I am suggesting that to the extent that evolution occurs, it occurs at the level of the organism. This suggestion differs sharply from the thesis of the NDT, which holds that evolution occurs only at the level of the population. Organisms contain within themselves the information that enables them to develop a phenotype adaptive to a variety of environments. The adaptation can occur by a change in the genome through a genetic change triggered by the environment, or it can occur without any genetic change.
Lee SpetnerMots clés evolution adaptation neo-darwinism genome environmental-evolution genetic-change phenotypes
There are many examples where species share common plastic traits. What appears to be convergence may just be the plastic response of the organism to its environment. Examples include the following: Limbs that protrude from an animal’s body have more surface area per unit mass than the rest of the body. In cold weather the animal loses more heat per unit mass from these limbs than from other parts of the body. In many species the tails and legs are shorter for those living in colder climates and larger for those in warmer climates. Gulls’ wings are shorter in cold climates than in warm. Hares and foxes also have shorter ears in cold climates than in warm. Eskimos have shorter arms and legs than do people living in warmer climates. . . . Jodan’s rule: Many species of fish tend to have more vertebrae when they live in cold water than do the same species living in warm water. These differences have been shown to depend on the temperature at which the fish have been reared.
What these rules show is not convergence. They show that different species adopt the same anatomical strategies when they have to cope with the same environmental conditions. We have seen that these strategies cannot come from random mutations. It is much more reasonable to say they come from environmental cues acting on the genetic program.
Mots clés evolution neo-darwinism convergence jodan-s-rule plastic-traits
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