Darwin has called 'natural selection', or the preservation of favored races in the struggle for life. Darwin promptly replied that Wallace's letter was "as clear as daylight. I fully agree with all that you say on the advantages of H.
Introduction What causes aging? Until the causes are understood there is little hope of devising effective anti-aging treatments. In fact our whole attitude towards aging is affected by our perceptions of the cause.
Research on the causes of aging are only of academic value. Research on aging may indeed lead to dramatic improvements in health. For example, nuclear background radiation could cause aging by causing increasing cumulative tissue or genetic damage. Other sources could cause an "accumulation of random damage to the building blocks of life".
Aging has no benefit to an organism and could not be an evolved characteristic.
Aging is not genetically programmed. Aging exists despite the best efforts of nature.
Some people think that living organisms eventually "wear out" in the same way that any mechanical device wears out. But living things have the capability of constructing themselves from raw materials and also have at least some capacity to repair themselves, unlike mechanical devices.
Perhaps there is a fundamental limitation, a biological equivalent to the mechanical wear out process, that affects living things. There could be accumulated errors in the process of copying DNA, causing accumulated random genetic damage, or accumulation of some toxic condition free radicalsetc.
If aging is caused by some fundamental process, how do we explain why average life span varies so dramatically from species to species? Some insects live for a matter of days, some live 17 years.
Why do men live so much longer than mice? Mammal life spans vary from less than a year to at least years.
Life spans in animals tend to be loosely proportional to size. Bigger fish live longer than small fish. Larger mammals tend to live longer than small mammals.
But there are obvious gross exceptions: Again there were difficulties, does a parrot have a slower metabolism than a horse? Various "evolutionary" theories attempt to explain why aging so resembles an evolved characteristic large variations between species, etc. If evolution "doesn't care" what happens after an animal stops reproducing, then aging could be the result of the accumulation of random bad genes that only affect animals later in life mutation accumulation theory.
Aging could also be the result of side effects of some characteristics that help an organism in its youth but accidentally, coincidently, hurt it in later life antagonistic pleiotropy theory.
The beneficial characteristics would evolve and the side effects, though adverse, would not affect evolution greatly because they only affect individuals after they had some opportunity to reproduce.
Despite the "inescapable biological reality" some reptiles and fish exhibit little or no aging. Aging does seem to share properties with evolved characteristics. Aging, like femur length, seems to vary somewhat between individuals of the same species, and, like femur length, varies to a greater extent between species.
Aging characteristics of animals are at least somewhat inheritable. Darwin and his contemporaries thought longevity was evolved.
But what possible benefit could aging be to a species? Therefore natural selection would select the animals which did not have the aging characteristic or had it to a lesser extent and it would eventually disappear.
This problem was actually cited by a Darwin contemporary as an argument against Darwin's theory. The growth of the populations of all species is therefore checked by a variety of factors such as predators, diseases, food supply, and environmental conditions so that in a stable population each individual has an average of only one progeny which survives to produce one progeny and so on.
All wild species are therefore in competition for survival. For example, if conditions changed such that increased height was a survival advantage for a particular animal species, then all the taller individuals would have a survival advantage, live longer, breed more, and the average height of the population would increase relatively rapidly until it was again optimum for that particular situation.
Some contemporaries thought new species were created instantaneously by massive mutations in a single individual. After all, humans had for thousands of years been causing domesticated species to change by selective breeding.
If small dogs were bred with small dogs for a long time men could evolve a Chihuahua.In biology: Evolution Charles Darwin suggested that “survival of the fittest” was the basis for organic evolution (the change of living things with time).
Evolution itself is a biological phenomenon common to all living things, even though it has led to their differences. In biology: Evolution Charles Darwin suggested that “survival of the fittest” was the basis for organic evolution (the change of living things with time).
Evolution itself is a biological phenomenon common to all living things, even . Nial Fuller is a professional trader, author & coach who is considered ‘The Authority’ on Price Action Trading.
In , Nial won the Million Dollar Trader webkandii.com has a monthly readership of , traders and has taught over 20, students. Set in the sizzling South African savannah, Survival of the Fittest, will pit a team of girls against a team of boys in the ultimate battle of the sexes.
survival of the fittest. Those best adapted to particular conditions will succeed in the long run, as in They've had to close a dozen of their stores, but the ones in the western part of the state are doing well—it's the survival of the fittest.
Therefore, "survival of the fittest" may not be the best way to describe what natural selection really is as it applies to evolution. Darwin did not mean it in these terms when he used it in his book after Herbert first published the phrase.