Can someone explain the theory of evolution? THANKS?

Answer 1

Other people have explained it quite well. (Except for Mousey ... she once again illustrates that there are many people who reject evolution out-of-hand without having a *clue* what the theory actually says ... it is NOT about monkeys becoming people.)

In short, members of a species compete for survival. The winners get to make more offspring. So any trait that provides some advantage in this competition (no matter how small) tends *on average* to spread into the population. That's it.

Some people like to object that "that's not evolution, that's adaptation." But that's just an argument over a word, not the process. Evolution just means "change at the population level." So there is no doubt that the above process produces such change ... so it is evolution.

Other people like to say that the above process doesn't explain how one species can become another. They like to draw a distinction between "microevolution" (short-term adaptation in a species) and "macroevolution" (long-term creation of new species ... what scientists call "speciation." Scientists generally hold that there is no such difference between 'micro-' and 'macro-'evolution ... macro-evolution is just micro-evolution on a longer time scale.

One part that people often miss is how two very different species can evolve from the same ancestor.

Three words: branching, branching, branching.

A single species generally consists of many subpopulations that nevertheless interbreed on occasion ... so those advantageous traits spread through the entire species. (E.g. think of human populations on the planet ... people from different regions look quite different ... different skin color, different facial features, etc. ... But they are all able to interbreed so they are all the same *species*.)

But if a subpopulation is separated from the main species for a very long time (e.g. a lake with one species of fish becomes two lakes), then they can start to develop *very* different traits, and eventually will lose the ability to interbreed. At that point they are separate *species* ... and they can never become one species again. At that point the two species can continue to evolve in *very* different ways.

That's how "speciation" occurs. (Actually that's only one way ... called "allopatric speciation" ... but that's the general idea.)

Answer 2

I think that what Alba J.J. is talking about is adaptation to environmental conditions. If you took wolves from the Arctic and bred them for many generations (a few hundred) in a hot climate their hair would become thinner - as you can see in domestic dogs today, which are mainly descended from wolves. Adaptation does not explain how some animal from many millions of years ago evolved in to bears in one direction, dogs in another and otters in another (for example). Same with antibiotic resistance in bacteria, adaptation. If it was evolution then the bacteria would have to evolve into something else that would not be bacteria. However, if you want to see evolution in action, there are many examples. But you must remember that us short-lived humans are only able to see a very brief snapshop of a process that takes millions of years. Consider, for example, penguins - evolving from birds - land-living aerial creatures, to sea animals - sea-living land animals. They can never go back to flying, So, theory of evolution in a nut shell, environmental pressure allows only the best suited to the environment to survive. This becomes a change over time in the heritable characteristics of a population of organisms and results from three processes: random mutation to genetic material, random genetic drift, and non-random natural selection. This is going to be a rather large nut shell, so I can only echo what Potbox said!

By the way, survival of the fittest does not mean survival of those most physically strong. It means survival of those that fit their environment the best.

And Mousey is talking nonsense! Monkeys turning into people, no-one has EVER claimed that this could happen. However, the distant ancestor of chimpanzees and the distant ancestor of man is probably the same creature (from maybe 8-10 million years ago, but I'm not too certain o the time scale)

Answer 3

Here's a very simple example of evolution in action that we can see happening in our every day life:

We invent antibiotics to kill bacteria that cause diseases. But, some very few of those bacteria survive and are resistant to the antibiotics. Those few reproduce. Lo and behold, most of their offspring are also resistant to the antibiotic. Thus, we have to keep inventing new antibiotics to keep up with the EVOLVING resistance.

This is evolution in a nutshell and everyone should be able to understand it. Next time you hear someone say "emerging" resistance to antibiotics, tell them you learned from me that the word should be "evolving" resistance!

Answer 4

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Natural Selection is actually the main force operating, it goes like this:
Those organisms that are better adapted to their environment leave more offspring.

A dog with thick hair will survive in the cold Arctic better than short haired dag.
So northern Wolves, live in cold areas, and short haired dogs live where it is warm.
Obvious to anyone

It is similar to selectively breeding cattle, corn, or dogs. You breed your best cow with your best bull, to get a bigger stronger animal. Everyone is familiar with this.

Evolution, takes the concept of natural selection, and adds the random chance of genetic mutation, . If that particular mutation favors survival, then through natural selection the creature may have numerous offspring that are also better adapted to their environment.

Simple ideas,
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Answer 5

The modern synthesis or neo-Darwinian synthesis unites the theories of Charles Darwin with Gregor Mendel's genetics, producing our contemporary theory of evolution. The modern synthesis was set in motion in 1918 by Ronald Fisher and William Bateson, and by the end of the 1940s genetics and the gene had been fully accepted by evolutionary biology.

The modern synthesis established mutation and recombination as the main sources of variation within populations, and introduced genetic drift as an evolutionary process.

Mutation is the ultimate source of variation on which natural selection acts. Heritable variation is a necessary requirement for Charles Darwin's theory of evolution; in the absence of new variation, natural selection can only make populations more uniform, and this would be unable to bring about long-term adaptive change. One of Darwin's greatest concerns was that he had no knowledge of where heritable variation came from. Unfortunately, he was unware of the work of Gregor Mendel, whose pioneering work on genetics was begining to uncover the nature of heritability.

Recombination is a process which has the effect of shuffling alleles to create new genotypes (producing genetic variation). Recombination is an important evolutionary process as it allows beneficial mutations to survive in the gene pool without having their effects countered by being paired, by chance, with harmful mutations (allowing gene selection rather than just individual selection to take place).

Variation is one of the two key parts of the theory of evolution. Variation is the name given to the processes which increase the diversity of the genome.

Variation is introduced by a number of processes:

Mutation - These create new alleles and thus a new characteristic.
1) Gene duplication produces new genes.
2) Recombination, Crossing Over - This creates a new set of genes in meiosis by creating a haploid (single set of chromosomes) cell by mixing the genes from the original diploid cell.
3) Sexual reproduction - Combines gametes that may carry different alleles never before found in that combination.
4) Gene flow, migration, Horizontal transfer - Transfers genes between isolated gene pools.
The product of variation is then subject to selection.

Genetic drift is a term in population genetics that describes stochastic effects on allele frequencies, mostly due to finite population size.

It is an evolutionary force that, like selection, reduces genetic variation. However, drift in one sense can be thought of as countering selection, in that the individual's relative fitness (or that of a haplotype, etc) is greatly lessened in those populations where drift operates. Another way of saying this is that if drift is important, the effects of selection are much lessened.

Genetic drift is often exemplified by the population bottleneck, in which a population spends some period of time at low numbers (more precisely, at low effective population size). In small populations, the probability that the most-fit individual will leave the most offspring is greatly reduced (he or she may be struck by lightning, after all). Chance events play a much greater role than they do in large populations. When a small pioneering group form a new population in a new location they bring with them just a small, unrepresentative sample of the genes of their parent population, a phenomenon known as the founder effect.

The stochastic effects of drift can be quantified by considering the probability distribution of an allele's frequency in the next generation. One simple model (the Wright-Fisher model) that does this assumes an hermaphroditic population that sheds gametes into a common pool where random gametes fuse. The question "what is the probability that there will be i copies of allele A in the next generation, given that the current allele frequency is p?" can be restated mathematically as: P(i) = Pr(i|p).

Answer 6

it took me a semester to learn it. cannot instantly understand the principles of evolution in a jiffy.

Answer 7

For the truth, i don't believe in evolution. Well for the truth ...there is no such thing. I mean monkeys turning into people. That's like ... wierd and so unreal. That's pretty much "what it is".