O
Oran_Taran
Guest
Ok, since most people don't know much about evolution, I'll explain the VERY basics of evolution. (again, this is VERY simplified, don't nag me about not mentioning sexual selection and stuff, because this is just to get things started)
First off, evolution can be defined by: the change of the frequency of genes in a population over time. (populations of organisms change over time)
It does this mainly through natural selection. Natural selection is a very simple concept to grasp:
1) Organisms have MANY more offspring than the environment can support.
2) Since there are limited resources (food, water, shelter, space), and other forces working against them (predation, etc), not all of them survive.
3) That means that there is a struggle for existance
4) No two offspring are alike, so some are more fit to survive than others.
5) Those fit enough survive and reproduce, thus passing their genes on.
6) After many generations, better genes replace less good genes.
That's it. That's evolution. Did you notice I never said anything about the origin of life? or the origin of the universe? or galaxies? the exact year humans migrated to north america? stars, moons, antimatter, etc? That's because the scientific theory of evolution does not deal with any of those. Evolution only says that populations of living organisms change over time.
Natural selection is NOT a creative process, it is an editing process. It does not create what is needed, it just replaces the good/bad by the better.
So how does new information arise? mutations. There are many types of mutations, most of which do not do anything, many which are bad, and a few which are good. There are mutations that just change existing information, others that add new information, and others that change existing DNA but which codes for nothing.
Beneficial mutations HAVE been observed many times, in organisms ranging from bacteria to humans.
Now, evolution explains a mountain of observations, of which I will make a small hill since I'm not here to teach a biology course.
Biogeography- Darwin noticed that species who live close to each other are generally more closely alike than species who live far apart. This applies even if the climate is very different.
For example, the sonoran desert and australian. The organisms in the sonoran desert are more alike to the organisms in north america, regardless of climate (say, they're like the organisms in decidious forests) than to those in australian deserts, even though both are deserts. This is because the organisms in the sonoran desert evolved from those in north america, not from those in australia.
for example, the mammals in the sonoran desert are all placental mammals. There may be rabbits, rats, and whatever else. This is in contrast to australia, where the mammals are marsupials. They may have kangaroos, and other small marsupial animals. (note that rats were introduced to australia. They're not native there)
PAST biogeography is the same way (fossils)
Evolution also explains homologies. Organisms that have common ancestors share similar DNA, proteins, and anatomy. For example, If you compare the hemoglobin (a protein) from chickens, fish, a lizard, a monkey, and a human, you will find that human hemoglobin is the closest like the monkey, then the (crap, I forgot the exact order...
) then the... lizard? then the chicken, and then the fish. (again, I might have mixed up the lizard and the chicken) Same with DNA.
and as for anatomy, you'll find that since bats, whales, humans, and cats are all mammals, they have very similar bone structures in their limbs.
here, take a look at this picture- http://www.bio.miami.edu/dana/160/homologous.jpg
Evolution also explains analogous structures. These are structures that superficially look similar and serve a similar purpose, but because they evolved separately they don't have the same structure. For example, bat wings and bee wings serve the same purpose (to fly), but they are VERY different structurally. A better example may be the fins of sharks and of dolphins. They serve the same purpose, and look very much alike, but structurally they are very different. The dolphin has a "hand-like" arrangement of bones, and the shark has many rays of cartillage instead.
This is because they evolved in the same environment, and therefore the pressures were the same, so they evolved similarly. But because they came from different ancestors, their structures are very different. You'll find the same with genes/proteins, the dolphin's will be more like other mammals than to the shark. And the shark will be more like other fish than to the dolphin.
Vestiges are also explained by evolution. Vestiges are things that at one point in time (in the ancestors), served a greater role than they do now. They may or may not serve a function now.
an example of an useful vestigial structure are ostrich wings. Ostriches evolved from flying birds, so they retain the same structures (wings), but they don't serve for flying anymore. Nowdays they do use them for their mating rituals, but they're still vestigial.
An example of a useless vestigial structure is the muscle that allows you to wiggle your ears. In our ancestors, they were used to orient the ears towards a sound (like in rabbits). Nowdays, most people don't even know how to wiggle their ears. Those muscles are useless.
Fossils: Fossils allow us to see the chronological order and geographical distribution of past life forms. We can see that as you go back further in time, the organisms look less and less like today's organisms. We also see many transitional fossils, which are fossils that are links between an organism's ancestor and today's organism.
Evolution also explains a wide range of many other observations, which I won't mention right now. The mechanisms of evolution have been observed, such as natural selection with guppies, HIV, the peppered moth, and many others; and evolution itself has been observed. Speciation (a population of one species becoming another species) has been observed quite a few times, with a quite a few organisms ranging from goatsbeard, mice, mosquitoes, to fruit flies and primroses.
and... I'll think I'll quit now. Like I said, there is much more to evolution than this, such as sexual selection, geographical isolation, reproductive isolation, ring species, and dozens more, but this was just to get things rolling. lol.
If you read all this, thanks! (remember I had to type it all... from scratch... no copying and pasting... ... yes, I'm just bragging now lol)
First off, evolution can be defined by: the change of the frequency of genes in a population over time. (populations of organisms change over time)
It does this mainly through natural selection. Natural selection is a very simple concept to grasp:
1) Organisms have MANY more offspring than the environment can support.
2) Since there are limited resources (food, water, shelter, space), and other forces working against them (predation, etc), not all of them survive.
3) That means that there is a struggle for existance
4) No two offspring are alike, so some are more fit to survive than others.
5) Those fit enough survive and reproduce, thus passing their genes on.
6) After many generations, better genes replace less good genes.
That's it. That's evolution. Did you notice I never said anything about the origin of life? or the origin of the universe? or galaxies? the exact year humans migrated to north america? stars, moons, antimatter, etc? That's because the scientific theory of evolution does not deal with any of those. Evolution only says that populations of living organisms change over time.
Natural selection is NOT a creative process, it is an editing process. It does not create what is needed, it just replaces the good/bad by the better.
So how does new information arise? mutations. There are many types of mutations, most of which do not do anything, many which are bad, and a few which are good. There are mutations that just change existing information, others that add new information, and others that change existing DNA but which codes for nothing.
Beneficial mutations HAVE been observed many times, in organisms ranging from bacteria to humans.
Now, evolution explains a mountain of observations, of which I will make a small hill since I'm not here to teach a biology course.
Biogeography- Darwin noticed that species who live close to each other are generally more closely alike than species who live far apart. This applies even if the climate is very different.
For example, the sonoran desert and australian. The organisms in the sonoran desert are more alike to the organisms in north america, regardless of climate (say, they're like the organisms in decidious forests) than to those in australian deserts, even though both are deserts. This is because the organisms in the sonoran desert evolved from those in north america, not from those in australia.
for example, the mammals in the sonoran desert are all placental mammals. There may be rabbits, rats, and whatever else. This is in contrast to australia, where the mammals are marsupials. They may have kangaroos, and other small marsupial animals. (note that rats were introduced to australia. They're not native there)
PAST biogeography is the same way (fossils)
Evolution also explains homologies. Organisms that have common ancestors share similar DNA, proteins, and anatomy. For example, If you compare the hemoglobin (a protein) from chickens, fish, a lizard, a monkey, and a human, you will find that human hemoglobin is the closest like the monkey, then the (crap, I forgot the exact order...
) then the... lizard? then the chicken, and then the fish. (again, I might have mixed up the lizard and the chicken) Same with DNA.and as for anatomy, you'll find that since bats, whales, humans, and cats are all mammals, they have very similar bone structures in their limbs.
here, take a look at this picture- http://www.bio.miami.edu/dana/160/homologous.jpg
Evolution also explains analogous structures. These are structures that superficially look similar and serve a similar purpose, but because they evolved separately they don't have the same structure. For example, bat wings and bee wings serve the same purpose (to fly), but they are VERY different structurally. A better example may be the fins of sharks and of dolphins. They serve the same purpose, and look very much alike, but structurally they are very different. The dolphin has a "hand-like" arrangement of bones, and the shark has many rays of cartillage instead.
This is because they evolved in the same environment, and therefore the pressures were the same, so they evolved similarly. But because they came from different ancestors, their structures are very different. You'll find the same with genes/proteins, the dolphin's will be more like other mammals than to the shark. And the shark will be more like other fish than to the dolphin.
Vestiges are also explained by evolution. Vestiges are things that at one point in time (in the ancestors), served a greater role than they do now. They may or may not serve a function now.
an example of an useful vestigial structure are ostrich wings. Ostriches evolved from flying birds, so they retain the same structures (wings), but they don't serve for flying anymore. Nowdays they do use them for their mating rituals, but they're still vestigial.
An example of a useless vestigial structure is the muscle that allows you to wiggle your ears. In our ancestors, they were used to orient the ears towards a sound (like in rabbits). Nowdays, most people don't even know how to wiggle their ears. Those muscles are useless.
Fossils: Fossils allow us to see the chronological order and geographical distribution of past life forms. We can see that as you go back further in time, the organisms look less and less like today's organisms. We also see many transitional fossils, which are fossils that are links between an organism's ancestor and today's organism.
Evolution also explains a wide range of many other observations, which I won't mention right now. The mechanisms of evolution have been observed, such as natural selection with guppies, HIV, the peppered moth, and many others; and evolution itself has been observed. Speciation (a population of one species becoming another species) has been observed quite a few times, with a quite a few organisms ranging from goatsbeard, mice, mosquitoes, to fruit flies and primroses.
and... I'll think I'll quit now. Like I said, there is much more to evolution than this, such as sexual selection, geographical isolation, reproductive isolation, ring species, and dozens more, but this was just to get things rolling. lol.
If you read all this, thanks! (remember I had to type it all... from scratch... no copying and pasting... ... yes, I'm just bragging now lol)
)