Could anyone give me facts about evolution?

Answer 1

Unsure why this is in the religious section; its a scientific matter.

Facts?

Firstly evolution IS a fact. Why is it called the theoryof evolution? The same reason its called the theory of gravity. Scientific nomenclature, a theory is a set of statements which explain the physical world. And can always be updated/upgraded/improved upon.

The fossil record, sampled millions of times from 1000s of sites all over the world, has never contradicted itself. Animals and plants appear at certain times (i.e. become visible in certain layers) and never before (never in deeper,older layers). This shows how species originate at set times by diverging from ancestor species.

Next theres radio-dating. No, its not an inadvisable pastime for lonely people, its a phenomenally powerful scientific technique which allows us to calculate the ages of pretty much anything.

Heres how it works. When created through geological processes, all rocks contain trace amounts of unstable atoms. These atoms spontaneously break down over time, releasing radiation and changing into different elements. A few of these breakdown products, the newly created type of atoms, take a long long time to break down further. Because we know

1) how much of each element is present in these rocks when theyre created

and

2) the half life of all types of radioactive atoms, that is, the time it takes for half the original amount of atoms to break down into something else,

we can simply find out how much of a certain element is left and multiply back up until we reach the original level.

Example

Lets say we know that rock A when created from clay under an ocean (for example) has 10g per kg of Skitterium in it and we know that skitterium breaks down such that theres only half left after 50 million years

we measure how much is in the rock we find our fossil in and we find theres only 2.5g per kg

2.5 x 2 = 5 and x 2 again = 10 so because each "x2" takes 50 milllion years, we can say that the rock, and hence the fossil is 100 million years old.

So fossils in a certain rock layer can thus be confidently regarded as being a certain, specific age, and we can say "this species first appears here, in rocks which are 100 million years old".

Molecular Biology is capable of even more accurate predicitons - it can show us which species' are more closely and more distantly related to one another.

The rate at which certain proteins change (mutate) are very very reliable indicators of how long ago the body containing the protein diverged from its ancestors - e.g. a horse and a pig have the same protein doing the same thing in their cells but each version of this protein is slightly different. Comparing changes in many different proteins in two species yields an estimate of how closely related the species are - how long ago these two species split from the original ancestor species.

Take us and chimpanzees. Molecular biologists have shown (using the haemoglobin proteins initially) that not only are we closest to chimps evolutionarily (i.e. chimps are the species we most recently share a common ancestor with), chimps are closer to US then they are to gorillas.

And we can do this for every species alive, including microorganisms, right they way back to around 3.5 billion years ago.

Folow this back up the tree of life and one conclusion swiftly becomes clear.

All life came from one original organism.

Which mulitplied. Again and again. And once there were millions then there was competition and then natural selection (only the fittest survive) could begin to forge differences. Better at eating then your fellows? You tend to breed more and then replace the population. Find yourself in a strange new environment? Then the individuals most suited to it will survive. And if isolated there for any reason, then you have the conditions for what are now effectiverly two separate groups of organisms to go their separate ways. Over time each group changes to suit its environment and becomes less and less like their old ancestral population. When talking about animals which reproduce sexually, the stage is reached where the two populations cannot interbreed. Two species now exist where once there was one.

As if the fossil record, molecular biology, current biology and taxonomy werent enough (they are) we have also seen evolution in action, both in terms of the emergence of drug resistant strains of bacteria/plants/insects but here is something truly amazing:

http://www.newscientist.com/article/dn14094-bacteria-make-major-evolutionary-shift-in-the-lab.HTML

this article describes the amazing experiment done by Lensky and his group in the USA, where he simply bred E.coli Bacteria, generation after generation after generation for 20 odd years and simply kept an eye on them.

What happened?

Well its almost a crime to cut such ingenous and elegant experiments down to the following summary but here we go:

they found that, over time, in a fixed environment E.coli bacteria evolved the ability to metabolise citrate - something that normal E.Coli cannot even begin to do.

And in order to metabolise citrate there were at least 3 necessary, sequential mutations required. In other words, the bacteria had to mutate at least 3 different times in a row in order to do this. And they did. And replaced all the "ancestral", non citrate eating bacteria.

This kind of evolutionary change is almost possible to see in most organisms as the number of generations needed for changes to occur means that, often, millions of years need to pass. Too long for most grant funding bodies...

So. To summarise:

1) New types of animals and plants appear in the fossil record suddenly and always in the same order. This shows that species appear over time and have not "always been there"

2) Using radio-dating we can prove the ages of the rocks the fossils lie within. Thus we can measure how long ago species diverged from common ancestor - this is how we know the age of the dinosaurs was over 150 million years ago, because that's how old the rocks containg their remains are.

3) By looking at the mutation rate among and between species, we can show which species are closely related and which arent and construct a "tree of life" - we can begin to play events backward. If we do this we see that all species converge on a single ancestor some 3.5 billion years ago

4) By comparing the results we get from the above 3 methods we should reach a consensus for each species. We do. All three separate methods agree with one another. This is enormously powerful evidence that evolution is a fact.

5) We have directly observed bacterial evolution.

Please please check these facts for yourself - read any journal, any textbook written in the last 10 years.

If you don't "believe" in evolution its like not "believing" in gravity:

Its still true.