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Evolution

Natural Selection

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The theory of 'natural selection' put forward by Charles Darwin and Alfred Russel Walace.

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Homo Erectus migrated to Asia, as seen above.

'Natural Selection' was a theory put forward by Charles Darwin and Alfred Russel Wallace. it is the survival and reproduction due to the environment. The rate an age of which an organism dies. How much they contributed to that species genetics as a result of reproducing. The study of Biology is based heavily around Natural Selection.

There are 2 categories of Natural Selection.

1. Ecological Selection which is organisms which survive and reproduce increase their amount of genes in a certain gene pool.

2. Sexual Selection is features on the opposite sex which make them more attractive. Thus increasing the rate of reproduction and the amount of that particular organism. Also increasing the amount of feature in that gene pool.

Natural Selection also provides us with mutations and other characteristics, these are;

Purifying which is the elimination of inferior genes in a gene pool and population. In example only the dominant alpha male is allowed to mate. Because, he has the superior and better traits in his genes.

Positive Selection is the increase in beneficial mutation.

Balancing Selection which is the variation in a population through a number of ways:

Over dominance where the heterozygote is more fit than the homozygous forms.

Frequency dependent selection where there are rare variants with a higher fitness.

Stabilizing selection which is the average traits of a species, decreasing the amount of variants.

Directional selection which favors the more extreme characteristic. Meaning a change in the average species or type of organism.

Disruptive selection which is favoring both extremes. Making the mean shifting or perhaps not shifting.

Mutations

Mutations not affected by natural selection are referred to as neutral mutations. Their frequency in the population is due to a genetic drift and gene flow. Without selection, organisms start to accumulate neutral mutations. Probable mutation effect is a gene not under selection will be destroyed by accumulative mutations. This is called genome degradation.

Baldwinian evolution states that human beings as diverse as they are capable of learning can change their environment or environment of species in a way which causes them to be selective forces.

F.A.Q. of the month!

I thought evolution was a theory? Why do some places refer to it as a fact?
 
Great question there Mike and this is why you win question of the month entitling you to an Xbox console prize worth over $300 dollars.
 
Well we know for a fact that biological evolution is a change in genetic characteristics over time. Biological evolution is the passing down of genetics from a common ancestor which is what gives it certain characteristics. But, even from fossil and information left behind by that animal it is still only considered a fact. Because, we weren't there at the time when they roamed the Earth. So whilst we have evidence it is not sufficient enough to become a fact. Whist general rules of evolution are a fact. The way a particular species adapts and lives and how they revolutionized is still a theory.

In the News

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Untangling Human Origins.

We get our weekly news curtosy of www.sciencenews.org. Thankyou to our team at sciencenews we were able to get this exclusive article.
 
"Nowadays, it's pretty easy to tell a person from an ape. Millions of years ago, the differences would have been much harder to pick out.

According to the scientific theory of evolution, apes and people have a common ancestor—one ancient animal from which both species evolved. At some time in the past, however, the creatures that would become humans started to differ from the creatures that would become apes and chimpanzees.

A few years ago, anthropologists digging in the African country of Chad discovered some intriguing fossils. They found a skull, along with some teeth and jaw pieces, that was between 6 million and 7 million years old.

Because the face and teeth resembled those of later human ancestors, the scientists said that the fossils were those of a human-like, or hominid, species—even though the skull could hold only a chimp-sized brain. They called this creature Sahelanthropus tchadensis.

Not everyone agreed with this conclusion. Another group of anthropologists argued that the fossil pieces came from an ancient ape.

Now, the scientists who found the bones have dug up more fragments. And, because some of the original skull bits had been squished, the researchers used a computer program to unsquish the pieces and fit them together into a three-dimensional picture of the skull.

The newly found teeth look more human than chimp, the researchers say. Moreover, the computer image of the skull shows a human-like flat face.

The way the skull meets the spine and neck might also have allowed this primate to walk upright, they add. To confirm this, however, scientists would have to find leg bones as well.

The new information strengthens the view that the old bones belong to the earliest known human ancestor, the scientists conclude. This creature lived just after the split between the human and chimpanzee evolutionary families.

Other anthropologists still aren't convinced that this is our earliest ancestor. Humans and ancient apes looked a lot alike 7 million years ago, they say, and some features of the fossil skull are more ape-like than human-like.—K. Ramsayer ."

EXTENDED FAQ's!!
 
How do you know the world is old. many say it's considerably young?
 
Thankyou Maddie for the question not known by many. Well according to many dating methods it is approximately 4 and a half billion years old.  
 

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By Jimmy K and Andrew H