Why is evolution scinece?

[Ravenstorm]

I don't see why evolution is science. Is there any scientific evidence of it?

[Fisherking]

]Firstly, let us be straight about what we mean by the word evolution.
For evolution to happen, you must have three things:

1. A population of self-replicating entities
   These could be any reasonably well defined entities, but most famously, it is applied to populations of life forms.

i.e. humans

[*]A replication process which is imperfect.
The process that generates the copies, does so with variation. The individuals in the next generation are not identical to the individuals in the current one.
(i.e. you probably look different than your parents)

see Genetics

[*]A Selection process
....natural selection, the ability to survive and ....reproduce....

If you survive, you have been selected to reproduce. If you have reproduced, you have been selected to survive. Brilliant.

We have found, that whenever these three elements are present, a process of evolution occurs. This process has become a powerful explanatory theory ....

For example, humans are capable of reproducing(sexually), their offspring inheriting traits from their parents, traits that will help the offspring survive and reproduce. If the traits do not help them survive and reproduce, the offspring will die (opposed to surviving), failing to reproduce.

Powerful

[JoeyKnothead]

From Post 11:

A Selection process
....natural selection, the ability to survive and ....reproduce....

If you survive, you have been selected to reproduce. If you have reproduced, you have been selected to survive. Brilliant.

The idea is that a mutation that increases your chance of surviving to a mating age, and increases your (and your mate's) chances of successful reproduction, will be carried onto your offspring.

The opposite would be a mutation that doesn't get you to that mating stage. There are also mutations that may help in early development, or later, that ultimately are harmful - but only after mating.

For example, humans are capable of reproducing(sexually), their offspring inheriting traits from their parents, traits that will help the offspring survive and reproduce. If the traits do not help them survive and reproduce, the offspring will die (opposed to surviving), failing to reproduce.

Close enough.

[Ravenstorm]

Everyone thank you for answering:).

[Ravenstorm]

May i ask how kinds evolve into different kinds?
Such as,How did asexually reproductive things evolve into sexually reproductive things?

things...as in bacteria, protists,or algae.

[McCulloch]

May i ask how kinds evolve into different kinds?
Such as,How did asexually reproductive things evolve into sexually reproductive things?

things...as in bacteria, protists,or algae.

Short answer: gradually.

You were once less than one meter¹ tall. If you are a normal human adult, you are now more than one meter tall. Yet, I'll bet that you cannot tell me which minute of which day you first were more than one meter.

Long answer: Wiki on the Origin of Sexual Reproduction

_________________
Americans, Burmese and Liberians, you can use one yard, it is close enough for this analogy.

[Ravenstorm]

May i ask how kinds evolve into different kinds?
Such as,How did asexually reproductive things evolve into sexually reproductive things?

things...as in bacteria, protists,or algae.

Short answer: gradually.

You were once less than one meter¹ tall. If you are a normal human adult, you are now more than one meter tall. Yet, I'll bet that you cannot tell me which minute of which day you first were more than one meter.

Long answer: Wiki on the Origin of Sexual Reproduction

_________________
Americans, Burmese and Liberians, you can use one yard, it is close enough for this analogy.

(making sure i got it right)

first it was like,mtiosis,then meisis....etc...untill now (like within...3 billion years)

[McCulloch]

How did asexually reproductive things evolve into sexually reproductive things?

Short answer: gradually.

(making sure i got it right)

first it was like,mtiosis,then meisis....etc...untill now (like within...3 billion years)

I don't know what those words are. Did you mean mitosis and meiosis ?

I was not going to get into the technicalities, since the details have not been worked out. Essentially, what I mean to get across, is that the process was gradual. Some asexually reproducing species, was able to alter its pattern of reproduction so that some of the time it reproduced using genetic material from another of its species. Then over many generations, that became the preferred method and the asexual version became less favored.

[Ravenstorm]

How did asexually reproductive things evolve into sexually reproductive things?

Short answer: gradually.

(making sure i got it right)

first it was like,mtiosis,then meisis....etc...untill now (like within...3 billion years)

I don't know what those words are. Did you mean mitosis and meiosis ?

I was not going to get into the technicalities, since the details have not been worked out. Essentially, what I mean to get across, is that the process was gradual. Some asexually reproducing species, was able to alter its pattern of reproduction so that some of the time it reproduced using genetic material from another of its species. Then over many generations, that became the preferred method and the asexual version became less favored.

Alter is pattern? what the heck were the first bacterias doing to each other?...don't have to answer....but how did the first to bacterias alter their pattern?

and yes i mean mitosis, and meiosis. (i fail at spelling?)

[JoeyKnothead]

Requested info:

Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets in two nuclei.

Significance:
Mitosis is important for the maintenance of the chromosomal set; each cell formed receives chromosomes that are alike in composition and equal in number to the chromosomes of the parent cell. Transcription is generally believed to cease during mitosis, but epigenetic mechanisms such as bookmarking function during this stage of the cell cycle to ensure that the "memory" of which genes were active prior to entry into mitosis are transmitted to the daughter cells.

Meiosis is essential for sexual reproduction and therefore occurs in all eukaryotes (including single-celled organisms) that reproduce sexually. A few eukaryotes, notably the Bdelloid rotifers, have lost the ability to carry out meiosis and have acquired the ability to reproduce by parthenogenesis. Meiosis does not occur in archaea or bacteria, which reproduce via asexual processes such as binary fission.

Significance:
Meiosis facilitates stable sexual reproduction. Without the halving of ploidy, or chromosome count, fertilization would result in zygotes that have twice the number of chromosomes as the zygotes from the previous generation. Successive generations would have an exponential increase in chromosome count. In organisms that are normally diploid, polyploidy, the state of having three or more sets of chromosomes, results in extreme developmental abnormalities or lethality [4]. Polyploidy is poorly tolerated in most animal species. Plants, however, regularly produce fertile, viable polyploids. Polyploidy has been implicated as an important mechanism in plant speciation.
Most importantly, recombination and independent assortment of homologous chromosomes allow for a greater diversity of genotypes in the population. This produces genetic variation in gametes that promote genetic and phenotypic variation in a population of offspring.

[Ravenstorm]

Requested info:

Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets in two nuclei.

Significance:
Mitosis is important for the maintenance of the chromosomal set; each cell formed receives chromosomes that are alike in composition and equal in number to the chromosomes of the parent cell. Transcription is generally believed to cease during mitosis, but epigenetic mechanisms such as bookmarking function during this stage of the cell cycle to ensure that the "memory" of which genes were active prior to entry into mitosis are transmitted to the daughter cells.

Meiosis is essential for sexual reproduction and therefore occurs in all eukaryotes (including single-celled organisms) that reproduce sexually. A few eukaryotes, notably the Bdelloid rotifers, have lost the ability to carry out meiosis and have acquired the ability to reproduce by parthenogenesis. Meiosis does not occur in archaea or bacteria, which reproduce via asexual processes such as binary fission.

Significance:
Meiosis facilitates stable sexual reproduction. Without the halving of ploidy, or chromosome count, fertilization would result in zygotes that have twice the number of chromosomes as the zygotes from the previous generation. Successive generations would have an exponential increase in chromosome count. In organisms that are normally diploid, polyploidy, the state of having three or more sets of chromosomes, results in extreme developmental abnormalities or lethality [4]. Polyploidy is poorly tolerated in most animal species. Plants, however, regularly produce fertile, viable polyploids. Polyploidy has been implicated as an important mechanism in plant speciation.
Most importantly, recombination and independent assortment of homologous chromosomes allow for a greater diversity of genotypes in the population. This produces genetic variation in gametes that promote genetic and phenotypic variation in a population of offspring.

Thank you.
as you see i am somewhat ignorant(i know evolution,jsut not that well) of evolution so i wish to understand it more before i debate a lot.