How life started?

[pakigang]

We know that amoeba divides is self to multiply. mammal, insects etc have reproduction.

My question is when life began from a simple organism which by multiplying itself grew how is it possible that is mutated or evolved into male and female and only count on reproduction for its existence. Hope you understand what i am trying to ask. It seems that there might be some external power(Aliens) or very heavy mutation to accomplish this?

 

[venk]

ignoring the creationist stories for a moment, it simply has to do with evolution, mutation, and natural selection. Sexual reproduction was a mutation of some non-sexual reproducing species and proved it produced creatures that are more hardy in times of catastrophy.

 

[CycloWizard]

Originally posted by: venk
ignoring the creationist stories for a moment, it simply has to do with evolution, mutation, and natural selection. Sexual reproduction was a mutation of some non-sexual reproducing species and proved it produced creatures that are more hardy in times of catastrophy.

I believe he means where did the first organism come from - before evolution, mutation, and natural selection could exist.

 

[Jack31081]

Originally posted by: CycloWizard

Originally posted by: venk
ignoring the creationist stories for a moment, it simply has to do with evolution, mutation, and natural selection. Sexual reproduction was a mutation of some non-sexual reproducing species and proved it produced creatures that are more hardy in times of catastrophy.

I believe he means where did the first organism come from - before evolution, mutation, and natural selection could exist.

mutation, selection and adaptation don't only exist in sexual living things.

How do you think bacteria develop immunity to antibiotics? Selection (albeit not 'natural'). Only the bacteria that have some kind of defense against the medicine survive, and they replicate. Now more of them are likely to have this defense. Repeat for a while, and eventually you have a strain of bacteria that can't be killed with that medicine anymore.

Anyways, his question was, 'How did sexual beings evolve from asexual beings?'. To answer that, you'd have to read some papers on the subject. More advanced than most of us here can probably tackle.

 

[cquark]

Originally posted by: pakigang
We know that amoeba divides is self to multiply. mammal, insects etc have reproduction.

My question is when life began from a simple organism which by multiplying itself grew how is it possible that is mutated or evolved into male and female and only count on reproduction for its existence. Hope you understand what i am trying to ask. It seems that there might be some external power(Aliens) or very heavy mutation to accomplish this?

The evolution of sex is one of the central questions of modern evolutionary biology. There's a short summary at http://biomed.brown.edu/Courses/BIO48/19.Evol.of.Sex.HTML

There's some tantilizing new evidence in this month's issue of Current Biology that single-celled eukaryotes may have sex. See http://www.sciencedirect.com/science?_o...0&md5=61abb95dfb613ce433e1b78aa3200c70
You can only see the abstract for free, but you can google for popular reports of the article.

 

[venk]

Originally posted by: Jack31081

Originally posted by: CycloWizard

Originally posted by: venk
ignoring the creationist stories for a moment, it simply has to do with evolution, mutation, and natural selection. Sexual reproduction was a mutation of some non-sexual reproducing species and proved it produced creatures that are more hardy in times of catastrophy.

I believe he means where did the first organism come from - before evolution, mutation, and natural selection could exist.

mutation, selection and adaptation don't only exist in sexual living things.

How do you think bacteria develop immunity to antibiotics? Selection (albeit not 'natural'). Only the bacteria that have some kind of defense against the medicine survive, and they replicate. Now more of them are likely to have this defense. Repeat for a while, and eventually you have a strain of bacteria that can't be killed with that medicine anymore.

Anyways, his question was, 'How did sexual beings evolve from asexual beings?'. To answer that, you'd have to read some papers on the subject. More advanced than most of us here can probably tackle.

Agreed, but sexual reproduction allows the mixing of distinct DNA mutations in creating the offspring, this meathod allows for more variation in organisms that are slow to reproduce (humans, animals, etc).

 

[alienal99]

there is a very simple answer for this. Evolution is not tealealogical, so there was no "working towards" aspect in creating sexual reproduction. Evolution involves simply random chance. Due to some random genetic mishap, two creatures could have been born that had different reproductive parts, and these two had children, and so on an so on. Or god could have just created one male and one female. Which ever way you like to look at it, it just happened.

alex

 

[mooncancook]

Due to some random genetic mishap, two creatures could have been born that had different reproductive parts

and coincidentally those two different reproductive parts happen to be able to join together, and when joined, the female (as labeled by human) happens to be able to carry offsprings... now i'm lost

 

[Matthias99]

Originally posted by: mooncancook

Due to some random genetic mishap, two creatures could have been born that had different reproductive parts

and coincidentally those two different reproductive parts happen to be able to join together, and when joined, the female (as labeled by human) happens to be able to carry offsprings... now i'm lost

Think single-celled bacteria reproducing by meiosis. You gotta walk before you can crawl (er, or something like that).

You don't need sophisticated 'reproductive parts' and the ability to carry offspring to have sexual reproduction. That stuff came later.

 

[cquark]

Originally posted by: mooncancook

Due to some random genetic mishap, two creatures could have been born that had different reproductive parts

and coincidentally those two different reproductive parts happen to be able to join together, and when joined, the female (as labeled by human) happens to be able to carry offsprings... now i'm lost

You're lost because you're overfocused on human biology. Most species don't have their reproductive parts join together the way that they do in humans. All you need for sex is a way to exchange DNA. Even in our own phylum, many species lay eggs that are fertilized outside the body, but looking beyond our phylum, we see a variety of species of insects and other arthropods who drop spermatophores into the environment for the females to pick up on their own, and of course, there's the entire plant and fungi kingdoms.

 

[CycloWizard]

Originally posted by: Jack31081
mutation, selection and adaptation don't only exist in sexual living things.

How do you think bacteria develop immunity to antibiotics? Selection (albeit not 'natural'). Only the bacteria that have some kind of defense against the medicine survive, and they replicate. Now more of them are likely to have this defense. Repeat for a while, and eventually you have a strain of bacteria that can't be killed with that medicine anymore.

Anyways, his question was, 'How did sexual beings evolve from asexual beings?'. To answer that, you'd have to read some papers on the subject. More advanced than most of us here can probably tackle.

Bah, apparently I am the one that didn't understand the question. NM

 

[mooncancook]

what is the advantage of sexual reproduction anyway in term of natural selection? with asexual (sorry if i spell it wrong) reproduction one needs not find a mate to reproduce, and the strong one can keep producing strong offsprings, wouldn't that increase chance of survival?

 

[cquark]

Originally posted by: mooncancook
what is the advantage of sexual reproduction anyway in term of natural selection? with asexual (sorry if i spell it wrong) reproduction one needs not find a mate to reproduce, and the strong one can keep producing strong offsprings, wouldn't that increase chance of survival?

While you're right that asexual reproduction is easier, there are a variety of evolutionary advantages to sexual reproduction. One advantage is that it increases the rate of adaptation. If a sexual organism has an advantageous mutation, it can share it with the rest of its species. An asexual organism with such a benefit would have to have its descendents wipe out the rest of the species for its adaptation to spread through its population. It also helps provide resistance to parasites by recombining defences of each parent in the new generation, so that parasites that had adapted to each individual parent's defences won't be adapted to the children's combination of defences.

 

[pinktank]

well, It's all fine and fun to dabble in science and religion, but then how was the first part made, be it carbon or god, or neither

 

[Jack31081]

Originally posted by: pinktank
well, It's all fine and fun to dabble in science and religion, but then how was the first part made, be it carbon or god, or neither

well, here's what the various groups will say:

bible literalists: there was no first part. Creation occured as it is described in the Bible.

bible 'reformists' (for lack of a better word): God created the first spark of life on the planet, and evolution took its root there.

non-religious: over the course of 1.5 billion years, abiogenesis created the first amino acids and proteins which formed to make the first self-replicating life on the planet.

Of course, there's no way to prove any of it, unless some scientist gets luckier than is conceivably possible and manages to create a self-replicating cell using a 'primeval goop' mixture and some electric currents.

 

[mooncancook]

well life is mysterious. It's more than just amino acid and proteins. we can break down an organism into its chemical composition and substances, but yet with the right substances life is not made. there must be an essentail ingredient that is not detectable - the life water, or maybe some kind of divine intervention...

 

[abj13]

Originally posted by: Jack31081
Of course, there's no way to prove any of it, unless some scientist gets luckier than is conceivably possible and manages to create a self-replicating cell using a 'primeval goop' mixture and some electric currents.

Well, abiogenesis is getting closer to being supported, as it appears RNA fills the perfect role as being created from the "primeval goop," while containing the three necessaries: genetic information , ability to self-reproduce (hypothesized, but not seen experimentally yet), and ability to catalyze other reactions (observed and happens everyday, ie rRNA and in certain bacteria). Now, if that is true, could the ancient form of RNA be considered alive, or the final step before protein and cellular development?