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moolmogo
New Member
4 Posts |
 Posted - 03/04/2004 : 02:42:46
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was there enough time for life to begin on it's own and then become the animals/humans we have today?
i'm not sure if my numbers are correct, but i think i've been told that: the earth is about 4.6 billion years old, the oldest fossils of single celled organisms are about 3.6 billion years old, and the oldest multicellular organisms are about 2 billion years old.
has anyone ever checked how much time is needed for life to become the way it is by way of evolution/natural selection/something non-creationist ?
i would like to know the following:
how much time it takes for the earth to form for life to come about on it's own.
what it takes for life to come about on it's own.
how long it takes for what it takes to happen.
for a single celled organism (or one of the earliest living things) to become an animal/human (or one of the most complex living things we have today or ever had),
how much time it takes...
how many changes/mutations/evolution steps/changes in dna needed
what the reasons are for the changes/mutations/etc to happen
how often the reasons occur for a change/etc to happen
how much time it takes for one change to occur, (i'll take the average or the minimal)
how often do the organism live on after a change.
how many of the changes/etc are dependant on other changes/etc to occur at the same time
how often that happens
why it happens
how often the reason why it happens happens
why the above happens
how often the reason above happens and repeat.
for instance, if it takes some environmental change for an organism to change/mutate/etc. how often and how much time does it take for the environmental change happen? and then what causes the environmental change? how often does the cause of the environmental change happen?
preanswers:
someone might say, we can't tell how much time it takes for a change to happen? to that i say, just give me an estimate. give me the shortest time it takes for the organism at it's stage. more simple organisms would probably change faster because they reproduce faster, but once they get more complex and reproduce slower i would think the time it takes for the organism to change would be longer.
someone else might say, "we have life right now the way it is, so there must have been enough time." to that i say, no. because we have life right now the way it is, would mean we just have life the way it is now. it could've happened another way. if we don't have enough time for it to happen that way, then i say, it didn't happen that way, or you have your dating methods wrong, or something went wrong.
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filthy
SFN Die Hard
USA
14408 Posts |
Posted - 03/04/2004 : 05:33:44 [Permalink]
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Greetings and welcome, moolmogo (neat handle, that)!
Wow! you've just asked the questions that evolutionary science has been puzzling over since even before Darwin and is still studying and arguing about today.
Ok, my take on it: I don't know.
No one is certain of the conditions that produced abiogenesis, if indeed that's how life on earth started (it could have been aliens of one sort or another or even a god(s)).
Evolution is anything but a steady progression. If an evolutionary niche is opened up, something will quickly (relitivly speaking) evolve to fill it. Darwin's finches (one of which is a vampire), Aldabra tortises, and Komodo monitors, for example. If an organism fits comfortably into a stable niche, it will show very little change -- the crocodile, the coelacanth, the horseshoe crab, cockroachs, et al, have been around since well before the dinosaurs. And indeed the dinos, all fitting neatly into their ecology, might still be our dominant species', were it not for some really foul luck in the shape of climate-changing, impact(s).
O'course, some of the dinos are still with us and making pigs of themselves at our bird feeders, whilst we're cutting others up for the skillet.
In short, evolution has no speed-governer either way. And as stated, no one knows the conditions present 3.5 + billion years ago that probably caused a replicating molcule. But it's being worked on. 
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"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
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filthy
SFN Die Hard
USA
14408 Posts |
Posted - 03/04/2004 : 05:41:35 [Permalink]
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Hmph. For some reason, the edit button ain't workin'
Just wanted to add: yes, there has been plenty of time for us to evolve, "goo to you, via the zoo," as Sarfati of AiG is so fond of saying. 3.5 billion years is quite a long time and we are a very young species. I'd like to refer you to a site that can give much of the nitty-gritty on it:
http://www.talkorigins.org/
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist!
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moakley
SFN Regular
USA
1888 Posts |
Posted - 03/04/2004 : 05:55:30 [Permalink]
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quote:
Originally posted by moolmogo
was there enough time for life to begin on it's own and then become the animals/humans we have today?
I'd say the odds of this actually happening are about 1 in 1. |
Life is good
Philosophy is questions that may never be answered. Religion is answers that may never be questioned. -Anonymous |
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jmcginn
Skeptic Friend
343 Posts |
Posted - 03/04/2004 : 08:44:33 [Permalink]
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moolmogo,
I will answer some of the points for now and look at the some of the others later:
Your ages are mostly correct, but multicellular life is about 1 billion years I think not 2, unless there is something I am unaware of.
" what the reasons are for the changes/mutations/etc to happen"
Mutations are natural copy errors although they can be enhanced by certain energies (e.g. radiation) or chemicals. They happen all the time every time a cell divides.
" how often the reasons occur for a change/etc to happen"
" how much time it takes for one change to occur, (i'll take the average or the minimal)"
The mutation is spontaneous and takes no time, they occur for instance on average 1.5 times for every sperm and/or egg you have or produce. Thus every human baby is born with on average 3 mutations. Thus mutations or changes of the genotype are happening at a constant rate every generation. Actually your body is accumulating mutations now (around an average of 30 will be accumulated during a normal human lifetime), but these are not inheritable most of the time (unless you are male and they happen to the sperm producing cells).
" how often do the organism live on after a change."
Almost always they live. Only under fairly rare conditions do the mutations cause fatality or infertility. In fact most mutations are neutral in tendency with no benefit nor harm done to the organism as they either effect DNA that has no function or they cause a silent substitution that does not change the amino acid the codon encodes for. Or the change in amino acid does not modify the protein it is in. Mutations like many natural phenomena form a bell curve with neutral mutations forming the peak of the bell curve. Mutations that are beneficial fall to the right and harmful ones fall to the left. However the bell curve does have a little spike on the harmful end at fatality thus roughly a little more than half of all mutations are either neutral or harmful and a little less than half are either neutral or beneficial to the organism.
" how many of the changes/etc are dependant on other changes/etc to occur at the same time"
Any mutation to the genotype that causes an effect on the phenotype (the actual characteristics of the organism) will be effected by other changes to the phenotype at the same time. I am not for sure what you mean however by "dependant". No mutation is dependant upon another that I am aware of. They occur independently. However when multiple mutations are combined they do form a different genotype and that combination may have an advantage or disadvantage of the other genotypes around it.
"for instance, if it takes some environmental change for an organism to change/mutate/etc. how often and how much time does it take for the environmental change happen? and then what causes the environmental change? how often does the cause of the environmental change happen?"
Mutations are independent of environmental changes and happen all the time (although certain environmental conditions might accelerate mutations beyond their normal levels, e.g. high intensity sun light). Environmental changes occur all the time and for a huge number of reasons. A few examples at various scales:
1. Continental drift causes a dramatic shift in climate by opening or closing various ocean currents and wind currents.
2. Continental drift pushes up a mountain range out of the ocean forming small tidal pools and dry land.
3. A river changes course introducing itself into a new area and dividing up the land.
4. Ocean levels rise producing salt marshes where there once was dry land.
5. River sediments continue to slowly accumulate forming a large river delta.
6. An earthquake or volcano dramatically effects the local landscape.
7. A new species moves into town.
8. An old neighbor species dies off or moves out of town.
9. Seepage from underground water sources introduces a new chemical agent into the environment (e.g. sulfur)
10. A tree falls opening up sunlight and providing a rotting log habitat.
11. Neighbor A starts to occupy a different niche than it previously did.
This list could go on and on and on. Some environmental changes can be instant (earthquakes, volcanos, fallen trees) others can take centuries or millennia to have an effect. However it doesn't take an environmental change for an organism to change. Organism genotypes are continuously changing despite if the environment is constant or not. Also note that organisms are not stationary and they can and often do move into new environments.
I have not addressed a few of your questions because they are considerably more complex and require some more thought and typing that I don't have time for now. Those being the ones about abiogenesis and how many mutations it takes and how much time it takes. |
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furshur
SFN Regular
USA
1536 Posts |
Posted - 03/05/2004 : 11:29:15 [Permalink]
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Time scales for evolution are not set in stone, so to speak. As the environment changes there will be coresponding changes in the animals that are living through the changes. So an animal like a croc that is suited to a fairly wide range of wet environs might only change slightly, while another animal may change drastically. The other point is when is a horse a horse, in other words what is your starting point.
That being said here are some examples.
The evolution of the horse - 55 million years
This is from a multi-toed 10-20" high to the shoulder animal to the modern horse.
The evolution of the elephant is about 25 million years. This is from the time that there was something 'close' to an animal that at least resembled an elephant.
Wolves. There is an extinct species of wolf (Dire Wolf) that died out ~ 12,000 years ago. The modern timber wolves are the direct decendants of the dire wolf. There is not a great amount of difference in the Dire and the Modern wolf but there is enough to put them in the category of different species.
Hope this helps.
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If I knew then what I know now then I would know more now than I know. |
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Dr. Mabuse
Septic Fiend
Sweden
9688 Posts |
Posted - 03/05/2004 : 12:59:21 [Permalink]
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Hello, moolmogo!
moolmogo quoted in RED
jmcginn quoted in BLUE
quote:
Your ages are mostly correct, but multicellular life is about 1 billion years I think not 2, unless there is something I am unaware of.
1 billion is the number I have too.
quote:
" how much time it takes for one change to occur, (i'll take the average or the minimal)"
The mutation is spontaneous and takes no time, they occur for instance on average 1.5 times for every sperm and/or egg you have or produce. Thus every human baby is born with on average 3 mutations.
My emphasis on born, in this case, is to point out that mutations are not restricted to production of the sperm and egg.
Mutations occur every time the genes are duplicated in preparation for a cell division. Once the egg is fertilized, it starts dividing into a cluster of cells. Each such division is subject to new mutations. A born baby will have more than just 3 mutations.
Incidentally, the book I most often fall back on is "Our Cosmic Origin" by Armand Delsemme. It was first published about ten years ago, so the numbers are probably a bit outdated.
jmcginn, what is your source for those numbers? I played a little with my calculator, and while I think that 30 mutations in an average in a human life is a bit on the low side, it's within a factor 2 of what I get when I back-trace us and chimpanzee, based on the assumption that we differ 1,2% and our common ancestor is 9 million years removed.
Delsemme's actual mutation-per-basepair number seems to be off by a factor 10 or more... which I feel a bit disturbing. I feel I need to resolve this, because I don't like this ambiguity.
Edit:
DOH!
Of course, when a sperm or an egg is produced, it is done by meiosis, that is, cell division without the genes being duplicated prior to the event. |
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| Edited by - Dr. Mabuse on 03/05/2004 13:08:40 |
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ljbrs
SFN Regular
USA
842 Posts |
Posted - 03/06/2004 : 17:15:00 [Permalink]
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moolmogo:
You asked:
was there enough time for life to begin on it's own and then become the animals/humans we have today?
More than enough, obviously. We are here now, and some 4 billion years (and counting) is a long, long time for evolution to succeed -- at least a much longer time than was given in the Bible -- or by the Bishop of Usher, for that matter.
ljbrs |
"Innumerable suns exist; innumerable earths revolve about these suns in a manner similar to the way the seven planets revolve around our sun. Living beings inhabit these worlds."
Giordano Bruno
(Burned at the stake by the Roman Catholic Church Inquisition in 1600) |
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Espritch
Skeptic Friend
USA
284 Posts |
Posted - 03/07/2004 : 13:48:33 [Permalink]
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Mutation occurs at a relatively constant rate. However, the rate of evolution is not constant. Speciation can happen very rapidly in some cases. In other cases, a species can remain little changed over vast periods of time. There are hundreds of cichlid fish species living in Lake Victory. Based on genetic relationships between different species and evidence suggesting that Lake Victoria dried up completely around 12000 years ago, it is believed that all these hundreds of species evolved in the last 12000 years (a mere eye blink in geological time) from a limited number of progenitor species that found their way into the lake when it refilled.
http://www.hagblomfoto.com/article_evolution.htm
On the other hand, evolution can move very very slowly. Modern horse shoe crabs very closely resemble those that lived before the age of dinosaurs. And the coelacanth fishes of today closely resemble their ancestor from 400 million years ago.
http://www.beach-net.com/horseshoe/Bayhorsecrab.html
http://www.dinofish.com/biologyandbehavior.html
The reasons for such profoundly different rates of evolution are complex, but they arise from the fact that evolution is driven not only by mutation but by natural selection. Mutation provides the raw material for evolution, but it is natural selection that ultimately determines whether mutations persist in a population. If a species is well adapted to it's current environment and faces few environmental pressures to change, natural selection will tend to act as a conservative force, removing genetic mutations which make it less well adapted to it's niche. The surviving coelacanths are deep water fish. The deep ocean tends to provide a relatively constant and stable environment over long periods of time so there is little pressure on coelacanths to change. Also, populations of deep water species tend to be small (compared to shallow water species), and this limits the amount of mutation in the species since mutations are spread over populations – a larger population means more mutations. Similar conservation in deep water species can be seen with the chamber nautilus, the six gill sharks, and many other deep water species.
In addition to environmental pressure, evolution and speciation also require available niches to evolve into and opportunities for populations of a species to become isolated. Although horse shoe crabs inhabit a more varied environment than coelacanths, they tend to be able to survive in oxygen poor polluted waters that other marine species cannot tolerate. This provides them a protected niche with little direct competition (horse shoe crab blood is copper based rather than iron based). They also have behaviors that work against speciation. Horse shoe crabs travel widely, but they congregate on the same beaches to spawn. This strategy of mass spawning works to insure that more eggs will be produced than the local predator population can eat, so some will survive. However, it also means that individuals that become isolated will tend not to spawn successfully. This limits speciation. Horse shoes crab speciation is also probably limited by the fact that the most of the alternative niches in the areas where they live are already filled by other creatures.
When the ancestors of the current Lake Victory cichlids first entered the lake, they found a varied habitat with few endemic species. The African rift lakes include numerous rocky outcrops separated by wide muddy or sandy areas. They include tidal zones, shallow bottoms and deep oxygen poor areas. A wide variety of habitats and many unoccupied niches are idea conditiona for rapid speciation.
Small cichlids that used rocky outcrops for protection tend to become isolated since crossing from one outcrop to another is hazardous for them. This tendency towards isolation of populations also encourages rapid speciation and evolution.
The main point in all of t |
| Edited by - Espritch on 03/07/2004 14:20:51 |
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moolmogo
New Member
4 Posts |
Posted - 03/25/2004 : 07:42:43 [Permalink]
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quote:
Originally posted by Espritch
The main point in all of this is that evolution doesn't occur at a fixed rate. It can proceed very rapidly when proper conditions occur. And such conditions have occurred repeatedly throughout the history of life on Earth.
is there evidence of what the proper conditions are and if they occurred and how many times they occurred?
because it can proceed rapidly, does it mean it did proceed rapidly?
if so, is there evidence for that?
because it can proceed rapidly in proper conditions, does it mean it did in the proper conditions?
if so, is there evidence for that? |
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Woody D
Skeptic Friend
Thailand
285 Posts |
Posted - 03/25/2004 : 14:15:14 [Permalink]
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quote:
Originally posted by furshur
Wolves. There is an extinct species of wolf (Dire Wolf) that died out ~ 12,000 years ago. The modern timber wolves are the direct decendants of the dire wolf. There is not a great amount of difference in the Dire and the Modern wolf but there is enough to put them in the category of different species.
Hope this helps.
Speaking of wolves. All dogs are (from) wolves and look at how many different breeds of dogs there are today. Some kinds formed in only a fairly short (100 yrs. or less) amount of time. Of course that's not really natural selection. But doesn't that show how fast changes can be made? |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 03/25/2004 : 16:36:37 [Permalink]
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Woody wrote:quote:
Speaking of wolves. All dogs are (from) wolves and look at how many different breeds of dogs there are today. Some kinds formed in only a fairly short (100 yrs. or less) amount of time. Of course that's not really natural selection. But doesn't that show how fast changes can be made?
All those breeds of dog are the same species, and yes, brought about through artificial selection. Many creationists would claim this as a point in their favor, by saying (in effect), "see? Intelligence (human) is required for such changes, therefore God exists." There are, obviously, flaws in that logic, however. |
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Woody D
Skeptic Friend
Thailand
285 Posts |
Posted - 03/25/2004 : 20:01:54 [Permalink]
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quote:
Originally posted by Dave W.
Many creationists would claim this as a point in their favor, by saying (in effect), "see? Intelligence (human) is required for such changes, therefore God exists."
Well, obviously that wasn't my intention to show that.
My point was that things can happen at a fast pace, didn't think of the human factor.
Not knowing much about the scientific part of evolution and just touching briefly on it in a philosophy class I can't say for sure but seems to me that lower forms of life could evolve quickly. Wouldn't it take only a few generations for some creatures to select the best of the species to avoid extinction?
quote:
There are, obviously, flaws in that logic, however.
I would hope so |
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As long as there's, you know, sex and drugs, I can do without the rock and roll.
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Dr. Mabuse
Septic Fiend
Sweden
9688 Posts |
Posted - 03/25/2004 : 21:25:05 [Permalink]
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quote:
Originally posted by moolmogo
quote:
Originally posted by Espritch
The main point in all of this is that evolution doesn't occur at a fixed rate. It can proceed very rapidly when proper conditions occur. And such conditions have occurred repeatedly throughout the history of life on Earth.
is there evidence of what the proper conditions are and if they occurred and how many times they occurred?
The question is badly formulated because it presumes that there are certain fixed conditions that are "proper".
"Proper conditions" depends on what species we are talking about, and what situation they are in, everything is fluid.
A change in weather pattern causing a little more rain on the African Steppe will not change the conditions for grazing animals, but the eucalyptus tree may grow taller. This will demand longer necks for the browsing giraffe. So the change in conditions will not have any impact on grazers but cause evolution in browsers.
quote:
because it can proceed rapidly, does it mean it did proceed rapidly?
if so, is there evidence for that?
because it can proceed rapidly in proper conditions, does it mean it did in the proper conditions?
if so, is there evidence for that?
You need to revise your questions. "Proper conditions" is not optional conditions for animals to choose from, where they can evolve. It's unconditional changes in the ecology, and animals (and plants) are forced to adapt in order to survive.
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