Could someone rationally explain how earth's life started from one cell organism and it became us?

Question

I'm an agnostics, whom believes generally in evolution, but I find the common explanation a bit far-fetched or rather I just can't picture it.

The earth is 4.57 billion years old, and us humans have been here roughly 2.2 million years ie the first 'homo'. Now personally, I'm sure we're not as complicated as what I thinks most likely is out in space, but I find it hard to reason how we developed from a single cell life form. Anyone have a chart of life's path from that to us...which would make some sense out of this?

I'm not saying there is or isnt' a god or that someone planted us here, but the conventional explanation of evolution is just not clear in my head. Could someone demonstrate a timeline that makes sense of earth's inhabitance from it's creation?

Answer 1

Your question is a very reasonable one --and brave, since you'll certainly get answers from religious zealots who have completely closed their minds. Let me start by saying my *only* personal agenda is a search for the truth, no matter where it leads me. Unlike many, I'm not here to shove my beliefs down anyone's throat.

The short answer is that I doubt it's possible in this kind of forum to get into enough details to convince a confirmed *creationist* that humans evolved from simpler life forms. But I hope to encourage an open-minded person to continue with their own research, and not be tempted by overly "easy" answers.

The long answer (most of it written by me, some of it transcribed manually; none of it pasted)...

I, too, was unclear about the evolutionary process for a long time. While I'm not an expert (and *nobody* has *all* the answers) I think I can help you get to a place where it makes *sense* to you as it now does to me, since you appear to have an open mind. (Agnosticism is good!)

After hearing people's arguments and questions for many years, I am convinced that there are six huge factors getting in the way of a general acceptance of the *overwhelming* scientific evidence for evolution.

1 - the common misconception that evolution claims apes or chimpanzees changed to human beings, and the perceived indignity -- and indignation -- that goes along with that idea... or with *any* suggestion that we evolved from a lower form. It's nothing but ridiculous human arrogance!
2 - the lack of human conception for the vast time life has had on Earth to evolve
3 - the human temptation to rush things and jump to ridiculous (and therefore naturally hard to believe) conclusions. Evolution involves not three or four steps, like fish to amphibian to ape to human!)... not hundreds, or even thousands of big, visible steps... but perhaps hundreds of millions of minute, subtle changes in a life form. Remember, we have had the time!
4 - the mistaken notion that creatures evolved because they "decided" to, or "wanted" to. When we say, for example, that fish needed to absorb oxygen more efficiently from the water, so they evolved gills, that's not to imply it was a choice. Evolution is about mutations... changes that were random from one generation to the next, over long periods of time. Those changes that happened to be good for the creature meant that creature survived long enough to reproduce, which meant there would now be lots of little babies with that same feature.
5 - a fearful and/or stubborn refusal to abandon faith in a Creator, since doing so might condemn the unbeliever to eternal suffering
6 - It's just *easier* to think about a Creator.

I know you want to see some details of our "life's path" to make sense of it, and I will provide that, below. Just a bit more, first.

The central ideas of evolution are that all life shares a common ancestor, and that it has changed over time (obviously, if we are to explain getting from A to B). While it's hard for many people to imagine the changes that would result in, for example, human beings from lifelessness, the first thing to keep firmly in mind is that we are talking about an *unimagineable* amount of time to play with... the earth having been around for some 4.5 billion years, as you said.

Understandably, few people can appreciate how much a billion is. Do you realize that roughly a billion *seconds* ago, "The Godfather, Part 2" was about to win the Academy Award for Best Picture?... that Richard Nixon was President of the U.S.?... that Hank Aaron had just broken Babe Ruth's record of 714 career home runs? 1974 was drawing to a close -- one billion seconds ago.

It's a lack of appreciation for this vast amount of time which, I think, makes people skeptical. They wonder how, in any amount of time they can envision, an ape can change to a human being. This, of course, is a common fallacy; evolution does not claim that this ever happened.

Though scientists still argue about the details, they are agreed that the evidence for life existing billions of years and changing over time is overwhelming. We've known for two centuries or so that life has a very long history. Fossil evidence shows how ancient life is, and that it has changed.

The most complete beginning-to-present sequence I've yet seen anywhere comes from one of the most thorough, intelligent, rigorously-cautious science documentaries of all-time, Cosmos, by Carl Sagan. I own the complete 13-volume set of this history-making television series on DVD, with science updates for 2000, and will refer to that segment, now. I cannot transcribe every word, of course, nor do I claim that this explanation fills every hole in my understanding, or that it will in yours! There are still way too many unknowns for scientists, let alone me, to give a detailed account of every evolutionary step. That doesn't hinder my belief, though, because I keep in mind that the *known* steps make perfect sense, and again we have lots and lots of time to play with. With each passing year, we learn more about the many steps involved.

As it is, it makes enough sense that I can easily envision the progression from lifelessness to life. I will paraphrase as accurately as I can. Dr. Sagan, with added commentary by little old me, says...

The first living things were not anything so complex as a one-celled organism, which already is a highly sophisticated form of life. The first stirrings of life happened on the molecular level, a fact, I might add, which should satisfy the skeptics who (quite reasonably) doubt that even a lowly amphibian just spontaneously crawled from the sea one day! It was much more humble even than that, Sagan says.

In those days of the primitive earth, when it probably looked more like our moon than like the earth of today, lightning and ultraviolet light from the sun were breaking apart simple hydrogen-rich molecules in the primitive atmosphere. The fragments were (as molecules do) spontaneously re-combining into more and more complex molecules. Experiments have clearly demonstrated that the "building blocks" of life can be created by simulating lightning in a primordial atmosphere.

I will interject to say: things that happen very rarely are increasingly likely to happen, given enough time. Most people would agree that hitting the lottery or the jackpot on a slot machine seems very unlikely and, like some people's vision of evolution, hard to believe if you limit your thinking to a few tries, or even a few years of trying! But pull that one-armed bandit's arm enough times and inevitably, the right combination of elements combines. This is exactly the way I understand the formation of these ever-more-complex molecules. Any chemist knows smaller molecules combine into larger ones whose properties change dramatically from the constituent elements. In the primordial ocean, there were a LOT of molecules, and a LOT of centuries during which random combinations were taking place every second. At some point, they hit the Lotto...

After perhaps *millions* of years (which is already a number outside ordinary human understanding), a very complex molecule combined with another one to form the ancestor of DNA. This molecule was able to make crude copies of itself, not by magic or divine intervention, but by the natural forces between the atoms involved, and the building blocks (other smaller molecules) floating all about it in the ocean.

As this molecule, and others, and even parts of molecules combined and re-combined, even more complex shapes and structures were formed, some which lasted, and some which didn't. A mutation is a combination that didn't work. That happens a lot, as you'd expect, because they're random. But when a combination *did* work, it naturally survived longer in the warm, turbulent, and growing sea. This is a molecular-level example of "survival of the fittest," and the heart of evolution, still... that random combinations which work tend to last, and those which don't obviously will not be around long enough to replicate themselves.

Four billion years ago, these ancestors of DNA were "competing" for building blocks and leaving crude copies of themselves. This is not to be seen as intelligent; merely a complex dance of minute particles in a fluid, combining, breaking, and re-combining according to molecular forces. There were no predators, and with reproduction, mutation, and natural selection, the evolution of "living molecules" was well underway.

At this stage, life seems to have reached a plateau for many hundreds of thousands of years, while another level of random combinations of more complex molecules took place. There are many missing bits of information about the details, causing both debate among scientists, and skepticism among creationists. But you wanted to know the progression as science (and I) know it, so far, so I'll continue...

Some molecules in the ocean were attracted to water on one side, and repelled by it on the other. This drove groups of them together into tiny, enclosed spherical shells, like soap bubbles. Within the bubbles, those ancestors of DNA were protected and could fluorish. The first cells arose.

It took hundreds of millions of years from this stage for tiny plants to evolve, giving off oxygen. Bacteria that could *breathe* oxygen took over a billion more years to evolve. From a naked nucleus, a cell developed with a nucleus inside. Remember we are still seeing natural forces at play, only with ever-larger structures as the result. These combinations are all explainable without the need for an intelligence watching over them.

Some of these amoeba-like forms led eventually to plants. Others produced colonies, with inside and outside cells performing different functions, becoming a polyp attached to the ocean floor, filtering food from the water. This gradually evolved little tentacles to direct food into a primitive mouth.

About 550 million years ago, filter feeders evolved gill slits, which were more efficient at straining food from the water. One evolutionary branch led to a creature which swam freely in the larval stage, but was still firmly attached to the ocean floor as an adult. Over the centuries, some of these retained the larval form throughout their life cycle, and became free-swimming adults with something like a backbone. They gradually evolved into jawless filter-feeding fish.

Remember, I said earlier that evolution is a series of a great many tiny, almost unnoticeable changes. We, like all other species living today, are the current (though ever-changing) result of a process which has been going on for over 4 billion years! It goes on, still. We are almost certainly not the same as our ancestors were even a few dozen generations ago, but the differences are almost imperceptible. Over a thousand years, one could probably find noticeable, though still subtle, differences -- in average height, for example. Over a million years, or two million, the differences become increasingly apparent, with such things as skull structure.

Gradually, those tiny fish I mentioned above evolved eyes and jaws. Fish then began to eat each other. If you could swim fast you survived. If you had jaws to eat with, you could now use your gills to breathe the oxygen in the water. This is how modern fish arose. During the summer, some swamps and lakes dried up, so some fish evolved a primitive lung so they could breathe air until the rains came.

Their brains were getting bigger. If the rains didn't come, it was handy to be able to pull yourself along to the next swamp. That was very important, because it resulted in the evolution of the first amphibians. Like fish, they laid their eggs in water, where they were easily eaten. But with further mutations and survivals, eggs developed with hard shells, meaning they could now be laid on land, where there were, as yet, no predators. Many of the reptiles hatched on land never returned to the waters. Some became the dinosaurs. One line of dinosaurs developed feathers, useful for short flights. Today, the only living descendants of the dinosaurs are the birds.

The forerunners of dinosaurs were also evolving, into small scurrying creatures with the young growing inside the mother's body. After the extinction of the dinosaurs, many different forms developed. The young were very immature at birth in the marsupials and in the placental mammals. The young had to be taught how to survive. The brain grew larger still. Something like a shrew was the ancestor of all the mammals.

One line took to the trees, developing dexterity, stereo vision, larger brains, and a curiosity about their environment. Some became baboons. But that's not the line to us.

Apes and humans have a recent common ancestor. Bone for bone, muscle for muscle, molecule for molecule, there are almost no important physical differences between apes and humans. Unlike the chimpanzee, our ancestors walked upright, freeing their hands to poke and experiment, and use tools. We got smarter, and began to talk.

Many collateral branches of the human family became extinct in the last few million years. We, with our brains and our hands, are the survivors. There's an unbroken thread that stretches from those first cells to us. But it took 4 thousand million years to get here.

Remember I have delineated only those general steps which trace the path of *human* origins. Before someone asks sarcastically why there are all these other types of animals if evolution led to us (ignorantly implying there can be only one result)... the question was about *our* history. Clearly there were innumerable *simultaneous* paths of evolution which didn't lead to us. The "life on earth" family tree is brimming with branches and twigs, depicting the paths -- partly unique and partly in common -- each living thing took to get where it is, today. We stand at the tip of only one of those twigs. Each of the other animals and plants that share this earth are on another... some close to us, since we have common ancestors not so long ago... some far from us, since a common ancestor last lived hundreds of millions of years in our distant past, giving us time for our characterists to diverge more noticeably.

No doubt many more of the details are known than I've presented here. But even if I was aware of all that scientists have learned, how could I rationally list the millions of subtle changes -- enough to convince a hardened creationist -- without typing and researching for weeks? As it is, I've been working on this answer for a few *hours* now, and it is understandably longer than many people will bother to read.

Further, there is much that *isn't* yet known of the details. This is something a scientific thinker isn't afraid to admit. Many religous fanatics don't have the courage to admit they don't have all the answers, either. They often claim to "know," based on extremely flimsy arguments, while making that very criticism about scientists who *have evidence* and are merely doing honest work to find the truth, whether it jibes with their pre-conceived hopes and beliefs or not. A fanatical creationist will often arrogantly and ignorantly cite the holes in our scientific knowledge as "proof" that what we *do* know is wrong. But unlike religion, science will continue to fill in the details as they are learned.

Answer 2

I don't accept the theory that this is all random chance - personally I believe in evolution, but 3.5 billion years seems way too short for life to evolve to such diversity as it has today. But I can't say I agree with these people spouting the Bible, for they simply ignore the scientific evidence. The Bible is a collection of stories picked by priests, written by man and not the word of god himself. Since all evidence suggests man, life, the earth and the universe is older than the 6000 years listen in the bible, we cannot take that as an explanation of the creation of life on this planet. What we do know is that life is highly organized and highly perfected. We know its constantly changing and adapting, and much of the evidence to date suggests the evolution of complex life from less complex beginnings. But if there's something organizing this diversification and promotion of life forms, we simply don't know.

Answer 3

It would be impossible for any type of plant or animal to evolve into a rational thinking human being. Why do all acorns only grow into oak trees or walnuts into walnut trees? That is their potential. Where did the original plan for the DNA to accomplish that come from? It had to be something greater than all the things created. How could any animal which lives only out of instinct evolve into a rational being which conceptualizes love or morality or justice? The only way a human could have been created is from something more intricate and intelligent than our finite minds. If you have ever tried to design an intricate machine, you know that trial and error is required to get all the bugs out and make it functional. With human life there was no second and third chance to get it right. The complex DNA that replicates all the systems that make up a human had to be created and could not come from nothing or a void. There had to be order to create and keep things continuing. I will put my money on God and praise Him for His wonderful creation.

Answer 4

Firstly, a one cell organism is not simple, it's in fact incredibly complex. We are infinitely more complicated than what is "out in space". Bear in mind as you ponder the rest of the forthcoming answers that there has never been a single case of evolution proved. i.e. information ADDED as is required for evolution to be remotely feasible. Mutations, information loss is NOT proof of evolution. There is a God, he's waiting for you to ask Him into your life and if you are serious enough about wanting to find out He will show you that He is there.

Answer 5

It's not rational. The chances of a single amino acid ( not even life, but something necessary for supporting it) just happening to form in a coagulation of goo are of the same likelihood as putting five monkeys in a dark room for a week with a typewriter and finding that they put together a fully-formed Websters dictionary while you were gone. And I'm not making that up.

Answer 6

Although I agree with the concept of evolution, until recently, I did have some trouble with it. I just read a book, Darwin's Ghost. I now understand how the genes could have already been in earlier organisms...
Read the book.

Answer 7

yeah...read a richard dawkins book

begin with *the selfish gene* or *climbing mt improbable* or *the blind watchmaker* or...

what you will find in a richard dawkins book is NOT much science, but LOTS of "just so" storytelling

his "scientific" explanation is add time and random mutation...and just "a little bit of luck" then poof...a frog turns into a prince

evolution is fact free junk science

not only is it not a fact, it is not a theory, it's not even a good working hypothesis...it's not even a reasonable explanation

evolution is in conflict with reality at virtually every turn

yeah...go read a pile of richard dawkins books (he's a gradualist)

or a pile of stephen j gould books (he's...well, dead for a couple of years now, but he was a "fits and starts" punctuated equilibriumist (punc eq, or punk eek! kind of guy)

and neither of them nor any of their celebrated colleagues/mentors (simpson, meyer, etc) ever gave us anything but fairy tales

where's the science

evolution is one of the only "sciences" that tries to explain what we can't see, what we can't find...rather than what we actually observe

good science, real science is great stuff (i enjoy it and lecture in molecular genetics)...but evolution is not science, it's not even logical philosophy

Answer 8

If you are really interested, read a Richard Dawkins book, might not be the easiest reading but very interesting and will answer a lot of your questions. You can start with the Selfish Gene: http://en.wikipedia.org/wiki/The_Selfish_Gene

Answer 9

LOL @ computer evolution. They're still made on a flat piece of silicon. They haven't evolved. They're like a city - they just got more roads.

Evolution cannot be explained because it's impossible. A bird can seemingly evolve over time (white to dark, fat to skinny, etc.), but it still only gives birth to a bird.

Answer 10

Just because you don't understand it, doesn't mean it's not true. There is not a clear cut timeline of evolution. It happend in fits and starts and leaps over MILLIONS of years.

Answer 11

Actually and Truthfully, the answer is found in the Bible. It is more easier to believe God created man than it is to believe man started from a cell. Reason it's easier is, WHERE DID THE CELL COME FROM? Answer goes back to God who created man to start with. No way to not see that God created it all. Start at the present and think back and it will lead to God, in everything that is in our world.