Evolution -- what sparked it? Eg, how single celled organisms came to be?

Question

my semi-creationist boyfriend and i are having a friendly debate wherein i'm trying to support evolution, and he's looking for evidence of "something that addresses the spontaneous life that sparked evolution to begin with. (aka how single cell organisms came to be)." I'm sure I could google away and find something, but does anyone have a good, easy-to-understand explanation? Even better, a website that explains it well?

Thanks!

The talkorigins site is awesome -- thanks!

FYI... trust me, I've thought about kicking this one to the curb in favor of a less religious boyfriend... unfortunately I love him to death and he's perfect for me in every other way, so we're going to see if we can't work this out.

Answer 1

Check wikipedia for "Miller-Urey experiment."

But never mind that. Go on the offensive. Which of these scenarios is more likely?

a) Simple protobionts self-assembled from pre-existing biologically interesting macromolecules and monomers present in "primordial soup."

OR

b) A superintelligent, all-powerful supernatural being self-assembled from "Chaos and Void."

If your stupid boyfriend brings up the Hoyle "747 in a junkyard" argument, emphasize point B. God is the ultimate 747-from-junkyard.

Personal recommendation: Ditch this boyfriend and get one who is able to think for himself. Your boyfriend is a fundy. If you marry him, be aware that he will expect you to "submit to the husband." Check your Bible.

Answer 2

That is still a mystery to science, but one which we are getting close to cracking.

Know this: no one expects that it was a spontaneous life, a fully formed cell that suddenly popped into existence from its constituent parts. There is a gradient from non-living to living, organic molecules to self-replicating units to fully functional organisms.

For instance, a virus is not a living organism, it cannot do anything that a living organism is expected to do. And yet it has the same chemical composition as living cells, and is able to reproduce upon hijacking the biological processes of a living cell. It is certainly not alive, yet you can't describe it as "dead" either.

One idea is that one of the "stepping stones" from non life to life was a form similar to a virus (but of course different in behaviour, there being no living cells to infect). Our cell membranes, are a double layer of phospholipids, in which one end is hydrophobic (repelled by water) and the other is hydrophilic (attracted to water). This holds our membranes together. Because of this, in water, free phospholipids will from double-layered spheres. If such a sphere were to form around a strand of DNA, then you will have a simple structure not dissimilar to a simple virus. Of course, if this ever occurred in reality then this is but a grossly simplified explanation of just one of the many required steps.

The thing is, each step would further facilitate DNA's ability to replicate itself. Those which do replicate will have their code preserved while those that don't clearly will not. This is natural selection at the chemical scale.

Because DNA is a polymer with four types of monomer, information could be stored on it, in the form of a "four letter alphabet". Once this struck up a relationship with amino acids (perhaps through the aid of a hypothetical third chemical party no longer present, a "scaffolding" to the union, if you will), then DNA could influence the structure of poly-amino acids, proteins. Although amino acids speak an entirely different language, a 20 letter one, which is why we now use RNA, a similar polymer to DNA, as a translator.

I'm not an expert in this field, nor am I privy to some of the more advanced and in-depth hypotheses. However, I do know that we are getting close to some definite answers. It is one of the most exciting prospects in science, the greatest (currently) unanswered question. I do know that there are plans in motion to repeat some important stages from what we think some of these stages were, and a particularly ambitious one to create self-replicating and evolving molecular systems based on entirely different substances, though a similar process.

The story of our search for evidence of the earliest life is a long one that I could not tell here, but it is interesting, entertaining and promising. The answers are within our grasp, so watch this space...

Answer 3

One *very* important point.

Evolution and the origin of life are two *very* different questions. This is important because people love to conflate the two.

Evolution is an *extremely* well-developed and documented theory ... the evidence is enormous. And there is a single dominant theory (Darwin's theory of natural selection) that is accepted by 95% to 98% of all scientists. This is the question of how life evolved from the first life forms to all the current species we see now by way of common ancestry.

The question of abiogenesis (the origin of the first life forms) is not nearly as well developed. There are several different theories still in contention.

It is important to keep these two questions separate because creationists *love* to throw them both under the same banner of "evolution". Why? Because they love to exploit the fact that the origins-of-life question is still under debate and development, and use this to imply that the theory of evolution (or common ancestry) is still under debate or controversial among scientists ... which it most definitely is NOT.

I.e. scientists are not sure how life started (but they're working on it), but they are quite certain that humans are related by common ancestry to other primates, and that all primates are related by common ancestry to all other life forms on the planet.

By the way, the cover story in the current (June) edition of Scientific American (white cover with a molecule on it) has a great story about the latest research about the origins-of-life question. It's a great article questioning whether replication came before or after metabolism.

I also highly recommend the talkorigins site. An amazing (and ever growing) piece of work.

Answer 4

There are still such things to this day!!! The Bahamian Gromia is a single-celled organism, fully one inch long that moves - very slowly - by rolling itself along the ocean floor. The distinctive trail that the Gromias leave is identical to mud tracks found in the fossil record. The fossil tracks pre-date the so-called "Cambrian explosion" 530 million years ago, which was a blossoming of multicellular life and complex body plans from what had previously just been simple, blobby life forms. But why your opposition to evolution? Are you a member of a sect or cult church or perhaps home schooled? The Pope, Catholic Church, Church of England and mainstream churches all accept the big bang and evolution!! Lord Carey the former Archbishop of Canterbury put it rather well – “Creationism is the fruit of a fundamentalist approach to scripture, ignoring scholarship and critical learning, and confusing different understandings of truth”!! Nice that christians and atheists can agree and laugh together even if it is at your expense!!

Answer 5

The short answer is: no one knows EXACTLY how it happened the first time.

The important thing is, once the ball got rolling, the molecules are inherently self-replicating, so there quickly became a lot of them; and random deviations would cause the molecules to come out different over successive generations.

Those molecules (or cells, or organisms) that had some sort of an advantage tended to get copied more often, and become more numerous in the gene pool. Those that didn't, died out.

This is the essence of evolutionary theory.

Answer 6

A chemical process called abiogenesis led to the start of life. We can replicate many essential parts of this process in the laboratory. For instance, we know how simple chemical reactions can produce key ingredients of nucleic acids such as ribose.

Many scientists believe that simple shards of RNA formed from chemical reactions and that eventually some shards of RNA had sequences of nucleobases that led to protein construction and replication. Other scientists argue that protein construction and information storage can take place in a chemical environment without RNA (lab experiments seem to indicate this is possible) and so preceded an RNA phenotypic world.

Whatever the sequence of the very first steps of chemical evolution were that led to biological evolution, it took another billion years of evolution before something as "simple" (what you refer to as a simple single celled organism cell is really biologically quite complex) as a single celled organism came to be.

Answer 7

The Miller-Urey experiments and subsequent experiments are good examples of how, under a number of varying pre-life atmospheric conditions, the complex molecules that make up living things could have arisen from. (Here's a website that explains the original experiment http://www.chem.duke.edu/~jds/cruise_chem/Exobiology/miller.html) Variations on the original model showed that these organic molecules could arise from other types of atmospheres. The site also lists another possibility of where these essential organic molecules came from--a meteorite in outer space.

There are some other theories--check out this site: http://talkorigins.org/indexcc/CB/CB010_2.html It lists several possibilities, and includes citations for various peer-reviewed research papers and biology texts.

If you're looking for an all-encompasing site that will help you in your debate, I'd suggest the TalkOrigins.org site, listed here: http://talkorigins.org/indexcc/list.html

Answer 8

Uh... Right.

Sorry, I saw the hyenas set in, and thought I'd try to help out.

First off, your boyfriend's opinion is his. He's entitled to it. It's just as valid of an opinion as your own. Healthy discussion is great. Attacks are not.

As for evidence, check out this site:

http://www.sciam.com/article.cfm?chanId=sa013&articleId=000D4FEC-7D5B-1D07-8E49809EC588EEDF&modsrc=most_popular

Mainly, one has to remember that if the first forms of life on earth came about without the help of a designer (or had extraterrestrial origins), that original form of life was very, very basic, and possibly what scientists refer to as, "protocells." These cells resembled nothing which exists today, for the complex structures which we see are products of billions of years of evolution. What's more, the earth we see today is nothing like it was billions of years ago.

Multiple hypotheses can be found here. They're a bit complex, but you should be able to get the point:

http://en.wikipedia.org/wiki/Protocell

Hope these help. If you need further reading, let me know.

Cheers.

Answer 9

Two questions are being asked, actually.

What causes evolution is simply random mutations. DNA is copied precisely every time a cell divides, but mistakes are bound to happen, especially with this much information getting juggled around. In nearly all cases, the result is of no consequence. This is because large portions of most chromosomes contain genetic information which is completely non-functional. This meaningless information is never used, but gets copied along with the rest of the DNA. Is is essentially "padding" which takes all the abuse of everyday life. Things are far worse if any of the useful information is damaged. These mutations are almost always fatal. Only once in a very great while does a mutation occur which actually benefits an organism. The odds of this happening are small, but they are not zero.

A good example of a near miss is sicle cell anemia. One mutation replaces a single amino acid in hemoglobin and this causes the protien to hook up to itself. The hemoglobin forms long chains which distort blood cells into a sicle shape. The cells then tend to get caught in capillaries, causing gangrine and severe pain. It also just happens that the deformation of the blood cells prevents their being infected with the paracite which causes malaria. Malaria kills more people every year than any other human disease. People with sicle cell disease are therefore malaria resistant. If another mutation ocurred which prevented the sicle shaped cells from getting caught in capillaries, then this pair of mutations would be a distinct advantage.

What caused life to begin in the first place is actually a question best answered using physics and chemistry. The universe is expanding and what this means is all the matter and all the energy is spreading out into empty space. Anything which can assist this process is encouraged to do so. Fire is just a molecule of fuel loosing its chemical energy in the form of heat, which is then lost to space. Fire isn't alive, but living things burn their fuel just like fire does.

All this burning of course depends on free oxygen, but when life first evolved, there was no oxygen in the atmosphere. Free oxygen only exists because of green plants. If all the green plants vanished, the earth's oxygen would soon combine with carbon in the form of fire, or iron in the form of rust. There it would stay forever because this form of matter has the lowest chemical energy.

However, there would still be things that could burn. Methane can form without any help from living cells. A prime example is Saturn's moon Titan, which has rivers and lakes of liquid methane. These would not exist if oxygen were present because methane is natural gas and is highly inflammable. The methane is liquid because the temperature is below -150 degrees.

On the early earth however, the temperature was high enough for liquid water to form. Water is H2O. The oxygen wasn't in the air - it was in the water.

The first forms of life used heat energy to split water into oxygen and hydrogen. The oxygen was then used to extract chemical energy from methane, forming carbon dioxide. In terms of entropy, CO2 is lower in energy than methane. Anything able to turn methane into CO2 was therefore a spontaneous chemical reaction. A series of these spontaneous reactions were ocurring all the time. When they became organized and compacted inside a membrane, the first forms of life had evolved.

In short, life is just a way of burning something without a flame. Light bulbs burn out, stars burn out and people burn out - all because of entropy. Anything in the universe that can burn is destined to do so whether it does it with fire, nucleur fusion or the spontaneous chemistry of life.

Life did not suddenly happen out of nothing. A broken egg did not leap up off the floor and assemble itself one afternoon. Bits and pieces of non living substances slowly came together in more and more complicated ways until there came a time when the whole system could replicate itself exactly. When this happened, the first living thing had formed.

There is little evidence for this today. It is because if any of those original molecules formed, they would be immediately absorbed by living things, since they are essentially "spare parts". However, experiments have been done showing they will form naturally. The most famous was preformed in the 1950's. A researcher mixed water, ammonia and carbon dioxide in a flask and introduced an electric spark. In several days amino acids had spontaneously formed. Amino acids are what living things are made of. The difference is that the amino acids are arranged into proteins and enzymes in living things. It is still reasonable to assume an ocean full of amino acids could have built up complicated structures over millions of years and this resulted in living cells.

One piece of evidence supporting this notion is all the useless information encoded into modern DNA. It is highly likley strands of DNA were being assembled just as the amino acids were. It was lifeless at first, but when it began to directly result in the formation of useful protiens, it was just 1 step away from becoming a truly living cell. When this did happen, the entire strand of DNA got copied, the useful information and the useless as well.

The thing to learn from all this is that life is spontaneous, but not instantaneous. It is driven by a fundamental characteristic of the universe known as entropy. It is nothing more than a complicated and elegant means of getting a rock to drop a little further and a little faster.

Answer 10

Science and theology do not always contradict one another. Big bang or creationism? Maybe they're the same thing with a different name. Faith or empirical data, once again, same thing different process. Mythology or history? You can not separate the two. Better to respect and entertain each others convictions. If your having the same debate 20 years from now you are doing very well. GL.