Evolution

Originally posted by googlefudge
hi there scottishinnz, could you give a decent account of the evidence for evolution as an observable phenomena today. You are far better qualified to do this than me and probably have better examples than me just looking some up. if not the no worries.

something like 96% (I will look it up when I wake up later today (it's so late it's early)) of lif ...[text shortened]... recent is possibly the best studied (as more evidence from this time is available to study).

Indeed. I'll give a brief synopsis of life on earth as we understand it, the major transitions, and the evidence we have for it.

The planet was formed some 4.5 billion years ago, or perhaps a little over that. The oldest known rocks are 4.5 billion years old, which indicates that this was when they last set. Around 3.95 billion years ago the first evidence for life is apparent from rocks. Spherical bubbles in the rock, which appear to resemble cells have been found. The jury is still out on whether this was life or not, but it seems plausible. Around 3.8 billion years ago there is rock evidence for oxygenic photosynthesis, as oxidised iron deposits are noted. All rocks older than that only contain reduced Iron, suggesting a very reducing atmosphere with no free oxygen. The oldest fossil stromatolites are around 3.5 billion years old - definative evidence for life. For around the next 1.8 billion years the microbes (cyanobacteria - aka blue-green algae) living in the sea were involved in oxygenic photosynthesis. Over that period a steady increase in the oxidation state of the sediments can be noted (i.e. more oxidised iron, less reduced iron). Around 2 billion years ago, the unthinkable happened - the cynobacteria ran out of iron! The oxygen they were producing started to build in concentration in the ocean, and degassed into the atmosphere. Initially, this would be little problem for the bacteria, but at around 1% O2 it would start to become toxic for the little guys. However, 1% O2 is our first magic number. It was around 1% O2 that allowed the evolution of eukaryotic cells. Eukaryotic cells are larger than prokaryotic cells (bacteria), and it's likely that they were predatory in nature. In the 1960's a scientist by the name of Lynn Marguilis came up with endosymbiotic theory - the theory which explains the structure of the eukaryotic cell. Marguilis looked at the cell and realised that some of the organelles where odd in appearance, having two double membranes, instead of one. The odd ones out are mitochondria and chloroplasts (and a variety of other plastids). Notably, both chloroplasts and mitochondria also contain DNA, and Marguilis concluded that these organelles are the decendants of bacteria which were captured in larger cells, which learned to capture them and use them like slaves. The newly evolved Eukaryotic cells contained the bacteria Mitochondrion, which could break down complex C chains using O2 as an electron acceptor, producing water and a comparitively large amount of energy. This meant that eukaryotic cells enjoyed a huge advantage over prokaryotes, provided there was O2 in the atmosphere. Oxygenation continued until around 800 million to 1 billion years ago, when the oxygen concentration in the atmosphere would have been around 2%. There is some evidence of 750 million year old soft-bodied multicellular organisms, but around 550 million years ago, life really got a hang of things by evolving calcification - strengthening through the use of calcium carbonates. Fortunately, microbes had been removing CO2 from the water for the last 3 billion years since, dissolved in water, CO2 becomes H2CO3, carbonic acid, which would have dissolved the shells etc. The Cambrian period seems to have been a major evolutionary playground, with many organisms that no longer survive. The atmospheric CO2 conc. was around 4%. This oxygen would be of utmost importance, since it formed ozone in the presence of the UV radiation from the sun. Ozone blocks UV-B, which would cause severe genetic damage to any organism trying to survive on land before 400 million years ago.

Somewhere around 400 million years ago life in the oceans was becoming quite dangerous, and pressure was exerted for things to spend at least some time on land, since there was a lack of predators. Animals, especially insects, seem to have made the first forrays onto land, although algae probably already existed as a foodstuff (and presumably also fungi). Land plants evolved around 400 million years ago. The simplest land plants are things like lichen, which are actually algal / fungal associations, rather than true "plants". Bryophytes (mosses) probably also evolved very early, from the green algae. Bryophytes have almost no vascular tissue, and minimal roots. Indeed they resemble algae (seaweed) in alot of ways. As plants covered the lands surface, soil built up. Soil, which is comprised mainly of organic matter residues, is good at retaining water. Once the soil surface was covered, the next evolutionary pressure was on growing tall, since this allows plants to outcompete their neighbours. Water can only diffuse (upwards) through cells for about a distance of 10cm before it is unable to supply evaporative demands. At some point, vascular tissue evolved, and still today many intermediates between vascular and non-vascular plants exist. Vascular plants could start to evolve larger and taller than non-vascular plants. They did, however, require other adaptations for successful life as "big things". The required roots, initially for physical support only, but later they were also adapted from nutrient and water uptake. Leaves became more efficient at capturing light when flattened out (although some primitive plants such a Psilotum still exist), and a cuticle and stomata helped retain water. Roots probably evolved as a mechanism to stored C somewhere is wouldn't photosynthesize more!

Around 330 million years ago, around the start of the Carboniferous period, the colonisation of land by plants way largely complete. O2 concentration had reached around 30%, and even wet vegetation could combust. The largest organisms were things like tree ferns, which could growth upto around 50 metres tall in the warm, moist climate that prevailed at the time. These plants became coal.

Around 250 million years ago one or several natural disasters ravaged the earth, possibly extreme volcanic activity cause by a meteor stike. This killed some 96% of marine species (although less genera and families, since these are often represented by multiple species), and signalled the end for the trilobites. This is known as the Permian extinction. Around 30% of land organisms are believed to have survived.

During the next 180 million years saw the evolution of both dinosaurs, and a radical new design of plant - the flower. Flowering plants were quite different to non-flowering plants, and it ushered in a new age of relationships between insects and plants, including the bumble bee. Around 100 million years ago mammals evolved, but could not displace the dominant dinosaurs.

65 million years ago a meteor crashed into the Yucatan peninsula, wiping out around 50% of species. This extinction event is believed to have taken upto 10,000 years to regain ecosystem stability. The initial problems would have been from global dust clouds, and possibly waves of noxious nitric compounds causing the death of many animals. Mammals seem to have escaped the worst of this, whether because of our burrow dwelling, noctural habit, our small size, our metabolic system or pure chance is unknown. The rarity of mammals, and the fact that we did not eat large prey (we were small insectiverous animals, essentially of badger size, i believe), thus resisting the bioconcentration of toxins, I don't know.

3 million years ago the rainforests that covered africa slowly started to retreat. This was due to a climatic shift, but it's result was forcing primates into living on the savannah. Life as a primate living an arboreal existance is pretty much upright - monkeys etc run though the trees, rather than climbing, as we do. This made life upright relatively easy for our ancestors, and our comparitive height allowed us to see over greater distances.

Obviously very incomplete, but hey - I'm writing from memory.

Originally posted by whodey
If it could be done in a lab I would have to concede it were possible in nature. As it stands now I am being asked to believe something happened without intelligent thought in an uncontrolled environment when it can't even be done with intelligent thought in a controlled environment.

Being unable to do something in the lab is not always an indicator of whether or not it is possible in nature. I have never seen a sun or star made in the lab, as far as I know even fusion the basic power source of the sun is very difficult to produce in a lab. Other important factors are: has anyone actually tried to produce life in a lab? How much money was available for the experiment? To do an experiment that mimiced the biogenesis that is hypothesised to have happened on earth, what sort of volume of material and time scale would be required?

Originally posted by scottishinnz
This is simply not true. Land plants evolved in the Silurian and Devonian from 400 - 330 million years ago. Much later than the Cambrian. Angiosperms (Division Magnoliophyta) evolved only 120 million years ago.

I think the implication for him saying that the bulk of life as we know it if not all the life we know today came from the Cambrian explosion. You could even argue that a few species possibly evolved from what came from the explosion such as the ones you poited out. However, I would think he would probaly say that the plants found in the Silurian and Devonian period simply have not been found during the Cambrian period. It does not necessarily mean they were not present during this period. I could be wrong and hate to speak for Dr. chein.

Originally posted by twhitehead
Being unable to do something in the lab is not always an indicator of whether or not it is possible in nature. I have never seen a sun or star made in the lab, as far as I know even fusion the basic power source of the sun is very difficult to produce in a lab. Other important factors are: has anyone actually tried to produce life in a lab? How much money ...[text shortened]... sed to have happened on earth, what sort of volume of material and time scale would be required?

It does not have to be in a lab but should be observable. I say it must be done in a lab because we simply do not see it in nature. Science is after all obseration and speculations about other observations.

Originally posted by scottishinnz
That link leads nowhere. Why not get your info from a real university (i.e. not devoted to finding out that the bible is correct)?

I think you are judging Dr. Chein and I a little to harshly. In fact, here is a quote from the article. Dr. Chien says, "I would not use any scientific findings as evidence to support Biblical creation. All science does is begin to tell us what happened 540 million years ago, and we have just little bits and peices." However, he does elude to the fact that the Cambrian explosion very much resembles that of the 5th day of creation in Genesis.

Here is another quote. "I would like to see Christians get into paleontology and take an interest in doing good science. I think that that's at least one way to reverse the church's withdrawal from science. Personally, I have an urge to popularize these ideas because although scientists are beginning to talk about the Cambrian explosion, and while a few people in the inner circle know about it, the general public is not aware of it. In fact, I have now in my hands a Chinese book on the Cambrian explosion that I would like to have translated into English and published in the US.......such books have little to do with religion than it does with the truth, and the truth will speak for itself."

Originally posted by Gaurav1
Evolution is a MAYBE but DARWIN'S THEORY OF EVOLUTION is FALSE. He said that human's first form evolved from apes approx 3 million years ago. Recently two scientists have proven that theory wrong. They found a footstep of a human being in a place, in Africa. These scientists took the 'proper', 'correct' type of DNA Test and discovered that the footsteps date ...[text shortened]... Evolution is still a maybe, like dinosaurs,etc but human evolution I don't believe in.

Are you talking about this?

"Laetoli footprints: according to most creationists, these are modern human footprints that are dated at 3.7 million years ago, long before humans were meant to exist. Creationists emphasize the close resemblance between these and modern human footprints, but often neglect to mention their extremely small size and the fact they may also be similar to the feet of the australopithecines living at the same time. Exactly how similar they are is a matter of some debate.

Tuttle (1990) thinks the footprints are too human-like to belong to A. afarensis, and suggests they may belong to another species of australopithecine, or an early species of Homo. Johanson, who has often said that Lucy was fully adapted to a modern style of bipedality, claims (Johanson and Edgar 1996) that the A. afarensis foot bones found at Hadar, when scaled down to an individual of Lucy's size, fit the prints perfectly. Stern and Susman (1983), who have argued that Lucy's foot and locomotion were bipedal but not yet fully human-like, believe that the footprints show subtle differences from human prints and could have been made by afarensis. Clarke (1999) believes that the Laetoli tracks could have been made by feet very similar to those of the new australopithecine fossil Stw 573.

In short, there is a wide range of opinions about the nature of the footprints and whether A. afarensis could have made them. Most creationists usually cite only Tuttle, whose conclusions they find most convenient. The most honest conclusion, for now, is to admit that although no-one can be entirely sure what made the Laetoli footprints, it seems quite likely that they belonged to australopithecines.*"

* - http://www.talkorigins.org/faqs/homs/a_anomaly.html

Might I add that it seems mighty dishonest to use scientific dating methods to give you 3.7 million years old but pass off all the dating of human remains that consistently place us much less than 1 million years old.

Originally posted by whodey
I think you are judging Dr. Chein and I a little to harshly. In fact, here is a quote from the article. Dr. Chien says, "I would not use any scientific findings as evidence to support Biblical creation. All science does is begin to tell us what happened 540 million years ago, and we have just little bits and peices." However, he does elude to the fact tha ...[text shortened]... tle to do with religion than it does with the truth, and the truth will speak for itself."

How can the days of creation at all resemble any thing in the data, when the plants were created before sunlight existed?

Originally posted by telerion
How can the days of creation at all resemble any thing in the data, when the plants were created before sunlight existed?

Good point. However, I would direct your attention to Genesis 1:3, "And God said, 'Let there be light; and there was light'." So you see, there was light. Granted our sun at the time was not the source of this light as of yet.

Originally posted by whodey
Good point. However, I would direct your attention to Genesis 1:3, "And God said, 'Let there be light; and there was light'." So you see, there was light. Granted our sun at the time was not the source of this light as of yet.

the existance of light (self reinforcing oscilations in the electromagnetic field) does not per say garentee that anyhting was lit. and even if some things were lit, that does not mean that the earth was. basing arguments on a literal reading of genesis is like trying to stand on thin air. if the light had no source then the earth was not lit. it's that simple, and the only significant light source around here is the sun.

Originally posted by googlefudge
the existance of light (self reinforcing oscilations in the electromagnetic field) does not per say garentee that anyhting was lit. and even if some things were lit, that does not mean that the earth was. basing arguments on a literal reading of genesis is like trying to stand on thin air. if the light had no source then the earth was not lit. it's that simple, and the only significant light source around here is the sun.

Psst. Perhaps the life-enfusing light came from the source of life. Need any hints? It's the same source which provided thin air, as well.

Originally posted by FreakyKBH
Psst. Perhaps the life-enfusing light came from the source of life. Need any hints? It's the same source which provided thin air, as well.

Very good Freaky. How about prophetic light sources in Revelation Chapter 21.

"And I saw a new heaven and a new earth for the first heaven and first earth were passed away......"And the city had no need of the sun, neither of the moon, to shine in it, for the glory of God did lighten it; and the Lamb was the light thereof."

It's enough to make an honest scientist go mad, no? I can just hear scientists screaming, "But you can't do that God, you can't do that!"

Originally posted by whodey
Very good Freaky. How about prophetic light sources in Revelation Chapter 21.

"And I saw a new heaven and a new earth for the first heaven and first earth were passed away......"And the city had no need of the sun, neither of the moon, to shine in it, for the glory of God did lighten it; and the Lamb was the light thereof."

It's enough to make an h ...[text shortened]... ? I can just hear scientists screaming, "But you can't do that God, you can't do that!"

Oh no, that's a little harsh on us scientists. We simply scream thus, "there is no evidence for any of this, and a huge amount for the way we think it happenned. You're either a lie or a liar, God".

Originally posted by scottishinnz
Oh no, that's a little harsh on us scientists. We simply scream thus, "there is no evidence for any of this, and a huge amount for the way we think it happenned. You're either a lie or a liar, God".

You made me spew spittle on my keboard due to laughing.

Originally posted by FreakyKBH
Psst. Perhaps the life-enfusing light came from the source of life. Need any hints? It's the same source which provided thin air, as well.

or maybe God just kept them alive without sunlight.

or maybe they were magic plants.

or maybe they all died that day, but their seeds went into the ground and grew again on the fourth day when the sun came out.

or maybe (insert your own!)

Really the harmonizations are only limited by your imagination. That's the wonderful thing about disregarding the laws of the natural world. Now let's not get all excited and go searching for this "life-enfusing" light. It's not like we really believe that's what happened.