I am a creationist and a staunch evolutionist. I see nothing about one that precludes the other.
I'd like to hear more. It sounds like you may understand the phrase, "according to its kind" more liberally than most.
Calling Cofty and others regarding evolution
by dubstepped 340 Replies latest jw friends
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TD
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Diogenesister
Otwo-ty !But if you are interested in seeing speciation in life that is a bit less complicated than animals, there are flowers and other plants that have been documented to evolve a bit quicker into separate species.
I believe fruit flies are the classic ones. Because their life cycle is so quick, I believe biologists have done various studies which back up evolutionary theory. ( again, I'm an amateur so feel free to correct me everyone)
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Diogenesister
Dubby I'd like to understand how "macro" is still occurring or if it is. Did large changes end with us?
Nothing ends with us. There is no "end game" for evolution...hence Richard Dawkins "Blind Watchmaker", a play on words from the paper by William Paley, whereby he finds a watch in the midst of a forest and argues that since there is a watch, there must be a watchmaker.
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dubstepped
These are not really phrases that would be used by most biologists. Changes in the frequency of particular versions of genes -alleles - accumulate over time. Deciding when micro becomes macro is very subjective. Obviously when a population has changed sufficiently that they can no longer interbreed with the parent species then an important line has been crossed. That can be a subtle as the difference between Herring Gulls and Lesser Black-backed Gulls or as startling as the gap between chimps and humans. It's all the same mechanisms at play.
Aha, so there is no real micro and macro so to speak. Or if there were just to play the word game the macro isn't like one huge jump, it is millions of years of micros and isolation that allows them to continue down that path.
Yes. The key thing to remember is that nothing ever adapts to its environment. Rather a variety of genetic variation exists within a gene-pool. When changes happen in an environment in an isolated breeding group then some of those variations will confer a slight advantage. The frequency of that mutation will then become more common - or even ubiquitous - in that population.
Okay, so adaptation is an incorrect term then? The environmental pressures do impact changes, but only in that they allow the various mutations that exist already to flourish or fail? Those that flourish eventually win over through breeding and the failing mutations disappear or go latent?
I'm getting hung up on the notion that nothing adapts to the environment. In Prothero's book he mentioned some birds and an island where the food source changed to nuts. So then, the birds that had beaks that could break open the nuts for sustenance already existed on the island, it isn't like over time they developed, but they now had an advantage? I could swear that I've read about animals that adapted to different climates and such. So that was incorrect?
Just to clarify we and chimps both evolved from a common ancestor about 6 million years ago. Both lineages have been changing since then. The genetic difference is now about 1.5% but that means that our genome has only changed by about half that amount in that time.
Oh, so we didn't evolve from chimps. Right, that's linear and not accurate. As the tree branches grew on this tree of life there was a limb that was common to us, but the branches off of that limb were different, gradually so of course and over time.
Three things to sort out here. One is that a change of just a few percent in a genome is still an awful lot of changes. We have three billion base pairs in our genome. Most mutations happen in the non-coding region and has a neutral effect.
That cures my issue with such seemingly "small" changes affecting such great differences. They aren't so small after all. Makes sense.
The other thing is to think about the genome more like a chemical formula or a recipe than a blueprint. A small change in a blueprint results in a small change in the building. A tiny change in chemical formula can have a radical change in the end result - be that a chemical compound or a sponge cake.
This blew my mind. I was thinking more of the blueprint. A change in the blueprint still results in a building being formed. Maybe different in appearance slightly, but still a building. Chemistry is on a whole different level. Fascinating.
The third point I want to make is about selective pressure. Life has evolved over millions of years to fill every possible niche on the planet. Having refined their design by natural selection there just isn't a strong pressure on most species to change.
So then, in some ways, evolution does kind of end with us, barring some strong change in environment. Of course, if environment itself evolves over time, so will other things. However, the isolation factor is not as easy to find anymore so that kind of removes one factor that contributes to a mutation's survival.
That is also why we get so many genetic illnesses in old age. There is no evolutionary pressure to eradicate those from the gene-pool.
So these illnesses come out because we can no longer procreate? With men still being able to procreate and women not being able to after a certain age, are there higher percentages of genetic illnesses found in the female population? Or am I missing this point altogether?
I hope I'm getting this. Feel free to correct any incorrect assertions above. Man, I don't know why this is so hard for me to grasp. I've always been a very linear thinker and the cult really pushed me in that way. I went and looked at some tree of life images to help me see things more clearly in my mind, and that video above from jp kind of helped too.
Thanks for working with me on this. I am sincerely trying to grasp this and change my mind over from the way I was taught. At the same time I don't want to just say that I accept evolution without understanding it, otherwise I'm not much better than my old creationist self, just accepting things blindly because an authority said so. I like that there is visible evidence for this stuff.
Oh, and are we related to the plants too? If I have to throw them in the mix my brain my break, lol.
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OrphanCrow
are there higher percentages of genetic illnesses found in the female population?
Actually, it is the male population that will exhibit more of certain genetic illnesses (hemophilia, for one)
The female will often be the one to carry genetic illnesses and the male will acquire it
This is because defects in the X chromosome can be overcome in the female with the other x chromosome making up for the defect. However, in the male, if they inherit an x chromosome that carries the genetic illness, they don't have another x chromosome to pick up the job and correct for the defective chromosone
Males are XY and their Y chromosome won't have the ability to overcome the x defect
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Driveby
I would suggest reading "A Short History of Nearly Everything" by Bill Bryson. It is entertaining and nontechnical but gives a good overview of how we got here.
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LoveUniHateExams
and are we related to the plants too? - only very distantly. Nothing to lose your mind over.
Plants are radically different from us and other animals in several ways.
Plants take in carbon dioxide and give off oxygen (opposite to humans!).
Plants make sugars via photosynthesis whereas humans and most other animals use a mouth or mouthparts to feed.
Plants often evolve or change their appearance and characteristics via polyploidy - and suffer no ill effects.
Polyploidy is the doubling or otherwise increasing the number of an organism's chromosomes.
(Any human babies born with polyploidy usually quickly die.)
PS - well done Dubstepped for being open-minded enough to start your own independent study of evolution. I hope you learn a lot and question a lot!
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cofty
In Prothero's book he mentioned some birds and an island where the food source changed to nuts. So then, the birds that had beaks that could break open the nuts for sustenance already existed on the island, it isn't like over time they developed, but they now had an advantage? I could swear that I've read about animals that adapted to different climates and such. So that was incorrect?
Yes it's misleading to talk about animals 'adapting' to their environment. Species adapt individuals don't.
This is well illustrated in the following study of feral pigeons - Something Darwin didn't say...
Imagine a population of finches where one or a few have a slightly stronger beak. In normal times it offers no advantage but if the environment changes so that seeds are less plentiful these individuals will get more food and even if it is by a small percentage leave more offspring. Big strong beaks don't happen suddenly but by numerous incremental changes.
Edited to add - You will find the sort of 'adaptation' language in some biological texts. It's a sort of shorthand as is talk about 'design' which refers to a correlation between form and function. It's important to recognise these or they cause confusion. Sometimes the author is just ill-informed especially in the popular press.
Oh, so we didn't evolve from chimps. Right, that's linear and not accurate. As the tree branches grew on this tree of life there was a limb that was common to us, but the branches off of that limb were different, gradually so of course and over time.
Yes that's right. Life is a tree not a ladder. Most of the branches were dead-ends. More than 99% of species that ever lived went extinct before humans appeared.
in some ways, evolution does kind of end with us, barring some strong change in environment.
There is probably some truth in that although it is controversial. The human species will go on changing insofar as there will be changes in the frequency of alleles in the human gene-pool. However our mastery of our environment has probably reduced the selective pressure that was faced by our ancestors. Evolution also shapes us from the neck up. I wonder if that is where we might see more rapid change.
So these illnesses come out because we can no longer procreate? With men still being able to procreate and women not being able to after a certain age, are there higher percentages of genetic illnesses found in the female population? Or am I missing this point altogether?
Not quite. The point is that individuals who have genetic defects that result in death or incapacity at an age before they leave offspring don't get passed on and tend to get removed from the gene-pool. Illnesses that tend not to appear until after we have produced copies of our genes are unseen by natural selection and tend to accumulate. There is a related reason why you shouldn't marry your cousin. Harmful recessive genes accumulate with impunity because we usually have another good copy. Close relatives are more likely to share the same defects resulting in all sorts of issues for offspring. This is becoming a real worry in some insular religious communities.
Oh, and are we related to the plants too? If I have to throw them in the mix my brain my break, lol
Yes absolutely!
For billions of years only 'simple' prokaryotic organisms existed like bacteria and archaea. An amazing event of endosymbiosis led to the advent of more complex eukaryotic cells. This made multicellular life possible. The problem of energy production was overcome by the mitochondria that were once free-living bacteria existing inside every cell. Bacteria produce energy across their surface membrane but the bigger a blob gets the surface gets relatively smaller compared to the volume. Cells began to specialise and build large complex bodies where the job of replication was assigned to just the sex cells. [Cancer is an illness where a cell has gone native and reverted to individual uncontrolled reproduction]
The origin of complex cells...
Multicellular life includes plants and animals although in fact it is not so simple to differentiate. If you look for 'cladograms' on google images you will see examples of how the tree of life develops.
Here is an interactive tree you can play with...
Dawkins book "The Ancestors Tale" covers this in detail
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cofty
The concept of the 'selfish gene' is a very useful way of understanding evolution. Bodies - whether that is a human, fish, insect or oak tree - are vehicles by which genes travel through time.
Combinations of genes that build bodies that are better at leaving copies of those same genes, by definition leave more copies.
Sexual reproduction shuffles the pack allowing favourable combinations to travel together and freeing them from less effective genes.
The vast majority of our genome consists of code that contributes nothing to the phenotype but hitches a free ride alongside the much smaller percentage of code that does the real work.
Keep in mind that the phrase 'selfish gene' is a metaphor. There is no agency or teleology. Genes that build bodies that are unselfish and cooperative members of social species are successful 'selfish genes'.
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dubstepped
Wow, so much to take in here. Thanks again Cofty and others. I've got some books to make my way through with time. I do certainly have a better understanding now. I'm less frustrated. That book frustrated me because every time I thought I was close to learning something he'd go on a rant again about creationism, and some of the searches that I did on Google turned up either confusing information or put me in the middle of some concept. Being able to have my questions answered from the jumping off point that I got through that book helped a lot.
I don't necessarily need or want to be an expert in the field but I want to have a working knowledge of the subject. For so long I thought I knew it all and knew nothing. Now I know very little but actually know something.