Ok, I will try. Birds in a population have a range of size of beaks, just like people have different sizes of noses. We can call that “genetic drift.” Maybe a tasty bug lives in the crevices of bark on the common tree, and in a time of climate change, that bug is the primary food. The birds with longer narrower beaks can reach the bugs and eat them. They are healthier, have more chicks, and over generations the birds with short beaks die out or come to live in areas that have other food sources, and the long beaked birds flourish. Rinse and repeat for thousands of generations with different traits and environmental pressures, and you wind up,with a bird quite different than when you started.
I have yet to see an example of irreducible complexity that is really irreducible. What they do, for example, is say consider a mouse trap. Remove one part and it no longer is a mouse trap. Which is true. But depending on the part you remove what you are left with might have many other functions. They just don’t include being a mouse trap. And if you do want to have a mouse trap consider how many different ways a mouse trap could be build. How can something be irreducibly complex when there are many different ways to get there?
That’s young earth creationist, which he has already said he’s not interested in.
I don’t know if a five year old could get this, but maybe fifth grade. If a longer thinner beak is advantageous in a certain population of birds because it helps them survive (find food, defend against predators) and reproduce (attract a mate), then it might evolve in the population as a whole as an adaptation. An adaptation is any inherited change in a trait of an organism that makes the individual more suited to its environment and more successful at surviving and reproducing. Beneficial adaptations become more prevalent in a population through natural selection.
Natural selection refers to a process originally described by Charles Darwin in which organisms better adapted to their environment are “selected” by nature for survival and pass on their beneficial traits to their offspring. It is considered one of the main driving forces of evolution. Natural selection causes the dominant features in a population of a species to change in small ways over many generations by acting on genetic variation within the population. Selective pressures (factors in the environment that affect chances of survival and successful reproduction) cause beneficial traits to become more prevalent in the population, whereas less beneficial traits become rare or are lost altogether.
Although all the organisms in a species usually share all the same genes, many genes can have slightly different DNA sequences in different individuals, resulting in differences in their traits. These various forms of the same gene are called alleles. In sexual organisms, each individual has two copies of most genes, one inherited from the mother and one from the father. These two copies might represent the same or different alleles. The specific combination of two alleles that an organism inherits from its parents is the organism’s genotype, and it affects how hereditary traits are expressed. Different combinations of alleles in a population lead to variation in the expression of a given trait within the population. For some genes, many different alleles can exist in the population’s gene pool.
The changes that make natural selection possible happen at the level of DNA and genes. Changes in genes are called mutations and are one way of introducing new alleles into a population. Mutations can be introduced into an organism’s genome by random errors in DNA replication or repair, or by damage caused by chemicals or radiation. Most of the time, mutations are either harmful or neutral. On rare occasions, a mutation is beneficial and leads to a trait that increases the organism’s fitness, its ability to survive and reproduce. Beneficial mutations become more prevalent in successive generations by natural selection, and they eventually spread throughout the population.
Individuals with a mutation that increases their fitness (like a longer thinner beak instead of a short fat one) are more likely to survive and pass on their genes (and the beneficial traits the genes control) to offspring, which increases the prevalence of the variant allele in the population over time. Over long periods of time, an allele may become fixed in a species, so all the members of the species have the trait that provides the beneficial adaptation.
Ahh, this is enlightening! I did not know that this was how it happened. Thank you. I feel stupid but at least I’ve learned something. But is this referred to as “evolution”? What is the term for this process. (Edit: I just read Christy’s post above so assume it is called “natural selection”?) Because this, to me, seems very, very different to the process of, say, going from a fin to a foot. The beak already existed, the bigger or smaller beaks bred, and passed on their traits to their offspring, the others died out, makes sense! But you can’t “breed in” an non-exsistent trait that doesn’t exist surely? I mean, I picture a fish in water and it starts to flop around on the land, and it breeds with another ground-flapping fish, but they both have fins, and the baby fish has fins? No? Evolution can’t “design” a foot? I get that if the fish was a big fish, or a brown fish, or a fish with long fins, that would be passed on to it’s offspring, and maybe over time it’s fins might get longer and longer, or it might get browner, or whatever.
Also, do the (presumably) millions of millions or more of species from amoeba to man exist in the fossil record? Is the age of the earth enough time to get from there to here?
Sorry if my questions are tedious, feel free not to reply if so lol.
I don’t know a huge amount about it but I found this video interesting: https://www.youtube.com/watch?v=VLlJXn0XOFg
And yes, he uses the mousetrap!
If there are problems with this idea maybe you or others can point them out. It seems logical to me, considering how incredibly complex even the smallest structures in a living thing are.
Thanks a lot for taking the time to reply in detail, I appreciate it!
Ok, so in my mind, based on the things I’m reading here in this thread there are at least two different processes: natural selection and random? mutation, and maybe other processes.
But these two processes seem very different. My post above to ‘jpm’ kind of explains my confusion there.
I now understand natural selection, it makes a lot of sense, and obviously it is a fact, it happens. But to me, going from a bird with a bigger beak because the birds with bigger beaks bred seems a lot different to getting from a trilobyte to a human.
Gah, I know too little and have too many questions. Maybe book recommendations would be good?
Christy do you accept human evolution as most atheistic scientists do, just with the difference being that God started the ball rolling by “planting” the first living thing on earth, or how do you view this whole thing?
The reason I’m trying to understand all this is because I want to reconcile it with my faith in a coherent, logical way - I don’t want to shut the walls of my mind to scientific truth just because it is hard to reconcile it with the Bible. But I also don’t want to end up having a crisis of faith, because I could see that happening if I accept a certain view of evolution.
Something I find impossible to reconcile is the Biblical account of Adam and Eve, their creation and fall, with evolution as we commonly hear it.
I’d be interested in your thoughts.
I think Dennis Venema’s series here at Biologos is excellent, also its free!
You can look at them as two different processes but they work together.
Natural Selection is just short hand for the results of reproductive success.
Mutations are what can create differences between organisms.
So the way in which they work together is that a mutation can give an organism a reproductive advantage increasing its reproductive success. (Reproductive advantage can look different depending on the kind of advantage gained).
I will use an example of human evolution to try and illustrate this.
Humans would become lactose intolerant after a certain age. What happens is this, when humans are born they produce an enzyme called Lactase which breaks down milk sugar for digestion. At a certain age most humans would stop producing Lactase and so were no longer to make use of milk as a food source, today we call people who stop producing lactase and cant digest milk when they get older lactose intolerant. For a long time there was no need for humans to digest milk when they were older, most human populations would rely on food sources and strategies that weren’t dependent on milk.
When some human populations began livestock domestication this made milk a viable possible food source. What happened in these populations is that mutation occurred which allowed some people to be able to digest milk into adulthood, this ability is referred to as Lactase Persistence. People with this mutation were able to take advantage of milk from domesticated livestock as a food source. What happened as a result of this is that this gave people in these populations a reproductive advantage (perhaps they were more likely to live to reproductive age, or they were able to grow up stronger and made more suitable mate choices, etc.) So what happens is that as time goes on this mutation is able to spread through population because of the reproductive success of those who have it.
This is an example how mutation and natural selection work together to produce a change in an organism (mutation) that gives that organism a reproductive advantage resulting in that change being spread through a population over time.
I had a similar problem with evolution at first. How is it possible to get something new? The answer is mutations. Once you understand the different types of mutations that can occur and how they can affect an organism it really isn’t too hard to understand that going from fin to foot is a matter of mutations affecting the fin that alter its structure to make it more and more foot like over time.
I think C. John Collins’s book Reading Genesis Well is great. I don’t agree in every detail with Collins, but I think he his approach is easier to get a handle on for people with a more literalistic understanding of Adam and Eve etc.
Here is an article describing different way people have tried to handle the issue of Adam and Eve
The Fossil Record accords extremely well with evolutionary theory here is another Biologos article that you can use to start thinking about fossils.
Finally I would point to this article by Dennis Venema where he puts together different pieces of evidence in consideration of whale evolution,
Natural selection is the process. It isn’t random, it is a response to selective pressures. Random mutations provide the genetic variation that natural selection works on. Mutations can add genetic material through gene duplication (where a gene gets copied twice by mistake). There are other processes that contribute to evolution like neutral drift, but they aren’t important to understand at the moment. And yes, natural selection can only work on the genetic variation that is available in the population.
Yes. By the theory of evolution every offspring is always the same species as its parents. Its only looking back at whole populations over long periods of time that you can draw lines. When one species diverges from another, it’s not a single moment because a new species was born. Part of a population gets separated in some way from the ancestor population, either by geography or ecological niche. For example in a population of birds, maybe the birds born with longer beaks spend more time eating insects because their beaks aren’t as effective as the fat-beaked birds for cracking seeds, but they can easily pick bugs out of tree bark that the fat-beaked birds can’t reach. So over time, it happens that the thin beaked birds mostly stay in the trees where the bugs are, and the fat-beaked birds stay on the ground where the hard to crack seeds are. The thin-beaked birds become even more prevalent in the trees and the fat-beaked birds on the ground until they stop mixing to mate. Over many generations the two populations would become reproductively isolated (either unable or unwilling to mate with each other) and that would signify that the two populations have evolved into a different species. The same thing could happen if a part of the ancestor population got blown to a different island in a storm and were geographically isolated. They would adapt to their new niche by natural selection until they could no longer reproduce with the descendants of their ancestors who stayed in the original place.
True. But all tetrapods (four-limbed creatures) share limb-creating genes and structures with lobe-finned fish. Genes that led to one trait and function in fish were appropriated for new traits and functions. It sounds crazy but it is actually well-understood and there are piles of evidence in fossil that can then be verified at the genetic level. That’s why we have so many “poorly-designed” but amazingly functional traits and why we have vestiges of our evolutionary past in our biology. The reason we get hiccups is genetically related to a nerve impulse that controls breathing both water and air in tadpoles, for example. Common descent provides an incredibly effective explanatory framework for countless observations about how we develop and why different functions work the way they do. I just got done reading Your Inner Fish to my son. It is a really interesting look at evidence for shared ancestry.
Not every species exists in the fossil record because fossilization is rare and some kinds of bodies (bony or shell) are much more likely to become fossilized. But many, many transitional species do exist in the fossil record. And the amazing thing is that evolutionary theory is highly predictive. The people who discovered Tiktaalik, a major transitional fossil between fish and tetrapods, predicted exactly where in the Arctic they would need to look to find it based on which fossils had been found in which rocks in other places in the world.
The earth is really old. There is enough time and we can calculate how long it took to get from a given here to there using rocks and fossils.
Yes, I think common descent is a well-documented scientific fact. I think we tend to categorize things as natural (things science can explain) and supernatural (miracles only God can do), but I think reality is actually an integrated whole that can’t be separated like that. I think God is involved in sustaining, providing for, and continuously creating all aspects of the natural world all the time. I think he does it in ways that can be described with reference to natural, scientific laws and processes, but that doesn’t mean those descriptions capture all of reality. Science can only describe the natural world, it can’t study God’s presence or action in it. I don’t see the scientific description of evolution as any different than scientific descriptions of anything else, like weather or planetary movement. Science only speaks to part of reality. I can scientifically describe how I got pregnant with my children, but that would only describe part of the whole reality of having a family with my husband and being a mother to my children. Love and commitment and the ties that bond humans together go well beyond the science of gametes meeting and forming a new organism. Similarly, I see evolution as one kind of description that provides part of the picture of reality. It definitely doesn’t answer any of my big existential questions.
Adam and Eve is a big question. I might have to get back to that. It basically comes down to how you read the Bible, which is a huge topic of its own.
By word of encouragement, I spent about five years “figuring out” how my faith and science could get along. No one does it in a week, so don’t feel like you have to work stuff out before some metaphorical buzzer goes off.
I would suggest some books that discuss Genesis and how it doesn’t conflict with modern science. Then you’ll be more free to explore science without risking your faith. It’s pretty common to be taught a false dichotomy - that either the Bible is true or evolution is true. Both can be true, as many here believe, including myself.
Books I’d recommend:
John Walton’s The Lost World of… series (Genesis One, Adam and Eve, the Flood)
Gregg Davidson’s Friend of Science, Friend of Faith
Carol Hill’s A Worldview Approach to Science and Scripture
All of these come from a viewpoint of a historical Adam and Eve and that the Bible is inerrant.
The fish will try its hardest to get up on land, and either it makes it or not. The fish is born with the only genome it will ever have, so its not as if the fish can picture having legs and suddenly grow legs. The fish also has no control over the mutations that are passed on to its offspring.
How this all works is evolution through natural selection. Mutations that provide new adaptations that allow for moving about on land are selected for in populations where that behavior is advantageous. Something like this happened in the mudskipper’s history:
Except he is wrong. He says “every part is essential” which is only true if you need a mouse trap. You can take away the bar, reduce the number of parts to 4, and still have a fully functional paper clip. Behe likes to talk about the complex cells because that generates a wow factor, but does he ever mention the cells that are not as complex? Researches are actually working on building a minimum cell. But life probably didn’t start out as a cell. There could be chemical systems that were the precursor to the cell. So even a cell is not irreducibly complex.
Friend @cristero, if evoluti0on is a blind, unthinking process then that statement is false. Dawkins would say that evolution is a blind, unthinking process which does create our ecosystem and humanity and that is why he does not believe in God.
Supporters of ID would say that because life is intelligently designed it has meaning and purpose, so it cannot be the product of evolution, which is blind and unthinking, that is without meaning and purpose.
I would say that Evolutionary Creationists would agree with ID in saying that life has meaning and purpose, but disagree in that they say that biology was formed by evolution because evolution is not without meaning and purpose. Evolution was created by God Who gave it meaning and purpose. .
The problem here is Western Dualism, Nature vs God, Physics vs Metaphysics. If the universe or nature is purely physical or natural as Dawkins says, then the universe must have no meaning and purpose, which only comes from God, the Supernatural.
ID in its desire to accept the scientific frameworks has bought into this dualism. It says that evidence that God created humanity must come from some supernatural intervention in the evolution of life
We need another option. Darwin, Dawkins, and other evolutionists have depicted “natural selection” as blind and unthinking. ID agrees with Dawkins that “natural selection” is blind and unthinking, but then it says that a blind and unthinking force could not create humanity which is meaningful and has purpose, and ID in this respect is correct.
EC says that God the Creator is working through natural selection, so it is not blind and unthinking, because God is not blind and unthinking. All three of these views are ideological, because they are based on ideological assumptions without supporting evidence.
The third option is based on supporting evidence and I call it ecological evolution. Ecological evolution demonstrates clearly how Natural Selection really works. It says that most of the dinosaurs became extinct because of climate change, which destroyed their habitat, except for the bird dinosaurs who were able to adapt to the new climate and ecology. God guides evolution through ecology because God created the earth which has changed over the past 13 billion years to become a home for you and me.
I can’t read Darwin’s or Dawkins’ minds, but I do think those conclusions are a bit more nuanced. Science could never say that evolutionary mechanisms are blind and unthinking in a metaphysical sense. At best, science can only say that evolutionary mechanisms are statistically indistinguishable from blind mechanisms. There is still room for the mystery of theology and philosophy.
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