How does evolution improve a species in time?

Question

bad mutations tend to hide in a population, so they build up over time, increasing the chances that a new organism won't be "fit" (when the mutations can't hide behind the original gene. The probability of this is called genetic load)
So, does mutation-selection, a.k.a Neodarwinism, come up with fitter creatures to replace the old ones? If so, how? If not, why do schools say it does? (It sounds like the evolution the schools teach us.)

Answer 1

Some creationists (such as Henry M. Morris and yourself) have suggested that mutational load would increase over time and thus make populations inviable. However, you ignore the effect of selection acting to weed out deleterious mutations.

Answer 2

The thing about mutations is this, they have to propagate. No breeding, no propagation. Mutations happen every day. Cosmic rays (gamma and x-rays from space, the universe and beyond) interact with your DNA and cause ionization which can change the DNA so that when it replicates, it does so with an error, i.e., a mutation. The only way to propagate this change is if it happens in a reproductive cell, the female egg or the male sperm (for us human types anyway) which will cause a mutation to come forth in the next generation. This mutation can exist in 3 forms, benign, beneficial or detrimental to the survival of the next generation. The color of your eyes is benign, if a cosmic ray causes your eyes to not match anyone else in your family, it will not aid you or burt you in your survival in life. A detrimental mutation will lessen your survival while a beneficial one will increase your liklihood of passing on your genes. Mutation is the randomness in the universe. It MAY be evolution, and then again it may NOT be. There is no proof either way, however, science tends to indicate evolution is POSSIBLE. People who promote intelligent design for where DNA came from always point to something like a car and say, look there, there must have been a designer for that car to exist and therefore there must be a designer for DNA. My argument is this, these people always point to a man-made object, not a living being, as being obvious that there must have been a designer somewhere. This is TRUE for all man-made objects, non-living things, as a man somewhere DID design that thing. However, this does not follow for living things as no man has ever MADE a living thing by design. (I'm skipping over the whole gene splicing thing here, on purpose) So my question is why must there BE an intelligent designer of DNA as the creationist/interrlgent designer proponents say?

A long time ago, I read a science fiction story about teenage joyriding aliens parking on what we call the Earth for a picnic and leaving their garbage behind, and lo and behold, life as we know it came to be several thousands of years later...

We could be the result of some intergalactic trash heap...

Answer 3

Let me try and answer this question with what I know...

Mutation is nothing but a variation from the so-called "normal" genetic pattern of an individual organism.. the "type-species", if you will, though that is not the exact comparision. As rightly pointed out in some other answer, it can be useful, harmful or benign. Traditionally (and THANKFULLY for people like me who are less patient), mutations are studied in bacteria maninly because the phenotypic expression is rapid as the bacterial reproduction time is, generally, a few minutes. So any change in the gene structure (mutation) is seen, generally, as a phenotypic change that can be easily observed.

It is said that there are latent mutations in every organism... waiting for the right opportunity to spring up to the fore and act as the savior of the cells that possess them, in bacteria. And I have seen in my experience that this is true. You can throw anything you want at a bacteria and in many cases, you are likely to end up with mutant bacteria. A case in point is antibiotic resistance (classical examples always help!!). If you treat a culture of bacteria with an antibiotic to which they are normally sensitive, and if you allow for the treated culture to grow, you are going to end up with a culture of antibiotic-resistant bacteria, the mutant population selected from within the population of sensitive cells. The danger is even more when you use sub-lethal concentrations of antibiotics (lower than recommended dosage), or discontinue use of the pills that your doctor prescribes.

Look at it this way... some of us are naturally more tolerant to say, cold conditions, even though we live in the tropics. If a cold wave were to strike the tropics, God forbid but hypothetically, the people naturally tolerant would stand a better chance of suri\viving compared to their counterparts who would perish. The hardier they are the longer they survive. In other words, survival of the fittest. The same thing happens in higher forms of life too. Classical Darwinism... but a new theory... well, not exactly new, at least a decade old, says that life can ADAPT to adverse conditions and survive. Here mutation is not latent, like in classical darwinism, but is INDUCED by the exposure to the agent. This was propoundd by a guy called Cairns, Australian, I think and now is finding acceptance with biologists all over... except for the proponents of the classical darwinists.

But in real life, I assume that there evolution happens due to a combination of the two... latent mutaion getting selected AND induced mutation at work... both select for the fittest among the population.

Hope this answers your question. Cheers

Answer 4

The species changes via evolution when a new trait arises that improves the chances for survival for individuals that carry that trait. One of Darwin's examples was birds - I think it was the different species of finches. Some had large powerful beaks that allowed them to crack tougher shells. This let these birds exploit a food source that other birds couldn't use. When they got more food, they had more chicks, and passed the genes for bigger beaks to them. Gradually they changed enough to become a species that was different from the others.

Another example: There is a moth that lives in England that changed color within 100 years. The peppered moth was originally light colored. It blended in well with the bark and lichens on trees. As the industrial revolution took place in England, the trees gradually became covered with soot. Light colored moths got picked off by the birds. A few dark ones lived longer, and reproduced more. After 100 years, 98% were dark. When pollution laws reduced the amount of soot in the air, the moths were again visible. Now, the dark moths were easier prey, and a change is happening again. Many more of the lighter ones are found in the area.

Evolution works - and can work relatively quickly.

Answer 5

dude - you sub-question is comlicated but the answer is simple. Lets say that there are two people walking down a street and come to an intersection. Both have been at this busy intersection but only one has short and long term memory to remember to look both ways (as mom taught long ago and as the intersection was busy last week) . . . th stronger of the two candidates will survive . . . now multiply that scenario a few billion times and and few million years . . . change the issue - like immune systems, changes in climate, etc . . . wallah . . . thats how evolution naturally occurs. Mutation selection creates different creatures - and that which can survive its surroundings will survive

Answer 6

This sounds like a well-known misunderstanding by creationist Henry M. Morris (and repeated on many creationist web sites) of the concept of genetic load, which was developed by geneticist J.B.S. Haldane. However, I think you put your finger on a point that I think Morris misses (or ignores).

It is indeed true that most mutations are recessive, and therefore partially "hidden" from natural selection. I.e. individuals can carry the gene without expressing its symptoms, and therefore nat. sel. doesn't act on it. In this way "bad" genes can accumulate in the gene pool ... this is the 'genetic load' of the population.

However, as you pointed out, the more the "bad" genes accumulate, the higher the odds of "unfit" individuals being born (offspring ending up with two copies of several of these "bad" recessive genes, and therefore expressing them). But that right there is the reason why genetic load cannot increase indefinitely, but must reach an equilibrium. The bloodlines with a higher number of these hidden "bad" genes get culled by natural selection ... these bloodlines are more likely to have combinations of "bad" genes expressed, and therefore produce fewer offspring in the long run. So the genetic load can't go higher ... it has reached an equilibrium state. If one "bad" gene goes up in frequency, another must go down in frequency to compensate. If a new "bad" gene enters the gene pool and starts to go up in frequency, other "bad" genes will go down in frequency ... and one or two may disappear from the gene pool completely.

In other words, as the number of "bad" genes goes up, the frequency of each in the population goes down. We see this in human medicine ... there are a *lot* of obscure genetic disorders that are found in an incredibly small number of carriers.

The same is not true for "good" genes. Even though these appear more rarely, when they do appear, they are more likely to stay and increase in frequency. Why? Because there is no selective pressure to cull these "good" genes when expressed, but precisely the opposite. Those who display the symptoms of the "good" gene, will displace creatures at the other end of the "fitness curve."

In other words, individuals with "good"-gene packages (the "fittest") tend to displace those with "bad"-gene packages (the "less fit"). Individuals with "bad"-gene packages displace each other. I hope that answers your question.

Answer 7

"Bad mutations" only hide in a population in insignificant numbers, if they didn't, they might become dominant and wipe the less "fit" out. Then that would explain evolution, wouldn't it?

I think you are falling victim to the popular illusion that there needs to be some element of deliberate design for evolution to be successful.

If you see a crack in the concrete that stretches out into the road in a strange shape, and there is a piece of crab-grass growing from the curb that fits the crack perfectly, which do you think is the more logical explanation?

i) The crab-grass was designed to fit the crack.

Or

ii) The crab-grass that grew in directions that got squashed by trucks died off, so over a period of time, it was the grass that "fit" that survived?

Answer 8

A "bad" mutation will tend to die out -- by definition. A "good" mutation will tend to survive -- also by definition. Many mutations have little or no effect on a species' survival; such mutations merely accumulate over time, and are useful at least to the paleobiologists who can use them for dating purposes. It is evident that isolation is useful for driving disparate evolution -- see the differences that have arisen in Australian life that have arisen in the fairly long time that the continent has been isolated from other land masses.

Answer 9

I think that your first premise is the more correct one in actuality. A rule of physics is that things tend to change to disorder rather than order, and if this premise holds true in genetics, most mutations are going to result in some sort of "disorder" in the system, thus in general, weakening or somehow changing the species for the worse under certain circumstances.
Hope that was not too confusing.

Answer 10

i could placed it as; evolution is the effect of the stories a physique of intelligence no count if or not it fairly is a single cellular or someone undergoes. of direction, basically the fittest stay to tell the story interior the nutrition chain whilst all are construction on journey or are in a getting to understand curve. So the ensuing is non-end progression at a some distance better or structures point on a similar time as at a unitary or a decrease point, entities age as they progression in the direction of previous age and come across the top of their existence spans. Having contributed to existence does the soul then replace into component to cosmos or does it start up yet another existence in a various length? Can this be referred to as a rebirth? Does the previous stories of the previous existence have something to do with the recent, or is it a case of beginning yet returned? if so became the previous basically for the strengthen of the extra modern-day generations basically, and no result to the souls after existence (assumption: existence won't be able to be in keeping with a feeble equipment the place death destroys souls too)....