Difficulty understanding evolution

[rootone]

Have you heard of Occam's razor?
It's rule of thumb which says the simplest idea is most likely to be right.
https://en.wikipedia.org/wiki/Occam's_razor
When you start introducing intention of some 'thing' to make the Universe and life what it is,
then you have a whole load of explaining to do as to how that 'thing' got to exist in the first place.
.

 

[Drakkith]

So first question is why do they lose their libido, second question is regarding stimulation, to get to a positive stimulation in reproduction is that trial and error? For example those that got a positive stimulation were more likely to reproduce?

For organisms that don't want to mate, the catchall reason would be because of "stress". That stress can be because of shortages of food and water, population pressure, disease, captivity, and countless other reasons.

Because it doesn't exactly feel horrible does it

For some species, mating is extraordinarily painful, stressful, or even fatal. For example, male bed bugs stab the female through the exoskeleton and release their sperm into the female's body, where it is transported through the hemolymph to the ovaries. In some species (such as some mantises), the male is sometimes eaten after mating.

and there are obviously very positive urges that can't have just "been" it must have been an evolutionary trait right?

Yes, but narrowing it down to some specific reason that the trait was selected for is usually very difficult. What may seem like a huge negative, like being eaten after mating, can actually be beneficial to the survival of the organism's genes (a well-fed mate is more likely to survive and pass on your genes than a hungry one).

 

[eltodesukane]

An interesting reference (a bit off topic):
About domesticating foxes by human/natural selection (like wolves were domesticated to become dogs over thousands of years)
"In the 1950s a Soviet geneticist began an experiment in guided evolution. He wanted to show how domestication works"
http://www.bbc.com/earth/story/20160912-a-soviet-scientist-created-the-only-tame-foxes-in-the-world

 

[Adamchiv]

An interesting reference (a bit off topic):
About domesticating foxes by human/natural selection (like wolves were domesticated to become dogs over thousands of years)
"In the 1950s a Soviet geneticist began an experiment in guided evolution. He wanted to show how domestication works"
http://www.bbc.com/earth/story/20160912-a-soviet-scientist-created-the-only-tame-foxes-in-the-world

Thats on topic for me, because I think that domestication over time is further proof of evolution. I wonder how information is preserved and passed down from generation to generation. On a basic level, instinct. I suppose its proof that the brain is a physical organism that works within itself and the soul is a stupid concept. Because everything within us is physical in some form, surely on a quantum level the instinct passed down from generation to generation must be observable in some sense, it must be detectable as some sort of neurological bar code or something

 

[Drakkith]

Instinct doesn't work on the quantum scale. It is the result of the particular way systems of neurological cells are connected to each other in an organism.

 

[BillTre]

Domestication is a very interesting subject. A lot is known about it.

The information determining the instinctive behaviors is genetically encoded within the animal's genome.
This is information in the order of the base pairs in the DNA double helix, as interpreted by the cellular environment in which it resides. Its not a quantum level thing.

That Genetic Information would then direct the development of the nervous system to make those neural connections mentioned by @Drakkith. This is a complex process working through a variety of encoded developmental processes.
Environmental Information: Some of the development would be influenced by general environmental sensory input (for instance to refine the visual map), but that would be refining the genetically determined developmental processes that set-up these refinements.
Culturally Inherited Information (among the domesticated) does not seem to be important since domesticated animals (or plants) don't have to be raised in groups to express their domesticated traits.

 

[Adamchiv]

Domestication is a very interesting subject. A lot is known about it.

The information determining the instinctive behaviors is genetically encoded within the animal's genome.
This is information in the order of the base pairs in the DNA double helix, as interpreted by the cellular environment in which it resides. Its not a quantum level thing.

That Genetic Information would then direct the development of the nervous system to make those neural connections mentioned by @Drakkith. This is a complex process working through a variety of encoded developmental processes.
Environmental Information: Some of the development would be influenced by general environmental sensory input (for instance to refine the visual map), but that would be refining the genetically determined developmental processes that set-up these refinements.
Culturally Inherited Information (among the domesticated) does not seem to be important since domesticated animals (or plants) don't have to be raised in groups to express their domesticated traits.

But if you take an individual memory, its a very complex image or mental video, surely it must be stored in the mind as a type of data? Its in there and can be accessed, its unique too, so as a stored unique thought, surely it must have some sort of a pattern or code etc

*maybe this is for another thread

 

[Adamchiv]

Its ok I've just looked into how memories are stored and I don't think I need to discuss it on this thread and also its going to get off topic.

Can we continue about domestication being passed down, because it is interesting

 

[BillTre]

Instinct is a kind of behavior.
It doesn't have in involve memory.
Most instincts (in lower animals) can be thought of as actions, perhaps in response to a sensory input, in a particular environment.
This can just be built into a nervous system when it develops.

Not all domestication traits are behavioral.
http://www.maizegenetics.net/genetics-of-domestication in corn deal with things like number of seeds, attachment to stem, etc.

 

[Adamchiv]

Instinct is a kind of behavior.
It doesn't have in involve memory.
Most instincts (in lower animals) can be thought of as actions, perhaps in response to a sensory input, in a particular environment.
This can just be built into a nervous system when it develops.

Not all domestication traits are behavioral.
http://www.maizegenetics.net/genetics-of-domestication in corn deal with things like number of seeds, attachment to stem, etc.

But the baby kangaroo climbs up into the pouch when its born, this is literally its first moments. There must be some instinct passed on, it can't be tought

 

[Drakkith]

But the baby kangaroo climbs up into the pouch when its born, this is literally its first moments. There must be some instinct passed on, it can't be tought

That's right. Instinct is stored and passed on in the genetic information of the organism. It is, by definition, complex behavior that doesn't have to be learned. Note that instinct isn't "hard coded" into the genome. There is no gene in sea turtles that says, "Okay, when you're done hatching and you see water, run towards it as fast as you can!" Instead, genes contain information having more to do with protein structure, timing of molecular signals, and regulatory sequences (e.g. promoters, enhancers, and silencers that affect the rate of transcription of that particular gene). The combination of many different genes governs the overall development of the organism and this initial development sets up the neurological and chemical "circuitry" that governs how the organism's instincts function.

Can we continue about domestication being passed down, because it is interesting

Domestication itself isn't something that's passed down. To quote wikipedia, "Domestication is a sustained multi-generational relationship in which one group of organisms assumes a significant degree of influence over the reproduction and care of another group to secure a more predictable supply of resources from that second group."

However, the traits that we usually select for when domesticating animals or plants are indeed passed on to subsequent generations in exactly the same ways that any other trait is passed down. The only difference is that we are doing the selection instead of nature. If you haven't already, take a look at the following article: https://en.wikipedia.org/wiki/Selective_breeding

 

[BillTre]

But the baby kangaroo climbs up into the pouch when its born, this is literally its first moments. There must be some instinct passed on, it can't be tought

Yes it is passed on, genetically.

 

[houlahound]

The silver fox experiment showed interesting traits re domestication. In the op you mentioned atheism and evolution, they are unrelated concepts. Why did you mention them together?

Not all mammals find their way to suckle, puppies that don't die within 24 hours unless hand fed.

I train working dogs, the traits that make them work contradict domestication. Its a balancing act of selective breeding to push traits back or bring them forward. The whole thing is fluid, there is no steady state.

 

[Drakkith]

In the op you mentioned atheism and evolution, they are unrelated concepts. Why did you mention them together?

Just a note for everyone: Let's stick to the topic of evolution, please. I've already had to remove one post that veered off into religious matters. Further off-topic posts may result in a locked thread. I hate to remove posts for this reason, but they're off topic and experience has shown that people tend to get very, very heated when it comes to religious matters, and discussions tend to fly out of control very quickly.

 

[BillTre]

I train working dogs, the traits that make them work contradict domestication.

What is this contradiction you speak of?
Is it a general affect or something specific to the task they are being trained for?

 

[houlahound]

It's a lot of splaining, in a nutshell a dog's survival instincts a what we can exploit for work, too much and the dog is unworkable, too little and the dog is a useless lawn ornament.

Modern society selects for the dull, useless lawn ornament with no sense of survival. Interestingly the demand for working dogs in the agencies is sky rocketing but the pool is almost empty.

Did you see the Whitehouse dogs fail? That right there shows the contradiction in full. Those dogs had no defense drive, no dominance, and failed because of it.

The harder dogs would not have got the job to start with being too offensive but were what was required in that instant.

My current idiot dog would have had to been choked off the guy and would have gone after the handler because he would have perceived the handler was challenging him, too much the other... see the contradiction?

Conversely when the balance is right you get the dog that got Osama with SEAL team 6. Those dogs are rarer than hen's teeth.

 

[stevendaryl]

I confess to not having read this entire thread, so I'm not sure if I'm saying something redundant, but the original poster is making a false assumption about the way that genetics controls the physical form of a creature. (I think the jargon is: how genotype influences phenotype). Random mutations do not lead (usually) to random bumps and appendages. Genes don't specify precisely what goes where on your body. Instead, their control over your body is very indirect--they (mostly? completely?) specify the presence or absence of certain proteins produced by your cells. The impact of these proteins is very indirect. Much of the development of a vertebrate should be thought of in the following way:

• There is a basic plan for a vertebrate: A spine, a head containing a brain, two eyes, and a mouth at one end of that spine, approximate bilateral symmetry, a heart, blood vessels, a stomach, etc.
• Genes mostly just tweak this basic plan. They enlarge some parts, shrink other parts, fuse parts, split one part into two, etc.

So you're not likely to have a mutation to a vertebrate that would make a second head at its knee, or have a third arm growing out of the back of its neck. If a genetic mutation is too extreme, by far, the most likely outcome would be that the creature would fail to live long enough to be born.

 

[Ryan_m_b]

I confess to not having read this entire thread, so I'm not sure if I'm saying something redundant, but the original poster is making a false assumption about the way that genetics controls the physical form of a creature. (I think the jargon is: how genotype influences phenotype). Random mutations do not lead (usually) to random bumps and appendages. Genes don't specify precisely what goes where on your body. Instead, their control over your body is very indirect--they (mostly? completely?) specify the presence or absence of certain proteins produced by your cells. The impact of these proteins is very indirect. Much of the development of a vertebrate should be thought of in the following way:

• There is a basic plan for a vertebrate: A spine, a head containing a brain, two eyes, and a mouth at one end of that spine, approximate bilateral symmetry, a heart, blood vessels, a stomach, etc.
• Genes mostly just tweak this basic plan. They enlarge some parts, shrink other parts, fuse parts, split one part into two, etc.

So you're not likely to have a mutation to a vertebrate that would make a second head at its knee, or have a third arm growing out of the back of its neck. If a genetic mutation is too extreme, by far, the most likely outcome would be that the creature would fail to live long enough to be born.

All generally correct, though mutations can occur that lead to gross physical changes (such as hox gene mutations, though I'm unsure how drastic they were in the wild vs the lab) they tend not to. One of the sticking points the OP had was difficulty keeping in mind that mutations tend to be very minor and evolution happens across long time scales. Anecdotally I've found this a very common confusion amongst non-biologists.

 

[stevendaryl]

All generally correct, though mutations can occur that lead to gross physical changes (such as hox gene mutations, though I'm unsure how drastic they were in the wild vs the lab) they tend not to. One of the sticking points the OP had was difficulty keeping in mind that mutations tend to be very minor and evolution happens across long time scales. Anecdotally I've found this a very common confusion amongst non-biologists.

Certainly, a mutation can result in huge changes, but it's a mistake to assume that there are genes that literally specify every aspect of an organism's body. There isn't a gene for "how many heads do you have", and a gene for "how long is your left pinky" and a gene for "what is the distance between your eyes" and separate genes for the locations of every hair on your head. Instead, a single gene (or sequence of DNA) typically modifies many different aspects of the organism.

 

[Ryan_m_b]

Yup, I am aware of that.

 

[DiracPool]

but I am always concerned it won't talk about the inbetweens that I worry about.

I'm going to cop stevendaryl's plea here and say that I haven't been following the thread even though I was the "first responder." That said, the issue of the "in-between" species or forms is a legitimate concern and the point to be made here is that there are plenty of intermediate forms that are found to be statistically significant. Those stats are low, though, because intermediate forms are an extreme rarity. Why? Because speciation and the genomes that embody them are like trajectories in chaotic attractors. A species is like a limit cycle attractor. It kind of goes round and round in it's own little niche until it is forced out of that niche for one reason or another. Then it (or more accurately the population) undergoes a bifurcation event where you separate the wheat from the chaff. You can call this the transitional or "intermediary" period, as you referred to it. What is the transition? You name it, maybe it's fins to arms, or to wings. Why don't we have transitional forms? Well we do. The problem is that fossilization of forms is an extremely rare event. So, to find evidence of a fossilization of a transitional form is something along the odds of multiplying a derivative by a derivative (or squaring a derivative), in which case we usually just regard it as a negligible value. Even so, we do do find intermediate forms, surprisingly enough. However, they are very rare for the reasons I described.

So the issue shouldn't be, "why don't we find more intermediate forms." the issue should be, "Wow, I can't believe we've found so many intermediate forms."

Another good metaphor to think about when you think about evolution is something else. Think about a bunch of salad bowls. Maybe 64 of them in an 8x8 array. Now think of a marble bouncing around in one of those bowls. Don't move the array. The marble stays in one bowl. Now shake the array slightly. The marble bounces around but still stays in one bowl. Now shake it some more. At some point the exaggerated shaking is going to bounce the marble out of that bowl and into another another bowl. This is a chaotic dynamics description of speciation. Once the marble transitions into the other bowl, or well, we have a speciation event.

But, the important point is that the marble, or more accurately. marbles (plural) can stay in that bowl indefinitley, for years or thousands or millions of years. It takes some kind of dramatic event to shake it up to the point where you can shake the marble from one bowl to the other. But it does happen and that is what we call a speciation event. But, again, as the analogy suggests, it is a very rapid conversion, akin (in geological timescale) to a ball rolling around in a bowl and then suddenly gaining enough energy to leave that bowl and fall into a different bowl. That is the transitionary period and it is very short. So, it's not wonder why there isn't a huge representation of these transitional forms in the fossil record.

 

[gmax137]

Sorry, I hope this isn't de-railing the thread (maybe this question should be the start of a new thread?) I'm going way back to Post #50, where eltodesukane said:

---
The regular use of Caesarean sections is having an impact on human evolution, say scientists.
More mothers now need surgery to deliver a baby due to their narrow pelvis size, according to a study.
Researchers estimate cases where the baby cannot fit down the birth canal have increased from 30 in 1,000 in the 1960s to 36 in 1,000 births today.
Historically, these genes would not have been passed from mother to child as both would have died in labour.
Researchers in Austria say the trend is likely to continue
"Without modern medical intervention such problems often were lethal and this is, from an evolutionary perspective, selection.
"Women with a very narrow pelvis would not have survived birth 100 years ago. They do now and pass on their genes encoding for a narrow pelvis to their daughters."
http://www.bbc.com/news/science-environment-38210837

Where are these narrow-pelvised women coming from, if the millions of years / generations have been selecting for wide pelvises? Is there a steady stream of mutation to unusually narrow pelvises? When we were talking about eye-spots it was noted that the individuals lacking the spots were eaten before reproducing, hence the population becomes spotted. Why hasn't the human population become entirely wide-pelvised?

 

[peety]

I suppose that as medical intervention and surgical technology improves we move towards survival of the less fit but more desired by the more affluent. Just as we have bulldogs with breathing problems we'll have more people with weak hearts and other survival disadvantages.

 

[Ryan_m_b]

No, human women aren't being significantly affected by ceasarians. PZ Myers (prominent blogger and biologist) went over the paper here:
http://freethoughtblogs.com/pharyng...-havent-been-shown-to-change-human-evolution/

 

[Kaura]

Natural selection is a self correcting system more or less
When dealing with large population traits that give even a slightly better chance of survival and reproduction typically emerge
This is why certain things such as random seemingly inconsequential deformities are not often to be passed down on a large scale

 

[grumpup]

One word - Darwin.

i.e. survival of the fittest, but remember the survival takes place in time. What is best at one point in time is not necessarily best at all points in time.

You said "I am and athiest and I believe on [sic?] evolution."

The Greeks thought faith to be assent by the intellect w/o evidence. What is there to believe about evolution that is not evidenced by nature? And I do mean evidenced not proved. Because nothing asserted by science can be "proved", only supported by evidence.

A few years back where I live there was a kerfuffle about stickers in science textbooks. A physics teacher was quoted in the newspaper that "I believe in science." I hold that was sufficient evidence to immediately either terminate his employment or send him for remedial education. He understood neither science nor faith.

 

[houlahound]

Good point, i don't believe in science. I accept the evidence.

 

[Drakkith]

Good point, i don't believe in science. I accept the evidence.

Remember that language is fairly flexible, and even if you're not using a word correctly, the overall idea you're trying to convey is usually intact.

That being said, the phrase "I believe in science" is perfectly valid. See the definitions of "believe" here: http://www.dictionary.com/browse/believe?s=t

 

[houlahound]

I don't believe the world exists. I don't believe the internet exists... said while posting to it.

That's how I use the word "believe". Yes it seems problematic as a general word.

 

[zinq]

"But surely some mutations that wernt asthetically pleasing or slightly non uniform wernt always a problem for survival."

They may not seem to have been a problem for survival. But besides the basic aspects of survival like getting air, water, and food, there is also the issue of whether one's genes will survive to the next generation. For better or worse, symmetry is extremely important with (at least) humans' mate selection. Many other animals also have very stringent standards for mate selection.

I don't want to pretend that evolution is a simple, obvious thing to me; it certainly is not. I'm usually not surprised about the traits that are bred *out* by natural selection. What amazes me is that there are enough *positive* mutations to create astonishingly specific and complicated structures (including mental ones) like Beethoven's ability to compose ineffably beautiful classical music — or even a parrot's brilliant flash of spectral colors.

But I chalk up my amazement at these things to simply not having an intuition that is equal to the task of imagining what is possible to occur in billions of years.

 

[houlahound]

I have seen wild boar mutate after 10 years of drought.

I have seen pet cats mutate into an unrecognisable feral species with colours you will not find in the domestic world.

The structure of skeletons, teeth, colour, scent... I have personally observed them mutate in my own life time.

 

[Drakkith]

I have seen wild boar mutate after 10 years of drought.

I have seen pet cats mutate into an unrecognisable feral species with colours you will not find in the domestic world.

The structure of skeletons, teeth, colour, scent... I have personally observed them mutate in my own life time.

Most of these are unlikely to be the result of mutations. They are probably the result of genetic recombination and gene expression.

 

[houlahound]

Agouti, sable, black brindle cats - where have you seen that in domestic cats??

All our wild cats here are from domestic stock.

 

[Adamchiv]

Just to let everyone know I fully understand the difference between blind assertion and imperical evidence, and that science doesn't really deal in facts, only theories that advance and become a body of evidence. Can I point out I mentioned atheism because I knew some of my questions would seem very phyloslophical and I didnt want to leave the impression that I was a creationist trolling this forum.

For the admin, I know this is becoming unscientific, and hope we can get back on topic asap

Can anyone tell me at roughly what point all the main organs became inherant, I know its gradual, but for example did our ancestors (i.e earliest life forms) live a long time without a liver, or kidney etc

 

[houlahound]

this is a physics community granted on a biology sub- forum. Have you considered joining a biology forum with a dedicated evolutionary biologist community.

No offense to the physicists here.