Gaining Insight into Evolution and Natural Selection

[ridahoan]

Just noticed this discussion. Not much to add, other than I appreciate the perspective that evolution via natural selection is mind-boggling, even if one accepts it as least one major player in evolution. We often lose the ability to express this, I think, due to the mindless attacks from creationists. For me, I always have to come back to the basic fact -- evolution expresses continuity with change -- which says almost nothing. How the leopard got its spots, and why any certain trait is advantageous, these are fun and at times important questions, but we do come up against the limitations of our minds that like simple cause and effect mappings, and stories.

 

[Drakkith]

To those who are curious about the thread title:

Grok/ˈɡrɒk/ is a word coined by Robert A. Heinlein for his 1961 science-fiction novel Stranger in a Strange Land. While the Oxford English Dictionary summarizes the meaning of grok as "to understand intuitively or by empathy, to establish rapport with" and "to empathize or communicate sympathetically (with); also, to experience enjoyment",[1] Heinlein's concept is far more nuanced, with critic Ishvan Csicsery-Ronay Jr. observing that "the book's major theme can be seen as an extended definition of the term."

https://en.wikipedia.org/wiki/Grok

 

[TeethWhitener]

Besides regular evolution of animal properties we must also consider the female's evolution of changing her selections of mate.

This is probably the most important thing on this thread that I hadn't seen discussed in detail. It's called sexual selection and it affects the course of evolution in sometimes unpredictable ways (e.g., peacock's tail). So maybe cows find long eyelashes attractive? Humans seem to, even though it provides no discernible survival advantage to us.

 

[TeethWhitener]

Random events like this would balance out in the long-term. Next century, a flashflood wipes out a population of long-eyelashed cattle.

Maybe. Gambler's ruin and all. But keep in mind that genetic drift (what you call random events) disproportionately affects smaller populations. So say you start out with 50 short-eyelashed cows and 50 long eyelashed cows and a random (1 per century, no connection with eyelash length) event wipes out 30 of the 50 short eyelashed ones and 20 of the long eyelashed ones. Over the next century, the total cow population rises 500% with eyelashes exerting no selection pressure. Another random event wipes out another 50 cows, but now the population consists of 100 short eyelashed cows and 150 long eyelashed cows. Even if all 50 of the cows wiped out are long eyelashed, that still only brings the two populations back to even.

EDIT: the point being that seemingly small random events in small subpopulations can propagate for long periods of time.

 

[houlahound]

Terriers are not all Earth dogs and there is no digging gene. Terriers in general have been line bred for extreme prey drive and hunt drive, the latter is prey drive on unseen prey. Some terriers have been bred with small bodies and flat chests to fit in small tunnels. Its their prey drive that sends them underground, they LEARN to dig.

 

[DaveC426913]

I guess what I'm talking about is terriers who have never enocountered another terrier, and were never taught to dig.

Yet they still try to dig. Stupidly - like into couches and hardwood floors.

 

[houlahound]

in fact take any high drive working dog don't give them any work and viola you will have dogs digging holes, chasing their tail until they drop dead, herding children, tearing clothes off the clothes line, compulsive moving, eating your house...all sorts of neurotic destructive behaviour instigated from boredom, it is not breed specific.

I have dealt with literally hundreds of such sad cases.
there is a pathetic fad on now involving a laser and a dog, pet owners think it is really cool and have a great old time with it. they are driving their dog into irrecoverable insanity, just another thing I deal with, I doubt these things are located on a specific gene although higher drive working breeds are more susceptible.

as far as inherited instincts imo dogs only have the following;

1. sex drive

2. food drive

subsets of 1. are survival of species, survival of pack, survival of self; in that order. extreme cases counter to nature would be the game bred pit dog, they would not last long enough in the wild to reproduce themselves, they are a horrific invention of unnatural selection by humans.

subsets of 2. prey, hunt, defence - every usable trait in working dogs comes from these three drives eg herding dogs have truncated prey where the trait to bite and dissect has been selected away from.

the holy grail of working dog breeding would be to locate these traits on genes in the scientific micro sense. I do not think it is possible or even exists unless in some polygenetic complex way too complex to identify, isolate or manipulate directly.

jmo.

 

[Planobilly]

First, I think that terriers dig because they can. Their design gives them that ability. I don't think that they necessarily need to be taught as it is possible for them to learn on their own. The incessant repetition of that behavior could indicate some sort of reward perception either of real use or because they enjoy it. Genetic issues are a likely vector involved in the behavior. Exposure to other terriers digging would likely reinforce the behavior.

I don't think it would be likely possible to know with any degree of certainty why they dig or what the implications of past survival issues related to digging would prove to be even if they could be known.

With all the science available today to try to answer these questions there is insufficient data available about all the conditions of the past that could have caused the behavior. How some animal evolves over the long term has many possible components. Evolution is most likely only part of the answer. We tend to look for some one to one cause and effect relationship to define things and it is seldom that simple. That easily causes most of us to be perplexed!...lol

Why does a Leopard have spots? We can assume because Leopards with spots survived to reproduce. Is that the reason? How does one prove that? Can Leopards survive without spots? Evolution can provide some very good information and guidance but I think there is a lot more to the puzzle.

Stay tuned for the next couple of hundred years...surely we will have better answers to our questions...lol

Billy

 

[DaveC426913]

in fact take any high drive working dog don't give them any work and viola you will have dogs digging holes, chasing their tail until they drop dead, herding children, tearing clothes off the clothes line, compulsive moving, eating your house...all sorts of neurotic destructive behaviour instigated from boredom, it is not breed specific.

Yeah. My wife's former roommate had an undestimulated Border Collie - of all the breeds to need stimulation...

there is a pathetic fad on now involving a laser and a dog, pet owners think it is really cool and have a great old time with it. they are driving their dog into irrecoverable insanity, just another thing I deal with,

I don't doubt you, but I'm curious how it drives them neurotic.

While it's certainly not a substitute for proper mental and physical exercise, surely it's somewhere better than no stimulation? I mean, they exercse their need to hunt and chase, do they not? (I imagine it doesn't help much if they never catch it, but still).

 

[houlahound]

i don't feel comfortable discussing the details (and effects) on a public forum but in effect you are directly causing a self destructive obsessive disorder that the animal gains no satisfaction from, only increasing extreme frustration with no release - it is mental torture, ignorance of that fact is not an not excuse.

there are many more productive ways to stimulate a dog that require little physical effort from the handler or the dog, eg scent games will tire a dog out and satisfy their drives long before chasing a ball will for example.

I feel the need to educate the public when the opportunity arises otherwise what is the point of having experience that others lack.

 

[Laroxe]

I wonder if there is an issue in seeing survival and fitness as being the same, they are related but the important thing in evolution is in passing on the genes in question, survival is only relevant in lasting long enough to achieve this, there are lots of examples of attempts to increase fitness reducing chances of survival. There are lots of things than can potentially induce mutations in the genes and many traits that exist along a continuum. Mutations are usually random chance events some being more common than others but there is then the issue of the animal being able to reproduce, another huge element of luck. To effect things at the population level usually involves the element providing an advantage in a given environment. There have probably been people with a natural resistance to HIV infection for centuries because of a common genetic variant but its only now that we could expect to see an increase in this variant in the population. A selective advantage may have nothing to do with survival it may just make the animal more attractive to the opposite sex.

 

[lavinia]

I clipped and sent the OP's opening post to a biologist friend and asked for any comments. I said that the post seemed skeptical about evolution Here is his response

"
... So, dealing with these issues one at a time...

1) Terrier digging. Assuming that terriers actually dig more than other dogs, then breeding for the trait involves selection on the basis of phenotype, NOT genotype. Whatever makes one dog dig more than the next is selected for positively, while the bad diggers are not allowed to breed. The genetic component of this behavior is not a single gene, but is a phenotype generated through the actions of multiple genes. The genes involved may encode structural proteins that somehow predispose to digging (bigger claws, let’s say), but may also produce regulatory proteins that affect the expression of multiple other genes. Final phenotype, aggressive digging, need not SURVIVE embryonic development. it might, in fact DEPEND on developmental processes in the embryo and fetus.
Subtle traits are thus the result of a complex orchestration of coding gene products, regulatory genes, interactions of cells during development, and events that may affect development after birth - that is, epigenetic factors. That these processes lead to highly complex and subtle traits may be mind boggling to the author here, but the development of a multicellular organism, and the myriad mechanisms that underlie this development, are very complex indeed. In this particular case, one could hypothetically envision selection for a claw structure that the dog finds irritating, with the irritation relieved by digging. That’s not so complex. I rather believe the trait is neurologically based, but my point is that from a genetic standpoint, seemingly complex traits might be simpler than they appear.

2) As for the post on dreaming, I’m not sure what the person is getting at. Obviously the brains of higher mammals are larger and more complex than those of fish, perhaps dinosaurs, or even shrews. That this greater size and complexity is associated with dreaming is simply an observation. Clearly there are some animals whose nervous systems would not seem compatible with dreaming - insects, for example. After all, insects and humans evolved from a common ancestor.

3) Cow tails. First of all, the cow is a domesticated species, and both its breeding and maintenance are not “natural” from the point of view of natural selection. If the ancestral feral cow had a tail or eyelashes that were less efficient at keeping away flies, and if fly bites hampered reproduction, then yes these traits are the product of natural selection. The author should consider the point that if one cow is bitten even a little more often than another because of its inferior tail or eyelashes, it might indeed breed less efficiently. Flies and other insects are vectors for disease, and a sick animal might well breed less successfully. The number crunching element of this post (what exactly is a gajillion, anyway?), seems to suggest that the author believes selective advantages are “all or nothing”. That is, the disadvantaged creature never has offspring, while the one with more fortunate genes always breed successfully. This is not usually the case. Over time, a small advantage in reproduction can go a long way towards evolution of better adapted phenotypes, even if the “inferior” members of the species continue to produce offspring, albeit with less success.

4) Pebbly skin and long legs. Here again, I’m not sure what the author is driving at. A factor in evolution that he/she seems to be underestimating is the importance of speciation. Once a critter has a significant advantage over others of its kind, it will breed much more efficiently with those members of the species that are more similar to itself. These process leads to reproductive separation, and ultimately, isolation from the predecessor. The consequence of this process is speciation, and each new species then “responds” to its selective environment in a new way. Note that the ancestral species might not even become extinct, though extinction is certainly a significant part of evolution. A scenario other than extinction night consist of the ancestral species being left in an ecological niche that favors short-legged, pebbly-skinned critters.

 

[houlahound]

thanks for seeking an insightful response.

in fact in working dogs I believe there has only been one attempt at a micro/gene level study of working traits and genes. the study was on working kelpies and was in part funded by the farm lobby.

one thing I can state is that working traits are not fixed in a line or breed, they can be made more stable by heavy line breeding (within families) but experience has shown that for something like herding instinct the trait can be greatly diminished as to be worthless within 3 generations hence in the real world often brutal testing and culling is performed on every litter. that is reality, that's how it has been done for centuries and precisely what created the various working breeds to begin with. of course these days a market has opened up for show and pet dogs so the culling has been replaced by selling which explains the world-wide diminishment of working traits in dogs.

 

[Bystander]

thanks for seeking an insightful response. ... the culling has been replaced by selling which explains the world-wide diminishment of working traits in dogs.

Ah-hah.

 

[houlahound]

nuff said;

http://www.documentarytube.com/videos/pedigree-dogs-exposed

 

[lavinia]

Continuing a little on the dreaming example. It seems that an evolved structure may have characteristics that were not directly selected for e.g. dreaming in mammalian brains. I asked my biologist friend and he wrote,

"That’s a good question. To answer that particular one we’d have to find the ancestral organism that first dreamed, and then try to figure out if dreaming provided some selective advantage. I think the general principle is correct, though, that structures with features that provide a selective advantage may have what’s called “emergent characteristics” which themselves were not the direct result of selective pressure. "

 

[Ygggdrasil]

Continuing a little on the dreaming example. It seems that an evolved structure may have characteristics that were not directly selected for e.g. dreaming in mammalian brains. I asked my biologist friend and he wrote,

"That’s a good question. To answer that particular one we’d have to find the ancestral organism that first dreamed, and then try to figure out if dreaming provided some selective advantage. I think the general principle is correct, though, that structures with features that provide a selective advantage may have what’s called “emergent characteristics” which themselves were not the direct result of selective pressure."

Stephen Gould and Richard Lewontin wrote a famous paper in the field of evolutionary biology about how traits can arise not as a direct result of adaptive selection, but as a byproduct of natural selection. They referred to such traits as spandrels.

 

[lavinia]

Stephen Gould and Richard Lewontin wrote a famous paper in the field of evolutionary biology about how traits can arise not as a direct result of adaptive selection, but as a byproduct of natural selection. They referred to such traits as spandrels.

Thanks for the link. I would love to read the paper.

 

[Ygggdrasil]

Thanks for the link. I would love to read the paper.

If you can't access the paper from the journal, a free version is available here: http://faculty.washington.edu/lynnhank/GouldLewontin.pdf

 

[houlahound]

Why are people insisting dreaming has to provide a survival advantage, it may just as well be a useless by-product of normal brain function.

 

[DaveC426913]

Thanks lavinia. Great answers. much food for thought.

houlahound. Agreed. I don;t think dreaming is a survival advantage, I think it's emergent too.

What I was trying to get at is that, for all creatures, no matter how separated in the tree of life, their common ancestor (that little shrew, running between the legs of T. rex) would have had that ability, passing its complex, dreaming brain on to all its descendants. Dreaming is ancient indeed.

 

[mfb]

What I was trying to get at is that, for all creatures, no matter how separated in the tree of life, their common ancestor (that little shrew, running between the legs of T. rex) would have had that ability, passing its complex, dreaming brain on to all its descendants. Dreaming is ancient indeed.

Not necessarily, things can evolve in separate branches of life separately. Eyes are a typical example, they evolved many times (estimates are 40-100) independently.

 

[DaveC426913]

Unlike its sister show, Star Trek, which tried to explain the tech and ended coming up with a lot of BS.

Not necessarily, things can evolve in separate branches of life separately. Eyes are a typical example, they evolved many times (estimates are 40-100) independently.

Yes. Convergent evolution.
Though I suspect in this case, it's really common ancestral trait.

 

[Pythagorean]

Yes. Convergent evolution.
Though I suspect in this case, it's really common ancestral trait.

I always wonder about this. For instance, the bill of birds and the platypus can be said to be a case of convergent evolution. But we're really only talking about macroscopic morphology aren't we? Do alpha and beta keratin ultimately come from the same ancestor and thus share the micro-structural morphology that allowed both animals to grow a bill?

 

[BillTre]

Just found this discussion.

Here are some other things to consider:

1)
There is a lot of genetic information in modern animals (including humans):

• 10⁸ to 10¹¹ base pairs (each a choice of 4 possibilities)
• 10-40,000 protein coding genes
• unknown numbers of other non-protein encoding genetic elements

There's lots of inherited information there. This information is available to each cell in each animal (billions in people) to possibly be used independently.

2)
Many (most?) traits are what I would call generative. They are not encoded directly in the genome. They are assembled during collaborative events during development, usually involving many cells using many sources of genetic information. Each of these cells and genetic factors will have some capabilities and dependencies that are different from other kinds of cells or genetic factors. This kind of stuff is somewhat hidden and not easily observed since it is microscopic and chemical in nature, and is often hidden inside developing eggs or a pregnant mother.

The nervous system and the behavior it generates is like this. Single genes can have an effect but they are embedded within the developing system in which they find themselves (the individual animal). The population’s shared genetic resources will affect the success of a novel gene in such a situation. If a gene is successful in one animal out of a population of a million, but the other animals in the population lack the supporting cast it will not workout well for the gene in the long run, until it can frequently encounter the right supporting cast as it makes its way through the succeeding generations into which it gets bred.

3)
Evolution usually deals with large numbers of individuals combined with many repetitions over time (a multiplicative increase in the number of adaptation tests). Weak traits (small adaptive advantage) can be strongly selected (to achieve high frequency in the population) in larger populations over many generations of time. The many repetitions of the selection process (each short generation) can continuously ratchet up a gene’s frequency as it gradually becomes more widespread in a population.

Cow tail/eyelashes could have a small effect on breeding success in a single generation but over many generations (involving small statistical differences in survival/breeding) can lead to a situation where all animals in a species have a particular trait.

Scenario: Perhaps the longer hairs reduce the likelihood of flies infecting the cows with as many parasites as its shorter haired relatives (or draining them of so much blood), which makes them better able to provide for their offspring, who are then more likely to go on and breed.

I think there are examples similar to this in biological aspects of aquacultural engineering where calories in/health vs. growth/reproductive state are studied quantitatively.

Perhaps the individual vs. the population could be thought of as something like wave and particles.
But wait, there’s more: Another way to think about these things is to consider genes and the selection on them as they get their genetic ride through generations of organisms. This is the idea behind the Richard Dawkins’s 1976 Selfish Gene book (https://en.wikipedia.org/wiki/The_Selfish_Gene).

4)
Dogs:
Hunting dog behavior has been lead people to following view:
Wolves (from which dogs are derived) had well developed hunting skills selected for over probably millions of years. People can along and domesticated dogs evolved. As people started to select dogs for traits that the people found useful, the ancestral wolf traits were modified. The genetic modifications most likely to be randomly generated are those that break things (most mutants people collect in mutant screens are the equivalent of throwing a monkey wrench into the biological mechanism). Different strains of hunting dogs are thought to use the wolf’s basic hunting sequence of actions (which might be: find something, chase it, kill it, and eat it) but different different genetic lines of dogs can have breaks inserted into this behavioral sequence at different places, resulting in different behaviors.

Generally, new traits are considered less likely to randomly evolve. However, given enough time and chances and an environment (as well as a supporting cast of other factors) where it would be adaptive, these kinds of things can pop up.

A recent example of such a mutation might be the cause of the evolution of a smoother gait in horse which arose about 1200 years ago in England and/or Iceland (https://www.sciencemag.org/news/201...asier-ride-horses-evolved-more-1000-years-ago).

I don’t know about the dog digging, but it seems to be something that all dogs do (in my experience). I would therefore think it is a primitive feature, not evolved anew in terriers.It maybe magnified however.

 

[ebos]

This is probably the most important thing on this thread that I hadn't seen discussed in detail. It's called sexual selection and it affects the course of evolution in sometimes unpredictable ways (e.g., peacock's tail). So maybe cows find long eyelashes attractive? Humans seem to, even though it provides no discernible survival advantage to us.

It probably does in the long run. However, it appears that at this moment in time, our sexual selection is questionable.