Gaining Insight into Evolution and Natural Selection

[Pythagorean]

These are combat advantages which are undeniably helpful, but I imagine that they're probably not as significant as advantages over constant challenges like disease (immune system) and climate (temperature regulation) and reproductive rate. Also, the ability to build walls around camps to keep predators out or to hide in trees probably went a long way too. Aversion strategies.

 

[Drakkith]

I have a difficult time imagining our ancestors fighting off predators with their hands. The dominant strategy for most prey, at least as far as I know, is to run away as fast as you can, hide in a hole/tree, or scare the predator away. Fighting is almost always a last resort and usually results in becoming a meal.

 

[DaveC426913]

I have a difficult time imagining our ancestors fighting off predators with their hands. The dominant strategy for most prey, at least as far as I know, is to run away as fast as you can, hide in a hole/tree, or scare the predator away. Fighting is almost always a last resort and usually results in becoming a meal.

True. Although mankind has never been very good at adhering to the role and behaviors of prey.

 

[Pythagorean]

I think the biggest advantage of our long arms and hands is tool construction and usage (which also requires cognitive advances that we see glimmers of in birds and other apes and some cetaceans).

 

[Fervent Freyja]

and reproductive rate.

Huh, I bet that the mounting success rate in humans is far higher than for any other animal, it takes minutes for some species to even position their sex organs to begin mating versus mere seconds for humans. I wonder if there are any comparison studies on this? Maybe the largest advantage in bipedalism/having free arms occurs in the ability to mount more quickly and keep the female stationary- was that what you meant?

Having hands on long arms that are free means we have much better reach than a wolf, who must move into within biting range.
Essentially, humans have three "mouths" to attack and defend with, two of which have a reach of several feet.

And you'll survive bites the to arms, if that's all an attacker can get near.

Would you seriously bite an animal? I'd rather run or claw their eyeballs out. Yuck.

 

[Drakkith]

Huh, I bet that the mounting success rate in humans is far higher than for any other animal

I don't think so.

 

[anorlunda]

Mutations sometimes have multiple effects. A trait such as long eyelashes may arise from a mutation that has several other effects with positive/neutral/negative selection effects. For example, resistance to some disease. That makes it impossible to conclusively say if the visible trait (eyelashes) was the primary, secondary, or neutral natural selection consequence of that particular mutation. Because of that, IMO speculations about the natural selection advantages of any visible trait are not helpful when trying to understand evolution. Going back to the OP, that's what he was trying to do, to visualize the logical connection between visible traits and natural selection.

To understand and explain what happened in past evolution to bring us to where we are today would require detailed knowledge of all the biological effects down to the molecular level, plus detailed knowledge of historical events and environments. IMO that sounds like an impossibly difficult thing to do; akin in difficulty to modeling a lump of coal as a quantum system.

To understand how evolution works in principle (including effects, side effects, accidents, drift, and more) I would favor the purely hypothetical software simulations.

 

[Fervent Freyja]

I don't think so.

I'm not talking about getting a date Drakkith!

I'm talking about how awfully hard it is for some animals to get their sex organs into position for penetration. For instance, the captive seahorse has to have an aquarium with enough vertical height in order to even swim into position, that's not even taking into account the energy placed into the 8 hour courtship ritual. The same difficulties still occur in the wild.

Mutations sometimes have multiple effects. A trait such as long eyelashes may arise from a mutation that has several other effects with positive/neutral/negative selection effects. For example, resistance to some disease. That makes it impossible to conclusively say if the visible trait (eyelashes) was the primary, secondary, or neutral natural selection consequence of that particular mutation. Because of that, IMO speculations about the natural selection advantages of any visible trait are not helpful when trying to understand evolution. Going back to the OP, that's what he was trying to do, to visualize the logical connection between visible traits and natural selection.

To understand and explain what happened in past evolution to bring us to where we are today would require detailed knowledge of all the biological effects down to the molecular level, plus detailed knowledge of historical events and environments. IMO that sounds like an impossibly difficult thing to do; akin in difficulty to modeling a lump of coal as a quantum system.

To understand how evolution works in principle (including effects, side effects, accidents, drift, and more) I would favor the purely hypothetical software simulations.

Best answer on here. I think that the misuse and overuse of the term "natural selection" has contributed much to the difficulties that can occur when trying to visualize the mechanisms behind evolution. It is often used as an umbrella term for, "we just really don't know", which causes the process to look too mystical for my liking. I would love to live to see the day that the term is eliminated from textbooks and replaced with more quantified descriptions of evolutionary processes. Like you said though, that's a tall order.

 

[Pythagorean]

Maybe the largest advantage in bipedalism/having free arms occurs in the ability to mount more quickly and keep the female stationary- was that what you meant?

I wasn't thinking so directly, no; I was thinking more that tool use and the intellect to alter immediate environment allowed more time for reproduction as it reduced time spent trying to survive.

 

[DaveC426913]

To understand and explain what happened in past evolution to bring us to where we are today would require detailed knowledge of all the biological effects down to the molecular level, plus detailed knowledge of historical events and environments. IMO that sounds like an impossibly difficult thing to do; akin in difficulty to modeling a lump of coal as a quantum system.

Yup. And this is what I'm trying to grok.

Because nature isn't a simulation. It really is grandly and subtlely causing selected traits to fluorish over zillions of years and zillions of critters by acting on individuals, not on populations - or models of populations.

 

[anorlunda]

Anybody who uses grok correctly in a sentence is OK in my book. . I suppose that dates us though @DaveC426913 . That book was from 1961.

 

[256bits]

Anybody who uses grok correctly in a sentence is OK in my book. . I suppose that dates us though @DaveC426913 . That book was from 1961.

"Grok may be the only English word that derives from Martian."

That explains everything!

 

[DaveC426913]

Martian is a dead language. Nobody but professors and authors speak it anymore.

 

[Andy Resnick]

A recent article discussing the 'rate' of evolution/adaptation that is of relevance here:

http://www.nytimes.com/2016/07/24/o...is-happening-faster-than-we-thought.html?_r=0

 

[ebos]

I should probably shaddup but since I have an opinion on most everything, I can't. While reading through the posts 2 things popped up in my head:
1, Epigenetics in regards to digging (or grabbing with jaws of steel and headshaking the 'rat' until it's torn to shreds like my terrier), and
2, Besides regular evolution of animal properties we must also consider the female's evolution of changing her selections of mate.
All I got. I mainly do Anthropology, religion.

 

[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.