Evolution By Natural Selection

[Laurens]

What do you think would be the best way to convince fence sitters/half arsed creationists that evolution is true?

My idea was to take them through some of the fundamental basics of science, such as coming up with hypotheses, explaining their purpose etc. Then introducing some hypotheses regarding evolution, things such as:

If evolution occurred then we'd expect to find evidence of it in the fossil record
If evolution occurred then we'd expect to find molecular evidence
If evolution occurred then we'd expect to find certain patterns in the distribution of species

etc.

Then they can be taken through the hypotheses and shown that we have actually confirmed them.

 

[Laurens]

Also I found this today:

New Theory Emerges for Where Some Fish Became Four-Limbed Creatures

I thought it might be interesting for some of you

 

[CosmicJoghurt]

Okay, so, even DonExodus says that from evolutionary predictions we would expect to see more complex organisms emerge from genetically simpler organisms over the course of time.

But why? I mean, if the over-complexity of an organism conflicts with its ability to survive, wouldn't simpler organisms survive better? Why couldn't an organism as complex as, say, a rabbit, have come up during the pre-Cambrian period, but then slowly become simpler?


EDIT: I realize I'm being very simplistic here, but I think it's a workable question.

 

[Deleted member 619]

But why?

Acquisition of resources, apart from anything else. Greater complexity will often come with the ability to move into new niches. Not to mention the role of drift in evolution, which has a major part to play in sending new alleles to fixation in finite populations.

I mean, if the over-complexity of an organism conflicts with its ability to survive, wouldn't simpler organisms survive better? Why couldn't an organism as complex as, say, a rabbit, have come up during the pre-Cambrian period, but then slowly become simpler?

Well, there's no barrier to such a course for a species, but you can't actually start with complexity. A complex species could, over the course of generations, become simpler, but even the complex organism would have to have simpler precursors, because at bottom, it's all just chemicals.

Certainly, though, there are instances of complex organisms becoming simpler over time. Ultimately, it's a question of economy. Blind cave fish, for example, live in an environment in which eyes are pretty useless, and additionally they are extremely expensive in resources to make, so these fish have basically lost the eyes possessed by their ancestors, which is a shining example of a species becoming simpler over time.

 

[sturmgewehr]

Well, there's no barrier to such a course for a species, but you can't actually start with complexity. A complex species could, over the course of generations, become simpler, but even the complex organism would have to have simpler precursors, because at bottom, it's all just chemicals.

Certainly, though, there are instances of complex organisms becoming simpler over time. Ultimately, it's a question of economy. Blind cave fish, for example, live in an environment in which eyes are pretty useless, and additionally they are extremely expensive in resources to make, so these fish have basically lost the eyes possessed by their ancestors, which is a shining example of a species becoming simpler over time.

But we haven't seen organisms get simple.

Why would primitive organisms get complex when their simplicity would be the best way to survive ?

wouldn't all chemicals or systems get simple over time but with Evolution we have them getting more complex?

 

[Laurens]

But we haven't seen organisms get simple.

Why would primitive organisms get complex when their simplicity would be the best way to survive ?

wouldn't all chemicals or systems get simple over time but with Evolution we have them getting more complex?

It depends what you mean by 'get simple', but there are examples of organisms losing the use of their eyes when they adapt to dark environments, you could say that loss of eye sight is 'getting simpler'.

Who says simplicity is the best way to survive? Clearly it's not. If it were then all life would be simple phospholipid bags with DNA in them. The fact that complex life exists shows that it is a good way of surviving otherwise it would not have developed. The main advantage I can think of in complexity is that it allows for greater specialisation and for functions to operate more smoothly.

Evolution would make sure that things are not unnecessarily complex insofar as it would weed out complexity that was not advantageous - such as limbs that serve no purpose or get in the way etc.

Organisms get more complex because it is advantageous, and allows them to become more highly specialised. There is no reason to expect that evolution would cause things to get simpler, unless being as simple as possible was a survival advantage.

 

[Deleted member 619]

But we haven't seen organisms get simple.

Except that we have, and I mentioned them above in the bit you quoted. Those blind cave fish are less complex than their ancestors.

Why would primitive organisms get complex when their simplicity would be the best way to survive ?

Who said that simplicity is the best way to survive? Not I, certainly!

In reality, there is no such thing as 'the best way to survive', nor can there be. There are simply survival strategies, and they either work or they don't. What works for one organism may not work for another, or in another environment.

wouldn't all chemicals or systems get simple over time but with Evolution we have them getting more complex?

Well, in a sense, systems do get simpler over time. This is closely bound to a principle known as 'entropy', although that isn't the whole picture. This doesn't necessarily hold for imperfectly reproducing organisms, however, not least because of the input of work in the form of solar energy. Not much of that is really relevant to the topic at hand, though.

In the end, if simplicity confers a survival advantage over complexity, it will be statistically selected for. Where a feature confers no advantage, especially where said feature is resource-hungry, it will be statistically selected against. Bear in mind that the resource cost of making and maintaining eyes, is high and, moreover, the eye openings are a potential source of infection, so in this specific instance, simplicity is selected for, and the cave fish lose their eyes over generations.

That's how evolution via natural selection actually works.

 

[sturmgewehr]

^^

Thank you both of you for your good explanations.

Are there any other species or organisms except those Blind Cave fish who got "more simple" in order to adopt to the environment they living ?

 

[Laurens]

^^

Thank you both of you for your good explanations.

Are there any other species or organisms except those Blind Cave fish who got "more simple" in order to adopt to the environment they living ?

Well there are several species of bird that have lost the ability to fly, you could say that they lost a complex adaptation and therefore are now 'simpler'.

Also our red blood cells lost their nuclei because they weren't necessary for their function - which again could be seen as getting simpler. (If you compare human blood cells, and frog blood cells under a microscope you can see that frog's blood cells have nuclei still).

 

[Inferno]

It really depends what you mean by "simpler". Less DNA? If that's your answer, how about... humans?
Yeah that's right, the CCR5 (CCR5-Δ32) mutation (a deletion of 32 base pairs) are virtually immune to AIDS.
But I wouldn't necessarily say that's "simpler" simply because that human now has MORE protection.

 

[Laurens]

I'd say that the best way to summarize the question of simplicity and complexity in evolution is to say; evolution does not specifically favour simplicity or complexity, rather it favours that which is necessary for survival. In some instances adaptations are lost because they are no longer relied upon for survival, for instance the loss of eye sight and flight that I mentioned earlier - this is because it is costly to maintain unnecessary adaptations. In other instances greatly complex adaptations aid survival such as echolocation in some species of bat, or eyes etc. There's no directionality towards something simple, or complex - adaptive evolution favours that which provides a survival advantage, so it's probably best not to think of evolution in terms of 'getting more complex' or 'getting more simple' but rather getting better adapted to exploiting certain niches.

 

[Deleted member 619]

Are there any other species or organisms except those Blind Cave fish who got "more simple" in order to adopt to the environment they living ?

Parasites provide the clearest example of evolved simplicity.

A good example is malaria, which has lost certain metabolic function due to living in a host capable of carrying out those metabolic functions on its behalf.

Another excellent example is Bacillus subtilis, an extremely useful organism that has been studied since the early-to-mid 19th century, and with a long history of medical, industrial and commercial uses.

Here I quote from Wiki:

B. subtilis is used as a soil inoculant in horticulture and agriculture. B. globigii, a closely related but phylogenetically distinct species[8][9] was used as a biowarfare simulant during Project SHAD (aka Project 112).[10][dead link]

Enzymes produced by B. subtilis and B. licheniformis are widely used as additives in laundry detergents.

Its other uses include:

A strain of B. subtilis formerly known as Bacillus natto is used in the commercial production of the Japanese food natto, as well as the similar Korean food cheonggukjang.
B. subtilis strain QST 713 (marketed as QST 713 or Serenade) has a natural fungicidal activity, and is employed as a biological control agent.
It was popular worldwide before the introduction of consumer antibiotics as an immunostimulatory agent to aid treatment of gastrointestinal and urinary tract diseases. It is still widely used in Western Europe and the Middle East as an alternative medicine
It can convert (decompose) some explosives into harmless compounds of nitrogen, carbon dioxide, and water.
Its surface binding properties play a role in safe radionuclide waste [e.g. thorium (IV) and plutonium (IV)] disposal.
Recombinant strains pBE2C1 and pBE2C1AB were used in production of polyhydroxyalkanoates (PHA), and malt waste can be used as their carbon source for lower cost PHA production.
It is used to produce amylase.
It is used to produce hyaluronic acid,[11] which is useful in the joint-care sector in healthcare.
It may provide some benefit to saffron growers by speeding corm growth and increasing stigma biomass yield.[12]

It should be pointed out that, in fact, it is far more common for an organism to lose a complex trait through mutation than it is to gain one.

 

[Inferno]

It should be pointed out that, in fact, it is far more common for an organism to lose a complex trait through mutation than it is to gain one.

OMIGOD then evolution clearly doesn't work, because we're all DE-VOLVING!!!

 

[Deleted member 619]

Natural selection: Changes in allele frequency due to difference in the fitness of phenotypes. NOT random. (For some reason black horses seem to be better at resisting a certain parasite than brown horses. The black gene has a fitness advantage and will spread through the population.)

A little clarification here, methinks:

Natural selection has to be looked at in two ways to be fully appreciated. The first is from the perspective of the population, at which level the effects of selection are seen. At this level, NS is most definitely not random, where 'random' means specifically 'statistically independent', because it can be probabilistically quantified. At this level, we see that, on average, advantageous alleles are selected for, in the form of being passed on to future generations with a statistical weighting. We also see that, on average, deleterious alleles are selected against, in the form of not being passed on to future generations, again with a statistical weighting.

This goes directly to my objection to the 'survival of the fittest' trope, which should be stated with greater accuracy as 'survival of the sufficiently fit, on average'.

The second way to look at NS is from the perspective of the individual organism, at which level selection actually operates. From this perspective, NS is random. The particular selection pressure that an individual organism will succumb to or indeed evade, is statistically independent, thus random. The organism with an allele that allows it to evade a particular selection pressure has statistical significance, but the means of checking out without issue are many and diverse, and which particular pressure said individual will fall prey to (pardon the pun) can only be treated in the broadest of terms.

 

[Laurens]

I have a question:

I understand that humans evolved to be largely monogamous because of the level of input needed from both parents in educating a child enough to be able to survive on its own as a hunter gatherer (and all the complex skills that goes with it).

Nowadays a child is likely to be able to survive regardless of whether the father has a role in their upbringing or not, due to modern advances in technology and civilization etc. Does this mean that we might expect a return to more polygamous sexual relations in our species, seeing as the original imperative for monogamy has decreased incredibly?

In the past having lots of children would be a disadvantage because the more children you had with different women, the less you could be around to ensure that those children were able to learn the necessary skills for survival, therefore they'd be more likely to die before giving you grandchildren. Nowadays you could have lots of children with lots of different women, and they would not be put at a disadvantage by not having the father round because a) a lot of the survival skills and knowledge once necessary are now not necessary and b) a child is unlikely to be left uncared for even in the absence of both parents in modern society, so your children are likely to raise grandchildren whether you're there or not.

Does that mean with the cost of polygamy reduced it might return in our species?

 

[Inferno]

For this, Laurens, I refer you to a German popular science magazine:
Sà¼ddeutsche Zeitung: Wissen, June 2009, "Mythos Monogamie", p.16-28

Translation: The myth of monogamy

The eight pages explore the statistics of relationships, including marriage, and they pretty much tell you everything: Monogamy as such doesn't work for most people. I also find that there are more marriages and less divorces in times of trouble, so it seems to be an economic thing.
Malcolm Gladwell talks about a marriage-tester called James Murray. Apparently he can predict how well your marriage will last based on snippets of conversation.
Another thing to look at is the "verflixte 7. Jahr", apparently that translates to the "7 year itch". It's basically a German saying about when you're most likely to get divorced or separate if it's a long-term committed relationship and if you pass that hurdle, separation is becoming far less likely. Why is there this big hurdle after seven years? Well I'd suggest because our ancestor's kids (a few million years ago) would leave the nest at that age, be more or less adults. We've increased our life-span by so much that this doesn't hold true any more, but that might be a reason why men will leave women around that time: To find another partner with suitable genes.

All of this suggests one of two things to me:
Our relationships will either become more monogamous, because we're trying really hard to keep a "perfect family" and because we can overcome our basic instincts. This doesn't seem likely to me.
The other possibility is that our relationships will change into something entirely different, from the serial monogamous relationship to either one of the following or something I can't even think of:

1) Polygamy, or rather free love. Sounds like the recipe to a huge orgy, doesn't it?
2) Rapid serial monogamy, moving from one partner to another in a matter of months instead of weeks. This doesn't seem likely to me at all.

3) A relationship like the Mosuo practice it, as described in Geowissen: Väter, issue 46, 18.10.2010
What basically happens here is that not your father raises you, but your uncles. Women go out to bars, hook up with men, have their child in the confines of their family, raise the child without its biological father but rather with the uncles and aunts's and grandmothers and granduncles. They may or may not see the guy again to have a booty-call relationship, but they never have a relationship as we know it.



I don't know how it will turn out, I myself am a huge fan of monogamy, even if it'll probably never be the case that I'll stay with one woman for the rest of my life. It's a shame, but I know the statistics are against me. And even if I don't divorce/separate from her, it's likely that the relationship is shit and we'll just stay together "for the kids". (The biggest sort of bullshit IMO, I grew up with my step-dad on the one side and my step-mom on the other side and look, I turned out O.K! Well, except the baby-eating part but then again everyone has their flaws.







As for your last question: No, polygamy won't return. Just think how much ONE wife/girlfriend costs, with all the dresses and shoes and jewellery and stuff. Do you really think anyone can afford more than one, especially in this crisis? :lol:

 

[Prolescum]

Inferno, thought you might appreciate this.

 

[Inferno]

Inferno, thought you might appreciate this.

I know, that's where I got the translation from. :lol:

 

[Proteus]

I have a question:

I understand that humans evolved to be largely monogamous because of the level of input needed from both parents in educating a child enough to be able to survive on its own as a hunter gatherer (and all the complex skills that goes with it).

Point of clarification humans have evolved towards a form of reproduction kinda towards monogamy (a better term would be pair bonded) but mostly against female infidelity. This has more to do with reducing sperm competition and mate pair bonding than it does with child rearing (it really doesn't take a village, or two parents, to raise a child) although easier offspring rearing could've been minor factor in our evolution.

In the past having lots of children would be a disadvantage because the more children you had with different women, the less you could be around to ensure that those children were able to learn the necessary skills for survival, therefore they'd be more likely to die before giving you grandchildren. Nowadays you could have lots of children with lots of different women, and they would not be put at a disadvantage by not having the father round because a) a lot of the survival skills and knowledge once necessary are now not necessary and b) a child is unlikely to be left uncared for even in the absence of both parents in modern society, so your children are likely to raise grandchildren whether you're there or not.

Depends on how far back you look in the past. We apes are k-selectors but that doesn't mean having lotsa kids is good for other organisms. That's what most small mammals do.

Does that mean with the cost of polygamy reduced it might return in our species?

Maybe it depends on the selective pressures. Given all of the irrational behaviors humans exhibit due to our big brain, plus societal mores and taboos it'd be too hard to say right now.

But the type of cost you're associating with polygamy really doesn't exist in humans or other apes. Another problem is culture. In the past circa prior 200 years ago having a lot of kids would be great for helping out on the family farm, after all a number of them are going to die. Hunter-gather societies on the other hand, which have a culture near the "natural" human state, have a moderate amount of children similar to industrial countries. You're also operating around the assumption that males are required to teach children adult tasks, they aren't. In fact in primitive societies men and women tend to share the same types of tasks with little or no gender barriers to hunting, fishing, clothes manufacture, ext.. Sorry if this seems a bit rambley but does that make sense?

 

[Laurens]

http://www.youtube.com/user/EvolutionDocumentary

The channel went down, but is now back, I'd recommend subbing