Evolution: The Scientific Evidence

[ewmayer]

Originally Posted by Xyzzy

We were just going to mail you the books to read and then you could mail them back.

That works for us - media mail is pretty cheap.

We're not sure it is wise to send pharmaceuticals by mail, without a prescription, so you are on your own for that stuff.

Not pharmaceuticals, "vitamins". The kind baseball's Mark MgWire and Barry Bonds take to help them get big and strong.

[Xyzzy]

Not pharmaceuticals, "vitamins". The kind baseball's Mark MgWire and Barry Bonds take to help them get big and strong.

I thought that was flax seed oil?

[T.Rex]

Originally Posted by cheesehead

... which can work on either side.

Sure. But, since creationism theory has less constraints/rules than evolutionism theory, it is easier for creationism advocates to build pleasant/attractive explanations !

... or like accepting evolution only because one has not heard the other side. So that, too, can work both ways.

Right.

Sorry ... I was only outlining, but you're right. AFAIK creationism is very much a USA phenomenon, and I don't know any details of its manifestations elsewhere, so I'll have to refer to US-specific events and structures, but I'll try to remember to explain for others.

Creationism seems also to be a problem with the muslim religion. These people too are reading a book that does not authorize the world to change. Or, probably, they are using the sentences in the surats that can help them, forgetting the surats that say reasonnable things.

That would be a welcome change from finding my own nation's politics to be alarming. :-)

I did not say that our politics are not alarming. I meant to say that many French politicians are completely crazy, especially those belonging to the Socialist party (PS), or -worse- to the Communist party (PCF), or -even worse- to some revolutionary party (LCR, LO). These guys simply want to apply in France the wonderful ideas that had such a wonderfull success in Russia after 1917 (seems that 90 years after, they haven't still been able to rebuild all that they have destroyed ...). These guys are so crazy that they believe that money falls from the sky instead of being the result of the work of all the people of a Nation. Since 1981 (Mitterrand), I feel ashamed of being French ... "Mai 68" spirit is still there, preventing French people to see and face the reality. As an example, our Politicians still talk about France as if it is still a great country. We WERE a great country. Now we only are the best country in the world to visit !
T.

[S485122]

Originally Posted by T.Rex

I meant to say that many French politicians are completely crazy, especially those belonging to the Socialist party (PS), or -worse- to the Communist party (PCF), or -even worse- to some revolutionary party (LCR, LO). These guys simply want to apply in France the wonderful ideas that had such a wonderfull success in Russia after 1917 (seems that 90 years after, they haven't still been able to rebuild all that they have destroyed ...)

I have to disagree there :
- The only socialism in the PS is in its name. Their economic politics are libertarian, their opinions on security are the same as that from the right wing parties (remember Vaillant defending the LSQ "law about the everyday security".)
- the only thing communist in the PC is once more in its name, it became a (not very) social democratic party.
- there are differences between the so-called revolutionary parties:
- LO is a marxist-leninist party advocating the dictature of the party, they have indeed learned nothing of history. "Don't let facts spoil your opinion".
- LCR doesn't know where to go, they try to flirt with the anarchists and the social democrats at the same time.
- You forgot the PT (party of the workers.) They are even worse than LO, their organisation is almost military.

Originally Posted by T.Rex

Since 1981 (Mitterrand), I feel ashamed of being French ... "

Funny, since Mitterand did only one thing that could be considered progressive : he abolished the death penalty. For everything else he had, especially when the government was "socialist" a right wing policy, privatising more than the right wing parties, enabling legislation detrimental to the civil rights... No big difference with the Chirac era there.

Originally Posted by T.Rex

Mai 68" spirit is still there, preventing French people to see and face the reality. As an example, our Politicians still talk about France as if it is still a great country.

May 68 had nothing to do with the idea that France was a big player on the international scene, it was a revolt against the sclerosis of the society, a similar movement was seen in many parts of the world more or less at the same time, from the USA to Czechoslovakia. It had certainly nothing to do with the PS or the PC. The later especially was adamant that the whole movement should be canalised and was instrumental in stopping it.

However, all this has little to do with Evolutionism versus Creationism.

Jacob

[Zeta-Flux]

I have a few questions about evolution I thought some of you might be able to answer. I asked cheesehead what predictive power the notion of "natural selection" has. His reply are the bullet points under point 3 at the link: http://www.talkorigins.org/indexcc/CA/CA210.html

The first bullet is: Darwin predicted, based on homologies with African apes, that human ancestors arose in Africa. That prediction has been supported by fossil and genetic evidence (Ingman et al. 2000).

Note this theory isn't completely settled, as scientists seem to have found older ancestors of humans in asia.
See: http://news.nationalgeographic.com/n...migration.html
But irregardless of how solid one feels the evidence is that humans came from Africa or Asia, the point seems to be the following: Evolution (but not necessarily natural selection) predicts that fossil ancestors of animals with similar homologies should be located at similar places on the earth. My question involves the following: How are bones decided to be from ancestors of humans (and not apes) except by homology? If there is no other way, then homology itself cannot be used except as a predictor that homologically similar bones will be found where homologically similar animals are still present.

Does this make sense? It may very well be that these bones in Africa are our descendants. It also may very well be they are just homologically similar (just as apes are). What methodology is used by scientists to discern the difference? Thanks!

My second question involves the entire bullet list. Is it just me, or do none of the bullet points expressly answer my question about natural selection? It is true they address the issue of evolution and common ancestry. It just doesn't address the issue of natural selection being the means of evolution. (I am not implying it isn't. I am just having trouble seeing any predictive power [or testability] from the idea that nature selects which species *evolve*. It is clear, in an obvious way that axiomatically ''nature'' selects which beings survive to reproduce.)

[jinydu]

You could try reading the book "Mathematical Models of Social Evolution: A Guide for the Perplexed" by McElreath and Boyd. I was very impressed by the first and second chapter; they demonstrated models of evolution that were mathematically quite rigorous. To get access, try emailing McElreath at rmcelreath@gmail.com.

It's important to note that to predict the future evolution of a particular species, lots of details about that particular species are required. The statement of natural selection is just the beginning. One must then go on to compute the fitness of each genotype, then solve a difference equation or differential equation.

Also, my impression is that when studying the past evolution of currently living species, the strongest and most precise evidence comes from DNA analysis. Let's face it, fossils are rare.

[cheesehead]

Originally Posted by Zeta-Flux

I asked cheesehead what predictive power the notion of "natural selection" has.

No, you asked (with my emphasis added), "What predictive power does the theory bring to bear?"

Quoting from http://mersenneforum.org/showpost.ph...9&postcount=14:

Originally Posted by Zeta-Flux

In what ways, as you understand it, is natural selection not random? What predictive power does the theory bring to bear?

You left it to me to interpret "the theory", and I thought you were referring to the theory of evolution. I happened to be in a hurry, and did not take time to contemplate alternate interpretations of "the theory".

His reply are the bullet points under point 3 at the link: http://www.talkorigins.org/indexcc/CA/CA210.html

< snip >

Note this theory isn't completely settled, as scientists seem to have found older ancestors of humans in asia.

Also note that:

(A) Creationists are fond of quoting statements by Charles Darwin that have been later shown to be incomplete, false, or otherwise imperfect. (This is just one example of the fondness for authoritarian figures among creationists and others holding the "strict father" worldview described by George Lakoff in Moral Politics.) But science does not depend on authority figures to proclaim truth. Any scientist, no matter how prominent, may have his/her statements/theories overthrown or shown not to be entirely true on the basis of later discoveries or reasoning. Darwin's importance is in the general theory he proposed, not in whether his individual statements are incorruptible.

(B) The statement, "Darwin predicted, based on homologies with African apes, that human ancestors arose in Africa", does not say that Darwin predicted that no human ancestors would be found outside Africa, or that the theory was settled. So your bringing-in of the non-African ancestors does not invalidate what Darwin predicted. Nor does the not-completely-settled aspect contradict what Darwin predicted.

My second question involves the entire bullet list. Is it just me, or do none of the bullet points expressly answer my question about natural selection?

I chose to link to that bulleted list on the basis of my (mistaken) interpretation of "the theory", as described above.

I am just having trouble seeing any predictive power [or testability] from the idea that nature selects which species *evolve*.

Natural selection is about which individuals survive and reproduce, not which species evolve.

The theory about which species evolve is the whole theory of evolution, not just the natural selection portion.

So, "trouble seeing any predictive power [or testability] from the idea that nature selects which species *evolve*" arises from mistaking the relative roles of natural selection and evolution.

[Zeta-Flux]

Originally Posted by cheesehead

Natural selection is about which individuals survive and reproduce, not which species evolve.

Okay. Then this goes back to my original question (which you now do not misunderstand). In what ways is natural selection not random?

[ewmayer]

Originally Posted by Zeta-Flux

In what ways is natural selection not random?

It is (at least fo far as we know) random with respect to types of genetic mutations that occur and arise all the time among all living species, viewed at large. I say "at large" because at the level of the individual, it may happen that e.g. a specific inherited mutation might result in decidedly non-random mutations, for instance the well-know expanding trinucleotide repeats implicated in many heritable genetic disorders.

Where things are decidely non-random on large scales:

1) Selection pressures are a fact of life for all species: These are functions of things like geography, climate, predation pressures, pathogens, etc. As such, they are nonrandom in the sense that are bound to occur and also viewed from the perspective of "given the known environmental pressures...". To deny selection pressures is to deny the very fact of death itself.

2) Response of species to selection pressures: This central tenet of evolutionary theory is at the same time incredibly simple to understand, yet having profound, far-reaching consequences. I've never understood how *anyone* who understands what it is saying could still seriously question that evolution occurs. Given what we know about genetic diversity between and within species and how selection pressures affect individuals and groups and vary with geography and time, how could it *not* occur? Anyway, the profoundly simple statement here can be summed up as, Among any species, those individuals who possess some trait which gives them a better chance to survive and thrive in their local environmental milieu will consequently have a better chance of reproducing and thus passing their genetic traits on to succeeding generations. Given a few thousand generations (to say nothing of millions or even billions) for said selection pressures to exert their effects, some pretty remarkable things can and do happen.

In a nutshell: genetic mutations and selection pressures may be more or less random, but their general effects over time on species are decidedly not random. I say "general" because although we may not be able to predict with any certainty in what precise form an adaptation to a particular environmental niche may take, but we do know with certainty (just as we know with certainty that death and reproduction occur) that such adaptation, due to differential survival and reproductive success in the face of environmental pressures, does occur.

[Zeta-Flux]

Originally Posted by ewmayer

1) Selection pressures are a fact of life for all species: These are functions of things like geography, climate, predation pressures, pathogens, etc. As such, they are nonrandom in the sense that are bound to occur and also viewed from the perspective of "given the known environmental pressures...". To deny selection pressures is to deny the very fact of death itself.

I think I understand. For example, we might give a very low probability to meteorite encounters. Other selection pressures would have higher probabilities like human encroachment on habitats; or predator prey models. Using all this information, we could make at least short term guesses on what will happen; and maybe a few long term ones too.

On the other hand, there are seemingly random pressures too. A virus mutates and kills a large population (for example). We might be able to predict with some degree of accuracy that there will be epidemics, but we cannot (currently) predict how they will affect the genetic makeup of the population; save that those who are less prone to get sick will survive.

2) Response of species to selection pressures: This central tenet of evolutionary theory is at the same time incredibly simple to understand, yet having profound, far-reaching consequences. I've never understood how *anyone* who understands what it is saying could still seriously question that evolution occurs. Given what we know about genetic diversity between and within species and how selection pressures affect individuals and groups and vary with geography and time, how could it *not* occur? Anyway, the profoundly simple statement here can be summed up as, Among any species, those individuals who possess some trait which gives them a better chance to survive and thrive in their local environmental milieu will consequently have a better chance of reproducing and thus passing their genetic traits on to succeeding generations. Given a few thousand generations (to say nothing of millions or even billions) for said selection pressures to exert their effects, some pretty remarkable things can and do happen.

I think I understand what you are saying here. The issue I have (with regards to randomness) is in us humans determining (beforehand), via some model, which traits will (on the *long* run) lead to thriving in the local environmental milieu.

In a nutshell: genetic mutations and selection pressures may be more or less random, but their general effects over time on species are decidedly not random. I say "general" because although we may not be able to predict with any certainty in what precise form an adaptation to a particular environmental niche may take, but we do know with certainty (just as we know with certainty that death and reproduction occur) that such adaptation, due to differential survival and reproductive success in the face of environmental pressures, does occur.

Yes. What isn't entirely clear to many is that this is the process which leads to speciation. It might be, and then again some speciation might be (and probably is) the result of "wild" mutations, unusual pressures on a population, or intelligent interference.

[cheesehead]

Originally Posted by Zeta-Flux

Then this goes back to my original question (which you now do not misunderstand)

... nor did I misunderstand it then.

You asked two questions. The first one referred to "natural selection". I responded to it with links that I thought were relevant to the nonrandomness of natural selection. My response began with, "So as not to wander farther off-topic here, I refer you to the second paragraph of http://en.wikipedia.org/wiki/Evolution". That Wikipedia paragraph starts "Natural selection, one of the processes that drives evolution, results ..."

Then I continued my response to your first question with "... or the article http://en.wikipedia.org/wiki/Natural_selection ..." which again refers specifically to natural selection.

It was only your second question in which I interpreted "the theory" to refer to evolution rather than natural selection. :-}

Originally Posted by Zeta-Flux

On the other hand, there are seemingly random pressures too. A virus mutates and kills a large population (for example).

So there are two species whose fitness for survival is affected: the virus, and its host.

In the host, some individuals' resistance (e.g., by antibodies) to the killer virus is a survival-to-reproduce advantage over those individuals not possessing that resistance. (This assumes the surviving hosts retain some reproductive potential. If only those individuals so aged as not to have any remaining reproductive potential before the viral infection survive, then resistance to the virus has no reproductive advantage for the host -- except indirectly, such as the aged individuals' contributing to the reproductive success of their near relatives via transmission of wisdom, etc.)

In the virus, it could work either way. If, as with the Ebola virus, it kills the host so rapidly that infected hosts have little time to spread the virus to other host individuals, that will tend to make epidemics (and, thus, viral reproduction) self-limiting. OTOH, as with cholera (or HIV), the hosts may remain alive long enough to spread (e.g., through bodily wastes or sexual transmission) viral descendents to other host individuals, which tends to prolong reproduction of the mutated virus relative to the nonmutated version.

We might be able to predict with some degree of accuracy that there will be epidemics, but we cannot (currently) predict how they will affect the genetic makeup of the population;

Of course we can. Hosts with resistance conferred by genetically-transmitted properties will tend to have more offspring, so that genetic resistance will spread.

I read about a study that found genetic properties in living people that correlated with whether ancestors lived (and survived) in the parts of Europe most affected by the bubonic plague back in the medieval period.

Sickle-cell anemia is more common in people whose ancestors lived in malaria-prone areas. The sickle-cell condition provides better resistance to malaria than normal blood cells. Sickle-cell anemia is less deadly than malaria.