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Author Topic:   Bones of Contentions.
JavaMan
Member (Idle past 2319 days)
Posts: 475
From: York, England
Joined: 08-05-2005


Message 145 of 240 (230120)
08-05-2005 11:05 AM
Reply to: Message 141 by John Ponce
08-04-2005 10:48 PM


Summary of your argument
Correct me if I'm wrong, but your argument seems to be as follows:
1. Anthropologists argue that human beings have large brains because large brains confer intelligence and intelligence conferred a selective advantage during evolution;
2. Current scientific understanding is that large brains and intelligence don't necessarily correlate;
3. Therefore the selective advantage of large brains can't be proven, and evolutionary theory therefore can't account for the fact that modern humans have large brains
Would that be a reasonable summary of your argument?
This message has been edited by JavaMan, 08-05-2005 11:14 AM

This message is a reply to:
 Message 141 by John Ponce, posted 08-04-2005 10:48 PM John Ponce has replied

Replies to this message:
 Message 149 by John Ponce, posted 08-06-2005 11:07 AM JavaMan has replied

  
JavaMan
Member (Idle past 2319 days)
Posts: 475
From: York, England
Joined: 08-05-2005


Message 151 of 240 (230460)
08-06-2005 2:24 PM
Reply to: Message 149 by John Ponce
08-06-2005 11:07 AM


Re: Summary of your argument
Thanks for the compliment.
However, the validity of the theory of evolution isn't dependent on anthropologists' theories about how a particular human trait arose. As Crashfrog says, anthropologists have lots of different theories about why humans developed large brain sizes (in fact, sometimes it seems that inventing a new theory is part of the rite of passage for an anthropologist). But even if every one of these different theories proved incorrect that would have no bearing on the theory of evolution itself.

The true mystery of the world is the visible, not the invisible

This message is a reply to:
 Message 149 by John Ponce, posted 08-06-2005 11:07 AM John Ponce has replied

Replies to this message:
 Message 152 by John Ponce, posted 08-06-2005 3:38 PM JavaMan has replied

  
JavaMan
Member (Idle past 2319 days)
Posts: 475
From: York, England
Joined: 08-05-2005


Message 180 of 240 (230763)
08-07-2005 6:33 PM
Reply to: Message 152 by John Ponce
08-06-2005 3:38 PM


Re: Summary of your argument
Would you agree?
No.
I think it would be very surprising if the development of intelligence weren't a factor in increasing hominid brain size.
The controversy you have been alluding to in your previous posts is about making simplistic correlations between brain size and intelligence within extant human populations. Racist and sexist anthropologists in the nineteenth and early twentieth centuries were very fond of saying things like 'women have smaller brains than men, therefore they're less intelligent' or 'Aryans have larger brain sizes than other races, therefore they have superior intelligence'. These ideas have been villified for the last 50 years or so, partly because of their appalling social consequences, and partly because they're scientifically naive.
What makes a human brain different from a chimpanzee brain, for example, is less overall size and more a change in the way the neurons are organized. So a small-brained human, with brain size close to that of a chimpanzee, still has a characteristically human rather than chimpanzee intelligence.
That being said, I don't see how rejecting these simplistic ideas about brain size and intelligence necessarily leads one to the conclusion that there isn't any relationship between brain size and intelligence. In fact, the alternative theory you quoted in one of your posts suggests that the development of expertise may have been a factor in causing the increase in brain size during hominid evolution. Expertise, of course, is an example of intelligent behaviour.
(You may be interested to know that another theory suggests that it was the development of an increasingly sophisticated social life that drove the devlopment of the human brain rather than the evolutionary advantage of greater problem solving skills. This has led to the suggestion that we should think of ourselves as the gossiping ape rather than the intelligent ape.)

The true mystery of the world is the visible, not the invisible

This message is a reply to:
 Message 152 by John Ponce, posted 08-06-2005 3:38 PM John Ponce has replied

Replies to this message:
 Message 181 by John Ponce, posted 08-07-2005 7:48 PM JavaMan has not replied

  
JavaMan
Member (Idle past 2319 days)
Posts: 475
From: York, England
Joined: 08-05-2005


Message 184 of 240 (230893)
08-08-2005 8:02 AM
Reply to: Message 182 by John Ponce
08-07-2005 8:15 PM


Re: More invalid conclusions & unsubstantiated assertions in place of any real argume
Step 2 of your argument is simple to refute.
2. Current scientific evidence finds no correlation between absolute or relative (to body) brain size and intelligence. In fact, the associated energy requirements and birthing difficulties of bigger heads seem to refute the Darwinian human evolutionary theory.
The first claim is not true. Both myself, in Message 180, and RAZD, more elegantly, in Message 146, have argued that, while one can't make simple correlations within a species, there are clear inter-species correlations between brain size and intelligence.
You and I are proof that the second claim is false (unless you were born by Caesarian section of course!).

The true mystery of the world is the visible, not the invisible

This message is a reply to:
 Message 182 by John Ponce, posted 08-07-2005 8:15 PM John Ponce has replied

Replies to this message:
 Message 185 by John Ponce, posted 08-08-2005 1:10 PM JavaMan has replied

  
JavaMan
Member (Idle past 2319 days)
Posts: 475
From: York, England
Joined: 08-05-2005


Message 186 of 240 (231137)
08-08-2005 6:16 PM
Reply to: Message 185 by John Ponce
08-08-2005 1:10 PM


Re: More invalid conclusions & unsubstantiated assertions in place of any real argume
JavaMan, I am having difficulty following your logic. You say (correctly) one can't make simple correlations (of intelligence to brain size) within a species. But that is precisely what Darwinian human evolutionary theory proposes.
In fact, that correlation between mutated brain size and intelligence within a species would be required - many times - over the supposed incremental transitions from critter to man. No?
Let's use a thought experiment.
Think about your extended family and the similarities and differences between them. Some of them are more intelligent than others, but you would probably be unable to find a correlation between brain size and intelligence within your family. Similarly, you probably wouldn't find a correlation between sense of smell and brain size (stay with me - there is a point to this!).
Now let's imagine we put half of your family on island A where there is selective pressure to develop a good sense of smell, and the other half on island B where life is pretty comfortable (a kind of desert island Florida) where there isn't much selective pressure
to develop any particular sense or mental ability.
Now fast forward a hundred thousand years and lets assume that the pressure to develop a strong sense of smell has caused a significant increase in the size of the olfactory bulb (and therefore a significant increase in brain size) in the people on island A. The change in size is very gradual and those who carry genes for the larger olfactory bulb produce more offspring than others, so the gene gets pretty evenly spread across the population, and from generation to generation you never see any significant correlation between brain
size and sense of smell.
So our original family group show no correlation between brain size and sense of smell, our group on island A show no correlation between brain size and sense of smell, and our group on island B, because they haven't changed significantly from our original group, they don't show any correlation either.
But, when we compare individuals from island A with those from island B, they do show a correlation, because island A individuals all have larger brains and stronger sense of smell than those on island B.
Now for island A inhabitants read Homo sapiens, for island B inhabitants read Homo erectus, and for sense of smell read intelligence. Does that explain my argument better?
Lost me again JavaMan! Do you have evidence that alleged groups of hominids had access to safe surgical procedures such as Caesarian sections? Until roughly 70 years ago, the leading cause of death among young women was complications in childbirth. No?
I'm sorry. I was being flippant. What I meant when I said:
You and I are proof that the second claim is false
was that you (if you weren't born by Caesarian section) and I, are proof that the difficulties caused by large head size aren't insurmountable. If they were, we would never have been born. Natural selection just requires survival, it doesn't require that birth be easy.

The true mystery of the world is the visible, not the invisible

This message is a reply to:
 Message 185 by John Ponce, posted 08-08-2005 1:10 PM John Ponce has replied

Replies to this message:
 Message 190 by NosyNed, posted 08-08-2005 7:49 PM JavaMan has replied
 Message 193 by John Ponce, posted 08-08-2005 9:56 PM JavaMan has replied
 Message 201 by John Ponce, posted 08-13-2005 1:14 AM JavaMan has replied

  
JavaMan
Member (Idle past 2319 days)
Posts: 475
From: York, England
Joined: 08-05-2005


Message 194 of 240 (231258)
08-09-2005 7:39 AM
Reply to: Message 190 by NosyNed
08-08-2005 7:49 PM


Re: correlations
I'm afraid I don't follow this.
You say those who carry genes for the larger olfactory bulb produce more offspring (implicitly because they are better at smelling ). Thus there must be some, perhaps very slight, correlation between bulb size and sense of smell and that this is subject to selection.
You're unlikely to see a correlation because the changes are small and there's little variation in the population as a whole - you'll only see a significant correlation where there's substantial variation from the mean.
So, if you do a statistical analysis of brain size/sense of smell in a particular generation on island A most of the results will lie around the mean, and any minor correlations between these two variables will be masked by other variables. If you do a statistical analysis of A islanders and B islanders, however, you will find a large group of individuals from A with brain size/sense of smell well above the mean, and a large group of individuals from island B with brain size/sense of smell well below the mean - thus you will find a statistically significant correlation between brain size and sense of smell.
John is having difficulty understanding how it's possible for there to be no significant correlation between brain size and intelligence within the extant human population, and yet for anthropologists to claim that intelligence was a determining factor in the development of large brain size in modern humans. I'm just trying to explain to him why it wouldn't be surprising not to find a statistically significant correlation within a particular generation of a species.

The true mystery of the world is the visible, not the invisible

This message is a reply to:
 Message 190 by NosyNed, posted 08-08-2005 7:49 PM NosyNed has not replied

  
JavaMan
Member (Idle past 2319 days)
Posts: 475
From: York, England
Joined: 08-05-2005


Message 195 of 240 (231261)
08-09-2005 7:51 AM
Reply to: Message 193 by John Ponce
08-08-2005 9:56 PM


Re: More invalid conclusions & unsubstantiated assertions in place of any real argume
Thank you for the thought experiment and helping to focus the debate. My first response was similar to Ned's but I am going to give it more consideration.
See my reply to Ned.
BTW, what is the picture below your name? I can't tell if it is a skull cap - something else.
It's a skull cap of Homo erectus found by Eugene Dubois in 1891. The fossil is popularly known as Java Man.

The true mystery of the world is the visible, not the invisible

This message is a reply to:
 Message 193 by John Ponce, posted 08-08-2005 9:56 PM John Ponce has not replied

Replies to this message:
 Message 196 by RAZD, posted 08-09-2005 7:28 PM JavaMan has replied

  
JavaMan
Member (Idle past 2319 days)
Posts: 475
From: York, England
Joined: 08-05-2005


Message 198 of 240 (231692)
08-10-2005 1:05 AM
Reply to: Message 196 by RAZD
08-09-2005 7:28 PM


Re: More invalid conclusions & unsubstantiated assertions in place of any real argume
welcome to the board
Thanks.
it has a nice overlay of the Java Man skull cap onto the Turkana Boy skull, and a nice refutation of typical Gish arguments of incredulity in the process
Yes. That's a pretty convincing refutation.

The true mystery of the world is the visible, not the invisible

This message is a reply to:
 Message 196 by RAZD, posted 08-09-2005 7:28 PM RAZD has not replied

Replies to this message:
 Message 200 by John Ponce, posted 08-12-2005 11:42 PM JavaMan has not replied

  
JavaMan
Member (Idle past 2319 days)
Posts: 475
From: York, England
Joined: 08-05-2005


Message 207 of 240 (232926)
08-13-2005 6:48 AM
Reply to: Message 201 by John Ponce
08-13-2005 1:14 AM


Re: More invalid conclusions & unsubstantiated assertions in place of any real argume
Thanks for the reply. Your message is quite long and I think it's going to take me a while to get through it!
But I can answer one question:
2) Is the supposed correlation of improved smelling ability and increased Olfactory Bulb volume based on any evidence?
For example, a common rat’s sense of smell is probably better than any human’s. Are the olfactory bulbs of a rat larger than a human’s? I have not been able to determine the answer yet, but my guess is they are not. If my guess is correct, the exercise would tend to support my postition.
The olfactory bulbs in a rat are enormous (See the following link). They make up a large proportion of the brain size. The same goes for any animal that depends so much on smell.
Rat brain
This message has been edited by JavaMan, 08-13-2005 06:49 AM

The true mystery of the world is the visible, not the invisible

This message is a reply to:
 Message 201 by John Ponce, posted 08-13-2005 1:14 AM John Ponce has not replied

  
JavaMan
Member (Idle past 2319 days)
Posts: 475
From: York, England
Joined: 08-05-2005


Message 218 of 240 (233159)
08-14-2005 12:33 PM
Reply to: Message 201 by John Ponce
08-13-2005 1:14 AM


Re: More invalid conclusions & unsubstantiated assertions in place of any real argume
You seem to agree that within a population (of finches, or butterflies, say) there exists some variation in genetic traits. You also seem to accept that natural or artificial selection can cause some traits to be preferentially expressed in such a way that the morphology of the organism can change. Where you seem to have difficulties with the theory of evolution is that:
1. You don't believe that the variations arise randomly, by mutation;
2. And you believe that there is a limit on the extent to which the morphology of organisms can change by the process of natural or artificial selection.
The second problem I'll leave to another day. For now I'd like to focus on the subject of variation.
Variation
To me the obvious question to ask when faced with this variation in genetic traits is, How did the variation arise?
Generally we find two types of answer to this question:
1. Variation is random and caused by mutation (Darwinian theory);
2. Variation is directed, either by being designed up-front by God or some super-intelligent alien (intelligent design theories), or resulting from changes in the behaviour of the organism (inheritance of acquired characteristics - Lamarckism).
So my second question would be, Do we have evidence for any of these processes causing variation in present day populations?
Random mutations
Well we certainly have evidence that random mutations occur. The following link is to a paper investigating the differences in spontaneous mutations between different strains of the Herpes virus:
Difference in Incidence of Spontaneous Mutations between Herpes Simplex Virus Types 1 and 2
Inheritance of acquired characteristics
No one has yet found evidence for the inheritance of acquired characteristics, despite a great deal of investigation, especially by Soviet scientists during the 1930s.
Lamarckism in the Soviet Union
Theories of intelligent design
Although we can't judge theories of intelligent design by the same criteria (because the theories generally claim that the variation was imposed in the past, so you wouldn't expect to see any changes in the current population), we can still make the following observations:
1. First of all, as we do observe change by random mutation in current populations, then it would seem that the total variation in a population must be due to the variation inherent in the original design plus any mutations that have occurred since that time;
2. Second, given observation #1 it must occur to any parsimonious scientist that the notion of an original design is a bit superfluous when the observed mechanism of random mutation could readily account for the development of variation from an unvaried initial state - there doesn't seem to be any need to posit an intermediate designed state;
3. Third, any directed mechanism for generating variation has a fundamental flaw - it must assume a particular future environment for the organism. When you see the word 'random' you probably understand something like 'accidental' or 'mindless'; when I see the word I understand 'unbiased by any assumptions about future conditions'. You see, it's the very randomness of the variation generation that provides organisms with the ability to adapt when circumstances change. The process is ongoing and random, so that at any point in its history the population has a large set of alternative traits that it can call on. If the process were directed by inheritance of acquired characteristics, small changes in environmental conditions would tend to push the whole population in a particular direction all at once. If the process were directed by intelligent design, then the initial variation would be limited by the designers' assumptions about future environmental conditions. Only an omnipotent God could design in all the variation required - but if you appeal to an omnipotent God, you're not doing science any more, you're doing religion.
This message has been edited by JavaMan, 08-14-2005 12:34 PM
This message has been edited by JavaMan, 08-14-2005 12:37 PM

The true mystery of the world is the visible, not the invisible

This message is a reply to:
 Message 201 by John Ponce, posted 08-13-2005 1:14 AM John Ponce has replied

Replies to this message:
 Message 219 by RAZD, posted 08-14-2005 2:32 PM JavaMan has replied
 Message 224 by John Ponce, posted 09-03-2005 2:40 AM JavaMan has replied

  
JavaMan
Member (Idle past 2319 days)
Posts: 475
From: York, England
Joined: 08-05-2005


Message 220 of 240 (233454)
08-15-2005 3:00 PM
Reply to: Message 219 by RAZD
08-14-2005 2:32 PM


Re: Mechanisms for Variations
Thanks.
By the way, I liked your snowballing macaque in the intelligent design thread. That made my day.

The true mystery of the world is the visible, not the invisible

This message is a reply to:
 Message 219 by RAZD, posted 08-14-2005 2:32 PM RAZD has not replied

  
JavaMan
Member (Idle past 2319 days)
Posts: 475
From: York, England
Joined: 08-05-2005


Message 232 of 240 (242852)
09-13-2005 8:40 AM
Reply to: Message 224 by John Ponce
09-03-2005 2:40 AM


Re: More invalid conclusions & unsubstantiated assertions in place of any real argume
JavaMan, thanks for your response. What did you think of the striking similarities between the JavaMan skullcap and modern human (fully intelligent) Aborigine skull's low forehead and skullcap in message 200? RAZD seemed to be overwhelmed by the different angle of the picture and would not comment.
Apologies for not replying to the original message, but I couldn't see the Aborigine skull until RAZD pointed out how to get it displayed. Now I can see it, I have to tell you that I don't have any way of making a judgement until you show me the skull in profile - it's like showing me photographs of two cars, one taken from the side and the other from the front, then asking me to judge which is the longer!
In fact, the photograph of the Aborigine skull is taken from an angle that foreshortens the forehead and skull casing, making them look smaller than they actually are. That wouldn't be deliberate would it?

The true mystery of the world is the visible, not the invisible

This message is a reply to:
 Message 224 by John Ponce, posted 09-03-2005 2:40 AM John Ponce has not replied

Replies to this message:
 Message 234 by RAZD, posted 09-13-2005 9:50 PM JavaMan has not replied

  
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