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Author Topic:   Human Brain Evolution Was a 'Special Event'
Chiroptera
Member
Posts: 6833
From: Oklahoma
Joined: 09-28-2003
Member Rating: 7.0


Message 31 of 65 (353095)
09-29-2006 9:57 AM
Reply to: Message 24 by skepticfaith
09-28-2006 11:27 PM


Re: Mutations.
quote:
That is not what I said.

Yes it is. You are the one that presented the paper for our consideration. You are the one you seems to feel that the paper presents an interesting challenge.

-

quote:
The scientists said in the paper ,"thousands of mutations in 20-25 million years is remarkable" .

Yes, and then when it was pointed out that some of us don't see it as particularly remarkable you began to change the problem. The authors mentioned thousands of mutations in 20-25 million years, and then you, without justification, decide to change it to the 5 million years since the time of Australopithecus, and then to the 10,000 years since civilization began. The paper is talking about the thousands of mutations that may have occurred in 20-25 million years -- the beginning of civilization or the time since Australopithecus is irrelevant to the parts of the paper you quoted.

It's alright to go on to other topics -- the initial post seemed to ask whether the paper presents some sort of problem, the answer is that it doesn't, and so that would make a pretty short thread -- but when you go on without acknowledging the previous point has been addressed you come across as unfocused.

-

quote:
Then YOU claimed that this is not a problem and it only requires a few mutations in a thousand years.

My claim was justified. It is simple arithmetic. It's not rocket science -- hell, it's not even College Algebra.

Take the total time, divide by the number of mutations, and you get the average length of time between successive mutations.

20 million years / "thousands" = about 10000 years between mutations.

It really is that simple. According to the passage that you quoted, we have about one mutation every 10000 years. I fail to see anything remarkable about it -- if there is something remarkable about it, then you haven't quoted that part.

-

quote:
Regardless of how valid you think evolution theory is, you have to admit that there is a very little that we know about the evolution of the brain.

That may be true. If it is, then it is an interesting exercise for scientists to try to work out the details. But just not knowing the details of a process isn't evidence that the process didn't occur.

-

quote:
Similarly we know very little of how complex organs have actually developed - there are numerous theories but no actual evidence.

Actually, we have lots of evidence that evolution occurred. The heirarchical classification of the species. The fossil record. The findings in genetics and molecular biology. The patterns we see in Endogenous Retroviral Insertians, vestigial organs, and atavisms. And so forth.

-

quote:
This is the major major stumbling block of evolution theory .

Since in actuality, evolution has always been based on evidence, and the evidence has always supported the theory of evolution, this is no stumbling block at all.


"The fact that a believer is happier than a skeptic is no more to the point than the fact that a drunken man is happier than a sober one." -- George Bernard Shaw

This message is a reply to:
 Message 24 by skepticfaith, posted 09-28-2006 11:27 PM skepticfaith has responded

Replies to this message:
 Message 32 by skepticfaith, posted 09-29-2006 3:17 PM Chiroptera has responded

  
skepticfaith
Member (Idle past 4060 days)
Posts: 71
From: NY, USA
Joined: 08-29-2006


Message 32 of 65 (353162)
09-29-2006 3:17 PM
Reply to: Message 31 by Chiroptera
09-29-2006 9:57 AM


Re: Mutations.
The paper does present a challenge to scientists to find answers in their lifetime. No doubt they are excited by it and are determined to do so.
However, the posters on this board are quick to dismiss their comment which is quite clear, they see it as a remarkable event. Of course I know they don't mean an act of creation (they don't, but a creationist will see this as furthering their cause). However, research in this field will either prove or disprove the mechanism of random mutations because of the time span (relatively short) that needs to be investigated.

quote:
without justification, decide to change it to the 5 million years since the time of Australopithecus,


My justification is clear. There is no evidence that the brains of Australopithecus was larger than chimpanzee. It just has not gone in the direction of brain development towards humans. Sure, if you can find a later species or intermeidate before erectus then we can increase the time span, but it certainly looks like around 5 million.

quote:
and then to the 10,000 years since civilization began.

I did not suggest any drastic change but said we mustobserve a few beneficial mutations related to the brain during the time of civilization. Additionally, from the dawn of civilization there was more natural selection pressures from humans to have even bigger brains and thus there should be some small indication of change from that period.
So in effect, we just need to find a small increase in brain size from the dawn of civilization to present - that is all. Has this been obvserved or not?
Because of the comparative recent times we are investigating, the verdict on this can be out pretty soon.
Actually I might have to restate what the major stumbling block of evolution is: when scientists start believing their little stories they make up (which are actually scenarios thought to fit the evidence and subject to change) as religion. It is so apparent in the silly series about the evolution of man running on the discovery channel.

This message is a reply to:
 Message 31 by Chiroptera, posted 09-29-2006 9:57 AM Chiroptera has responded

Replies to this message:
 Message 33 by Chiroptera, posted 09-29-2006 3:38 PM skepticfaith has responded
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Chiroptera
Member
Posts: 6833
From: Oklahoma
Joined: 09-28-2003
Member Rating: 7.0


Message 33 of 65 (353176)
09-29-2006 3:38 PM
Reply to: Message 32 by skepticfaith
09-29-2006 3:17 PM


Re: Mutations.
quote:
they see it as a remarkable event.

Evidently they do. But it isn't clear what it is that they find so remarkable. It can't simply be the number of mutations. Over 20 million years, thousands of mutations doesn't seem to be so large.

-

quote:
but a creationist will see this as furthering their cause

Creationists see everything as furthering their cause. The hierarchical classification of the species is excellent evidence for evolution, yet creationists see it as furthering their cause. There are many good evolutionary lineages in the fossil record (the lineage from A. afarensis to H. spapiens being one of the good ones), and creationists see them as furthering their cause. I honestly can't think of anything that wouldn't further their cause short of Jesus Christ himself returning to earth and telling them to knock it off.

-

quote:
However, research in this field will either prove or disprove the mechanism of random mutations because of the time span (relatively short) that needs to be investigated.

I doubt that the research will either prove or disprove evolution. For one, evolution is already as well "proven" as a theory can get -- there is already a tremendous amount of evidence that supports it. And to disprove evolution -- well, someone would still have to deal with all the evidence that supports it.

-

quote:
There is no evidence that the brains of Australopithecus was larger than chimpanzee.

It's also irrelevant to the points in the paper. They were not only estimating the number of mutations that simply increase brain size -- that might be a much smaller number. Evidently, they were estimating the number of mutations that might have occurred in the last 25 million years. So, the time since Australopithecus is not relevant to their estimate.

-

quote:
Additionally, from the dawn of civilization there was more natural selection pressures from humans to have even bigger brains and thus there should be some small indication of change from that period.

Actually, there would have been some selection pressures for smaller brains -- the large head of a baby at birth puts the mother at increased risk during childbirth. Mortality of both baby and mother were relatively high in the good old days. Also, large brains take more energy to develop and maintain. As it is, the brain is one of the most energy hungry organs in our bodies. I would say that there is a clear equilibrium between large brains and smaller brains.

-

quote:
Actually I might have to restate what the major stumbling block of evolution is: when scientists start believing their little stories they make up (which are actually scenarios thought to fit the evidence and subject to change) as religion.

That might be a stumbling block. But as long as the scientists continue to collect data, compare the data to the theory, and modify or discard the theory as the data suggests, then I don't think we have too much to worry about this particular stumbling block.

The clear stumbling block, in my opinion, is when religious fundamentalists start believing their myths as fact.


"The fact that a believer is happier than a skeptic is no more to the point than the fact that a drunken man is happier than a sober one." -- George Bernard Shaw

This message is a reply to:
 Message 32 by skepticfaith, posted 09-29-2006 3:17 PM skepticfaith has responded

Replies to this message:
 Message 36 by skepticfaith, posted 09-29-2006 9:10 PM Chiroptera has responded

  
nator
Member (Idle past 508 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 34 of 65 (353215)
09-29-2006 5:06 PM
Reply to: Message 25 by skepticfaith
09-28-2006 11:30 PM


Re: Hey, you! Bring that goal post back over here!
quote:
Creatures adapting to habitat and undergoing (very) minor changes has been observed.

Many minor changes combine to produce large scale change.

This has been inferred, because the timescales involved do not allow us to directly observe them as they are happening.

quote:
Most people claim to know a 'Grand Designer' He is normally called GOD

LOL!

This is exactly what the Discovery Institute hopes people stop saying aboutIntelligent Design. They are trying to appear scientific and therefore take great pains to avoid any mention of God, but Creationists have messed that up for them on many occasions.

But anyway, how do you know that your version of god designed everything?

It certainly seems to look much more as though much of life was designed by comittee, there are so many design flaws.

I take that back; it looks very much like life wasn't designed by an intelligent designer at all, but a pretty dumb one.

What designer, pray tell, would design our skulls with a sharp ridge of bone on the inside of our skulls?

Edited by schrafinator, : No reason given.


This message is a reply to:
 Message 25 by skepticfaith, posted 09-28-2006 11:30 PM skepticfaith has responded

Replies to this message:
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RAZD
Member
Posts: 20326
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.6


Message 35 of 65 (353225)
09-29-2006 6:18 PM
Reply to: Message 21 by skepticfaith
09-28-2006 7:37 PM


brain size evolution ... again ...
It still is remarkable since the history of civilization is over a few thousand years or so, then have any mutations occurred throughout history that we have discovered? Have our brains grown bigger - are we still evolving?

You are talking about the last 4-5k years when homo sapiens has been a species for ~160,000 years and has shown little development in brain size in that period (~3% of our species existence). The time since the start of brain development circa Australopithicus afarensis is ~3 million years. What you would notice in such a brief time is very very small incremental change if any.

The other thing to consider is that the brain size may well be maxed out -- any larger and viable babies cannot be born from living mothers by natural means -- and it is only very very recently that C-sections have become an alternative to natural birth, so further increases lead to deaths of baby or mother.

This forces further brain development to work inside the existing size limits by increasing the ability of the brain to process information.

There is evidence that this too has been occurring, and could well STILL be occurring, as this gets around the size limitations, but you won't see it as readily as growth in brain size.

There was another thread that discussed this in more detail ... Bones of Contentions. ... although it starts out a little differently (on racism).


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This message is a reply to:
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skepticfaith
Member (Idle past 4060 days)
Posts: 71
From: NY, USA
Joined: 08-29-2006


Message 36 of 65 (353251)
09-29-2006 9:10 PM
Reply to: Message 33 by Chiroptera
09-29-2006 3:38 PM


Re: Mutations.
quote:
It's also irrelevant to the points in the paper. They were not only estimating the number of mutations that simply increase brain size -- that might be a much smaller number. Evidently, they were estimating the number of mutations that might have occurred in the last 25 million years. So, the time since Australopithecus is not relevant to their estimate.


Are you sure about this?

From the article -

quote:
The researchers focused their study on 214 brain-related genes, that is, genes involved in controlling brain development and function. They examined how the DNA sequences of these genes changed over evolutionary time in four species: humans, macaque monkeys, rats, and mice. Humans and macaques shared a common ancestor 20-25 million years ago, whereas rats and mice are separated by 16-23 million years of evolution.

And all I am saying from this bit:

quote:
In addition, the rate of evolution has been far greater in the lineage leading to humans than in the lineage leading to macaques.


Is that this rate of evolution must have happened in the time during erectus and after A. afarensis . If I am wrong then please tell me during which period when most of the brain evolution took place ..

This message is a reply to:
 Message 33 by Chiroptera, posted 09-29-2006 3:38 PM Chiroptera has responded

Replies to this message:
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 Message 40 by nwr, posted 09-30-2006 12:30 PM skepticfaith has not yet responded
 Message 41 by Chiroptera, posted 09-30-2006 6:52 PM skepticfaith has not yet responded

  
skepticfaith
Member (Idle past 4060 days)
Posts: 71
From: NY, USA
Joined: 08-29-2006


Message 37 of 65 (353252)
09-29-2006 9:18 PM
Reply to: Message 34 by nator
09-29-2006 5:06 PM


Re: Hey, you! Bring that goal post back over here!
quote:

I take that back; it looks very much like life wasn't designed by an intelligent designer at all, but a pretty dumb one.

What designer, pray tell, would design our skulls with a sharp ridge of bone on the inside of our skulls?


You say its a dumb design, yet you are the product of this design! Perhaps this Designer wanted to have a little laugh at these insignficant humans who dare to question Him! You know he may have delibrately designed you badly.. God did not make you perfect, so this 'dumb' design is part of the drawbacks of being human.. Really, you can't argue for evolution by trying to disprove God - it is silly.

Like how Microsoft Windows is designed - not so perfect either..


This message is a reply to:
 Message 34 by nator, posted 09-29-2006 5:06 PM nator has responded

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NosyNed
Member
Posts: 8868
From: Canada
Joined: 04-04-2003
Member Rating: 7.2


Message 38 of 65 (353264)
09-30-2006 11:33 AM
Reply to: Message 36 by skepticfaith
09-29-2006 9:10 PM


Mutational TIme Frame
And all I am saying from this bit:

quote: In addition, the rate of evolution has been far greater in the lineage leading to humans than in the lineage leading to macaques.

Is that this rate of evolution must have happened in the time during erectus and after A. afarensis . If I am wrong then please tell me during which period when most of the brain evolution took place ..

Well, you obviously can't say that from that bit since macaques are not Australopithicines. The research gives an average rate of mutation over the time period. What you've shown us with this study is that the average rate of mutation is "small" (i.e., a conserved mutation every few 1,000 generations). It doesn't say anything else.

I don't think anyone doubts that there were times of more rapid change within that time but that's NOT an issue with the study you posted.

Brain size may be something which can be "rapidly" increased by only a few mutations.

see: Message 1

Edited by NosyNed, : correct two spelling erros

Edited by NosyNed, : No reason given.


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jar
Member
Posts: 31764
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.6


Message 39 of 65 (353266)
09-30-2006 11:55 AM
Reply to: Message 38 by NosyNed
09-30-2006 11:33 AM


As is often the case, multiple causes.
I would imagine that like most things, human brain size and function will turn out to be the result of a whole host of things. I imagine that diet, environmental stimulus such as moving into a new niche, the genetic equivalent of the old Xerox Machine problems where the machines simply kept cranking out copies of a gene which meant that those copies could be modified without losing the function of the original, all these likely played a part.


Aslan is not a Tame Lion

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nwr
Member
Posts: 5587
From: Geneva, Illinois
Joined: 08-08-2005


Message 40 of 65 (353273)
09-30-2006 12:30 PM
Reply to: Message 36 by skepticfaith
09-29-2006 9:10 PM


Re: Mutations.
quote:
In addition, the rate of evolution has been far greater in the lineage leading to humans than in the lineage leading to macaques.


Is that this rate of evolution must have happened in the time during erectus and after A. afarensis . If I am wrong then please tell me during which period when most of the brain evolution took place ..

Here is my conjecture.

I am proposing that relatively rapid brain evolution occurs in the evolution of social cooperation. Thus I would expect similar "special" events in the history of prairie dogs and naked mole rats (for example).

If my conjecture is correct, then when this "special" evolution occurred for humans is when they went social. I have no idea whether that was before or after afarensis.


This message is a reply to:
 Message 36 by skepticfaith, posted 09-29-2006 9:10 PM skepticfaith has not yet responded

  
Chiroptera
Member
Posts: 6833
From: Oklahoma
Joined: 09-28-2003
Member Rating: 7.0


Message 41 of 65 (353330)
09-30-2006 6:52 PM
Reply to: Message 36 by skepticfaith
09-29-2006 9:10 PM


Re: Mutations.
quote:
And all I am saying from this bit...is that this rate of evolution must have happened in the time during erectus and after A. afarensis .

Except that you cannot get that from that paper. The paper is comparing humans to macaques. Their estimate for the number of mutations, therefore, is for the time period since the last common ancestor of humans and macaques. Australopithecus is irrelevant to their estimate.

-

quote:
If I am wrong then please tell me during which period when most of the brain evolution took place ..

I don't know. You don't know, either. Maybe no one knows; if someone knows this, then it will be in a different paper than the one that you chose. You will have to find a paper that estimates the number of mutations since Australopithecus. The paper that you chose is inappropriate for this.


"The fact that a believer is happier than a skeptic is no more to the point than the fact that a drunken man is happier than a sober one." -- George Bernard Shaw

This message is a reply to:
 Message 36 by skepticfaith, posted 09-29-2006 9:10 PM skepticfaith has not yet responded

  
nator
Member (Idle past 508 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 42 of 65 (353331)
09-30-2006 7:06 PM
Reply to: Message 37 by skepticfaith
09-29-2006 9:18 PM


Re: Hey, you! Bring that goal post back over here!
quote:
You say its a dumb design, yet you are the product of this design!

Yes.

It's dumb to design our skulls with a sharp ridge on the inside.

I mean, if you are saying that the Intelligent Designer is an all-powerful, all-knowing, all-loving God, then why would He make so many dumb mistakes?

I mean, why would He have made us with such weak lower backs and knees? Why would He have given us crossover food and air pipes that make is so easy for us to choke? Why would he have created our eyes with a blind spot on our retinas? Why would He have made our skulls so large that it is incredibly difficult to get infants' heads through the birth canal, making human birth much more difficult than practically every other mammal?

I can understand why these things could have evolved, since nature will create creatures with good enough design most of the time. Our design is quite good enough, but there are tradeoffs.

quote:
Perhaps this Designer wanted to have a little laugh at these insignficant humans who dare to question Him!

Perhaps. But this isn't a scientific question.

Also, if true, he's having a "laugh" at all of the believers who do not question him. You have all of the design flaws, too.

quote:
You know he may have delibrately designed you badly.. God did not make you perfect, so this 'dumb' design is part of the drawbacks of being human.. Really, you can't argue for evolution by trying to disprove God - it is silly.

I'm not arguing for evolution.

I am arguing against the notion that humans were designed by an omnipotent, omnicient supernatural entity.

If you want to believe that humans were designed by a sort-of-intelligent designer who is also kind of a dick, then that's your choice, but that's certainly not science, is it?

Edited by schrafinator, : No reason given.


"Science is like a blabbermouth who ruins a movie by telling you how it ends! Well I say there are some things we don't want to know! Important things!"
- Ned Flanders

"Question with boldness even the existence of God; because, if there be one, he must more approve of the homage of reason than that of blindfolded fear." - Thomas Jefferson


This message is a reply to:
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melatonin
Member (Idle past 4547 days)
Posts: 126
From: Cymru
Joined: 02-13-2006


Message 43 of 65 (353341)
09-30-2006 8:25 PM


Thought this would be interesting in the context of this thread. Not sure how to upload pics, maybe someone else can.

Here's a link to Nick Matzke's recent summary of cranial capacity vrs time for hominins (australopithicus to homo sapiens).

http://www.pandasthumb.org/archives/2006/09/fun_with_homini_1.html

Edited by melatonin, : No reason given.


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Taz
Member (Idle past 1630 days)
Posts: 5069
From: Zerus
Joined: 07-18-2006


Message 44 of 65 (353348)
09-30-2006 8:45 PM
Reply to: Message 43 by melatonin
09-30-2006 8:25 PM



This message is a reply to:
 Message 43 by melatonin, posted 09-30-2006 8:25 PM melatonin has responded

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melatonin
Member (Idle past 4547 days)
Posts: 126
From: Cymru
Joined: 02-13-2006


Message 45 of 65 (353353)
09-30-2006 9:03 PM
Reply to: Message 44 by Taz
09-30-2006 8:45 PM


cheers gasby :)

If we look really closely at 6000-10,000 years ago, squint a bit, you can almost see where the soul was injected...

(j/k)


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