Genetics and the Evolution of the Human Brian

[mark kennedy]

I won't bore you with the specifics off the bat. It is impossible for the brain related genes to evolve to humans from apes. I will ask a very simple question, what is the basis for the evolution of the ape brain to that of modern humans? I warn you, random mutations is a wrong answer. My guess is that none of the evolutionists have the guts to answer the question directly.

Oh and by the way. You will be seeing the link to this read regularly if you like the forum.

 

[SteveB28]

Could I rename this discussion 'The Life of Brian' perhaps?

 

[florida2]

I won't bore you with the specifics off the bat. It is impossible for the brain related genes to evolve to humans from apes.

Could you please provide some evidence for this? We'll then have a starting point for discussion.

 

[Gracchus]

There is some evidence that the brain development of humans was an indirect result of a mutation that weakened human musculature. The reduction of the strength of the jaw muscles allowed the skull to continue to expand beyond of the limits of those primates with stronger muscles.

 

[DogmaHunter]

I won't bore you with the specifics off the bat. It is impossible for the brain related genes to evolve to humans from apes.

How have you determined it to be "impossible"?

I will ask a very simple question, what is the basis for the evolution of the ape brain to that of modern humans? I warn you, random mutations is a wrong answer.

It's not "just" random mutations. It's mutations followed by selection.

But anyhow, you are not looking for honest answers, are you?
Because your question is akin to "explain why people don't float into space when they jump. I warn you, gravity is a wrong answer".

My guess is that none of the evolutionists have the guts to answer the question directly.

My guess is that none of the "evolutionists" have the will to humor you, because obviously you are not here to actually learn about it or have an intellectually honest discussion about it.

 

[mark kennedy]

How have you determined it to be "impossible"?

Because the effects of mutations in brain related genes are always deleterious.

It's not "just" random mutations. It's mutations followed by selection.

Natural Selection is nothing more then an assumption:

All change in the organic, as well as in the inorganic world, being the result of law, and not of miraculous interposition. (Darwin, On the Origin of Species)​

Mutations are a failure of DNA repair:

In the living cell, DNA undergoes frequent chemical change, especially when it is being replicated (in S phase of the eukaryotic cell cycle). Most of these changes are quickly repaired. Those that are not result in a mutation. (Kimball, Mutations)​

But anyhow, you are not looking for honest answers, are you?

I'm not expecting one.

Because your question is akin to "explain why people don't float into space when they jump. I warn you, gravity is a wrong answer".

It's a direct question with a comprehensive answer, akin to what is 3 plus 1:

Single-nucleotide substitutions occur at a mean rate of 1.23%...On the basis of this analysis, we estimate that the human and chimpanzee genomes each contain 40–45Mb of species-specific euchromatic sequence, and the indel differences between the genomes thus total ~90Mb. This difference corresponds to ~3% of both genomes and dwarfs the 1.23% difference resulting from nucleotide substitutions (Initial Sequence of the Chimpanzee Genome, Nature 2005)​

Yet when announcing the results in their web focus article they say it's 98%:

What makes us human? We share more than 98% of our DNA and almost all of our genes with our closest living relative, the chimpanzee. (The Chimpanzee Genome)​

My guess is that none of the "evolutionists" have the will to humor you, because obviously you are not here to actually learn about it or have an intellectually honest discussion about it.

I'm not expecting one, that much is sure.

Have a nice day
Mark

 

[crjmurray]

I won't bore you with the specifics off the bat......

By all means, bore away.

 

[Oncedeceived]

There is some evidence that the brain development of humans was an indirect result of a mutation that weakened human musculature. The reduction of the strength of the jaw muscles allowed the skull to continue to expand beyond of the limits of those primates with stronger muscles.

What evidence could show it was an indirect result of a mutation that weakened human musculature? What is the evidence that expansion allowed increased intelligence?

 

[mark kennedy]

By all means, bore away.

You asked for it:

The 118-bp HAR1 region showed the most dramatically accelerated change with an estimated 18 substitutions in the human lineage since the human–chimpanzee ancestor, compared with the expected 0.27 substitutions on the basis of the slow rate of change in this region in other amniotes/ Only two bases (out of 118) are changed between chimpanzee and chicken, indicating that the region was present and functional in our ancestor at least 310 million years (Myr) ago. No orthologue of HAR1 was detected in the frog (Xenopus tropicalis), any of the available fish genomes (zebrafish, Takifugu and Tetraodon), or in any invertebrate lineage, indicating that it originated no more than about 400Myr ago. (An RNA gene expressed during cortical development evolved rapidly in humans, Nature 2005)
​

So for hundreds of millions of years only two substitutions are allowed, then suddenly there are 18 following the split between chimpanzees and humans, which would have been about 2 mya.

 

[mark kennedy]

What evidence could show it was an indirect result of a mutation that weakened human musculature? What is the evidence that expansion allowed increased intelligence?

I forget the specifics but they identified a gene that is specific to the development of the jaw, he is alluding to a genomic comparison. It should be noted that when there are differences between chimpanzee and human DNA it's automatically assumed to be the result of a mutation but they are really just differences.

 

[Oncedeceived]

I forget the specifics but they identified a gene that is specific to the development of the jaw, he is alluding to a genomic comparison. It should be noted that when there are differences between chimpanzee and human DNA it's automatically assumed to be the result of a mutation but they are really just differences.

My point is that whatever the evidence they are using for the conclusions they are making, it doesn't present any information on whether it was an indirect result of anything including a mutation nor does it show that intelligence is due to this change or expansion.

 

[Papias]

I warn you, random mutations is a wrong answer.

Mutations such as your earlier claim that mutations are transcription errors?

mark wrote:

No, what I did was mention transcript errors and other mutations saying I was not sure how much they had to do with adaptations. He doesn't know what he is talking about if he thinks that transcript errors have nothing to do with mutations.​

http://www.christianforums.com/threads/genetics-and-genesis.5090795/page-4

Papias

 

[USincognito]

Could you please provide some evidence for this? We'll then have a starting point for discussion.

His personal incredulity. It's the same tired schtick he's been foisting upon the forum for a decade now.

 

[crjmurray]

You asked for it:

The 118-bp HAR1 region showed the most dramatically accelerated change with an estimated 18 substitutions in the human lineage since the human–chimpanzee ancestor, compared with the expected 0.27 substitutions on the basis of the slow rate of change in this region in other amniotes/ Only two bases (out of 118) are changed between chimpanzee and chicken, indicating that the region was present and functional in our ancestor at least 310 million years (Myr) ago. No orthologue of HAR1 was detected in the frog (Xenopus tropicalis), any of the available fish genomes (zebrafish, Takifugu and Tetraodon), or in any invertebrate lineage, indicating that it originated no more than about 400Myr ago. (An RNA gene expressed during cortical development evolved rapidly in humans, Nature 2005)
​

So for hundreds of millions of years only two substitutions are allowed, then suddenly there are 18 following the split between chimpanzees and humans, which would have been about 2 mya.

So?

 

[USincognito]

Because the effects of mutations in brain related genes are always deleterious.

Evidence?

It's a direct question with a comprehensive answer, akin to what is 3 plus 1:

Oh this is awesome. This is the same Mark who couldn't read the table showing there were 200,000 ERVs in the human genome and provided us with this gem.

"Nearly all of the human insertions are completely covered, whereas only half of the chimpanzee insertions are completely covered. Analysis of the completely covered insertions shows that the vast majority are small (45% of events cover only 1 base pair (bp), 96% are <20 bp and 98.6% are <80 bp), but that the largest few contain most of the sequence (with the approx 70,000 indels larger than 80 bp comprising 73% of the affected base pairs) (Fig. 5). The latter indels >80 bp fall into three categories: (1) about one-quarter are newly inserted transposable elements; (2) more than one-third are due to microsatellite and satellite sequences; (3) and the remainder are assumed to be mostly deletions in the other genome." (Chimpanzee Genome, Nature 2005)

73% are over 70,000 in length. That's my problem Steve. Then when we can look at where they are and how genes are effected we can talk about the a priori assumption of a common ancestor.

Note the parts in bold. He reads 70,000 indels being larger than 80 bp making up 73% of the affected base pairs to mean that 73% of the affected base pairs are over 70,000 pb in length.

 

[USincognito]

What evidence could show it was an indirect result of a mutation that weakened human musculature? What is the evidence that expansion allowed increased intelligence?

A mutation in the MYH16 gene caused the jaw muscles to grow smaller. Since the jaw muscles didn't need to attach high up on the skull, this allowed the cranium to grow physically larger allowing the brain to grow as well.
http://genetics.thetech.org/original_news/news8
>> Some researchers now think that they may have found one of these mutations, in the MYH16 gene. Humans all have this mutation but other primates including the chimp don't. As explained above, this is only one of the many differences predicted between human and chimp. What tells us that this particular change was important for human evolution?

The mutation in the MYH16 gene probably gave humans weaker jaw muscles. So how do weaker jaw muscles lead to a bigger brain? Studies have shown that when muscles change, the bones attached to them can change too. It is possible that smaller jaw muscles allowed for the reshaping of the skull and at some point for the enlargement of the brain

Another piece of supporting evidence is that the mutation appears to be about 2.4 million years old. This is about 400,000 years before humans developed smaller jaw muscles and our brains started to enlarge. The mutation may have been necessary for the morphological change. <<

 

[USincognito]

So?

So nothing. It's the same tired argument from personal incredulity he's been a making since 2006 or so.

 

[USincognito]

In addition to the myosin gene duplications and subsequent mutations in SRGAP2 and ARHGAP11 fostered brain evolution and development in humans.

SRGAP2C - helped our brains grow larger.
http://www.nature.com/news/human-brain-shaped-by-duplicate-genes-1.10584
ARHGAP11B - fostered folds and evolution of human cerebrum.
http://www.sciencemag.org/content/347/6229/1465.abstract

 

[Oncedeceived]

A mutation in the MYH16 gene caused the jaw muscles to grow smaller. Since the jaw muscles didn't need to attach high up on the skull, this allowed the cranium to grow physically larger allowing the brain to grow as well.
http://genetics.thetech.org/original_news/news8
>> Some researchers now think that they may have found one of these mutations, in the MYH16 gene. Humans all have this mutation but other primates including the chimp don't. As explained above, this is only one of the many differences predicted between human and chimp. What tells us that this particular change was important for human evolution?

The mutation in the MYH16 gene probably gave humans weaker jaw muscles. So how do weaker jaw muscles lead to a bigger brain? Studies have shown that when muscles change, the bones attached to them can change too. It is possible that smaller jaw muscles allowed for the reshaping of the skull and at some point for the enlargement of the brain

Another piece of supporting evidence is that the mutation appears to be about 2.4 million years old. This is about 400,000 years before humans developed smaller jaw muscles and our brains started to enlarge. The mutation may have been necessary for the morphological change. <<

What is the connection to this gene to actual increase in brain size. Meaning how does the correlation of larger space equate to larger brain?

 

[USincognito]

What is the connection to this gene to actual increase in brain size. Meaning how does the correlation of larger space equate to larger brain?

Reduced jaw and jaw muscle size mean that those muscles could anchor lower on the skull. Without that pressure, the cranium was able to expand in volume. Please read the links on SRGAP2C and AHRGAP11B for how the brain grew in size and complexity. There was no single mutation that led to the human brain. It was a series of mutations that occurred after the C/H common ancestor population split.