Did humans descend from other primates?

[McCulloch]

Man did not descend from the primates.

Did humans descend from other primates?
Are humans primates or should there be special biological taxonomy for humanity?
Please cite evidence.

[otseng]

One item that is not being address is the fact , while there might be some disagreement about the speed of the genetic clock, the last common ancestor of the microcephalin, a gene that regulates brain growth, is 5 times older than the oldest Mt-dna ancestor. The last common ancestor for the Mt-dna gene, with the current best knowledge for the molecular clock is 200,000 years old. The last common ancestor for microcephalin gene is a MILLION years ago.

That does not fit the 'creation' model at all, and it falsifies it.

Could you provide some references for the assertion of the microcephalin gene from a million years ago?

[Goat]

Thus there must exist a single woman whose is the matrilineal most-recent common ancestor of everyone in set of humans alive today.

Actually, I have no contention with this. And this fits with the human creation model. But in evolutionary theory, at the time of that single common mother, there are tens of thousands of other females who did not result in any lineage alive today. Those others that did not pass on their mtDNA is what needs to be explained.

If one of them had left matrilineal descendants, then that would not change the facts of the necessity of mEve, just require the calculation to be pushed back some generations.

And what I'm saying is that it pushes it back to only one female that existed. There is no need to posit thousands of other females who left no evidence of their existence.

The existence of the Mitochondrial Eve is no longer in any doubt.

And fully predicted by the human creation model before genetic studies proved her existence.

What ISN"T predicted by the 'creation model' is the fact that the microcephalin common ancestor is from 1 million years ago, a full 800 years before the 'mt-eve' ancestor'...

Nor does the creation model explain why the 'y-adam' and the 'mt-eve' lived 100,000 years apart.

For a model to be valid, it has to explain all the data, not cherry pick data.

The microcephalin common ancestor being 1 million years ago falsifies the creation model. That is a point that you seem to refuse to answer.

[nygreenguy]

One item that is not being address is the fact , while there might be some disagreement about the speed of the genetic clock, the last common ancestor of the microcephalin, a gene that regulates brain growth, is 5 times older than the oldest Mt-dna ancestor. The last common ancestor for the Mt-dna gene, with the current best knowledge for the molecular clock is 200,000 years old. The last common ancestor for microcephalin gene is a MILLION years ago.

That does not fit the 'creation' model at all, and it falsifies it.

Could you provide some references for the assertion of the microcephalin gene from a million years ago?

We further demonstrate that this accelerated evolution is coupled with signatures of positive selection. Statistical analysis suggests that about 45 advantageous amino acid changes in microcephalin might have fixed during the 25–30 million years of evolution from early simian progenitors to modern humans.

Reconstructing the evolutionary history of microcephalin, a gene controlling human brain size

1. Patrick D. Evans1,2,
2. Jeffrey R. Anderson1,
3. Eric J. Vallender1,2,
4. Sun Shim Choi1 and
5. Bruce T. Lahn1,*
Hum. Mol. Genet. (2004) 13 (11): 1139-1145.

In summary, our study showed that there are accelerated amino acid substitutions of microcephalin gene in primates, especially in human populations, possibly due to the combined influence of recent population expansion and positive selection. During the origin of the last common ancestor of humans and great apes, there were adaptive sequence changes in microcephalin paralleling the drastic brain enlargement from lesser apes to great apes.

Molecular evolution of microcephalin, a gene determining human brain size

1. Yin-qiu Wang1 and
2. Bing Su1,2,*
Hum. Mol. Genet. (2004) 13 (11): 1131-1137.

[Goat]

One item that is not being address is the fact , while there might be some disagreement about the speed of the genetic clock, the last common ancestor of the microcephalin, a gene that regulates brain growth, is 5 times older than the oldest Mt-dna ancestor. The last common ancestor for the Mt-dna gene, with the current best knowledge for the molecular clock is 200,000 years old. The last common ancestor for microcephalin gene is a MILLION years ago.

That does not fit the 'creation' model at all, and it falsifies it.

Could you provide some references for the assertion of the microcephalin gene from a million years ago?

We further demonstrate that this accelerated evolution is coupled with signatures of positive selection. Statistical analysis suggests that about 45 advantageous amino acid changes in microcephalin might have fixed during the 25–30 million years of evolution from early simian progenitors to modern humans.

Reconstructing the evolutionary history of microcephalin, a gene controlling human brain size

1. Patrick D. Evans1,2,
2. Jeffrey R. Anderson1,
3. Eric J. Vallender1,2,
4. Sun Shim Choi1 and
5. Bruce T. Lahn1,*
Hum. Mol. Genet. (2004) 13 (11): 1139-1145.

In summary, our study showed that there are accelerated amino acid substitutions of microcephalin gene in primates, especially in human populations, possibly due to the combined influence of recent population expansion and positive selection. During the origin of the last common ancestor of humans and great apes, there were adaptive sequence changes in microcephalin paralleling the drastic brain enlargement from lesser apes to great apes.

Molecular evolution of microcephalin, a gene determining human brain size

1. Yin-qiu Wang1 and
2. Bing Su1,2,*
Hum. Mol. Genet. (2004) 13 (11): 1131-1137.

And we can see the last common ancestor was 1.1 million years ago because of the work of Dr Lahn. From http://www.msnbc.msn.com/id/15611031/

Lahn's team found a brain gene that appears to have entered the human lineage about 1.1 million years ago, and that has a modern form, or allele, that appeared about 37,000 years ago — right before Neanderthals became extinct.

"The gene microcephalin (MCPH1) regulates brain size during development and has experienced positive selection in the lineage leading to Homo sapiens," the researchers wrote.

Positive selection means the gene conferred some sort of advantage, so that people who had it were more likely to have descendants than people who did not. Lahn's team estimated that 70 percent of all living humans have this type D variant of the gene.

[SailingCyclops]

Could you provide some references for the assertion of the microcephalin gene from a million years ago?

Evidence that the adaptive allele of the brain size gene microcephalin introgressed into Homo sapiens from an archaic Homo lineage

[...]
Here, we examine the origin of haplogroup D. By using the interhaplogroup divergence test, we show that haplogroup D likely originated from a lineage separated from modern humans ≈1.1 million years ago and introgressed into humans by ≈37,000 years ago.
[...]

I found more on this here:

Reconstructing the evolutionary history of microcephalin, a gene controlling human brain size

Fascinating!

Bob

[nygreenguy]

And we can see the last common ancestor was 1.1 million years ago because of the work of Dr Lahn. From http://www.msnbc.msn.com/id/15611031/

Lahn's team found a brain gene that appears to have entered the human lineage about 1.1 million years ago, and that has a modern form, or allele, that appeared about 37,000 years ago — right before Neanderthals became extinct.

"The gene microcephalin (MCPH1) regulates brain size during development and has experienced positive selection in the lineage leading to Homo sapiens," the researchers wrote.

Positive selection means the gene conferred some sort of advantage, so that people who had it were more likely to have descendants than people who did not. Lahn's team estimated that 70 percent of all living humans have this type D variant of the gene.

true, but my source shows the gene being tens of millions of years old! Really falsifies any young earth ideas.

[nygreenguy]

I found more on this here:

Reconstructing the evolutionary history of microcephalin, a gene controlling human brain size

Fascinating!

Bob

I already posted this!

[Zeeby]

I just ran the model and (somewhat amazingly) the number of surviving lines did drop to 1, after approx 14600 generations. Is this unexpected? Didn't we establish that lines dying out is a predictable outcome?

Is there any way I can see your source code? Also, I think I might have to write a simulation myself to see what would happen.

The algorithm is as follows (parameters can be changed) (person means breeding female):

Start with 5000 lines
For each generation:
- For each line, each person in the line generates 0 to 3 offspring at random
- Set a population target p (e.g. 5000 + generations/2)
- For each person, kill them with probability (1-p)/total population

That's the whole thing. I will send you the actual program via PM (as my implementation runs fairly slowly after a while).

I am glad you are also considering writing a simulation - I will be interested to see if you obtain different results.

[otseng]

What ISN"T predicted by the 'creation model' is the fact that the microcephalin common ancestor is from 1 million years ago, a full 800 years before the 'mt-eve' ancestor'...

I'm not sure what you mean by "a full 800 years".

Also, the microcephalin common ancestor is not a fact. The authors state:

By using the interhaplogroup divergence test, we show that haplogroup D likely originated (emphasis mine) from a lineage separated from modern humans ~1.1 million years ago and introgressed into humans by ~37,000 years ago.

http://www.pnas.org/content/103/48/18178.full

But this is problematic because if microcephalin introgressed into humans ~37,000 years ago, did humans not have large brains before then?

Their dating methodology also assumes humans and chimpanzees share a common ancestor.

First, the MRCA of all of the chromosomes in the sample was obtained by using chimpanzee sequence as the outgroup. The average sequence divergence separating the MRCA and each of the chromosomes was then calculated. Last, this average divergence was scaled to mutation rate as obtained from human-chimpanzee divergence in the region to produce coalescence time.

Dating was generated by using a simulation software that they wrote.

All software programs developed for the study are available upon request. The coalescent process as implemented in the ms software (31, 32) was used to simulate genealogies under the following parameters ...

In regards to microcephalin, it states:

The gene microcephalin is a critical regulator of brain size. In humans, loss-of-function mutations in this gene cause a condition known as primary microcephaly, which is characterized by a severe reduction in brain volume (by 3- to 4-fold) but, remarkably, a retention of overall neuroarchitecture and a lack a overt defects outside of the brain (26). The exact biochemical function of microcephalin has yet to be elucidated, but this gene likely plays an essential role in promoting the proliferation of neural progenitor cells during neurogenesis (26). microcephalin has been shown to be the target of strong positive selection in the evolutionary lineage leading from ancestral primates to humans (27, 28). This observation, coupled with the fact that this gene is a critical regulator of brain size, suggests the possibility that the molecular evolution of microcephalin may have contributed to the phenotypic evolution of the human brain (27, 28).

A mutation of a gene that causes a small head does not necessarily mean that the mere presense of that gene would cause a larger head.

Further a large head/brain by itself does not mean that something is more intelligent.

In this study, we investigate the origin of the microcephalin D allele in modern humans. We show that the D allele is unlikely to have arisen within a panmictic population. Instead, our data are consistent with a model of population subdivision followed by introgression to account for the origin of the D allele. By this model, schematized in Fig. 4 B, the lineage leading to modern humans was split from another Homo lineage, and the two lineages remained in reproductive isolation for ~1,100,000 years. During this period of reproductive isolation, the modern human lineage was fixed for the non-D allele at the microcephalin locus, whereas the other Homo lineage was fixed for the D allele. These two alleles are differentiated by a large number of sequence differences accumulated during the prolonged isolation of the two populations. At or sometime before ~37,000 years ago, a (possibly rare) interbreeding event occurred between the two lineages, bringing a copy of the D allele into anatomically modern humans. Whereas the original D-bearing Homo population had since gone extinct, this introgressed copy of the D allele in humans had subsequently spread to exceptionally high frequency throughout much of world because of positive selection.

But even if microcephalin is a factor in the development of a larger brain because of associations with microcephaly, then it would only be one of six genes that would be necessary.

"Microcephalin (MCPH1) is one of six genes causing primary microcephaly"
http://en.wikipedia.org/wiki/Microcephalin

A derived form of MCPH1 called haplogroup D appeared about 37,000 years ago (anytime between 14,000 and 60,000 years ago) and has spread to become the more common form throughout the world except Sub-Saharan Africa.

Haplogroup D may have originated from a lineage separated from modern humans approximately 1.1 million years ago and later introgressed into humans.

Shouldn't MCPH1 be common among all humans living in the world, not just particular regions of the world?

Our results not only provide genetic evidence in support of the possibility of admixture between modern humans and an archaic Homo lineage but also support the notion that the biological evolution of modern humans might have benefited from the contribution of adaptive alleles from our archaic relatives.

If MCPH1 causes a reproductive advantage, how can it be explained the ancestor of it has become extinct?

[otseng]

What is your definition for man?

The broadest and simplest definition I can come up with is this:

The ever-evolving species of hominid beginning with those hominids who Mastered Fire and tool making, (about 1 to 1.6 million years ago) to those living today and beyond.

When you say "ever-evolving", wouldn't all species be ever-evolving according to evolutionary theory?

When you say "species", would hominids constitute different species?

How would you define "hominid"?

Is the distinction of humans based only on technological capabilities (mastering fire and tool making)?