Skip to comments.How our DNA differs from that of Denisovans, our extinct cousins
Posted on 09/01/2012 5:42:46 AM PDT by Pharmboy
Scientists are beginning to analyze the DNA differences between modern humans and our extinct archaic relatives, the Denisovans. (National Human Genome Research Institute)
Genome of ancient Denisovans may help clarify human evolution
Scientists recently reported they had pieced together a high-quality sequence of an archaic human relative, the Denisovans.
Among other things, the researchers took a close look at the ways in which we differ from these people, who were named after the place where their traces were discovered: Denisova Cave in the Altai Mountains of Siberia....snip
It's "fascinating" to see the DNA changes that spread to most or all modern humans since our line split off from that of the Denisovans and the Neanderthals, said senior author Svante Paabo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. It's like taking a look at the last steps in human evolutionary history.
"The amazing thing to me is that [it is] not an astronomically long list," he said at a press conference on Wednesday. ...snip
Boring down even further, the researchers found 23 amino-acid changes that we have but Denisovans and monkeys and apes don't have. These might be especially likely to be important in making us who we are, Paabo said.
"It's quite interesting to me that eight have to do with brain function and brain development ... and some of them have to do with genes which, for example, can cause autism when the genes are mutated," he said.
And the autism-linked genes are interesting because a lot of what it takes to get by in human society, with all its politics and manipulation, has to do with being able to "read" the likely feelings of others, to get inside the head of another person.
(Excerpt) Read more at latimes.com ...
What I’m waiting for is a step by step description of the genetic mutations—that is, a scientific illustration of the process as our “cousins” evolved into us.
This should include a description of the changes in phenotype which correspond with each change in genotype.
Now you might say this is not evolution or speciation, but think about this: if drug-resistant malaria suddenly became a worldwide problem, those with the sickle cell trait might be the only survivors. The environment would have acted on this genotype and 'selected' it for survival. And, if enough time goes by, this remnant human population might become a distinct species.
The more subtle neuro-cognitive connections may not be teased out in our lifetimes.
Another one who doesn’t understand the 2nd Law of Thermodyanics, I see...
Nice one...perhaps his dart-throwing ability comes directly from his Denosivan ancestors’ ability to throw spears.
Changes to genotype may not necessarily be expressed phenotyplically. Likewise, there the a high degree of phenotypic plasticity in some species. And what of convergence between unrelated species?
What about basic morphological changes like skull size and skull shape?
Can anyone recommend a readable concise introduction to evolutionary genetics?
Very interesting, thank you.
Those types of changes are more likely to be seen in regulatory rather than structural genes. The secrets of regulatory genes remain largely unknown...and will likely continue to be for the immediate future. Patience is required, to be sure...but many things have indeed been discovered in the last 50 years.
It’s all about arrows.
Order to disorder is one arrow.
Self organizing and replicating organisms arising from dust is another, and it points in exactly the opposite direction of the first arrow.
All statements about the Second Law of Thermodynamics in post # 4 appear to be true.
Speciation is phenotypic change.
If we don’t have one species changing into another, we don’t have evolution.
If my responses seem to cover many different areas it’s because the theory of evolution contains uncertainties in many different ways.
For example, natural selection is logically flawed in that it conflates agency with environment and it contains a consistent ambiguity regarding the problem of survival. That is, for the mouse is the hawk the problem or is the mouse’s fur color the problem? If the fur color is the problem, the agent of solving the problem is the in the mouse’s genes, not in the environment.
God placed his creatures on a very dynamic planet. But he also built deep within the stuff of our being the ability to reprogram our stuff to be able to deal with the radical changes we endure on this planet.
Who else could have thought up such an elegant solution? What a creative and competent and loving God He is.
That understanding of that law seems to be violated after every meal. The the churning mess in your stomach gets transmogrified into bone and blood and mitochondria and DNA. Endlessly complex structures by the billions. Seems like defying the 2nd Law (as you understand it) is the hallmark of life.
As to your mouse example, to the individual mouse the hawk represents a direct existential threat, i.e. he may get killed and eaten. To the mouse population, the presence of hawks serves as a benefit; hawks remove the slower, non-cryptically colored, or otherwise less capable mice from the gene pool, improving the overall survivability for the mouse population in the presence of hawks. Now imagine two different substrates, one sand and another duff - in the sandy environment a lighter colored mouse will be favored for survival, but in the other situation, a darker mouse. The mice are the same species, but their phenotype varies by environment. If the environment were to change, the mouse population will adapt to the change by favoring the individuals most likely not to be eaten.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.