Evolution By Natural Selection

[CosmicJoghurt]

Is it possible to get any kind of DNA from very, very old fossils? So, that way the genetic tree is more complete? Or does all of the DNA get destroyed.

 

[Inferno]

Is it possible to get any kind of DNA from very, very old fossils? So, that way the genetic tree is more complete? Or does all of the DNA get destroyed.

DNA yes, tissue no.

 

[Laurens]

Ernst Mayr wrote an interesting piece called 'The objects of selection'. In it he is quite critical of Dawkins and the 'selfish gene theory':

The proposal by Williams (7) to adopt the gene as the object of selection not only conformed to the prevailing reductionist spirit of the time but also fitted into the thinking of many geneticists who in the mathematical analyses of population genetics had adopted the gene as the principal entity of evolutionary change. Williams's proposal was strongly endorsed by Dawkins (9). This idea of the gene as the target of selection was at first widely accepted, for instance by Lewontin (10). But eventually it was severely criticized (11, 12), and even its original supporters have now moderated their claims. The critics pointed out that "naked genes," "not being independent objects" (9), are not "visible" to selection and therefore can never serve as the target. Furthermore, the same gene, for instance the human sickle cell gene, may be beneficial in heterozygous condition (in Plasmodium falciparum areas) but deleterious and often lethal in the homozygous state. Many genes have different fitness values when placed into different genotypes. Genic selectionism is also invalidated by the pleiotropy of many genes and the interaction of genes controlling polygenic components of the phenotype. On one occasion Dawkins (ref. 13, point 7) himself admits that the gene is not an object of selection: ". . . genetic replicators are selected not directly, but by proxy . . . [by] their phenotypic effects." Precisely! Nor are combinations of genes, as for instance chromosomes, independent objects of selection; only their carriers are.

What do you guys think?

 

[sturmgewehr]

http://www.youtube.com/user/EvolutionDocumentary

The channel went down, but is now back, I'd recommend subbing

Good documentary, I watched it from the beginning to the end.

Now the question is, if Homo Erectus has rafted from the neighboring Islands to that Island that would imply that Homo Erectus was the typical Homo Erectus with the typical height of a Homo Erectus, now they claim that Homo Erectus shrank due to evolutionary pressure BUT where are the intermediate skeletons ??? If Homo Erectus shrank there in that Island then we should find Normal Homo Erectus skeletons as well or some intermediate ones at least.

I found it more impressive how they had found the skeletons of dwarf Elephants and some other animals.

 

[Inferno]

@ Sturmgewehr: Which documentary? EvolutionDocumentaries has 106 videos online at this time, I'm not going to guess which one you mean.

As for intermediary fossils: We could be lucky enough to find some, but we don't "have" to find them.

@ Laurens: I'm still reading and trying to understand, nearly 2 weeks after you posted it. I'll answer soon.

 

[sturmgewehr]

@ Sturmgewehr: Which documentary? EvolutionDocumentaries has 106 videos online at this time, I'm not going to guess which one you mean.

As for intermediary fossils: We could be lucky enough to find some, but we don't "have" to find them.

@ Laurens: I'm still reading and trying to understand, nearly 2 weeks after you posted it. I'll answer soon.

I apologize for not mentioning the Documentary.

It was the Hobbit Documentary, the supposedly shrunk descendant of Homo Erectus, they also named it Homo Florensis since it was found in Florensis Island in Indonesia.

This documentary more precisely:

http://www.youtube.com/watch?v=BipHAYv6TyM&feature=plcp&context=C4ee2855VDvjVQa1PpcFPiS5VZiY-zYAGCuU6rgeEWCh4DMspSOG8=

 

[Inferno]

This paper suggests a method (wrist comparison) of understanding how Homo Floresiensis is related to other Hominins. If I understand it correctly, it seems to suggest that the wrist of H. Floresiensis may have evolved earlier. "Our analyses support hypotheses that LB1 is descended from a hominin ancestor that migrated out of Africa before the evolution of the shared, derived wrist morphology that is characteristic of modern humans, Neandertals, and their last common ancestor." This may suggest Homo Habilis as a possible ancestor to H. Floresiensis.

The abstract of this paper also seems to suggest H. Habilis as the possible ancestor. This would make sense, given that both stand about 1m tall.

I doubt that H. Erectus is a viable candidate in the long run, after all they were pretty damn tall.