Foxes to Dogs

[rogue06]

The unexpected and unintentional side-effects of selectively breeding for tameness in Russian silver foxes are what I found most interesting. Not only did they alter their temperament and behavior but as a by-product also changed them physically as well.

They started exhibiting physical characteristics seen in domesticated dogs such as floppy ears rather than pointy ears, curving, turned up tails rather than down and going into heat every six months rather than once per year. Presumably, the genes responsible for docile behavior have other effects as well. Such changes indicate pleiotrophy which is when one gene influences multiple phenotypic traits that are seemingly not connected.

All of this suggests that when you wonder what a given trait's survival advantage is in the evolutionary sense that you may be asking the wrong question. It might be that the trait you are examining was the result of the development of some other, more important, trait to which it is pleiotropically linked.

[rogue06]

That's extraordinary. The baby looks more human than the actors in Planet of the Apes.

Here are two more images available for comparison. The first is the skull of a chimpanzee shortly before birth and the second is the skull of an adult chimp

[rogue06]

The unexpected and unintentional side-effects of selectively breeding for tameness in Russian silver foxes are what I found most interesting. Not only did they alter their temperament and behavior but as a by-product also changed them physically as well.

They started exhibiting physical characteristics seen in domesticated dogs such as floppy ears rather than pointy ears, curving, turned up tails rather than down and going into heat every six months rather than once per year. Presumably, the genes responsible for docile behavior have other effects as well. Such changes indicate pleiotrophy which is when one gene influences multiple phenotypic traits that are seemingly not connected.

All of this suggests that when you wonder what a given trait's survival advantage is in the evolutionary sense that you may be asking the wrong question. It might be that the trait you are examining was the result of the development of some other, more important, trait to which it is pleiotropically linked.

Speaking of pleiotropy... Just came across a paper on it over at CARM (hat tip to Promethean) wrt malaria. For those interested: Antagonistic pleiotropy as a widespread mechanism for the maintenance of polymorphic disease alleles which seeks to explain how an apparently deleterious mutation remains in the population, and in frequencies higher that we would expect.

[magellan004]

It's worse than that. The clip shows two groups of foxes, a tame group and an aggressive group, both of which are descendants of a common ancestral population of wild foxes.

Are you saying that the aggressive foxes were a variation of the wild foxes?

You won't understand my question so I'll try another way -
The experimenters captured various silver foxes from the wild.
They interbred the foxes.
Some offspring were aggressive, some were tame.

Are you saying that the original foxes were the common ancestor?

You couldn't be that dumb. So let's move on.

The experimenters split the foxes into two groups. They bred the foxes and in one group the experimenters killed any that seemed aggressive. In this 'tame' group the experimenters kept breeding and killing any aggressive children.
Slowly this 'tame' group' had more tame children than aggressive children

So who was the common ancestor?

Magellan

[USIncognito]

Dawkins also writes about it in his "Greatest Show on Earth" as well along with the attempts at silver fox domestication and the results.

He also mentions both in The Ancestor's Tale. The neotony is covered in "The Axolotl's Tale".