Which road is the chicken crossing?

[cosmos 2.0]

I agree with this. So in the absence of any other evidence (as a non-biologist, I'm not very aware of the archeological evidence collections out there), I can not be convinced that a chicken descends from a flying creature. Looking at a chicken alone, it could still be on its way from a non-flying creature, towards a flying one. It's on stand-by.

By continuously breeding the top percentile that manages to stay in the air the longest (by jumping and gliding) when I scare them, in millions of years, we'd get flying "chickens".

Heck, even by breeding mammals this way, I don't see why we wouldn't get there.

If chickens did or did not descend from bird, humans are certainly controlling its evolution now They may become an extinct species in the future. They are being being bred, how would it affect their genetics. will they be able to fight deadly infections in the future ?

 

[Dr Lots-o'watts]

If chickens did or did not descend from bird, humans are certainly controlling its evolution now They may become an extinct species in the future. They are being being bred, how would it affect their genetics. will they be able to fight deadly infections in the future ?

I won't go into infectiology (it adds unimaginable complexity), but I'll add that geography also plays a huge role. Chickens living on an island without any predators will have a greater chance (become dodo-like or kiwi-like). With predators, they need to evolve as sprinters (such as ostriches) or flyers.

I think evolution is interesting, but nothing can be said with certainty about the future, and the theories about the past are always pending on the discovery of a new fossilized creature ("missing link").

 

[Ken Natton]

Once more, with feeling…

Firstly, paleontological evidence is far more extensive than many people seem to realize.

But in any case. Knowledge of the evolutionary past of species does not depend solely on paleontological evidence.

Here’s one of my personal favourite evolutionary stories. The reptilian ancestor of all modern mammals that lived around the time of the dinosaurs was a small creature with short legs that moved low to the ground. It picked up ground based vibration through its lower jaw. Over time, as it evolved, small pieces of its lower jaw broke away to form the bones of the modern mammalian inner ear. It was then able to pick up air borne vibration as well.

So how do they know all this? Well, there is actually quite powerful paleontological evidence in support of this story, and I should even be able to find the Scientific American article about it, if anybody wants the reference. But if you want to scoff at this evidence, proof of the story is not actually dependant upon it. That little piece of our evolutionary history, of small pieces of lower jaw bone breaking away to form the bones of the inner ear, is replayed in every modern mammalian embryo as it develops.

 

[DaveC426913]

I agree with this. So in the absence of any other evidence (as a non-biologist, I'm not very aware of the archeological evidence collections out there), I can not be convinced that a chicken descends from a flying creature.

I am confused.

Are you saying that, because you do not have the knowledge of evidence of the descent of flying birds, you have decided that you won't be convinced it's true?

Looking at a chicken alone, it could still be on its way from a non-flying creature, towards a flying one. It's on stand-by.

No. This is a complete misunderstanding of how evolution works. Didn't we just clear this up?

 

[Dr Lots-o'watts]

No. This is a complete misunderstanding of how evolution works. Didn't we just clear this up?

There may be enough evidence to show chickens come from a flying ancestor, I haven't looked it up. Examining the genes is probably the most convincing evidence.

But if the conditions (geography, ecosystem, human interference or lack of etc.) were right, I don't see why they couldn't evolve to fly again.

 

[DaveC426913]

There may be enough evidence to show chickens come from a flying ancestor, I haven't looked it up. Examining the genes is probably the most convincing evidence.

Again, I think that, by definition, all birds are descended from a flying ancestor. If some descended from one ancestor and some from another, they would be separate classes. They're not. They're all the same class.

But if the conditions (geography, ecosystem, human interference or lack of etc.) were right, I don't see why they couldn't evolve to fly again.

Absolutely they could.

 

[HallsofIvy]

Not only are we descended from apes - we are apes.

Don't play games with words. We are NOT "apes" as that word is scientifically defined. Nor did we evolve from apes- we and apes evolved from a common ancestor that was neither human nor ape.

It's pretty likely that the ancestors of chickens once flew. The odds that all their ancestors back to lizards were flightless, and yet evolved feathers, chest bones, wings and beaks - all adapted to flight - but never flew is rather unlikely.

Haven't you been reading the previous posts. Yes, chickens evolved, fairly recently, from Asian fowl that could fly, to a least and extent.

Although the immediate ancestors of domestic chickens were ground dwelling fowl that if they flew at all it was probably limited to fluttering up into trees to sleep

That has already been said.

 

[ViewsofMars]

Two points of interest regarding the current page of discussion about apes and the chicken.

1. A quote from the Human Genome Project- Functional and Comparative Genomics Fact Sheet:

The often-quoted statement that we share over 98% of our genes with apes (chimpanzees, gorillas, and orangutans) actually should be put another way. That is, there is more than 95% to 98% similarity between related genes in humans and apes in general. (Just as in the mouse, quite a few genes probably are not common to humans and apes, and these may influence uniquely human or ape traits.) Similarities between mouse and human genes range from about 70% to 90%, with an average of 85% similarity but a lot of variation from gene to gene (e.g., some mouse and human gene products are almost identical, while others are nearly unrecognizable as close relatives). Some nucleotide changes are “neutral” and do not yield a significantly altered protein. Others, but probably only a relatively small percentage, would introduce changes that could substantially alter what the protein does.
http://www.ornl.gov/sci/techresources/Human_Genome/faq/compgen.shtml

2. From BioMed Central:

Evolution of the chicken Toll-like receptor gene family: A story of gene gain and gene loss
Nicholas D Temperley1, Sofia Berlin1,2, Ian R Paton1, Darren K Griffin3* and David W Burt1*
1 Department of Genomics and Genetics, Roslin Institute (Edinburgh), Roslin, Midlothian EH25 9PS, UK
2 Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvagen 18D, 752 36 Uppsala, Sweden
3 Department of Biosciences, University of Kent, Canterbury, CT2 7NJ, UK
BMC Genomics 2008, 9:62doi:10.1186/1471-2164-9-62
Abstract:

Background
Toll-like receptors (TLRs) perform a vital role in disease resistance through their recognition of pathogen associated molecular patterns (PAMPs). Recent advances in genomics allow comparison of TLR genes within and between many species. This study takes advantage of the recently sequenced chicken genome to determine the complete chicken TLR repertoire and place it in context of vertebrate genomic evolution.

Results
The chicken TLR repertoire consists of ten genes. Phylogenetic analyses show that six of these genes have orthologs in mammals and fish, while one is only shared by fish and three appear to be unique to birds. Furthermore the phylogeny shows that TLR1-like genes arose independently in fish, birds and mammals from an ancestral gene also shared by TLR6 and TLR10. All other TLRs were already present prior to the divergence of major vertebrate lineages 550 Mya (million years ago) and have since been lost in certain lineages. Phylogenetic analysis shows the absence of TLRs 8 and 9 in chicken to be the result of gene loss. The notable exception to the tendency of gene loss in TLR evolution is found in chicken TLRs 1 and 2, each of which underwent gene duplication about 147 and 65Mya, respectively.

Conclusion
Comparative phylogenetic analysis of vertebrate TLR genes provides insight into their patterns and processes of gene evolution, with examples of both gene gain and gene loss. In addition, these comparisons clarify the nomenclature of TLR genes in vertebrates.
Please read on . . .
http://www.biomedcentral.com/1471-2164/9/62

I hope everyone is enjoying life on *our* planet.

 

[bobze]

Don't play games with words. We are NOT "apes" as that word is scientifically defined. Nor did we evolve from apes- we and apes evolved from a common ancestor that was neither human nor ape. Haven't you been reading the previous posts. Yes, chickens evolved, fairly recently, from Asian fowl that could fly, to a least and extent. That has already been said.

I think you're getting confused with the often used (by creationists) "monkeys". Apes are all Hominoidea--That's the scientific definition.

By definition then, humans are apes and our last common ancestor with all Hominoidea would have been, an ape. In other words the coalescent point of Hominoidea is an ape. Even another way of looking at it would be (and probably better) that "ape" describes a distinct lineage within the order of primates.

So it would be perfectly acceptable to say that all Hominoidea share a line of descent from a common ancestor who was an ape. However, we are not monkeys, which describes a distinct and separate lineage of primates from our own.

You could, if speaking of Old world monkeys, say we are both Catarrhines. And we shared an ancestor who was undoubtedly a Catarrhine, but was neither an ape nor monkey. As both ape and monkey describe two distinct lineages of Catarrhini.

 

[eggomaniac]

That seems to be a pretty common misconception that people have of evolution. By and far, selection is capable of producing measurable change much, much faster than we actually observe.

Even so, it still produces measurable change over very short periods of time. For example, http://www.pbs.org/wgbh/evolution/library/01/6/l_016_01.html" (I think you'll find this most interesting Ken).

Doesn't dog breeding, though unnnatural means were used, at least show that species can change, or be changed, over short periods of times? Those finches in the Grants link were of the same species with different 'traits', right?