Unfortunately, I originally forgot to close the quote mark at the end. Sorry ’bout that. But generally I stand by what was said.

Your assertion that “… evolution only gives the apperarance of trying to go in a smart direction but really it could stump itself and create a species that is only attracted to the prettiest but most burdened members rather that the best survivors, and actually wipe itself out.” is a generalisation that could be proved for some species, but I feel the vast majority just gets on with trying to exist, you know, where’s the next meal coming from? There are symbiotic relationships across most of the Life-forms, some highly unlikely, Others rely on good seasons, where there is abundant food available, meaning that somebody had an easier time for a while. It seems that an inbuilt control mechanism obtains. I think Human-kind is starting to realise this and recognises that there is no free lunch, because it has to be paid for somewhere, somehow, and sometime, eventually.

We tend to not appreciate the timescales involved, or imagine that they all have the same duration, and that the effects are all equal. A small variation in food supply for one creature, may have dire consequences up the food chain. A snake can exist for a month on one decent meal, it managed to catch. I reckon the next day if another suitable meal came along it would have it for desert, and not say “Nah, I’ve already dined this month”. No, it would try to eat as much as it could, and the left-overs would provide a meal for some other scavenger. I grant there are probably as many scenarios as species.

Ivan.

It’s a good point but i’m not sure.. I think there doesn’t need to be ANY underlying adavntage of the pretty tail. There could even be a strong disadvantage. Remember, evolution only gives the apperarance of trying to go in a smart direction but really it could stump itself and create a species that is only attracted to the prettiest but most burdened members rather that the best survivors, and actually wipe itself out. I’d be interested to know if this kind of thing happens…

Liam

I suggest it may be a “Boy named Sue” syndrome. (Remember the Johnny Cash record way back when?) If you had to battle for existence, but also needed to carry a huge colorful decoration almost all the time, a la the name “Sue”, ( no reflection on all the Sues in the world), then you would be the better fighter. If not, the genes would not get passed on. Simple as that.

That there is a Lyrebird means that tactic worked at least. With the environment varying over the centuries, some changes take much longer to happen. What use is the human appendix? Or the residual back legs of the whale? They (the legs) have almost disappeared, but not quite in some species. It is the hidden advantage that is important.

Ivan.

The way i think it really works is that it just does.. The tail, singinig ability, etc, is indicitave of nothing, but is nevertheless attractive to the opposite sex. once such a system gets going the females who are most attracted to pretty tails mate with the males who have the prettiest of the pretty tails and produce male babies with the prettiest tails and female babies most inclined to be attracted to pretty tails.

Yes, that is a description of sexual selection. However, the missing element is that prettier tails are presumed to make the peacock easier for predators to spot, and harder for them to escape. Different selection pressures work against the big tails. So how come the big tails win out, despite being a disadvantage? That is the point of understanding how it makes the animal more successful.

I dont think you need to find a reason that the trait makes the animal more sucessful for an explaination of why it happens.

I’ve always thought the idea that species are attracted to indicators such as the peacocks tail beacause they reveal underlying genetic survival ability must be mistaken. Surely such a system would breakdown quickly as peacocks with bad survival ability happened to learn to grow pretty tails and all of a sudden had loads of bad-surviving-babies.

The way i think it really works is that it just does.. The tail, singinig ability, etc, is indicitave of nothing, but is nevertheless attractive to the opposite sex. once such a system gets going the females who are most attracted to pretty tails mate with the males who have the prettiest of the pretty tails and produce male babies with the prettiest tails and female babies most inclined to be attracted to pretty tails.

I know it sounds like a bit of a circular argument and doesnt answer the question of how it starts. But leaving that aside it is clear that sexual selection like this can push evolution in a strange, pointless direction and produce starteling abilities (impersonation) or colours with no survival purpose other that attraction.

Also I’m not saying this is the case with the lyre bird, just pointing out it’s not necessarily necessary to search for a survival value to explain it’s ability.

Liam

My grandmother once had a mockingbird here in the US imitating what she was playing on the piano, which confused her at first until she figured it out. For the most part, the mockingbirds outside my window go through a non-stop program of over 20 songs. Apparently they can mimic over 200 different bird songs.