That is a great reflexion, but I want to add one thing: From my point of view, not an organism which is in the end of a filogenetic branch is the most advanced (it is supposed that is the most adapted).

The best example are microorganisms (from domain Bacteria and domain Archaea). How many dogs which respire with sulphate, sulphur, nitrate, amonium, hydrogene, etc do you know? Or, how many people who has fermentative metabolism do you know?

Microorganisms are very simple organisms and the most primitive form of life in this planet, but they have a huge variety of metabolism, adaptations, habitat, etc.

I hope this isn’t going too off-topic but I wanted to bring up sea stars which are bilateral (so more advanced, right?) but isn’t it a theory that because the adult form is radial that they evolved to become less advanced? I mean, they’re still considered bilateral because of their larva. Even though they are less advanced than most bilateral adults they are pretty kick-butt in their environment. (With the ability to regrow lost body parts even when cut in half and how great they are at calm-hunting.)
So is being less advanced more advanced? There are a lot of paradox or problems with this kind of assortment, phylogeny right?

Thanks,
what I was kind of trying to get at was that some organism that arn’t highly advanced at all are so perfect for their environment and so good at survival that I think being advanced isn’t always better.
I agree with you that the highest abilities should be considered, but in the starfish I think the common theory is that they were first more advanced as an adult then evolved to be radial and less advanced to adapt.
Dinosaurs were more advanced than cockroaches but the cockroaches survive when the dinosaurs didn’t, their advances were their downfall.

Like bacteria, you can’t kill them off but it sure would be easy for us to kill off the cheetahs or buffalo because they are more advanced. But then again an individual does get to live longer, but in the way of reproduction and success…

One organism being more advanced than another doesn’t necessarily mean that it is more fit. When you’re comparing two taxa that are monophyletic, the more advanced taxon has a characteristic that the other doesn’t and this characteristic developed after the two diverged from their common ancestor.

In the case of mollusca, bivalves (clams) are considered to be more advanced than the highly intelligent cephalopods (including squid and octopods) because of their more recently derived characteristics (loss of the radula feeding structure).

Echinodermata (including sea stars, sand dollars, sea cucumbers…) sort of went backwards when they developed radial symmetry as an adaptation for a sessile existance. Formerly, all radial symmetric animals were grouped in the taxon "radiata," which also included cnidarians (jelly fish…) and ctenophora until the bilateral echinoderm larval stage was discovered. In this case, radial symmetry is an advanced character because they developed from a bilaterally symmetric ancestor. Now some echinoderms are again reverting to bilateral symmetry as an adaptation for predation!

Difficulties with a concept are often linked to the definitions we use for the terms that describe it. It is better to think of "advanced" as "newer" not as "better".

I think if you want to compare two unrelated (distantly related) taxa, like aves and mammals, you might be better off comparing them in terms of fitness rather than advancedness.

example : comparing the fossil. which is advanced is younger than the other. so that we know the segmentation of time on this earth.

i though you are asking the use of "advanced" word on something?
well, "advanced" ,as i know, is depend on the complexity of the thing.
more complex is more advanced…it can have more ability than less advanced. –this imply to the ability to survive in the habitats–
–if i use primitive..this word also corelated to the "advance".–

then about your first post in this topic.
…the key word is complexity–as you said before–., and ability to survive and get the aim, maintaining the species. you are talking about how to describe "advance"–why this word can appear again? hah!–right?
if this is the matter, i will said that the more complex-the specialized organs/ cell/tissues to do the valueable thing in its habitat are included-.

i think we all have the same oppinion(?)

oh well.
i think my post was out to the what you want to said to, right? haha..
hope that do not make any sense to you.

yes. you are correct.
🙂

You should have known! 😆