A debate on the conseqences of biological evolutionary forces.

a reply to: chr0naut

Yep, this is one of those mirror sites. Their other links are also mirrors of ATS threads. I've seen this before.

a reply to: chr0naut

As others have noted, sometimes the burden of evolved characteristics like eyes or limbs, do not give a survival advantage. For instance in a low visibility environment, the extra biological burden of having eyes confers no survival advantage and therefore is selected against. Or in an aquatic environment, arms and legs create drag to movement and therefore a creature without them (aquatic mammals) survives better than one with.

Exactly 100% right. And that is not "devolution". It is evolution.

By the way, technically, blind fish did NOT lose their sight and cetaceans did not lose their limbs.

The first animal that got 'trapped' in the cave was almost certainly sighted, and the blind fish is now a completely different animal (that is it is a different species). Likewise, the ancestor of the whale was NOT a whale. It was some other kind of animal but not a whale.Llets say for argument sake, but NOT necessarily correctness, that is was something like a "proto-hippo". "Proto-hippo" eventually evolved into actual hippopotamus and whales and others. Before "proto-hippo" was probably something kind of ruminant, (say "proto-cow") that evolved into actual cows and "proto-hippopotamus" and others. And etcetera.

The point being that whales didn't lose their limbs, and they still contain the 'remnant' bones that formed the limbs of their ancient ancestor on land - right down to 5 fingers/toes - 'hidden' in their flippers. And blind fish still have their eyes - they are just useless.

That's how we know that the whales ancestors were land animals, that and the fact that they breathe air which could only have evolved on land. Not every land animal has the same leg structure after all, why should we be surprised that whales just have a variation on the theme? A whales flipper does not resemble a fishes fin in anyway other than its shape and usefulness in the water.

So that is two simple ways to tell when some animal has evolved a new trait (living in the water) that resembles (but is not the same as) a trait that was held by some extremely ancient ancestor.

originally posted by: Astyanax
a reply to: chr0naut

Since there is no preference towards the gaining or loosing of a trait, should they not arise with similar frequency?

Are the biochemical processes involved in losing a trait the same as or similar those involved in acquiring one? Do the elements of these processes have a comparable likelihood of occurring? Are the resulting organisms viable? Are they comparable in their viability to their progenitors? Is their selective fitness comparable? All these questions need to be answered in the affirmative before the discussion becomes worth having. What information do you have on them?

Also, how would you know if any particular species had not successively gained and lost multiple traits in the process of adaption to a dynamic environment.

If we can't tell, what is the point of this discussion? It's totally hypothetical, without reliable evidence to support any conclusion.

I have not done an audit of all life on Earth but the little bit I do know shows what I believe is a clear disparity between the loss of traits and the gaining of them. You can't argue with the numbers.

So, although we cannot reliably deduce, from living specimens, genetics or the fossil record, whether losses of 'complexity' (what's complexity?) are more or less frequent than increases, you've decided to assume that the 'numbers' support your -- what did you call it -- 'pet theory'? Breathtaking.

Firstly, from studies I have done so far, a block point deletion appears to be the most frequent type of mutation (nearly twice the frequency of any other). Similarly, the loss of a trait, from a block point deletion, is more likely than gaining a trait by any other method. This doesn't mean I am right. Just that I am right in every case that I have examined so far. It is also simple biochemistry.

The point is that simple evolutionary theories are not as clear cut as such a reductionist view of things may appear. Reality is clouded by complexity and variety. To conclude that because an explanation works in one particular case, that it is applicable to all cases, is not particularly well reasoned.

Aside from that, you are looking at historical evolutionary trends and applying them to the future, which I do not think is valid. Now that we have the tools to control genetics, and have an appetite for novel technological solutions, we will be likely to drive future changes.

Pierre Teilhard de Chardin among others have proposed that this change of tack, in an evolutionary sense, is immanent and that we are now, in fact, heading for a goal (that he describes as the Omega Point) rather than simply surviving. It is that which I wished to discuss.