What change must have occurred during the evolution from invertebrate chordates to vertebrate chordates?

Ithink sanforcisco california (i am not 100% sure) if you feel the opposite so that lol

Because some people pollute water ans waste it

Ibelieve this is the answer:     evolution has no "goal". it is "simply" the survival of the fittest under a given condition. what should be the advantage of living longer? getting kids (=spreading the own genetic information) is done latest until the mid-40s after that we have not much biological meaning.  in addition,  not only does evolution not have a "goal," evolution doesn't necessarily mean "make us better! " it's absolutely possible to evolve negative traits.    hpe i could : )