Why do fossil records only show one-directional evolution when the earth returns to more primitive s

reply to post by ElOsoDurmiendo

If evolution is a species changing to keep up with the environment isnt it still evolution if a trait or feature is lost? Using the Alaska and Florida example, if you moved back to Florida and your hair thinned back to original thats evolution and adaptability at work. Even tho you are going back to the way something was in the past you are still evolving.

Correct with the proviso that individuals don't evolve; populations evolve. Every generation is a little bit different from the previous.

If your hair is thicker in Alaska than it is in Florida, then that is a trait that you, as an individual, possess: the ability to thicken or thin your hair depending upon the environment. You are not 'evolving' that trait, you are just taking advantage of a trait that was passed to you from your parents. Your parents may have had that trait or may not have. If then did not, then it is one of the little differences between your generation and your parents. A lucky 'random mutation'.

If that trait gives you an advantage over others that don't have that trait so that you can attract a better mate or feed yourself better so that you can produce more or stronger children, then that trait will, over time, increase in frequency in the gene pool. Each generation will have more and more individuals with that trait. It is the population that is changing over time, not the individual. Individuals die with the genes they are born with.

Damage to your genes can of course occur, but you don't suddenly 'evolve' a sixth finger when you are 30 years old, or suddenly find you can thicken or thin your hair at will. Of course, changes to reproductive cells and cell division errors happen all the time, that is the source of 'random mutation'. Those changes affect the offspring, not the parent, each generation is a little bit different that the previous. Sometimes it is a bad difference; sometimes it is a good difference; the overwhelmingly majority of the time the difference makes no difference at all, 'natural selection' describes how that 'good, bad, indifferent' process plays out.

Having said all that, the idea you are trying to get across is correct. A change is not 'backwards' or 'forwards'. It is just different than before.

I think a better example might be your credit card balance. Suppose you have a credit card balance of $135 and buy a chair for $100 on your credit card resulting in a new balance of $235, then make a $100 payment so you are back to $135 (ignoring interest and fees for the moment). Then you buy a table for $100 so your balance is again $235. Your balance is changing up and down, but it isn't 'devolving'. Your account after the chair is not the same as the account after the table even though the balance is the same; it has several 'extra' transactions for a start. Those transactions may have other effects that are not immediately noticeable, like transaction fees or interest or account taxes, whatever.

reply to post by rnaa

reply to post by rnaa

reply to post by ElOsoDurmiendo


Sorry, I can't quite understand what you are saying there.