make that 3 evolutionary questions (this ones easier)

Philosophy Forums Philosophy
1

yeah hermes i almost rudely posted this in response to yours…

how can you learn things and store the ideas in your genes. i thought all we ever learned was in some kind of electric form that zapped around inside or near our brain.

i mean a brain is necesary to learn and understand things, and as far i know a brain doesnt have the ability to recode your DNA.

so if im a fish living in an area with a dry season that dries the lakes so that sometimes if im unlucky, ill get stuck in a little lake that dries way up. and i have learned, using my brain, that i need to flop out of it and try and land in a nearby bigger one. ill also learn that i wish i could breathe air to make this easier.

so does that mean my brain tells my genes to start building lungs instead of or in addition to gills, and then also tells my kids the same?(id obviously say no: how does my string of atoms know how an air breathing machine works?)

are lungs nothing but gills that have tried to breathe so much air that by the end of their tortured life they actually are able to breathe air better than when they started?

or do i just one day somehow have a mutant kid who gets smacked with gamma radiation when hes a fetus and hes born with lungs at random (instead of a swirly-shaped-liver-foot-like thing in the middle of his face, like his brother got stuck with) and he ends up ruling the fish world and having millions of lung-ed babies?

i would have said god zapped some lungs into me because of overcrowding in the oceans, or some fact about land animals that makes them a superior goal to evolve your planet towards, definetely not random luck, because if it were random, couldnt you say its possible for a plutonium breathing lung to be randomly formed in some kid? for no good reason? theres not much reason to think that it hasnt… but… comon…

so what is the mechanism that decided to give that fish a lung? his brain? gill damage caused by trying to breathe air? random fetus-radiation-induced organ invention? or every smartass’ worst enemy, god?

2

well, it was human brains that developed the science to do just that…

aleph.se/Trans/Individual/Body/genes.html

I think you are confusing learned behaviours and instinctual behaviours…

-Imp

3

how do you learn an instinctual behavior?

id say you dont! i think most people would agree

then what do you call it when an animal suddenly has a new instinct that his dad didnt? evolution? how did it happen? im saying that we cant learn instinctual behavior the same way we learn learned behavior.

so what aims evolution at molding the lifeform the right way? ie how did something decide to make a lung?

do not explain natural selection, i know what that is. im looking for something along the lines of ‘when he was a fetus the mudskipper got gamma radiated and that bashed around his DNA in a crazy random fashion. just so happens that that crazy randomness scored him a lung’

is that it? is there nothing besides the randomness?

4

the same way as unlearning instinctual behaviour…

and why does there need to be anything besides the randomness?

-Imp

5

why do i keep thinking that people say stuff on this board just to annoy others?

if your gonna be sarcastic, you should be making a statement with it indirectly; i see no statement except that, like i said, you cant learn instinctual behavior (or unlearn it right?)

no problem with randomness? a velociraptor fetus can be zapped with gamma radiation in such a specific way that it can zap into him the knowledge that if he makes himself really light, turns his scales into feathers and learns how to build a nest by twisting twigs into a knot, then

oh wow he can be a bird except oh wait the gammarays perfectly made him a bird except one thing: liver for a face… damn now that kid is a waste, who knows how long before the fetus randomly mutates into the exact niche animal we are looking for.

how come we dont see some serious randomness today? elephant man isnt random, random is you build a special new lung that extracts oxygen from an ocean full of liquid plutonium. if you say air lungs were random then thats like saying that we can randomly invent a new organ that suddenly extracts oxygen from whatever the hell we want.

even better, if you can evolve from a plant to an animal then you can actually randomly create the ability to ‘move’ when nobody else has ever moved before. you can from animal to the next step. imagine the comparison of those two analogies.

plant is to animal
as
animal is to superman

i think we are just about due to see somebody evolve randomly so that they can fly and have infinite strength and changes color. not.

6

-Imp

7

dude are you trying to turn this into a pfloyd-POR type fight post? cause i wanted to learn about evolution

thanks a lot

8

Biology class people…attend it. All you seek will be answered there.

the lung did not simply appear magically one day beacaue of gamma radiation. considerign the sheer volume of DNA coding for lung structures, to have radiation that destroys DNA molecules wholesale to magically create perfect lungs in an offspring is quite unliekely.

What is much more likely is that the lung evolved slowly from precursor organs. A lung is just a folded wet membrane trough which gases can pass to and from the bloodstream. the folding is just to optimize surface area/voume. the skinof a frog serves the same purpose. One can imagine an evolutionary path…

An animal hides form a predator in shallow water, maybe even creeping out of the water to escape. it’s wet thin skin lets it absorb some oxygen, surviving long enough to avoid being eaten. Animals that could survive longer outside of the water had an advantage because dray land was unpopulated at this stage.

There are many such paths toa lung, some more likely than others.

The important thing is, randomness accounts for the variety of genes. radiation, transcription errors…then the enviornmental conditions and sheer dumb luck pick the best ones.

Or so the theory goes. fo course there are subtleties i’m omitting because this post would be too long if i balbbed on about everything.

9

tminionman: you need to post here at least half as much as i do, and mostly just talk to me

thank god ive been waiting for someone to say that for a while

so i am to understand that the blood cells in all organisms from precambrian protojellyfish forward (or all of them? doesnt matter)can absorb oxygen just by rubbing against the molecules in whatever medium they are contained?

how does the skin of a toad evolve so that it can connect to the throat and trachea? could that happen to a human today?

do the gills of a fish connect to anything resembling its throat or trachea or do they just inhale from the slots on their side? can gills turn into lungs?

most importantly, what is the mechanism?

obviously, the only thing i can think of is radiation hitting a small, contained fetus so that one cells dna gets mashed around randomly and its spreads the message to a sufficient number of its neighbors to change the final structure of the baby.

it seems like you have said its possible that a toad can stay out of the water for a good amount of time, and by doing so change the dna that he sends to his children so that they have a greater ability to breathe through their skin.

i would say there are three ways that a toad can improve his air breathing ability. one is that, through breathing, he stretches out those pores by increasing the amount of air travelling through them by using his muscles to expand and contract his whole body like a lung. more air than normal flows through them so they stretch. and if this is the case, then the dna doesnt change and the toad never evolves into the land lizard.
another way would be that the toad uses his brain to realize that this throbbing he does involuntarily is actually what increases his skin breathing capacity, so he then makes sure that he throbs passionately whenever he is out of the water for whatever reason. this brain knowledge then has the as yet unexplained ability to rewrite the toads genetic code.
the other option is the dna in the cells of the toad, the skin cells, brain cells, all of them… wherever they are, the cells themselves, who seem to exclusively hold the ability to manually rewrite dna, those cells realize that increasing pore size will help air breathing and therefore they rewrite their own dna so that the toad and his children will have better air breathing pores than their grandfather.

evolution moves forward because the dna of an organism changes. what physical process makes it change?

10

Answering your last point first, that’s not what I was saying. I said (or meant to) that the proto-toad that can climb out of water longer has a greater chance of survival than creatures captive to the oceans, and so will more likely pass his genes that give it that ability onto offspring. In the random variation of the next generation, some toads will likely be a little better at it than the original, and so they survive and reproduce. That’s Darwinian evolution.

There are 2 barriers that keep Lamark’s process from happening.

  1. The whole DNA-protein system is not bidirectional. A change in DNA will change the body by changing and regulating proteins and cells. However, a change in the cells will not change the parent DNA.

That said, there are molecules that can regulate the expression of DNA. Proteins can bind to a gene, inactivating it. Such signal molecules can change an organism this way (sexual hormones do exactly that).

  1. That doesn’t help Lamark, however, because the signal molecules only make a difference in somatic cells. Reproductive cells have their own preprogrammed regulation (they have to develop correctly). A change in somatic cell DNA or its regulation does not automatically change the reproductive cells’ DNA.

You are correct about early animals absorbing oxygen directly. Animals didn’t need circulatory systems until they got so big that the oxygen wouldn’t diffuse into their inner cells.

Diffusion is the “rubbing” thing you were talking about. Oxygen, CO2, and other small molecules will naturally diffuse through a cell membrane. The bloodstream has chemical called hemoglobin which bonds to oxygen and delivers it to your cells.

As for how the lung actually evolved, that’s just my late night postulate. It may have nothing to do with skin at all. I just wanted to show you that a lung really isn’t that “magic”…it’s just a membrane. It’s not one big step at all, but a series of small and seemingly insignificant steps that over time craft a lung or stomach or something like that.

Humans might evolve such things if some pressure selected for humans that could stay underwater the longest. It would be very difficult, however, because our bodies are so specialized for land. We don’t have any precursor organ to evolve gills from.
Remember, whales and dolphins were land animals at one time…millions of years later they still don’t have gills.

There is no one physical process that makes it change. It’s more that many factors contribute to variety of offspring. Radiation, transcription errors, changes in the regulatory molecules, and so on all create genetic diversity. The variations of genes in the “right” direction survive, and the variations in the wrong direction die….statically speaking.
Also, DNA in complex animals is regulated extensively. Scientists are finding now that RNA and other molecules control the direction of an organism’s development almost as much as the DNA itself.