Like what KTC said. Maybe some people where born immune to certain diseases/viruses/infections like the flu and strep throat. I know I am because it's rare for me to get the flu and I never had strep throat when my sister did. I never had H1N1. Also I didn't have the vaccine for it.

@binas: You're misunderstanding what I said. I was talking about about how depending on the environment (in sickle cell's case, malaria), it might be more beneficial to have a defective gene (sickle cell) than to be normal.

Hence, one cannot say that one genetic variation is superior to another since it's not that simple.

I am not sure about that.
But in any case, having everyone survive means evolution has stopped. Because even if there is a new mutation, there is no chance for it to spread. Because even if it does have an edge against other "normal" genes, it won't become "more popualr" and will soon dissappear, because all the other individuals with the noraml genes will survive just the same.
That's for evolution.
And if you are saying that there is never clear advantage to certain genes compared to others, then you are basically saying natural selection does not exist.
Then why people prefer more attractive people as partners? Whether it is being smarter, more beautiful and etc.
If it is no clear who's gene's are better, then you are saying there is no connection between the genes of a person and who we choose as a partner. Which means there is no evolution and no natural selection.
And we have stopped to evolve.

There are more benefical and detrimental phenotypes, both naturally (being more/less endurant, allergic, etc), and socially, but I don't get your correlation between survival rate and evolution rate. It's...unclear.

Sargon, i'm sorry but you argument is invalid.

In biology, locis present tons of mutations, but a few ones, like you mentioned, are kept by the natural selection process.

However, having a mutation that gives you a genetic advantage ( IE better chance of reproduction , either because you counter a problem improving your chances of surviving to certain odds or, in case of humans, by improving attractions others have towards you ) will eventually spread it.

Also , don't be confused ; there are tons of allels for the same loci that exist. That is why we all have different genetic material. But the fact that all the allels fix themselves in a particular way (IE : all the individuals of a certain population have the SAME genetic material for one particular gene) is quite unlikely, because of various phenomens that nature created to make sure that genetic material stays diverse and variable.

Out of these phenomens, I can write you about a few of them (but forgive my translation mistakes, might happen. I took my class in french so I don't know the exact english terms)
--> control of the phenotypical devloppement
--> dilpoïdy (the fact that we recieve random allels from our mother AND our father to form our locis, that will determine our phenotypes)
--> epistasis (A gene will modify the action of another gene. For exemple, siamese cats present epistasis of the fur color ; on cold regions of the body [IE the head, the paws and some regions of the legs, and also their cute tails] the gene stating the color of the fur becomes inefficent, making the fur white)
--> incomplete dominance of certain allels ( for exemple, let's say the allel for the color of the petals of a rose is C for a red one and c for a white one, we could have CC (red) , Cc (pink) or cc (white) if roses are diploïds like us )
--> neutral variation (IE : genes that are there "for fun" )
--> Innefficacity of the natural selection ( EX : You don't have better chances of reproduction if you have a mutant gene that gives you two iris of different colors )

So don't worry for evolution, nature has its tricks, and they work since life has started, for what I can remember

PHENOTYPE : A particular trait we can see , that is variable with genes, from one individual to another

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So basicly, my point is that yes, natural selection DOES exist, but it's not the only evolutionary force in place, and that evolution is a dynamic equilibrum, not a static one. Evolution is maintained, don't worry about it.




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EDIT : Wow, I get the feeling the topic drifted a bit when I look at this biology thesis I just wrote and the title, that was "love, Marriage and committement".

I'll restart the discussion about it ;
What makes a relationship work --> Mutual trust, communication, the conservation of "that spark" that happens when you first see this person and realize you love it from the very deeps of your heart.

How your relationship with your current partner differs from that of your past ones --> It works. Easy answer! But more seriously, I think that the most flagrant difference in the relationship I have right now and the one I had is that me and my lover do share the same major interests, as well as lots of points of view. He also has this maturity of accepting he can be wrong sometimes, just like I can be mistaken, instead of just go to the easy way and "close" the arguments when he doesn't know what to say left. The ability of stepping on his pride is something I never had in my previous relationships and it was really frustrating for the communication part. And sometimes, even the mutual respect.
How children have affected your marriage : I'm not married yet, I don't have children yet, and that is for in a few... couple of years. Honestly, I'm not even sure we will get children (because, at first, it's my partner's wish) and he's not out of the closet yet, and feels too comfortable inside. And i'm not really fancy about the idea of letting him have a fake mariage just for his parents and friends to think he's straight? Nah.

How you manage arguments and disagreements and work past the tough times, etc --> We simply communicate, share our point of view, and stop at the point where we are criticizing each other's judgement. If possible, make a compromise, if not, try to change the problem to get a solution easier on the new one.

Lol what makes marriage work is love and commitment period. Don't get any Rick Santorum ideas here people.

If only Love and commitment were enough to make a marriage / handfasting / civil union / others work, there would be no divorce, honey.

Every couple (except those that only want to fraud insurances) love each other when they decide to build their lives together.

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There is no better chance of reproduction\survival, because modren medicine makes most people able to survive and reproduce(in westren countries).
People can make 8 babies at once(octomom) with modern medicine.
If anything, being in a sane loving relationship is a disadvantage in terms of reproduction.
Most people who make many kids do it from the wrong reasons, or at least, not because of love and commitment.

oo a debate topic! I wonder if this should be turned into its own thread though...

Well, with regard to biology/evolution, it seems to me with how hard the food industry works to keep us ingesting addictive poisons (ie HFCS) we will eventually eschew the need to eat and become reliant on a form of chlorophyll that, instead of reacting to sunlight, will be based on temperature. Or maybe artificial lighting.
Oh, and we'll be immune to cancer and AIDS, since modern medicine fails at healing these things and scoffs at the folk remedies some of which actually work.

Hooray for pure speculation! this is how most some science gets started.

Also,
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Those people (who have kids by the barrelfull) also tend to live in conditions/areas where most of their kids are going to die or go to prison before the age of 25

Love = Not a legitimate emotion on it's own, but a combination of lust & friendship.

Commitment = Natural for some species, unnatural for humans & primates.

Marriage = A business deal between two or more persons, & in some countries, a form of slavery.

I don't believe love is about lust and friendship. What about asexual people? They can love without lust.

I met my husband in a truck stop-I was homeless and without any where to go, I was bumming around the country via hitchhiking with truck drivers. Then I decided I wanted to drive a truck for a living. I soon found out how hard it is to get out of the loop of being homeless. You can't get a job because you don't have a permanent address. You can't get an address because you don't have a job. You can't get training because you don't have an address and on and on. At least that is how it was 32 years ago.

I got lucky this time. He took me in and helped me to stand tall while I learned my trade. He knew how skittish I was on marriage (I'd been married 3 times before) and didn't push me. As I grew and matured I realized that there will never be the perfect someone to come in and provide me with a life. That it was up to me to do that for me. But there was man who was willing to share it with me.
They said that our marriage wouldn't 6 weeks. Well in 11 days we will celebrate our 32 years of being together. Yet through all the ups & downs he has stood by me and forgave me when I've hurt him or royally screwed up. As I've done for him. There is more to love than the warm fuzzies. I wonder if more people would realize it how the divorce rate might go down. So don't give up on finding love. It is out there. And you're right about asexual people. You don't have to get all hot & bothered in order to love someone. After all sex starts in the brain, does it not?

"After all sex starts in the brain, does it not?"

^technically, if my understanding of the Limbus system is correct, all emotions stem from the brain. ;P

BTW it seems I have actual 'love/crush/whatever' emotions somewhere in my decrepit brain:
I have a huge crush on a fictional character.
It's much stronger than any of my real life crushes.
I think I'm going to huddle in my corner and cry since now I understand partially what those Twihards go through
(Doesn't help the story she's in ends badly)

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The thing is that a sane loving relationship comes after some time. The initial feeling is lust which is what is necessary for reproduction. Love comes from getting along with the person along with having lust which is a natural response, again which helps evolution. If you love and look out for your species, the chances of its survival increases. If all the members fight, the chances decrease