How is Natural selection a mechanism?

CRR writes: Even though gay people can have children natural selection should work so long as on average they have less children than straights. One explanation is that being gay is not due to genes, not heritable, so then natural selection won't have any effect. Perhaps it is a trait that appears randomly in each generation.

It is also possible that homosexuality is a somewhat rare side effect of another attribute that is being selected for, such as group empathy, heterosexual sex drive, or intelligence. As long as the side effect remains low then the much more common effect that is being selected for will continue to maintain the attribute in the population.

AndrewPD writes: Here is a simple analogy of entropy. You drop an uncooked egg and it shatters. I don't think there has ever been an instance where that egg has in the next moment or later returned to being an unbroken egg.

That has more to do with quantum mechanics than thermodynamics. As far as thermodynamics goes, if you dropped the egg into a bowl, and then lifted the bowl back to the height the egg was previously at you will have moved the system back to the entropy it had before. The energy used up in the system was the gravitational energy released during the fall.

Human interventions do seem to effect entropy because volitional actions and intelligent perception allow us to create improbable states of order.

Not restricted to humans. Birds can arrange fallen twigs, leaves, etc into a nest. Beavers can dam up streams. Both are examples of entropy decreases in a part of a system.

Edited by NoNukes, : No reason given.

Here is a simple analogy of entropy. You drop an uncooked egg and it shatters. I don't think there has ever been an instance where that egg has in the next moment or later returned to being an unbroken egg.

What about a salt solution precipitating a crystalline structure?

If that's not, according to your meaning, a "decrease" then dissolving the same crystalline salt structure must be...

So which way is it, according to your understanding?

Honestly, you haven't completely grasped the concept of entropy yet.

Do you have any idea what natural selection is?

Natural selection happens when there is differential reproductive success over multiple generations. Those that have more offspring are favoured and those with less are disfavoured.
It's not necessarily the fastest or the strongest that succeed.
Over 1 generation chance can play a big factor but over multiple generations it tends to even out.

All of that is quite true. It's somewhat like how sickle cell trait provides some immunity to malaria. In that case sickle cell trait is a harmful mutation affecting red blood cells and malaria resistance is a side effect. In malaria prone areas at low allele frequencies the beneficial side effect is stronger than the harmful ones, but by the time it reaches 20% the harmful effects dominate. (If it's not a malaria prone area the trait provides no benefit.)

And if homosexuality is not heritable then natural selection won't work at all. AFAIK it's not heritable so no natural selection.

CRR writes: And if homosexuality is not heritable then natural selection won't work at all. AFAIK it's not heritable so no natural selection.

I don't think there are specific mutations that are directly linked to homosexuality, but there rarely are for complex characteristics or behaviors. I would view sexuality as more of a spectrum and the result of many, many genes interacting, along with social interaction.

What we may also be ignoring is the nurture side of the equation. Higher population density may trigger different types of social and emotional development. A good example can be found in some insect species, such as high population density turning grasshoppers into swarming locusts that includes obvious morphological changes. Homosexuality may actually serve a positive role when population densities get high by reducing competition for mates while maintaining kin selection.

Of course, what we ought to do is not determined by what is being selected for or against, otherwise known as the Is/Ought problem.

CRR writes: Natural selection happens when there is differential reproductive success over multiple generations. Those that have more offspring are favoured and those with less are disfavoured...

Nearly accurate, but not quite. One thing you forgot to mention is the environment.

You forgot about those organisms who don't have a lot of offspring; yet their genes spread amongst the population in the environment which they live in.

Any good summary of natural selection will include mentioning the environment...

Edited by Pressie, : No reason given.

Edited by Pressie, : No reason given.

Taq writes: I don't think there are specific mutations that are directly linked to homosexuality, but there rarely are for complex characteristics or behaviors.I would view sexuality as more of a spectrum and the result of many, many genes interacting, along with social interaction.

Exactly. It's a combination of genetics, the chemicals experienced in the womb, the environment people are raised in, etc.

Let's start with genetics. Some people are born with both male and female genitalia.

No choice involved.

Edited by Pressie, : No reason given.

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Edited by CRR, : No reason given.

AndrewPD, has your original question been answered yet?