[unoti]

It seems to me that natural selection is, for the most part, broken now for humans. Intelligence and other positive characteristics don't seem to get involved in whether they have surviving offspring today the way I imagine it did a few thousand years ago. Is it true that natural selection for humans is mostly dead? Perhaps I'm wrong about this, but it's something that interests and concerns me.

[maratd]

I can't stress enough how important it is to read Darwin's original work. Contemporary understanding of evolution outside of academia is deeply flawed.

There are two forces at work in evolution. Natural selection (survival of the fittest) and sexual selection (reproduction of the sexiest). Out of the two, natural selection is by far the weaker force.

> Intelligence and other positive characteristics don't seem to get involved in whether they have surviving offspring today the way I imagine it did a few thousand years ago.

You're thinking very narrowly in the "survival of the fittest" mode.

You're ignoring sexual selection entirely.

It doesn't matter how hot, strong, or brilliant you are, if you have zero kids, from an evolutionary perspective ... it's the same as if you were killed and eaten by some wild animal.

And, of course, the quality of your offspring matters as well and is determined by mate choice.

There's plenty of evolutionary pressure around today. Actually, I would say it's far more extreme today than ever before, especially in our urban areas.

[Scriptor]

It's rather odd when someone says natural selection is completely 'dead'. Do they think everyone in the world has an equal chance of finding a partner and has the same number of children? Of course not. Even to this day there are factors that determine whose genes are passed down more frequently than others.

I can't stress this enough, but there is simply no goal for evolution. Up until relatively recently, it just so happened that larger brains and other features we consider 'human' have been beneficial. Even if it may not be a big factor now, don't decry it as evolution being 'dead', or even worse, that people are devolving.

If certain genetic traits allow certain people to pass their genes down to more offspring then you have all you need. It's a very simple concept with major consequences.

[seanmcdirmid]

As parent informed us, mate selection is called "sexual selection" and is a force that complements, but is not the same, as "natural selection."

It is good to know the name for that.

[tmh88j]

>It doesn't matter how hot, strong, or brilliant you are, if you have zero kids, from an evolutionary perspective ... it's the same as if you were killed and eaten by some wild animal.

I don't agree with that 100% (the same as just dying part), solely because of the technology and globalization that we currently live with. Even if you don't have children, by simply starting a business where you employ many people, you're essentially providing a means to life for others. If your business is successful, you will have brought life to others via work for possibly generations(which essentially means others can provide a life for themselves and their families). I know that's a bit of a reach, but it's probably true to a small extent, at least in first world countries. Hundreds of years ago, I completely agree with you.

We live in a world where your work can potentially impact billions of people. Sure, you may not reproduce, but you may have enabled many others to do so.

[maratd]

Experiments, both on humans and other animals, have repeatedly shown that there is no such thing as pure-as-white-snow altruism. Whatever appears to be altruistic is either a misfire (essentially error, in biological terms) or is found to be long-term self-interested behavior.

That billionaire is giving his wealth away because he wants better social standing, etc.

In the end, evolution doesn't favor altruism and we have mechanisms that actively discourage it. If that weren't the case, Mother Teresa would have been the happiest person on earth (she wasn't).

> Even if you don't have children, by simply starting a business where you employ many people, you're essentially providing a means to life for others.

The businessman isn't helping others to reproduce. He's being exploited by his employees for their own benefit.

Your example fits within the confines of a parasitic relationship. In evolutionary terms, he is getting nothing from the relationship ... while they are reaping the rewards.

In reality though, even if he didn't start the business ... he still would not have reproduced, so his starting a business is irrelevant and was simply used by others to improve their circumstances.

[ogoffart]

Imagine you have a gene that will make half of your kids very strong, but unable to reproduce. Because of the tendency to protect the familly, your strong kids might help their sibilings to survive and reproduce, propagating their genes.

Another example is the ants. A gene that gives workers good abilities will help the hole colony, even if the worker themself do not reproduce.

[maratd]

It's better to think of a hive of ants/bees/etc. as a single organism. The individuals are cells. Things make much more sense in that context.

You're previous point, though, is spot on. In fact, I think we have genes just like that and not with regard to just strength. You might have a brother who becomes very famous because he's bright/sociable/etc. and your business prospers in the process, allowing you to have more kids. He wins that way, although indirectly. I think this happens a lot.

That's why it's such a pain to talk about these things in such simplistic terms ... life is just so much more complex and frankly, the evolutionary process is so brutal that there really aren't any losing strategies around. You can bet if somebody is doing something, they're benefiting somehow ... we just don't know how yet.

[Zimahl]

Ants have a intrinsic instinct to help the whole colony mostly because they are related the the entire colony.

I may have an evolutionary interest in supporting my nieces since they are my sister's children. However, I probably don't have an evolutionary interest in supporting my nephew since he is my wife's sister's child. Biologically I have zero relation to him.

[aneth4]

I think the point is that businessman selects employees who then make more money, are healthier, and therefore more reproductively interesting and successful. This means that a one can influence evolution without reproduction. This is something like an externally caused drift. The businessman can select who is more likely to reproduce, likely biasing work ethic, respect, etc.

It's a valid point. One should not be so quick to dismiss ideas.

[kristofferR]

Please don't spread the myth of Mother Teresa as an altruistic person, she was anything but.

She cared a lot about her missionary work, but not about the poor. In fact she believed that the suffering of the poor was a good thing and denied painkillers to be administered for that reason (while she was always receiving painkillers for her own medical issues). Sure, she funded a lot of what she called "houses of the dying" where people were left to die instead of often easily treated with antibiotics, but she only really cared about her missionary work.

[emiliobumachar]

I'm curious about the definition of these "misfires" (links?). If any action that does not contribute to one's selfish goals can be classified as an error, then it seems circular logic to conclude there is no true altruism.

[baddox]

Sure, you can do all those great things, but your genes won't pass to the next generation unless you reproduce. Evolution is a specific thing: the ongoing change in the inheritable traits of a population. Humanitarian efforts are great, but they have nothing to do with evolution in this context.

[tmh88j]

> but your genes won't pass to the next generation unless you reproduce.

The comment on which I commented said something along the lines of "you might as well just die if you don't reproduce", in reference to evolution. Yes, that is true (in regards to carrying on genes), but that's not the point I was making. I essentially said in today's world, if you're successful in establishing a business which creates jobs, you are essentially harboring other's abilities to reproduce. I guess you could say you can "indirectly reproduce" due to globalization and technology.

[da3da]

Your points are valid but I think you're arriving at the same conclusion that the parent is. Since the population groups that have lots of children are generally less intelligent and poorer, evolution is currently selecting for less intelligence. Though the parent called this natural selection, he was really refering to sexual selection, which as you noted is the more important force.

[jonathansizz]

And I can't stress enough that selection and evolution are not equivalent; selection is only one evolutionary force, and in humans probably not a very powerful one due to our historically low effective population size. Other forces in evolution include genetic drift, migration (gene flow) and mutation.

As the article discusses, the major characteristics of human populations in the recent past centre around demographic changes i.e. small populations where drift dominates, giving way to massive population expansion, where mutation and drift likely play a much more powerful role than selection does (for nearly neutral variation, which is the vast majority of variation).

This could potentially change if the human population ceases its expansion, stabilizing at a greatly increased level for a long period and with high levels of gene flow. In this case, selection could have more of an impact on nearly neutral variation than it previously has.

[baddox]

Although there is obviously some debate among scientists, natural selection is considered to be the most important force by far.

[jonathansizz]

By whom?

I suggest you read up on nearly neutral theory and think about the fate of nearly neutral mutations (the vast majority) in groups with small effective population size (like humans).

[cup]

Would this then make the case even more pessimistic, considering there is an inverse correlation between family sizes and parental education levels.

I.e. smarter individuals have less (or no) kids.

[mahyarm]

Urbanization in general reduces family sizes. Something like free RISUG procedures for 13+ males, and the procedure being promoted during sex ed classes would probably reduce irresponsible pregnancies significantly. Even the US government would benefit significantly from reduced expenditures with a program like that.

[bicknergseng]

The Mike Judge/Idiocracy Theory of Evolution.

[baddox]

It might be pessimistic if you're egalitarian, but nature doesn't seem very egalitarian.

[baddox]

Did Darwin really make a distinction between natural and sexual selection? As far as I know, the distinction doesn't really exist in modern biology. Natural selection is simply selective pressure that comes from the environment, and the psychology and behavior of potential mates are part of the environment.

[e40]

Your comment made me think of Idiocracy (the movie), which is always a good thing. :)

[crusso]

The first few minutes of Idiocracy covers all the bases and is very insightful in its presentation.

[emmelaich]

I you consider the gene as a the unit of selection then it is not necessary to have children for selection to occur.

[pyre]

Just because Natural Selection(tm) isn't selecting for attributes that you regard as important doesn't mean it's dead. What it takes to have a better chance of survival now might be different than it was decades/centuries/millennia ago.

If "having what it takes to climb the corporate ladder" is what gives your offspring a better chance of survival, then that is what is being selected for.

[potatolicious]

"Survival" in the evolutionary sense is not "survival" in the social sense. Natural selection only works if unfit individuals are killed off prior to breeding.

I don't think it's a stretch to say that, even in the least developed areas of the world, this is no longer the general case.

Humans are no longer subject to natural selection, since nearly everyone survives to breed.

[lotharbot]

Natural selection doesn't require death, it just requires different reproduction rates based on genetics.

Natural selection works strongly when group A dies before reproducing and group B does not. It still works, though more weakly, when group A has an average of 2.0 offspring and group B has an average of 2.1 offspring.

In some parts of the world, natural selection is still significant (the common example: sickle cell anemia drastically increases malaria survival). In many parts of the world, though, differential reproduction appears to be a result of culture / religion / personal choice; it's not well understood how much this relates to genetics, and therefore not clear how much it deserves to be called "natural selection".

[pyre]

  > Natural selection only works if unfit individuals
  > are killed off prior to breeding.

  > since nearly everyone survives to breed.

No one needs to be killed off for natural selection to work. If they have some attribute that prevents them from finding a mate, that is also natural selection at work.

[shard]

Right, in other words, they are killed off by old age prior to breeding.

[baddox]

> Natural selection only works if unfit individuals are killed off prior to breeding.

That's not true. Even in the hypothetical scenario that all humans reproduced exactly enough to replace themselves then died immediately (i.e. a completely constant human population), there would almost certainly be gradual change in the inheritable traits of the human population (i.e. evolution). If sexual partners are chosen, and those choices are inheritable traits (i.e. genes influence your choice of mate), that's textbook natural selection.

> even in the least developed areas of the world, this is no longer the general case.

A very large portion of the most successful pride of lions probably also breed, since they're not worrying as much about food or predators. Does that means the entire species is not evolving?

[lotharbot]

If genes change in proportion because they make people more or less likely to reproduce, that's "natural selection".

If the genes change in proportion just due to randomness (they're all equally fit, but some were passed on more times than others as a fluke), we call it "genetic drift" [0].

Evolution involves mutation and gene flow [1] adding new genes to a population, and natural selection and genetic drift changing the relative proportion of various genes within the population.

[0] http://en.wikipedia.org/wiki/Genetic_drift

[1] http://en.wikipedia.org/wiki/Gene_flow

[baddox]

I didn't mention any changes due to random sampling. I was careful to qualify that the choice of mate is influenced by genes. Wouldn't that qualify as natural selection more than genetic drift? Although, now that I think of it, the two are probably more like directions on a continuum, since choice of mate would be influenced by both genes and random sampling. Is that accurate?

[lotharbot]

If choice of mate is influenced by genes, and there's a difference in fitness level due to those genes, then it would be natural selection. That is, if Alice-Bob have more kids than Claire-Dave for genetic reasons, natural selection is favoring AB over CD.

If choice of mate is influenced by genes, but there's no difference in fitness level, then you're looking at a natural drift scenario. That is, if Alice-Bob have more kids than Claire-Dave due to some random effect like happening to meet much earlier in life, AB's gains over CD are classified as drift.

Both effects are usually present, but sometimes one is much more significant than the other.

[Scriptor]

Even if everyone survives long enough to have children, that doesn't mean they all have equal numbers of children.

[azakai]

> Intelligence and other positive characteristics don't seem to get involved in whether they have surviving offspring today the way I imagine it did a few thousand years ago.

Selection is always active.

First, there is sexual selection, not just natural selection, and there is no reason to assume that is not important today.

Second, as the article says, there is more genetic variety than before - we accumulated a lot of variation in recent millenia. That's the necessary foundation for selection.

Finally, a quick look around shows that some people have more children than others. You mention "Intelligence and other positive characteristics", but the fact is, it isn't clear intelligence was ever more important than say brute strength/social skills/etc. in our evolutionary history, so the fact it isn't the main factor now says little. But there definitely are factors that do contribute to having more (thriving) children today, and we are selecting heavily for them, for better or for worse.

[nhaehnle]

it isn't clear intelligence was ever more important than say brute strength/social skills/etc. in our evolutionary history

The juxtaposition of intelligence vs. social skills is amusing given the Machiavellian Intelligence Hypothesis, which suggests that our general intelligence basically evolved precisely as a means to get ahead in the social games that are relevant for sexual selection.

If you can reason abstractly about what some rival is going to do and examine the "game tree" of potential actions, that is surely an advantage both for sexual selection and, say, debugging or proving theorems.

[jnhnum1]

One thing the article mentioned was that people are choosing not to have kids. In this case, it seems that there should be an extremely high selection pressure for people to be genetically more predisposed to want kids. And if this does evolve to be the case, then as long as technology does not make reproduction free (in economic terms, there is currently a finite "supply" - the number of fertile women in the world times one baby per year), then competition on other traits will begin to be more relevant.

So while people are saying that evolution is "selecting for less intelligence", this may be a short-term effect in which we are first as a species shifting to stronger reproductive urges at the expense of general intelligence, and only then increasing intelligence in a way which doesn't allow philosophical objections to having children.

But evolution is pretty complicated, and difficult to reason about. Other people have also mentioned the "selfish gene" effect, in which altruistic / kinship behavior can be good for a gene, but suboptimal for an individual. It's possible some weird effect like that is going on also.

[lindbergh]

At any rate, it seems evolution has shifted from an individual action, to a cultural (or, dare I say, a civilizational) action. And from a cosmic point of view, it makes a lot of sense.

[baddox]

Why would natural selection be dead? I don't see why humans would be any more immune from natural selection than any other species. At the bare minimum, people still choose their mates (and some die without reproducing), so unless these choices are completely unaffected by genes they should be causing a gradual change in heritable traits among the human population.

[nooneelse]

Indeed, and we are probably facing new selection pressures. Such as the propensity toward addictions to substances our ancestors would not have had (http://www.guardian.co.uk/society/2012/nov/28/painkiller-add...).

[baddox]

Not to mention the constant arms race with biological pathogens.