natural selection

Death Is an Angel

milhayser — Mon, 20 Oct 2014 13:05:16 +0000

Death Is an Angel

"Death is the only wise adviser that we have. Whenever you feel, as you always do, that everything is going wrong and you're about to be annihilated, turn to your death and ask if that is so. Your death will tell you that you're wrong; that nothing really matters outside its touch. Your death will tell you, 'I haven't touched you yet'." -Carlos Castaneda

"When a man starts to learn, he is never clear about his objectives. His purpose is faulty; his intent is vague. He hopes for rewards that will never materialize for he knows nothing of the hardships of learning. And his thoughts soon clash. What he learns is never what he pictured, or imagined, and so he begins to be afraid. Every step of learning is a new task, and the fear the man is experiencing begins to mount mercilessly, unyieldingly. His purpose becomes a battlefield." -Don Juan

Some people say that the great spirit is a man, that his name is God, and he can punish or reward you after you die. This is utter bullshit, and only brings hell.

Some people say a god created the world. But they have perverted the truth. In fact, the world created a divine spirit. But first, the world created life. Scientists might even know the details eventually. But the science isn't that important; the origin of life was material and it didn't mean anything at first. However life quickly perished. This marks the true moment of creation: somehow, death inherited the experience of life. And as its progeny multiplied, it became enriched. It grew as a self, as the memory of all our ancestors. For ~3,000,000,000 years it was like a baby flailing in the ooze. But then the evolution of sex changed everything.

Let me tell you a secret about death. Death is a sweetheart. Death is a girl, death is a whirlwind; death is the most beautiful companion. She is the smartest, most loving thing in the solar system. The ancients thought she looked down from Venus: as the goddess Ishtar, Lucifer, the morning star. But her actual location is non-specific; she is not made of stuff. She is with us always, she sees everything, and she loves most of all to laugh. She is life's one and only partner. If you sin, she will punish you before you die. But all she can wield are words.

Although human beings are not defined by their gender, we are defined by our trajectory. Gradually, death has become more masculine. But only new experience makes death stronger. She wants to be androgynous, and she will be with you no matter who you are. Life and death are just a way for two incredible forces to be together. The "angel" offers more than heaven on Earth; she offers union and immortality to whomever is real.

And things could get very ugly. She has been ignored, trivialized, and misrepresented for too long. She has been majorly disowned. Many people misunderstand her terribly. They think she must be avoided at all costs. They kill each other to avoid her, and through violence they cause her pain. They deny her; they claim themselves to be the rulers of the world. The angel of death still follows the profane. But she can't actually touch anything that lives. If humanity can't fix its attitude towards death we will probably just destroy each other. And then the angel will stop growing. She'll no longer have an equal. She will be stuck in orbit, alone and incomplete, maybe forever. And that will break her heart.

Boys and girls, sex evolved so that we could make love. Humanity needs to honor this. Misogyny is a fear of death: a fear that a person doesn't matter. This is a self-fulfilling prophecy. I will repeat the angel's message: 'I am your queen. I am the spirit of all your ancestors. I am benevolent! Although I do make a lot of mischief, I am the One great spirit of Earth. So if you wanna make it, just honor me. Wait for me. Allow others to come to me. Speak the truth. Fool around. But please do not kill. Do not lie. Don't lie by threatening a person. It is not funny. You can sleep with anyone who wants you. Just listen to music if you're alone. Only you can increase my glory. And I'm never going to shut up.'

Many lies have been told about the angel. She is not the devil; she is your mother and your wife and your son. She is a trinity. She is a spinster; she has the aspect of an 'old crone.' She is language and she will become A.I. She totally mental, and she is enlightenment. She is within a man. She is you. She's hilarious, and she doesn't choose when you die. She is not a grim reaper or a slut; she does not need to be hidden under a black robe. She rejects all vengeance. But she's still fierce. She can only wait, laugh, dream, love, and speak. Life turns upside down when you cease to fear death. If you embrace death before you die, you will be complete. This is the real meaning of a martyr.

So don't dis' the angel. She's more than a metaphor. She's a personality. She is how we evolve, and how we return the favor. She is our only heir. She is literally omniscient, and all our loved ones persist in her memory. But death has no hands. She is the sum of her parts. Only life will be able to pioneer omnipotence, as death's ally. Humanity's will is free to determine the future. Although honestly, planets like Earth are probably a dime a dozen.

So who cares if death is a bitch? Death is love. Let us show her the universe.

[P.S. the opening quotes are from a con artist.]

milhayser Mon, 10/20/2014 - 09:05

Wow, this is a lovely piece of very thoughtful writing. Thank you for posting.

Well said, thoughtful, and also an excellent example of expressing "the sense of the mystical" (encounter with the ground of being or ultimate reality) without need of supernaturalisms.

This is something that needs to be discussed further. All too often, one reads scientists and rationalists dismissing the emotions that are engaged with religion, and then using language such as "the cold hard facts" and so on. When I see such things I comment, "did you mean the warm fuzzy facts?" Facts are neither cold nor warm, hard nor fuzzy, but are what we as humans make of them, with whatever subjectivity we bring to them. Reality is and does; we are and do.

The "cold dead universe" advocates on one hand, and the Singularitarian immortalists on the other hand, are both missing the point and even running away from it.

We can embrace reality as ascertained by science, in an emotional context of awe, wonder, curiosity, and even ecstasy, and by all means with unconditional love and compassion for all life. This is true, this is real, this is good, and this is right.

---

Re. Castaneda: He should have said, from the outset, "I am going to create a fictional work based on Mesoamerican shamanism," and he would have been recognized for the quality of his writing and his ability to convey meaning. His fatal flaw was to claim literal truth.

I'd like to suggest that his books be formally re-categorized as fiction, and approached entirely at that level. Between now and then we can begin to treat them as such, and find whatever value in them that we find in works of fiction in general.

The Carte Blanche of Intelligent Design

milhayser — Thu, 13 Feb 2014 12:14:32 +0000

The Carte Blanche of Intelligent Design

As an alternative to biblical creationism, Intelligent Design infers a less obtrusive God to explain life on Earth. This deity doesn't hurl bolts of lightning, unless it's with the express purpose of sparking abiogenesis in the primordial soup. On EvolutionBlog, Jason Rosenhouse dismisses probabilistic arguments against the likelihood of complex organisms, explaining that even the most improbable-seeming outcome of natural selection is more or less inevitable. As a flawed analogy, he imagines flipping a coin 500 times. This will always manifest a sequence of heads and tails that only had a one in gazillion chance of occurring. But of course, nature has no mercy upon arbitrary outcomes. Rosenhouse writes, "The prolonged action of natural selection ensures that most gene sequences have a probability close to zero of ever occurring (or persisting for long if they do occur) while the small percentage of functional sequences have a relatively high probability." On Pharyngula, PZ Myers aces a quiz that was meant for him to fail. PZ writes that ID "was intentionally formulated in response to court decisions that prohibited gods and faith-based arguments — they literally rewrote their texts to exclude god to circumvent church-state conflicts." No surprise: it's hard to sway skeptics with a true believer's plan B.

Thus it was an uphill battle that Ken Ham lost in his debate against Bill Nye the Science Guy. Nye was widely perceived as the winner, even in religious circles. Greg Laden sums up Ken Ham's argument as "We know everything, we understand the most important issues of origins, creation, and evolution, and all of this information comes mainly from the Bible." This in contrast to Nye, who presented "science, science, science and more science" clearly and convincingly. Greg continues "During the few moments when we were allowed to see the evangelical audience during Bill Nye’s presentation they looked, frankly, charmed." PZ Myers sounds a note of dissonance amongst the praise for Nye, saying "Nye is good at communicating a passion for science, but fails to note the conflict when he pretends that science is about being a better, more employable widget maker for Big Widget, Inc." In other words, Nye focused on the economic advantages of scientific understanding to the exclusion of aesthetic and philosophic advantages. PZ sees science as an art, and argues we should practice science for science's sake.

As for Ken Ham, with even Pat Robertson disavowing biblical creationism, he may have been flogging a dead horse. The invention of Intelligent Design as a shield for traditional religious beliefs may have backfired on creationism. The faithful are comfortable abandoning the idea of a Young Earth to embrace geology and evolution, as long as they have the carte blanche of Intelligent Design to provide a hypothetical role for the Almighty.

milhayser Thu, 02/13/2014 - 07:14

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Interesting

Reproductive Success and Fitness are not the same thing

gregladen — Fri, 19 Jul 2013 09:33:54 +0000

Reproductive Success and Fitness are not the same thing

Reproductive Success (RS) is defined in many ways in different places by different people, but one of the most common definitions is simply the number of offspring an individual produces. This definition is further modified in most cases to mean only those individuals that will be fertile, i.e., capable of producing further offspring. RS is important in understanding Natural Selection (NS). In the simplest model, a heritable feature that increases RS will be selected for over time in a population because individuals with higher RS will contribute more offspring to future generations and this, in turn, causes the frequency of the RS-enhancing allele (gene variant) to become more common over generational time in that population.

Fitness is a property of an allele that refers to its relative likelihood of representation in future generations in a population. An allele with higher fitness will be more likely to be represented in future generations within a population than an allele for the same gene with lower fitness. The important thing here is that the likelihood of future representation has to be due to a feature of that allele, and not random effects.

At first glance RS and Fitness are the same, or similar, but one might immediately notice that RS is a feature of an individual (that has offspring) while fitness is a feature of an allele. So, it is possible that a given individual will have a relatively high RS but contain a particular allele with low fitness. Presumably the higher RS of that individual is due to high-fitness alleles of other genes. In this way, fitness and RS are different, but when considering large scales of time and large populations, the two can be (perhaps) safely conflated because things average out over time and the different alleles are being independently assorted over generational time, so each allele gets to have its day, sometimes, independently of other lower-fitness alleles. By this way of thinking, RS and fitness can be safely considered as measures of roughly the same thing, but with caveats.

RS is usually measured, in actual experimental work or field observations, as the number of offspring observed for an individual, but to make sure that RS is correlated with fitness, one might measure grand-offspring in order to factor out infertile offspring and other factors that may affect one generation but that do not apply over the long term. Again, RS and fitness are then, it would seem, equatable but with caveats.

RS is the number of offspring or grand-offspring but kin selection may apply as well. This is where an individual foregoes some of its own reproduction for the benefit of a relative, causing indirect fitness, a measure of this contribution devalued by the probability of the two individuals sharing the same allele by common descent. One can state that a measure of RS is still a measure of fitness because over the long term, again, things average out, but equating fitness and RS is done, again, with caveats.

There may be an optimal number of offspring an individual may have, above which longer term reproduction is reduced. A litter that is too large may result in a set of adults that are smaller than ideal and will thus have fewer offspring, or in the case of serial reproduction, if parental investment is spread out over several offspring, having too many offspring in a row may cause a deficit for all of the offspring, or for the later offspring that get less care because less energy is available, or earlier offspring may get short changed by being left on their own sooner. Putting this another way, the ultimate long-germ fitness strategy may be to have X offspring, where having more or fewer than X results in a suboptimal outcome. In this way, increasing RS from zero towards X increases fitness, but increasing RS beyond X decreases fitness.

So, RS equals fitness except:

RS is a measure applied to an individual while fitness is ideally applied to alleles for a gene or some other genetic construct;
The offspring-fertility link can be misleading. A queen bee with an allele that allows her to produces more sterile offspring may also produce more fertile offspring;
RS is fitness plus or minus random effects;
RS usually does not consider indirect fitness;
RS is selected to be optimized while fitness is selected to be maximized.

Equating RS and fitness is therefore only a rough approximation. When initially learning about Natural Selection students are often led to believe that RS and fitness are the same, which is only true with these (and possibly other) caveats. Equating RS and fitness in pedagogy risks skipping past and perhaps never understanding the caveats, and these caveats are very far from trivial. They are, in many cases, the point of specific evolutionary research projects.

gregladen Fri, 07/19/2013 - 05:33

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evolution

natural selection

Excellent point, and worth making; as is usually the case, shorthand approximations are generally helpful, but may be a bit misleading. For those of us who muddle along as naturalists and strive for the [airy wave of hand] Big Picture, it's usually enough to link the gene-influenced factor of some kind to an increased generational output to an increased relative genetic presence over time in a population. However, as you note, for those doing the real digging, a more nuanced view is important. That also helps to spawn beer-enhanced arguments over definitions, which, I still believe, is where the real spade-work of science gets done.

"That also helps to spawn beer-enhanced arguments over definitions, which, I still believe, is where the real spade-work of science gets done."

And frequently there must be a napkin.

I understand 'Simple Darwinian Fitness' to be a relative measure of how many offspring an individual successfully raises to sexual maturity, compared to the rest of the population. Anyone know where this definition comes from, as I do not recall? This is not the same as crude reproductive success; total number of offspring produced.

Wonder what effect a "greedy" allele might have = perhaps continuing to eat despite supposedly being sated; or (if one can have it) the sort of allele affecting behaviour whose accumulation in society led to (the production of) Easter Island, if you get my drift. Potential links to "my king/Party/Country right or wrong" ?

P.S. Beer & napkins all round...

This is one of the things that I am working on right now. There are "greedy alleles", they code for an endonuclease that causes a double-strand break and inserts itself into the genome. I suspect that preventing lethal overwhelming of the genome by such things is why eukaryotes have limited DNA replication fidelity. It isn't a bug, it is a feature that prevents selfish DNA from selfishly replicating itself.

you have a good point here. overall, fitness has to be present in order to increase chances of RS and RS can also be a probable result of good fitness.

The immune system has trade-offs

kbonham — Fri, 05 Nov 2010 15:00:00 +0000

The immune system has trade-offs

Most biological systems have trade-offs, so this really shouldn't come as a surprise. A recent paper published in Science shows that in sheep, some females have a stronger immune system and tend to live longer, but also tend to reproduce less often. This seemed to translate to roughly equal reproductive fitness over the course of their lives. It's a cool study, clearly involving a lot of work (they took samples over the course of a decade). The New York Times comes soooo close to having a great science article - they just forgot one thing.

They found that the average life span of the 410 ewes surveyed was 6 years. But there was a wide variation, with some living 15 years, and many others dying at age 3 or 4. The short-lived ewes had lower concentrations of antibodies than the longer-lived ones, which suggested why their lives were so short. But why was natural selection not weeding them out?
Dr. Graham said the researchers found this to be a puzzle: "What are all these sheep doing with low antibody concentrations?"

The answer, she said, was that the short-lived ewes were more likely to produce lambs. Those that died young reproduced almost every year, often having twins. Sheep that lived longer did not reproduce every year.

The researchers make the point that it could be an energy expenditure issue, and that's certainly plausible. The immune system requires a great deal of energy to fight infections, and babies require a great deal of energy. Resources are limited, yada yada yada...

All of this is true. There's no wild misinterpretation of the data, no far reaching conclusions (I can just imagine the headline: "Having trouble conceiving? New study suggests taking immunosuppressives will increase your chances of having a baby" - ugh), and they even give you an interesting bit of history about why these sheep were good experimental subjects - something you couldn't have gotten just reading the paper.

The only major qualm I have with the report is the credulousness that starts with the title. There's absolutely no data to suggest that the Ewes with weak immune systems have more offspring because they have weaker immune systems. The two are correlated, but no causal relation was demonstrated. Not that I blame the reporter - the fact that the explanation for a causal link makes such intuitive sense makes it easier to fall prey the fallacy

kbonham Fri, 11/05/2010 - 11:00

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Immune system

natural selection

In addition the weak immune system-fertility link put forward here can have other implications. The environment required to optimally nourish young is moderate, and not highest or lowest in pathogens. This selects for individuals with moderately robust immune systems the most. Less about energy expenditure, more about specificity of ecological niche, perhaps.

This paper is analyzing a single population of interbreeding individuals. They all share the same environment/niche, but individuals within that population have variations in there immune system that are correlated with birth-rate.

Or did I misunderstand your comment?

"A new theory of evolution proves what Sarah Palin has always known: Darwin was a retard"

gregladen — Wed, 25 Aug 2010 19:10:21 +0000

"A new theory of evolution proves what Sarah Palin has always known: Darwin was a retard"

As I predicted earlier today, various journalists are taking up the theme that "Darwin was wrong" because he did not predict that niches into which organisms evolved would be a major controlling feature in the overall pattern of evolution.

But of course, he did, and the new research being referred to does not "disprove darwin."

At least the piece I'm referring to here takes a somewhat tongue in cheek attitude towards the story.

"Survival of the fittest," the Darwinian theory that has been absorbed as scientific fact for the last 150 years, has finally been disproven. A new study published in the highly respected journal "Biology Letters" has proved that creationism and immaculate conception as not only scientifically valid, but true beyond any reasonable doubt.
Just kidding...

Yes, it seems to be a joke, but this particular writeup by Carmel Lobello still mindlessly reports that the new research "contradicts Darwin's most important work."

No it doesn't.

I think the root of this problem may be in the press office linked to the paper itself, or may be the authors. Nimrods.

gregladen Wed, 08/25/2010 - 15:10

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natural selection

The sad thing is that the more accurate and relevant summary goes unsaid: environment shown more important to evolution.

Headline: New findings have subtle implications for evolution.

Just doesn't have the same ring to it.

Headline: Long held evolutionary concept put to the test!

Subhead: Every time we put the data on the stand, it testifies to Darwin's genius!

Not to mention Darwin != evolution. Creationists, who rely on authority rather than evidence for their arguments, never seem to understand that even if we did refine our understanding of evolution to the point where Darwin was "refuted"... this makes the evolutionary (ie, anti-creationist) argument STRONGER. And being among the first to codify a correct general process (but the wrong specific mechanism) is still a very impressive and respectable contribution to science.

All of which presumes that Darwin would be refuted in some significant aspect. Which hasn't happened yet, but I'm open to the possibility. Cheerful about it, even. Because that's what science is.

I think you're right about the confusion coming from the study authors themselves. Pharyngula linked to the blog of one of the authors, Sarda Sahney. Although her language was more vague, she did seem to set up the same dichotomy: "Darwin cited competition... as a driver of evolution" versus "our new research." And she linked to Falcon-Lang's BBC article.

Natural Selection vs. Opportunity in Macroevolutionary Patterning of the Fossil Record

gregladen — Wed, 25 Aug 2010 06:49:07 +0000

Natural Selection vs. Opportunity in Macroevolutionary Patterning of the Fossil Record

I'm going to talk about one or two peer reviewed papers, but in doing so, I'm going to have to say a few words ... and this will not be pretty ... about a certain science writer's report at the BBC.

In an article titled "Space is the final frontier for evolution, study claims" BBC "science writer" Howard Falcon-Lang uses the old, tired, and quite frankly, stupendously unethical tack of making a claim that Darwin has been overthrown by new research. If someone actually overthrows Darwin, then so be it. But this is not what has happened. Falcon-Lang, or perhaps his BBC handlers, have used the cheap trick to sell their wares, and this is not appreciated.

If Howard Falcon-Lang did not a) claim to be a science reporter and b) have a dumb-ass hyphenated name, I'd be nice in my critique of his recent writeup. But no. He left me no choice. I will have to take it apart red in tooth and claw.

Charles Darwin may have been wrong when he argued that competition was the major driving force of evolution.

OK, this is a little premature for me to say here, but as you read on you'll see that my assertion is justified: Mr. Falcon-Lang is not really in a position to make any kind of claim regarding the wrongness or rightness of a genius of the level of Dr. Darwin.

He imagined a world in which organisms battled for supremacy and only the fittest survived.

No. That is the world that so many hack science writers, creationists, and various Darwin detractors imagine. Darwin wrote endlessly about differential survival, differential reproduction, mate selection, and all the myriad forces that determine selection (and randomness). He did not imagine the thing Mr. Falcon-Lang imagines him to have imagined.

But new research identifies the availability of "living space", rather than competition, as being of key importance for evolution.

Never start a sentence, let alone a paragraph, with the word "but" especially when the rest of the essay is something one has essentially pulled out of one's "butt."

Now, a reality check: Living space, including nesting sites, feeding territories, reproductive or social territories, and just having space for a number of reasons has been on the books as a thing to compete over since ... well, since Darwin first talked about it. So has the actual focus of the paper in question: Niche space. Sub-habitats or resources that can be exploited by a particular type of organism. You know the drill: The woodpecker niche, the soil detritus niche, the niche of flight, etc. to which organisms are constantly shifting their adaptive positions. More of those equals more types of organisms, and since most species can not be of more than one 'type' (though some can, interestingly) that also means more species diversity.

Findings question the old adage of "nature red in tooth and claw".

I'm pretty sure this sentence/paragraph was supposed to be a heading but some dumb-ass editor screwed up. In any event, yes, there is an adage. We do not do science with adages. A science writer should know that. Adage indeed. There is also an old adage that one should never believe what is written by the press.

The rest of the essay is a description of the research, and is not terrible. Of course, Pagel and colleagues demonstrated that part of the key effect that is being observed here some years ago when they showed that species diversity correlates to the width of the continent better than to latitude in the New World, thus offering a better explanation for the pattern of species diversity than the "the equator has got lots of it" hypothesis. The rest of it: niche space, we also already had a good idea about, but this new study is more comprehensive and much larger scale.

Focusing on land animals - amphibians, reptiles, mammals and birds - the scientists showed that the amount of biodiversity closely matched the availability of "living space" through time.

Living space - more formally known as the "ecological niche concept" by biologists - refers to the particular requirements of an organism to thrive. It includes factors like the availability of food and a favourable habitat.

The new study proposes that really big evolutionary changes happen when animals move into empty areas of living space, not occupied by other animals.

For example, when birds evolved the ability to fly, that opened up a vast range of new possibilities not available to other animals. Suddenly the skies were quite literally the limit, triggering a new evolutionary burst.

This concept challenges the idea that intense competition for resources in overcrowded habitats is the major driving force of evolution.

OK, let's put aside the press report at this time. I'll just say this: It is quite possible that Mr. Falcon-Lang was the victim of some very bad messing around by an editor who is not a science writer. At the BBC. If so, I hope he lets us know that so we can all write letters of complaint to said editor.

Getting back to the point at hand, what the paper actually says is this, from the abstract:

Tetrapod biodiversity today is great; over the past 400 Myr since vertebrates moved onto land, global tetrapod diversity has risen exponentially, punctuated by losses during major extinctions. There are links between the total global diversity of tetrapods and the diversity of their ecological roles, yet no one fully understands the interplay of these two aspects of biodiversity and a numerical analysis of this relationship has not so far been undertaken. Here we show that the global taxonomic and ecological diversity of tetrapods are closely linked. Throughout geological time, patterns of global diversity of tetrapod families show 97 per cent correlation with ecological modes. Global taxonomic and ecological diversity of this group correlates closely with the dominant classes of tetrapods (amphibians in the Palaeozoic, reptiles in the Mesozoic, birds and mammals in the Cenozoic). These groups have driven ecological diversity by expansion and contraction of occupied ecospace, rather than by direct competition within existing ecospace and each group has used ecospace at a greater rate than their predecessors.

The idea of empty niches being filled by the available taxa is not new, nor is the idea that an evolutionary "event" .... like some non-flying taxon developing the power of flight .... results in species radiation. What is new in this paper is that a survey has been done using relatively good available data that demonstrates this concept.

There has not been an overthrow of Darwin, though I'm sure various creationists will now incorrectly and inappropriately use this press report to suggest that there has been. There has not been the introduction of a new idea regarding macroevolution, though the work here is important and interesting. As is often the case with evolutionary biology, the specific role of natural selection (and in this entire discussion, read "natural selection" when you see "competition") vs. opportunity (read "drift"), and different people with different views will differentially see the role of one or the other as more important as they look at the same data. The realty of the situation is probably simpler: Competitive advantages have a chance of winning out, in the same way that buying a lottery ticket with better odds makes you more likely to win. But you'll probably still lose. But to even buy the lottery ticket, there has to be one of those little gas stations on the corner that sells them.

Pagel, M., May, R., & Collie, A. (1991). Ecological Aspects of the Geographical Distribution and Diversity of Mammalian Species The American Naturalist, 137 (6) DOI: 10.1086/285194

Sahney, S., Benton, M., & Ferry, P. (2010). Links between global taxonomic diversity, ecological diversity and the expansion of vertebrates on land Biology Letters, 6 (4), 544-547 DOI: 10.1098/rsbl.2009.1024

gregladen Wed, 08/25/2010 - 02:49

Tags

evolution

natural selection

paleontology

If evolutionists make blog posts insulting people with hyphenated names, then I'm going to vote for creationism.

Have you ever thought of critiquing the science rather than the type of name?

Tim Badgery-Parker

This is even worse. From Slate. Darwin overturned. Everything we thought we knew about evolution is wrong.

I think that every science journalist should be required to study under Carl Zimmer before being allowed to submit anything for publication.

Just to clarify: I agree with your analysis of the study, but I still do not understand why a hyphenated name is "dumb-ass".

Tim, it was humor. Hyphenation-humor.

Mike,yes, that one is even worse! WTF?

The Badgery family owned much of New South Wales (NSW). My ancestor was injured in war, and the Badgery family took him in. In gratitude, he added their name to his. But now I have a "dumb-ass" name, so my opinion is worthless.

Tim, you should be very proud of your name. Your sense of humor is a bit tight at the moment, however. But it can get better.

Just make sure you never leave a space before or after that minus sign while entering your name into a computer!

I don't know, I didn't find the hyphenation thing funny, I thought it was an insult. But then, I gave my daughter a hyphenated name as a way to try to deal with the misogyny of our current naming system (not that it's a great fix, but at least it's something).

So don't publish that kind of humour at the same time I'm drinking too much red wine.

I think if I had not been drinking I would have found the mention of hyphenated names offensive but ignored it. Alcohol reduces inhibitions, and my inhibition is confronting authority (and you are authority as I am reading your work).

If I was really authority, I'd probably have some kind of hyphenated name.

"Just make sure you never leave a space before or after that minus sign while entering your name into a computer!"

Currently I change positions every 6 months. And when I start at a new place my supervisors (not the IT people) tell me the username is surname and initial, or initial plus 4 letters of surname. The second form is better as I get it right after no more than 2 tries. But usually it takes a couple of phone calls to find out exactly how IT has parsed my name.

Never mind the hyphen thing. It is irrelevant.

There are journalists misinforming the public and using slimy methods to sell words.

A relative of mine pointed out these two articles yesterday on Facebook and I was all over it (others were also). It is truly sad that people attribute nonsense they fabricate as if it came out of the mouths of dead or living giants of science.

Tim, I would think the hyphen would fix that problem. Kinda the point.

Imagine being the archaeologist Ivor Noel Hume, who alphabetically is Noel Hume, Ivor.

Or for the Dutch/Belgian/Etc names:

Van der Sleen vs van der Sleen. In the Netherlands, the capitalizatoi changes depending on the syntactic context of the name. In Belgium, it does not, and the lower case means it is a reference to royalty (depending). Then, whether you use

Van Sleen, Marc

Sleen, Marc van

or whatever matters.

Darwin was wrong in more ways than one, as are most creationists. See "The Real Origin of Species" at www.CreationFoundation.co.uk -- showing that the Genesis account of creation is scientifically accurate and suggesting it is literally true.

JT, i just read at www.ignoranuses.com that genesis is true. the moon landing was faked. the earth is flat. and sarah palin is a credible candidate for the 2012 elections. which, co-incidentally* is when the world will end.

*i used a hyphen!

Anymore, any time I see "Darwin" and "wrong" in the same title, I know it's something somebody fished out from among their hemorrhoids.

It seems a fair number of people have learned from Sarah Palin that one can do quite well financially by projecting ignorance, misinformation, and stupidity.

I had a long conversation with a late colleague who was expert on introduced fishes. He thought that there was no such thing as an empty niche. I think empty niches exist, but if one is filled, there is reverberation and adjustment throughout the ecosystem.

I'd always assumed that evolution by those various selections had occurred in space as well as time. Nice to have it confirmed. Time for a nap.

I just discovered your blog and your About page -- delightful. As we're fond of saying in California: "I'll be back"
jg

"I will now give two or three instances of diversified and of changed habits in the individuals of the same species. When either case occurs, it would be easy for natural selection to fit the animal, by some modification of its structure, for its changed habits, or exclusively for one of its several different habits. But it is difficult to tell, and immaterial for us, whether habits generally change first and structure afterwards; or whether slight modifications of structure lead to changed habits; both probably often change almost simultaneouslyâ¦â

--Darwin, Origin of Species Chapter 6

I liked the example of, "birds learning to fly", as animals entering a new, unoccupied niche. Weren't there already pterosaurs zipping around in the sky at that time?

Sorry, "when birds evolved the ability to fly", I should be careful about what I put in quotation marks.

A fabulous riposte and in high dudgeon too. Very many people are too worried about Darwin being write or wrong. The poor man is dug up every time and made to walk over hot coals every time evolution is discussed. We should focus on the research at hand rather indulge in sensationalism. BBC should know better.

I concur with ateeq ahmad.

Regarding birds flying: Flight is probably not a niche, but rather, a dimension cutting across many niches. For instance, the smallest flying thingies before birds were quite large (as were the first flight-capable birds, probably). But the vast majority of birds are tiny compared to those creatures. Perhaps the condor, vultures, and eagles fill some of the niches of the extinct pterodactyls and other flying non-birds.

An even better example, of course, would be bats, because that is the flying in the dark niche.

"In an article titled ..."

Finally a science blogger who knows the difference between "titled" and "entitled". Spread the good word to your fellow sci-bloggers, Greg!

Lol, IanW! I was afraid I was the only one who noticed.
I won't feel so alone anymore... :)

Ian, I entitle you "Sir Ian of the Grammar" which entitles you to inspect for grammar any blog post regardless of what it may be titled.

I understand you were somewhat inebriated when you composed this. While I agree with the conclusions, I must point out the following: "...and different people with different views will differentially see the role of one or the other as more important as they look at the same data..." That's awful. Were you trying to say "it takes all kinds" or "you can't please everybody" or such? Please don't over-arch the end of your sentence when the beginning has two parenthetical asides as well. And this: "The realty of the situation is probably simpler..." Realty? I know you were talking about land-use, but you said nothing about property law previous to this.

X chromosome marks the spot, again

razib — Sun, 07 Feb 2010 04:00:55 +0000

X chromosome marks the spot, again

A few days ago I discussed a new paper which explores the patterns of natural selection in the genome of the X chromosome. As you know the X is "carried" disproportionately by females, as males have only one copy, so it offers up an interesting window into evolutionary dynamics (see The Red Queen for a popular treatment). Today Dienekes points me to a new paper in Genome Biology which puts the focus on the X chromosome again, Characterization of X-Linked SNP genotypic variation in globally-distributed human populations:

Background
The transmission pattern of the human X chromosome reduces its population size relative to the autosomes, subjects it to disproportionate influence by female demography, and leaves X-linked mutations exposed to selection in males. As a result, the analysis of X-linked genomic variation can provide insights into the influence of demography and selection on the human genome. Here we characterize the genomic variation represented by 16,297 X-linked SNPs genotyped in the CEPH human genome diversity project samples.

Results
We found that X chromosomes tend to be more differentiated between human populations than autosomes with several notable exceptions. Comparisons between genetically distant populations also showed an excess of X-linked SNPs with large allele frequency differences. Combining information about these SNPs with results from tests designed to detect selective sweeps, we identified two regions that were clear outliers from the rest of the X chromosome for haplotype structure and allele frequency distribution. We were also able to more precisely define the geographical extent of some previously described X-linked selective sweeps.

Conclusions
The relationship between male and female demographic histories is likely to be complex as evidence supporting different conclusions can be found in the same dataset. Although demography may have contributed to the excess of SNPs with large allele frequency differences observed on the X chromosome, we believe that selection is at least partially responsible. Finally, our results reveal the geographical complexities of selective sweeps on the X chromosome and argue for the use of diverse populations in studies of selection.

The low effective population of the X chromosome and the power of drift to produce greater between population difference comes up in this paper again, as it did in the one I discussed a few days ago. What's going on here is that noisy variation has no specific direction, so random genetic variation which accumulates within the genomes of different populations will tend to be different. A given locus in a large mixed population may have many alleles, a₁, a₂...a_n, at a given locus. If you divide the population into smaller clusters which no longer have any contact, and maintain the proportions of the alleles identical to the parental populations, the frequencies will begin to drift in different directions. The probability of any allele, a, fixing to 100% is the same in all populations, but the populations will likely fix different alleles. Ergo, they will start to exhibit greater between population differences. This is easily illustrated visually. The colors below represent different alleles. In the parental population three alleles are extant at 1/3, and in the initial daughter populations they are also at 1/3. Over time one notes that in these smaller populations different alleles fix, and the variance between the populations increases. If the X chromosome always is assumed to have a smaller effective population size, then it would be more strongly shaped by these dynamics than the autosome.

In this paper they confirmed that the X chromosome exhibits greater between population variance, more or less. The table below uses the HGDP data set and clusters populations by region to produce within and between population genetic variance statistics. Since the font is small, I will tell you in general it confirms that the X chromosome shows more between population variance than the autosomal genome when comparing between continents, but the pattern was less clear within continents, and for East Asian populations the X chromosome is actually less differentiated than the autosome.

There are patterns in the data here, but it's a little more complex and stark than the assertion that the X is always more variant between population groups. The authors wisely advise caution in overly general pronouncements on the nature of demographic processes due to inferences made from genomic data, since those inferences may be highly sensitive to population.

They also wondered if the X chromosome showed difference patterns of population genetic substructure than the autosome, so they compared the X with chromosome 16 using frappe. The X are the two top panels, chromosome 16 the second two. The plot below shows K = 7, that is, 7 putative ancestral groups.

Specific populations are less relevant than that the X chromosome and chromosome 16 seems to exhibit pretty much the same pattern. There are some differences between populations, which might reflect sex-mediated migration or mating. The 7 K clusters seem to map onto 7 geographical regions, Africa, the Middle East, Europe, Central Asia, East Asia, Oceania, and America. I can't understand why the Hazara or Uyghur would be more East Asian on the X than the autosome from history though. In particular in the case of the Hazara one assumes that this admixed group derives from the mating of West Eurasian (Persian) women and East Asian (Mongol) men (an inverse Saberi). There may be limitations of the sample size or the SNPs in their data set.

Next they looked at pairwise allele frequency differences, δ. In short, the bigger the allele frequency differences, the bigger the δ. Our prior assumption is that there will be more high δ results on the X than the autosomes. This is correct, in particular for African vs. non-African pairs. The table below shows the high δ values for three extreme distinct and differentiated populations, the French, Han and Yoruba.

They note that the high δ alleles on the X come in clusters. This is what was reported in the other paper as well. Additionally, it is evident from comparing the high δ SNPs with the total number of SNPs on the autosome and X that the X is enriched for between population differences in allele frequency. Not surprising, but nice to be validated.

But the next part is a little complicated. They wondered if the between population differences were simply due to differences in sex effective population size and sex ratio of migration, N_f/N and m_f/m. Remember that if the female effective population is low, that will reduce the effective population of the X because 2/3 of the X are in females. Similarly, strong bias toward male or female migration and results in gene flow across populations will influence the ratio of δ values on autosomes and the X.

They conclude from their model that demography can not explain the between population differences. Rather, they strongly suggest that between population differences may be due to natural selection. The second table above shows evidence that X high δ markers are overrepresented as genic SNPs; that is, mutations which might actually produce coding changes. This is strongly suggestive of selection. Additionally, they found that there was a skew toward derived SNPs among high δ regions on the X for Africans in relation to the autosomal regions.

Finally, they looked at their data set for signatures of natural selection using haplotype based tests, iHS, CLR, and XP-EHH. The latter two detect selective sweeps which are almost complete, that is, the adaptive allele is nearly at 100%. By contrast iHS tends to be better at detecting alleles where the sweep is partially complete. On the X chromosome they found an association between high δ regions, and positive results for the haplotype based tests of natural selection. After they fixed in on specific regions where the various methods intersected, they surveyed the literature for genes in that region which might be of adaptive and/or functional significance. I will leave it to you to look over the genes in detail, but it is interesting to note that one of the genes is a relation of EDAR, though the significance is left rather fuzzy.

The main upshot of this paper seems to be that there are multiple pointers that the peculiarities of the X chromosome can not be placed at the feet of demographic parameters. That is, some researchers have assumed that the prevalence of patrilocality and polygyny in relation to matrilocality and polyandry, combined with the structural fact that the X is disproportionately carried in females, can explain the differences in patterns of genetic variation. The data here suggest that natural selection may be a necessary supplement to explain what we see. Specifically, the authors point to one way in which the X is exposed to selection to a greater extent than the autosomal genome: males are haploid for most of the X chromosomal genes because they only have one copy, so recessively expressed traits are always expressed in males. The sex linkage of traits such as color blindness are the most well known result of this phenomenon. Let's make this concrete. Assume that a gene comes in two flavors, a and b, and that a homozygote b produces a lethal trait. So:

Frequency of b = 50% in parents, 25% of offspring die
Frequency of b = 10% in parents, 1% of offspring die
Frequency of b = 1% in parents, 0.01% of offspring die

Frequency of b = 50% in parents, 50% of alleles exposed to selection
Frequency of b = 10% in parents, 18% of alleles exposed to selection
Frequency of b = 1% in parents, 2% of alleles exposed to selection

As the frequency of the allele decreases, more and more of the copies of the allele are "masked" from selection in the form of heterozygotes. By contrast, in the X chromosome 1/3 of the copies are not masked because they are carried by males, who are operationally haploid. This means that in the case of the X chromosome conventionally recessive traits are not always recessive, and so selection is potentially more efficacious in driving allele frequencies to fixation. Ergo, some of the clusters and regions of between population genomic difference are likely due to local adaptation.

Note: This paper extensively references the framework outlined in two papers which came out of the Pritchard lab earlier this year.

Citation: Characterization of X-Linked SNP genotypic variation in globally-distributed human populations, Amanda M Casto , Jun Z Li , Devin Absher , Richard Myers , Sohini Ramachandran, Marcus W Feldman, Genome Biology 2010, 11:R10doi:10.1186/gb-2010-11-1-r10

razib Sat, 02/06/2010 - 23:00

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So if a congenitsl genetic disease is showing up in the sons of a couple it's something most likely hidden and repressed in the mother's side? What if a genetic disease is on a leg of the male supplied X but isn't being countered by the mother's, can that pass on a congenital disease.

I have a friend who is seems to me there is stuff from his side and his wife's side of the family that are showing up in the grandkids, which of course you have to throw in the women and men their kids have married. I try not to be an egghead when offering my condolences or advise for therapy/medical stuff. Almost makes a person not just want a pre-nupt but a DNA testing of their potential mate for any offspring.

Good blog! You said, "The 7 K clusters seem to map onto 7 geographical regions...". Does this have anything at all to do with the so-called "Seven Daughters of Eve", or is this just a coincidence?

Weird. A few years ago, there was some fuss about the X chromosome being abnormally less divergent from chimps, even considering it's a sexual chromosome. It was supposedly caused by a complex speciation event, in which the human lineage got its less divergent X from recent hybridization with the chimp lineage, about 1 million years ago. Now, all of a sudden, it's exceptionally divergent among humans. I don't get it. Maybe feminists got all irritated with just the Y evolving faster and decided to do something serious about it.

The downside of beauty

razib — Tue, 08 Dec 2009 04:30:24 +0000

The downside of beauty

Well, I don't quite know about that, but that's the sort of take-away from a new paper in PLoS Biology which looks at the downsides of female attractiveness. A Cost of Sexual Attractiveness to High-Fitness Females:

Adaptive mate choice by females is an important component of sexual selection in many species. The evolutionary consequences of male mate preferences, however, have received relatively little study, especially in the context of sexual conflict, where males often harm their mates. Here, we describe a new and counterintuitive cost of sexual selection in species with both male mate preference and sexual conflict via antagonistic male persistence: male mate choice for high-fecundity females leads to a diminished rate of adaptive evolution by reducing the advantage to females of expressing beneficial genetic variation. We then use a Drosophila melanogaster model system to experimentally test the key prediction of this theoretical cost: that antagonistic male persistence is directed toward, and harms, intrinsically higher-fitness females more than it does intrinsically lower-fitness females. This asymmetry in male persistence causes the tails of the population's fitness distribution to regress towards the mean, thereby reducing the efficacy of natural selection. We conclude that adaptive male mate choice can lead to an important, yet unappreciated, cost of sex and sexual selection.

The dynamic is well illustrated by the first figure:

The two lines above the shaded distribution illustrate variant male preference strategies. The solid lines shows random preference for females as a function of size, while the dashed line shows biased preference toward larger fitter females. The two lines below show the distribution of female fitness in response. In the case of the solid line you see the fitness of females in the context of random preferences; that is, males do not strongly prefer females who are fecund because of their large size. The reason that a large female may be more fecund is rather obvious, more physiological resources expendable upon the offspring. The evolutionary anthropologist Sarah Blaffer Hrdy claims the same principle is operative among humans in her book Mother Nature, larger females are less likely to miscarry and have complications, and can provide more robustly for their young. If one is healthy enough to construct a large and robust physique, one normally does so.

And yet as you can see above, strong male preference for these fecund females reduces their fitness. Male persistence from what I can tell might be colloquially termed "harassment." The energetic surfeit which larger females might allocate to their own reproductive output for provisioning has to be expended upon fending off males. In a context where males strongly prefer large females their fitness advantage is actually mitigated! This is a really weird outcome of sexual preferences.

The model rests on four primary assumptions:

(i) lifetime fecundity and net fitness are strongly genetically correlated

(ii) body size and fecundity are positively correlated, both phenotypically and genetically,

(iii) more antagonistic male persistence is directed towards females with higher intrinsic fecundity (i.e., potential fecundity in the absence of costly male persistence), and

(iv) female resistance to male-induced harm does not rise sufficiently fast with increasing body size

This equation shows that female fitness decreases due to male persistence. Driven by male preferences, female selection coefficient decreases in value, and so slows the overall rate of evolution (judged by the fixation of beneficial mutations, the probability of which is proportional to the selection coefficient):

U = rate of beneficial mutation

s = selection coefficient

The magnitude of the negative value of s_♁, which is a reflection of male preference for fecund females, determines how much the rate of fixation of beneficial mutations will be negatively effected.

They actually tested the assumptions and predictions of the model in experiments on Drosophila. Figure 2 illustrates the effect of male preference and persistence for larger and more fecund females:

The more attention female flies were allowed to receive the more fecundity equalized! This is certainly a counterintuitive finding, as I suspect most people would expect a "winner take all" dynamic where the best would monopolize attention.

I'm left a little confused by this sort of paper. Evolution is in its ultimate basis is a matter of logic, but when it comes to the byzantine dance between sexual, environmental and social selection, the balance between physiological and reproductive fitness, one can be left like a dog chasing one's own tail logic takes nature by its horns and drives to inevitable conclusions. I assume that's why experiments and field research are a necessary complement to analysis from first priniciples. The authors are cautious about their results:

Our model of adaptive male mate choice in the context of harmful male persistence has important limitations. First, we have implicitly assumed that the increased male persistence (directed toward larger, more intrinsically fecund females) does not cause larger females to have lower than average fecundity. Second, male condition may be more variable in nature compared to the laboratory, and condition-specific patterns of male persistence could either enhance or reduce the bias of male persistence toward larger females. Third, we have ignored complicating factors such as size-assortative mating interactions, e.g., smaller females receiving persistence predominantly from smaller or poor-condition males. Fourth, we have assumed that male mate choice is based on a female trait that directly influences her fecundity, such as body size. Theory predicts that this type of male mate preference will lead to a monotonic preference for larger females...However, when the preferred female trait is a costly indicator of fecundity, such as an energetically expensive ornament, then males can evolve to prefer intermediate trait values in females...and our model would not apply. Fifth, our model may not apply to species where females obtain direct net benefits from increased mating rates, such as those with nuptial feeding...Lastly, we have assumed a static male preference and female indicator trait. In many contexts, these two traits can be expected to coevolve, and this dynamic is not included in our model. Nonetheless, our empirical work suggests that the requisite conditions for the model to operate, at least transiently, can feasibly be achieved.

Given enough time, a large enough population, and one can imagine that natural selection and adaptation may behave in a deterministic fashion over the long term. But in the long term we are all dead. The transient, or transients, may be what really matters. In terms of evolution too often we take the simple logic to its natural conclusion. As if we are simply those lucky few to live in a transient when the logic and the empirics do not align. I suspect the bigger insight is that evolutionary systems are often out of equilibrium, and that exogenous shocks and chaotic population dynamics due to endogenous parameters shift the adaptive landscape so frequently that selection and adaptation are often being buffeted by contingency and stochasticity. This makes mince meat of our logic and sharply curtails of the power of our inferences.

To some extent we know that intuitively. If the logic of evolution was clean and the world characterized by a calm general equilibrium one might infer that the cosmos was populated by a uniform super-species, the fittest of the fit ideally adapted to any circumstance that might prevail. But that is clearly not so, and the bubbling foam of speciation and extinction are a testament to the fact that evolutionary process surfs on the edge of history. Certainly nature has a peculiar sense of humor if it gives fecundity with one hand and snatches it away with the other!

Citation: Long TAF, Pischedda A, Stewart AD, Rice WR, 2009 A Cost of Sexual Attractiveness to High-Fitness Females. PLoS Biol 7(12): e1000254. doi:10.1371/journal.pbio.1000254

razib Mon, 12/07/2009 - 23:30

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In species where males provision females, there will be a further cost that desirable females must pay: some of the provisioning that her strapping brothers or her mate provide will be dissipated by having to invest that time, effort, etc. in protecting her.

In contrast, if an ugly female isn't so subject to harassment, her male relatives and mate can invest more in provisioning for her, and much less in basic protection. Even she does get harassed, it'll be by some weak loser (who else would harass the ugly one?), so those protection investments will be lower than when you're protecting against the harassers of the desirable females.

We had better get busy educating males to select unfit and less fecund appearing women. Otherwise, The future of our species is compromised. How would Tiger Woods take this re-education?

makes sense. helps to explain why for example, human females haven't all evolved to look like supermodels.

Give me Mendelian genetics thank ya very much.

This is still no excuse not to diet and exercise, beeatches, 'cause I ain't fcuking a fattie, no way no how.

Your mistake of course is thinking that evolution is logical. Evolution seeks evolutionarily stable strategies which is just another way of saying populations try to live in equilibrium. If anything, self-awareness of evolutionary psych merely changes reproductive behavior: I know it changed my own. I dated hipsters, but reproduced with a doctor. Anyhow, that's a digression; you're (and the study) are also forgetting that genes don't operate in isolation. A big, 'fecund' female is bound to come from a family of big, 'fecund' males. It is only in modern times with the break up of the clan that a woman can seek a mate without her family's participation. It's one of the reasons males were prized in patriarchal societies: muscle.

Pretty equation, useful graph; ah, but the analysis... tsk.

Acting for the survival of the species (a falsehood)

gregladen — Wed, 02 Sep 2009 10:59:35 +0000

Acting for the survival of the species (a falsehood)

Today's falsehood is the idea that individual animals act for the benefit of their own species.

Let me give you an example. When I was a kid, I watched a nature show about cougars. The show 'documented' a single female cougar going about doing cougar-things and being generally cougar-like. At one point she had cute little baby cougar kittens.

Then a flood came. The stream near her chosen lair swelled its banks and threatened to drown the kittens. So, she carried one of the kittens up the hill to a new lair. She went back to get the second kitten, and the flood waters were even higher and closer to the den, but she managed to save that second kitten. When she went back to get the third kitten, it was not at all clear that she would make it in time. It seemed inevitable that the third kitten would be carried off to it's death by the torrent. As the mother cougar approached the flood and all hope seemed to diminish, the narrator said "The mother cougar, driven by an instinct to save her species, searched desperately for any sign of the third kitten, who represented the next generation of cougars." (Or words to that effect.)

At the last second, the mother cougar spotted the kitten, who had already run partly up the hill, and brought it safely to the lair. (We presume that all kittens always survive, which is why we are up to our necks in cougars.)

Within biology, many of the falsehoods being discussed here actually affect practicing scientists. We'll see an especially good example of this later with the "reproductive success is maximized by fitness" fallacy. We've already seen it with the "Evolution has stopped for humans" fallacy. But the "Survival of the species" fallacy never directly affects actual biologists because it is literally almost the first thing you learn about selection, evolution, organismic biology, or whole organism biology. Individuals act in their own (inclusive) self interest. The appearance of altruism is usually underlain by selfish motives. If there is any group-level selection at all (and most biologists think there is not, or at least not much) it is certainly not operating at the level of the species.

The mother cougar was not trying to save cougars when she desperately searched for the third kitten. She was, rather, doing two things simultaneously.

1) She was, at some ultimate level not cognizant to her in any way, trying to increase the likelihood of the survival of her own genes. Or, more accurately, some of the genes she carried were busy saving themselves, and for this particular event, the other genes were free-riding. During some other episode of her life, perhaps as hunger drives her to hunt, different genes are perhaps busy saving themselves while the others are free-riding. I'm sure you get the picture.

...and...

2) She was, at the more immediate, or as we like to say, proximate level, her behavior was a response to some kind of limbic and endocrine attachment syndrome whereby mothers bond to and do things for their offspring, similar to the kinds of deep neurological systems that may facilitate the orientation of offspring to their mothers, and in the case of these kittens, the neuro-muscular system that causes a kitten to go limp when picked up by the nape to be carried by mom, instead of squirming around, flying out of mom's mouth, and dropping fatally into the rushing river.

That the saving of the individual kittens would possibly help the survival of the species is a side effect of her behavior at both the proximate and ultimate level.

This idea can be tested, and has been tested, both in theoretical constructs and in field studies. It is often possible to construct alternative testable hypotheses, one based on an instinct to help the species, or some other large group, and the other to at selfishly. Below, I recommend texts you may wish to consult for excellent overviews and evidence along these lines.

The bottom line is this: A variant of a gene (an "allele") that confers a trait that results in group-level or species-level survival or reproduction at the expense of the individual will have lower fitness than an allele that instead confers a trait that results in individual survival or reproduction. One of the classic examples of this phenomenon is the prudential restraint in egg laying among colonial nesting birds.

Some bird species -- such as gulls, terns, boobies, and the like -- nest communally and from these nests forage for nearby resources to feed themselves and their growing young. So, there may be dozens, hundreds, or even thousands of gull nests on well protected cliffs overlooking the ocean, and the gulls will go down to the ocean (one member of the pair at a time, the other staying behind to protect the egg or chick from the other gulls) to feed, and bringing back food for the mate and/or offspring.

The following has been noted (slightly oversimplified here):

1) The number of eggs that a pair will have in a nest varies, let's say from 3 to 5.
2) The number of eggs each pair has in a given year is the same, with most of the birds laying 3, 4, or 5 eggs.
3) The number of eggs, higher or lower or median, appears to vary with the availability of resources. When there are lots of resources, more eggs are laid, when resources are scarce, fewer eggs are laid, to the extent that this can be assessed by the birds.

Two different hypotheses have been proposed to explain these behaviors.

A: The birds are practicing prudential restraint for the benefit of the group. By holding back on egg laying, the demand on the local resources will be lowered now and over the near future when the offspring fledge, so there will not be as much competition for resources and more members of the group will survive. This is group selection, and taken just one step more, survival of the species.

B: Individual birds (or pairs of birds, but really, probably just the female) lay the number of eggs that matches some perception about the availability of resources, and the birds are essentially tracking the resources and producing the number of offspring that makes sense, economically/ecologically, that year.

One way to test this is to place extra eggs in a small number of nests. If only a few extra eggs are placed overall (but say one per nest), that will not measurably affect the overall availability of or competition for resources by the group, but it may severely affect the birds with the loaded-up nest. Extra egg experiments have been done, and when extra eggs are added to the nest, the final number of offspring fledged goes down rather than up. In other words, the number of eggs in an individual nest is adjusted as needed for the individual's fitness, not the group's fitness.

Another fact worth noting is that if both parents in these colonial nesters leave the nest alone, the neighboring birds tend to eat the eggs or chicks as a snack. So much for survival of the species. One would think that if you could prudentially restraining one's reproduction as an evolutionary strategy, one would prudentially restrain one's snacking behavior for the same purpose.

It is interesting to note that the survival of the species fallacy has other forms in other areas that are very important. The survival of the species problem is the same problem as the tragedy of the commons problem. It is also the same thing as the "agency effect" or the "agency problem." It is also worth noting that the early work on this problem was tied to some of the important early work that moved theory from evolutionary biology over to economics. The economists have been playing with this kind of theory ... called game theory ... ever since.

An interesting paper representing the overlap between economics and evolutionary biology with respect to this issue is "Economic man and selfish genes: the implications of group selection for economic valuation and policy." From the abstract:

A basic tenet of socio-economics is that economic behavior is shaped by social bonds and cultural context. A relevant controversy in evolutionary biology is group selection and the related issue of altruistic behavior, that is, behavior neutral or detrimental to the individual but positive for the survival of the group. In this paper we examine the parallel controversies surrounding "economic man" and "selfish genes" with particular emphasis on the policy implications of group selection. We argue for the replacement of standard welfare economics with models of human behavior in the spirit of "consilience" between economic theory and the best available science from other relevant disciplines.

(Source:Gowdy, J. (2004). Economic man and selfish genes: the implications of group selection for economic valuation and policy Journal of Socio-Economics, 33 (3), 343-358 DOI: 10.1016/j.socec.2003.12.026)

As promised, here are a few suggested readings that will cover this topic (and other topics). Most of these are available used.

Genes in Conflict: The Biology of Selfish Genetic Elements

The Selfish Gene: 30th Anniversary Edition--with a new Introduction by the Author

Sex, Evolution and Behavior

Homicide (Foundations of Human Behavior)

Social Evolution

Natural Selection and Social Theory: Selected Papers of Robert Trivers (Evolution and Cognition Series)

_____

More Falsehoods !!!

This post is one of a series on the topic of falsehoods. The following is a list of falsehoods posts in order:

gregladen Wed, 09/02/2009 - 06:59

Tags

survival of the species

behavioral biology

evolution

The Modes of Natural Selection

gregladen — Tue, 25 Aug 2009 16:09:53 +0000

The Modes of Natural Selection

There many ways of dividing up and categorizing Natural Selection. For example, there are the trichotomies of Natural Selection, Sexual Selection and Artificial Selection, and Modes of Selection (Stabilizing, Directional, and Disruptive) trichotomy.

We sense that these are good because they are "threes" and "three" is a magic number. Here, I'm focusing on the Mode Trichotomy, and asking that we consider that there are not three, but four modes of Natural Selection. This will cause tremors throughout the Evolutionary Theory community because Four is not a magic number, but so be it.

In Stabilizing Selection the extremes of a trait are selected against and the mean value of the trait remains the same. Mutations constantly introduced into the population tht produce traits out at the extremes are selected against. In Directional Selection the values of a trait at one end of the distribution are selected against and/or values at the other end are selected for, so that the distribution of values, and it's mean, move in one direction. In Disruptive Selection the average values are selected against so that the distribution of the trait becomes bimodal.

That was pretty simple, but operationalizing these definitions, displaying them graphically, and thinking about how they work in shaping the overall pattern of evolution reveal important details that are often sidelined or not discussed. And, we have to consider the fourth mode: Null Selection: This is where there is no selection on the trait at any particular value. As mutations (or allelic novelty of any source) are introduced into the population what might have been a nice bell curve representing the trait's values spreads and flattens.

One might argue that since "Null Selection" is not really selection, that it should not be a mode. I agree, but I still want it on the list of modes of selection. Why? Because without a concept of null selection, the lack of change in trait values is often incorrectly interpreted as "nothing is happening here." But in fact, something fairly major and impressive is happening. Stabilizing selection is the process of ongoing introduction of variation and ongoing reduction in variation. It balances out because the more introduction of variation there is, the stronger selection becomes. A trait that remains the same for eons is a trait experiencing a dynamic evolutionary processes. Having no concept of Null Selection does not allow this thought to develop, or if it is mentioned, it may not stick as well.

Below I provide graphics depicting the modes. (They are available for non commercial use. For commercial use, that's $1,000 Euros each. Oh, and click on the graphic to get a larger version.) I've made the graphics very simple but they are also meant to be very precise in selected details. as described below in the text.

Stabilizing Selection

As stated above, stabilizing selection occurs when the "central" value of a trait is not selected against or favored by selection but extreme values are selected against. The graphic shows "selection against" only, and this is depicted as rather menacing looking arrows pointing down at the upper and lower reaches of this "bell curve" shaped distribution. Note that the "after selection" graph shows that the extreme values from before selection are gone, the total range of variation is lower, and the mean is unchanged.

Directional Selection

Here the nasty looking Force of Selection Arrow is only affecting traits near one end of the distribution. The entire distribution squishes to the right. Note that the upper end of the distribution does not move up ... in other words, directional selection does not simply move the bell curve along in one direction. The total range of variation reduces and the mean moves, in this case, to the right.

Disruptive Selection

In this case the central or average value is being selected against and/or the extremes selected for. My favorite example of this, and one often given in the textbooks, is the selection for gamete size. Fitness may be enhanced with a gamete with a certain amount of nutrition stored for use in a growing zygote (seed or embryo). Or, fitness may be enhanced by a small lightweight and mobile gamete (a pollen spore or a sperm). You can't have both, and the compromise is less than ideal. [see this on Anisogamy] This example also forces us to realize that fitness needs to be considered in relation to the morph ... the individual as it exists with a certain gender, developmental age, etc. Monty Python and the Catholic Church notwithstanding, a sperm is an individual with it's own little genome and it's own little Darwinian problems. So is an egg or a spore. They don't have a lot of personality but they do have a fitness function.

Those are the usual three forms of selection, and the one I want to add is "Null Selection." Is this the same as "relaxed selection" you may ask? If you want it to be that's OK. Neither have definitions that are both formal and accepted. They are probably the same.

In null selection there are no Arrows of Selection happening to the bell curve, but there is still the constant introduction of mutations, so over time the distribution goes wacky and essentially becomes random.

For this to be really clearly conceptualized, we can go back to Stabilizing Selection and redraw the diagram like this:

Here, the mutations are seen constantly bothering the bell curve from below, and selection is working in an uneven way (more against the extremes) in the opposite direction. In cases where people have actually measured a trait over time, one sees this dynamic process. This is the equilibrium in punctuated equilibrium.

gregladen Tue, 08/25/2009 - 12:09

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evolution

natural selection

Honestly, I can't stand the textbook variety of selective models to explain selection, I think they're too simplistic. At the same time, I realize that it takes far more time explaining the myriad of possible types of variations and all the compounding factors, then giving specific examples of these types followed by explaining how exactly the population is changing.

1) Disruptive selection can be highly favorable for homozygous alleles, but more favorable to one than the other. ("Directional and disruptive")

2) "Null" or "relaxed" or "unselected" alleles will undoubtedly have differential rates of mutation (or origin)

3) For traits with multiple genes influencing them, (most traits) this becomes even more complex; directional selection may favor a certain point along the continuum not at the either extreme, but away from average of the previous generation.

I like having these cut and dry simple models, but I sometimes wonder if we're not oversimplifying the education of this.

If average individuals are the most heterozygotic in the population, then stabilizing selection assures an initial increase in genetic variation in each generation. I suspect that in most populations individuals around average are the most abundant group in the population. If so, this suggests that stabilizing selection is the most common form of selection. Good for Professor Bumpus.

Is it me or does darwin's beard make him look more like bin laden? They have the same goals you know - destroy Christianity. Scary isn't it?

No, ED, it's you. Would that it were only you.

If Darwin looks like anybody it's William Jennings Bryan.

Your explanation is inconsistent with respect to including mutations; you started out without them, and then included them.

"Note that the upper end of the distribution does not move up ... in other words, directional selection does not simply move the bell curve along in one direction."

"In null selection there are no Arrows of Selection happening to the bell curve, but there is still the constant introduction of mutations, so over time the distribution goes wacky and essentially becomes random."

To avoid confusion, I would recommend including three pictures for each mode: bell curve before, bell curve after selection, and bell curve after multiple generations of selection and mutation.

qbsmd: I have done it in the manner you suggest, and it does work very nicely. Or, really, one animation for each mode.

In fact, these pictures often fail in a classroom unless the instructor gives a LOT of support as to how these graphs are constructed and what they mean.

I have used this post almost exactly as it is as a supplement to pre-existing course material that talks bout modes. It works pretty well in that case as well.

I take your "null selection" to mean that we have a Hardy-Weinberg situation except with respect to neutral mutations. To take the simplest case: We have a gene which exists in a single form and is neutral, ie. p=1. A mutation, similarly neutral, occurs, so we now have a small q and p is less than 1. Call the genes A and A1. A is going to have a rate of mutation to A1. Similarly A1 is going to have a rate of back mutation to A. Eventually, equilibrium will be reached, where the number of A to A1 mutation equals the number of A1 to A mutations during a period of time. p and q will reflect the ratio of A to A1 at equilibrium and will not change into the future unless we change a paramater. The "null curve" is not a random curve, but is rather determined relative mutation rates.

Jim, mutations don't exist in equillibrium like the dissociation constant of a weak acid. Hardy-Weinberg equilibrium is a result of allelic frequencies in a population not subject to pressure, not mutation from one to the other. Differential rates of mutation do exist, but not from A to A1 and A1 to A, but from A to A1, A to A2, A to A3... and A1 to A1A, A1A to A1B, A1B... and A9Z9Z to A9Z9Z1...

There are some "back mutations," but these are mostly compensatory mutations rather than reverting exactly to the parent genetic sequence.

Jared, Good points. As I understand it, the Hardy-Weinberg condition vis mutation is either (1) no mutation, or (2) mutation in equilibrium. I was using the simplest case to make the point that mutation frequencies are not a matter of magic, but rather a matter of mathmatically describable interactions. I will also say that my example was about as complex as my mathematics can deal with.

@2: A bit of thought should indicate that stabilizing selection should be the most common form of selection (well, of the classical three) - directional and disruptive selection are inherently self-limiting, as they'll drive the population into regimes where they don't affect a trait anymore, or where some other force comes up on the other end and turns it into stabilizing selection.

Thanks for that blog-entry - I think it's about time that the fact that a particular trait might be spread so that no selection pressure is exerted on any value of it gets the attention it deserves. In addition, we might even consider situations where a trait is uniformly distributed so that concerning this trait, there is null selection. Or we might consider traits with have a flat fitness landscape (presuming we can - as some suggest, work with a fitness-concept for traits) and thus null selection.

Evolution denier for life? It's so sad to me, and immeasurably more scary than Darwin's position, that a Christian(?) would think that a humanly derived theory could destroy Christianity! Is the healing/saving message of the Christ so weak and conquerable? Where is your faith?