Beta
×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

PageRank Algorithm Applied To the Food Web

Soulskill posted about 5 years ago | from the dodo-got-googlebombed dept.

Earth 94

An anonymous reader brings word of a new application for PageRank, Google's link analysis algorithm: monitoring the food web in an ecosystem. A team of researchers found that a modified version of PageRank can predict with great accuracy which species are vital to the existence of others. Quoting: "Every species is embedded in a complex network of relationships with others. A single extinction can cascade into the loss of seemingly unrelated species. Investigating when this might happen using more conventional methods is complicated, as even in simple ecosystems, the number of combinations exceeds the number of atoms in the universe. So, it would be impossible to try them all. Co-author Dr. Stefano Allesina realized he could apply PageRank to the problem when he stumbled across an article in a journal of applied mathematics describing the Google algorithm. 'First of all, we had to reverse the definition of the algorithm. In PageRank, a web page is important if important pages point to it. In our approach, a species is important if it points to important species.'"

cancel ×

94 comments

Sorry! There are no comments related to the filter you selected.

hooray (-1, Offtopic)

Anonymous Coward | about 5 years ago | (#29320131)

first post

Why is this surprising? (4, Interesting)

Anonymous Coward | about 5 years ago | (#29320135)

Pagerank is just a repeated application of a transformation matrix. It has the effect of running a Markov model (a way to model discrete states) until there is convergence. He just used a Markov model the way that it is supposed to be used...

I dont get it... what's notable here?

Re:Why is this surprising? (2, Funny)

PC and Sony Fanboy (1248258) | about 5 years ago | (#29320399)

I dont get it... what's notable here?

We're finally able to figure out what species will have the most impact if it is removed. Likely, the folks at google are turning this into some sort of biological warfare device - They want to figure out which species of mosquito we have to kill in order to remove all mouth-breathers from the planet, leaving all the hot women alive for the rest of us.

More seriously, if we can figure out which species are most important (and which are least important), doesn't that give both the tree-hugging sea-kittens at PETA more firepower? And doesn't it enable logging companies to say "Well, that species of rat isn't actually important to anything except the animals that live in this forest anyways ... "

Either way, I approve of this message.

Re:Why is this surprising? (1)

The Archon V2.0 (782634) | about 5 years ago | (#29323713)

Likely, the folks at google are turning this into some sort of biological warfare device - They want to figure out which species of mosquito we have to kill in order to remove all mouth-breathers from the planet, leaving all the hot women alive for the rest of us.

Hey, hey, what's with all this "us" stuff?

Re:Why is this surprising? (4, Funny)

xenocide2 (231786) | about 5 years ago | (#29320403)

It's remarkable because a biologist discovered math and possibly statistics.

Re:Why is this surprising? (2, Funny)

invalid_user (253723) | about 5 years ago | (#29320829)

Actually the Markov model is prevalent in bioinformatics, as well as other statistical methods. However, the biologists are an entirely different race, typically unfamiliar with advanced mathematics. In fact, the entire field of biology works on foundations and culture so alien to science (fondness for objectivity and modesty) sometimes I wonder whether it is right to call them scientists, or just group them with the social scientists and psychologists.

It's a pity they dominate the big science journals.

Re:Why is this surprising? (1)

Teancum (67324) | about 5 years ago | (#29332639)

In fairness to biologists, their science has only recently (compared to other sciences) become a "hard" science with strong foundational theories and strongly determinant principles that could be applied to arrive at a conclusion. Largely, it still is in the fuzzy region between the hard sciences (like physics and astronomy) and the social sciences (like anthropology and psychology). I've even seen biologists use anthropological tools and study methods when investigating animal behavior, to give an example. He literally got into computers by reading a book and then buying a computer for his bio-research lab and didn't look back.

By hard science, with the discovery of DNA and a solid foundation of organic chemistry knowledge, biology has the potential to be as rigorous of a science as any other. In theory, you can even "design" a creature or plant to be created simply by organizing the organic molecules in the right order and combination... simply by pushing a button in a laboratory. That such potential exists scares the hell out of some people too.

Is biology there yet? No, but the "primitive" tools to get them there have already been built, and the rest is trying to make order out of the trillions of trillions of combinations that can be made with organic chemistry and how all of those chemicals interact with each other. It isn't an easy task, and certainly there is room for new scientific research in this area. IMHO this is one of many reasons why it dominates scientific journals, as the breadth of this field is quite huge.

More to the point, it is far and away much better shape than when Linnaeus first was trying to make sense in the first place about how to catalog what is a living thing. They are trying and if they are a little behind the other sciences, it has to do with the mountain of information they are dealing with and trying to get a handle upon.

As a footnote, I had a Computer Science professor who happened to have a PhD (his only one) in Biology. Frankly one of the best CS profs I ever had (he even specialized in computer graphics). He got into the position when a CS department was brand-new idea and you couldn't get a PhD in computer science, and so "switched" to a new field that seemed exciting to him at the time. Too bad that he is retired now, as he was a wealth of information and knowledge, not to mention his background in biology tended to keep the CS lectures from getting too dry.

Re:Why is this surprising? (1)

Teancum (67324) | about 5 years ago | (#29332669)

Excuse the screwup I just had with the above section. Firefox just re-located a sentence I had intended for the last paragraph that ended up in the first one. Oops.

Re:Why is this surprising? (1)

jpmorgan (517966) | about 5 years ago | (#29321149)

Isn't that a sign of the apocalypse?

Re:Why is this surprising? (2, Informative)

speedtux (1307149) | about 5 years ago | (#29322257)

Mathematical biology has a history that goes back further than computer science. Many biologists probably know a lot more math and statistics than your average computer scientists.

Re:Why is this surprising? (0)

Anonymous Coward | about 5 years ago | (#29326471)

I'm fairly certain there are some breeds of dogs that know more math than your average computer scientist.

Re:Why is this surprising? (1)

xenocide2 (231786) | about 5 years ago | (#29336871)

On the other hand, I've seen biologist written perl code [oxfordjournals.org] that terminated on div-by-zero, and closed, re-opened then seeked into the input file rather than implement a linear processing of data. I've also met plenty of biology grad students who basically said their technique for analysis was to invite a statistics co-author. If you're going to claim Mendel as a mathematical biologist, we might as well call Babbage a computer scientist, and he built the diffrence engine 30 years before Mendel's pea experiment.

I also know of computational biologists who debug laptop BIOSes, and have a firm grasp of math. I believe them to be a minority, but perhaps there's selection effects I'm unaware of. Anyways, at this point I have to believe that math and statistics is vital to understanding the wealth of genomic data we face, and I expect most successful researchers meet or exceed my own humble understanding of statistics.

Re:Why is this surprising? (1)

papershark (1181249) | about 5 years ago | (#29330385)

Not to mention SEO and PR... he must be reapplying for funding soon!

Re:Why is this surprising? (5, Informative)

DeadDecoy (877617) | about 5 years ago | (#29320405)

Because it's a novel use of an existing method? It was published in PLoS and not some mathematics journal. So, while the algorithms are not new, they may be new to the intended audience. The actual claim of the article is that it can offer a predictive analysis of extinction rates of a species and validated them on some in-silico experiments. This could be useful for bench-scientists, as they could figure out what might happen in an experiment before running expensive tests. This might be useful for conservations trying to make sure whole ecosystems don't die out due to the removal of a species; the 'might' is significant as real-world ecosystems are generally more complex. But anyways, it's interesting because the models have practical application outside of theory to help us understand the world.

Re:Why is this surprising? (4, Insightful)

jpmorgan (517966) | about 5 years ago | (#29321095)

Yes, it is notable that this wasn't published in 'some mathematics journal'. Pagerank is computing the limiting distribution of a discrete-time markov chain applied to webpages using a certain statistical model of hyperlinks. It makes no sense to talk of applying 'pagerank' to things other than webpages, because that's what makes pagerank special! As soon as you take pagerank out of the web-context, it's just a steady state analysis of a markov chain, which is a standard statistical technique covered in undergraduate statistics courses. It's like saying applying bayesian inference to a problem in ecology is using a 'spam filter.'

For me, this tells me that perhaps these researchers should wander over to their local mathematics department more often. They might find all sorts of goodies that mathematicians have developed in the past few centuries. Dr. Allesina might have discovered that there was no need to reverse engineer the algorithm, since the underlying mathematical principles have been well understood for over a hundred years. We might have a better understanding of the world if most sciences took mathematical models as seriously as physicists do.

Re:Why is this surprising? (1)

martin-boundary (547041) | about 5 years ago | (#29321671)

Quite so. The problem with PageRank is that it's quite a crude approach to simulation, in fact. The steady state distribution is just an average, whereas we already understand how to do so much more, eg looking at the sizes of random fluctuations and maxima and minima.

It would be good if these biologists who are impressed with this example were to read a book about Markov processes, or took a postgraduate course in stochastic processes. This isn't rocket science, it's quite commonly used by engineers, physicists, medical statisticians... and even actual biologists!

Re:Why is this surprising? (0)

Anonymous Coward | about 5 years ago | (#29323853)

It never fails that every science story has the inevitable post where someone points out some glaringly obvious flaw as if that wasn't the first thing the researchers noticed.

Re:Why is this surprising? (1)

JorDan Clock (664877) | about 5 years ago | (#29320457)

No, you're right. It's not notable. Whenever one area of knowledge is improved, every other area is instantly aware of this discovery and can utilize it with 100% efficiency right away.

Less sarcastically, I am not surprised a biologist is unaware of such mathematical models. It's notable for the fact that they're applying a rather simple method to a rather old problem and it's extremely effective.

Re:Why is this surprising? (1)

shelly.green (1631649) | about 5 years ago | (#29321435)

i am also qant to know the pagerank algorithm !may be you need to find a seo .http://www.igolfyoo.com

Re:Why is this surprising? (0)

Anonymous Coward | about 5 years ago | (#29321583)

But this uses facebook ... it's what idiots crave.

Re:Why is this surprising? (1)

Psychochild (64124) | about 5 years ago | (#29327027)

Because it's an improvement of the old eBay feedback system biologists were using before. They found that system was open to "retribution" feedback if the prey didn't rate the predator highly enough.

Review by vole:
(positive) Fox was an excellent predator!!!! Would be eaten again!!!!! A+++++++++++!!!!!

Looks like i am the first to comment (-1, Offtopic)

SKJDot (1169063) | about 5 years ago | (#29320139)

Looks like i am the first to comment

Re:Looks like i am the first to comment (0, Offtopic)

Rip Dick (1207150) | about 5 years ago | (#29320169)

Looks like you're a colossal failure

More than atoms in the universe? (2, Interesting)

JordanL (886154) | about 5 years ago | (#29320143)

What factorial does it take to equal that number? I know that its very easy in math to get numbers that large, but this wasn't a place I expected to find it.

Re:More than atoms in the universe? (2, Interesting)

cmseagle (1195671) | about 5 years ago | (#29320455)

Yeah, I would tend to call BS on that particular statistic. Let's say the average water bottle is .5L. In that one, single water bottle that is sitting on my desk, there are 5.01*10^25 atoms. That's one hell of a number.

Now, let's pretend God has a really good magnifying glass and a really small set of tweezers, and he's removing atoms from this water bottle at a rate of 1 per second. Conservative estimates put the universe at 13.5 billion years old, which converts to 4.25*10^17 seconds.

So, since the beginning of time, God has removed 4.25*10^17 atoms from my water bottle. A lot, right? Not quit. (4.25*10^17)/(5.01*10^25)=8.00*10^-9.

Even removing an atom every second since the beginning of time, only a few trillionths are missing from my bottle of water. That's just a bottle of water, now imagine the number of atoms in the ocean, or in the sun. Something does not seem right with the "More than number of atoms in the universe" claim.

Re:More than atoms in the universe? (3, Informative)

MyLongNickName (822545) | about 5 years ago | (#29320549)

What does your tweezers and removing atoms have to do with combinations? It is trivial to come up with a situation where there are more possible combinations that atoms of the universe. The number of possible chess games starts to get close (magnitude of 50 versus 80 for the atoms in the universe. Slightly more complex scenarios would easily go past 10^80. The trick is to find a way to model the complexity with a much simpler algorithm.

Re:More than atoms in the universe? (0)

Anonymous Coward | about 5 years ago | (#29320725)

How in the hell is 10^50 close to 10^80!

Re:More than atoms in the universe? (0)

Anonymous Coward | about 5 years ago | (#29320867)

Indeed, raising anything to the power of 80! (80 factorial) is going to be big.

Re:More than atoms in the universe? (1)

Teancum (67324) | about 5 years ago | (#29332829)

How about raising 1 to the power of 80!. Yeah, that is going to be a really massive number.

Re:More than atoms in the universe? (1)

Hognoxious (631665) | about 5 years ago | (#29321793)

Are more obvious one would be the different sequences you could make from all the atoms in the universe.

Re:More than atoms in the universe? (2, Informative)

MyLongNickName (822545) | about 5 years ago | (#29320491)

Here ya go [wordpress.com] . About 59.

Re:More than atoms in the universe? (1, Informative)

Anonymous Coward | about 5 years ago | (#29320663)

According to Wikipedia, [wikipedia.org] our best estimate of the number of atoms in the universe is 10^80. The smallest factorial greater than this number is 59! = 138 683 118 545 689 835 737 939 019 720 389 406 345 902 876 772 687 432 540 821 294 940 160 000 000 000 000 = 1.39 * 10^80. (The next smallest factorial is 58! = 2 350 561 331 282 878 571 829 474 910 515 074 683 828 862 318 181 142 924 420 699 914 240 000 000 000 000 = 2.35 * 10^78.)

Re:More than atoms in the universe? (0)

Anonymous Coward | about 5 years ago | (#29323523)

What factorial does it take to equal that number?

59!: about 1.4 x 10^80
Estimated number of atoms in the universe: 10^80.

According to Wolfram|Alpha

Surprised.. (0)

Anonymous Coward | about 5 years ago | (#29320175)

they didn't use Pigeon Rank on the food web.

Bioinformatic Algorithm for Standard Americans (1, Funny)

Anonymous Coward | about 5 years ago | (#29320177)

A species is more important if it points to my stomach.

Also see my upcoming research topic:

Bioinformatic Algorithm for Standard Texan-Americans with Retro-Dissonant Suppositions

I expect to prove that BASTARDS are essential to the American way of life.

Re:Bioinformatic Algorithm for Standard Americans (0)

Anonymous Coward | about 5 years ago | (#29320593)

A species is more important if it points to my stomach.

ME AGREE! OM NOM NOM NOM!!!

Re:Bioinformatic Algorithm for Standard Americans (0)

Anonymous Coward | about 5 years ago | (#29320777)

A species is more important if it points to my stomach.

I've done a lot of work with TasteRank, which quickly finds species that are deliciously important.

Re:Bioinformatic Algorithm for Standard Americans (1)

TheLink (130905) | about 5 years ago | (#29324219)

> A species is more important if it points to my stomach.

Especially if it points using a very sharp spear, or a shotgun. Then you can really talk about extinction and things "vital to the existence".

But solve the real problem? (-1, Troll)

macraig (621737) | about 5 years ago | (#29320193)

Now, if only they could find a way to use PageRank to solve the underlying problem - human overpopulation - we might finally be on the way to realistically saving all the endangered species. As it is, without solving that 800-pound-gorilla problem, all we can do is manage to keep them on life support for a few decades. Does anyone remember 'Silent Running'? We're headed for a scenario that will require us shipping a whole lot more than just trees and plants out to the orbit of Jupiter.

Re:But solve the real problem? (1)

Darkness404 (1287218) | about 5 years ago | (#29320231)

We are humans. Really humans are the only species that in the end matter. So long as we have enough food and oxygen, all is good and the survival of our species is guaranteed (assuming no effects of huge disasters such as an asteroid impact, etc.)

Re:But solve the real problem? (1)

macraig (621737) | about 5 years ago | (#29320343)

I'm guessing you've never watched 'Silent Running', but given what you said you might wanna start your re-education with another old movie: 'Soylent Green'.

As long as the world is this overpopulated we'll always have enough food. Cannibals aren't bad people, they're just pragmatic.

Re:But solve the real problem? (1, Interesting)

Darkness404 (1287218) | about 5 years ago | (#29320397)

Please tell how you think we are currently becoming overpopulated? For one we have enough food to feed -everyone- the problem is corrupt government and lack of education that causes hunger in third-world countries. In first world countries its quite easy to get food and shelter so no one should ever die of hunger. Yeah, you won't be eating steak and shrimp every night, but you aren't going to starve to death. Take a drive to North Dakota sometime if you don't think we have enough space. If you read the UN's projections for birth rates (http://www.un.org/esa/population/publications/wpp2006/WPP2006_Highlights_rev.pdf) it shows a -sharp- decline in birth rates for most of the developed world. And in general a "bubble" of population increase then a decrease (because there is a large amount of old people who are going to die). Even a doubling in human population isn't really a huge deal with increasing technology leading to increased crop yields and the ability to farm previously unfarmable areas. And we have way more than enough space.

Re:But solve the real problem? (2, Insightful)

macraig (621737) | about 5 years ago | (#29320509)

If you're under 40 and in good health you're in for a rather rude awakening, with those beliefs. You'll likely live to see the shit begin to hit the fan in a serious way. Google and other online sources should be education enough for you. I'm too disorganized to do anything more than plant the seed; you'll have to water and feed it.

Re:But solve the real problem? (0)

Anonymous Coward | about 5 years ago | (#29320583)

Most of us know (or at least believe with a good likelihood of being correct) that our current use (abuse) of fossil fuels is changing the planet in ways that will make it a more difficult place for humans live. You would think that those with children and grandchildren would be the most aware of this, however, this set seems to be the ones who take the most delight in SUV's and vacation flights across the world. Presumably this is the same group that recognizes the dangers of using cell-phones while driving on an intellectual basis, but continues to use them.

Re:But solve the real problem? (2, Interesting)

Darkness404 (1287218) | about 5 years ago | (#29320603)

So lets see here, I'm supposed to believe some random person on the internet because of A) Sci-Fi films, B) "facts" that contradict reputable sources such as the United Nations and C) ideas that don't make much sense. Lets see here, we have technology that allows us to grow more crops in a single area than ever before, technology that lets us grow more crops with less effort (we have less humans employed as farmers than before yet have more crops than before) and technology that will let us grow crops in places that could never have had crops planted before. We similarly have lots of habitable space, more than ever before. Someone could live in the middle of the desert, yet still have food, a habitable place to live and water.

So in the end, we have more food than we know what to do with, technology enabling us if there was some kind of food shortage to grow our own food in our basements if need be, no shortage of space, etc. Seriously, part of science fiction is... fiction. If it was true, well perhaps I should start carving Ego in big letters in rocks in case humanity forgets about individuality and the word I (for those not in the know this is a reference to Ayn Rand's book Anthem). But really take a look at http://en.wikipedia.org/wiki/File:Population_growth_rate_world.PNG [wikipedia.org] -large- portions of the world have a negative birth rate. So with no science to back up your claims, other than a few science fiction movies, why should I believe you?

Re:But solve the real problem? (0)

Anonymous Coward | about 5 years ago | (#29320933)

So let's see here, I'm supposed to believe some random person on the internet A) pooh-poohing science fiction (irony piled on top of irony here), B) who considers the UN to be a "reputable" source (I suppose it is for cases of "reputable" such that "reputable is equal to as least as credible as a huckster selling snake oil"), both of which are C) ideas that don't make much sense.

Good luck growing food in your basement if there is a food shortage serious enough to require people to grow food in their basements. Maybe you can get a few crops in when you're not otherwise engaged in keeping the looters out as they try to see if there's anything to eat in your house.

P.S. The UN and Ayn Rand probably don't mix too well. The only place for ego in world government will be in the leadership. "Individuality" and "I" will be about as much use for those who are not in charge as they are for chickens in an industrial hen house.

Re:But solve the real problem? (1)

Mikkeles (698461) | about 5 years ago | (#29323493)

Living is more than not starving.

Re:But solve the real problem? (1)

PC and Sony Fanboy (1248258) | about 5 years ago | (#29320431)

Let's start with a car analogy: You tell me that things in the mirror may appear closer than they actually are... to which I respond "Who the hell looks in their mirrors"?

I'm guessing you've never watched 'Silent Running', but given what you said you might wanna start your re-education with another old movie: 'Soylent Green'.

I think you need to re-educate yourself with another movie: The Omega Man. If that's where we'll end up anyways, who cares how we get there? Eat drink and be merry, I say. Isn't there some movie about people being brainwashed with media and living in a world that isn't real (but they think it is) because they're too plugged into modern culture to know the difference? I mean, if hollywood is providing you with all your examples, you'd best take the good with the bad.

Re:But solve the real problem? (1)

Hognoxious (631665) | about 5 years ago | (#29321625)

To paraphrase Thomas Hobbes: You're a winner or you're dinner.

Re:But solve the real problem? (1)

smoker2 (750216) | about 5 years ago | (#29322815)

This has to be a troll right ?

Seriously, "so long as we have enough food and oxygen, all is good" ? Where the fuck does that food come from, idiot ? What processes combine to create that food ? Which lifeforms are necessary to provide those processes ? Which out of the millions of bacteria is it safe to eliminate before we are unable to digest food at all ?

I suppose you think fossil fuels are good because they are effectively free, all you have to do is dig them up. And that is relevant, as without fossil fuels, there is not enough energy on the planet to sustain our current food supply. We are using stored solar energy to grow food more quickly than nature can alone. When that stored energy runs out, we'd better have a new source lined up or a large number of people will starve.

But apparently we don't need other life forms at all. Instead of pesky insects eating plants or each other, we'll just eat plants or each other. Except there will be no plants without other forms of life to pollinate, spread seeds, provide nutrients and generally be part of the whole process.

Re:But solve the real problem? (1)

macraig (621737) | about 5 years ago | (#29327839)

Guess who actually got modded as Troll, though? Nope, not the "idiot"... it was my original comment pointing out the larger context being ignored (for the sake of TOFA). Modded as Troll not just once, but repeatedly.

If there's one thing about Slashdot that should change, it's the removal of anonymity when people moderate.

Other uses come to mind as well (0, Troll)

sehlat (180760) | about 5 years ago | (#29320219)

In some respect, an economy can be considered as a sort of ecology. If this research holds up, it would be interesting to do the same sort of analysis to rank the importance of industries and occupations. Which ones are necessary and vital and which ones (MPAA?) can be discarded without harm or even with benefit to the rest of the ecology.

Re:Other uses come to mind as well (0, Offtopic)

bhtooefr (649901) | about 5 years ago | (#29320279)

Problem is, a lot of companies point to companies that point to the MPAA.

Such a model may rate the MPAA and RIAA as higher ranked than the biggest single companies around.

Re:Other uses come to mind as well (0)

Anonymous Coward | about 5 years ago | (#29320451)

All industry associations can be discarded with benefit to the rest of ecology.

Who could submit this article anonymously? (1)

melikamp (631205) | about 5 years ago | (#29320225)

And why?

Re:Who could submit this article anonymously? (1)

PachmanP (881352) | about 5 years ago | (#29320341)

And why?

Sergey Brin. The nefariousness is obvious isn't it?

Importance (2, Interesting)

Darkness404 (1287218) | about 5 years ago | (#29320243)

In PageRank, a web page is important if important pages point to it. In our approach, a species is important if it points to important species.'"

The difference is, its pretty obvious to a human if a page is important. On the other hand there are a lot of species that we don't know if they are important or not. So how do we know what the "important" species are? Other than humans, we don't know of any real "important" species. Could the ecosystem survive without X? Theres no way we can really know that.

Importance is easy to determine... (2, Funny)

PC and Sony Fanboy (1248258) | about 5 years ago | (#29320439)

Have you learned nothing from history? We can know if an ecosystem survives without certain members.

It just isn't a good idea to experiment.

Re:Importance is easy to determine... (1, Troll)

Darkness404 (1287218) | about 5 years ago | (#29320469)

Well of course, we know that above all things nature simply survives. But we can't know for certain whether they are "important" for it to survive on its own. Especially with the ever-changing nature of the world. If a predator dies will another predictor eaten by the other predator move in? Will the prey multiply like crazy? Its these things that will make the PageRank algorithm useless in biology.

Re:Importance is easy to determine... (1)

PC and Sony Fanboy (1248258) | about 5 years ago | (#29320503)

Its these things that will make the PageRank algorithm useless in biology.

I suppose you're right. Since you disagree, the entire idea must be without merit.

Re:Importance (3, Informative)

JorDan Clock (664877) | about 5 years ago | (#29320475)

The model helps determine if a species is important. That's the whole point. Previously, we didn't have an easy way to determine a particular species impact on an ecosystem until it was almost extinct or already gone. Now by using "PageRank" to determine their importance, we can model what will happen if specific species are no longer part of the food web.

Re:Importance (2, Insightful)

Onymous Coward (97719) | about 5 years ago | (#29322955)

I was worried about this. Either underspecifying "importance" or using it in a simplistic way (though you may not actually be doing these things).

It measures a kind of importance. Not importance in all respects. Specifically, it measures importance in interdependence. Which only very roughly translates to an idealized general or universal importance.

Remove humans from the web and you won't get much "impact on [the] ecosystem" (in the form of cascading die off). Yet humans are generally regarded as "important".

It should be noted (now and in each subsequent discussion of this topic) that the value of a species needs to be assessed by other measures as well. Like how beautiful its plumage is.

Re:Importance (1)

JorDan Clock (664877) | about 5 years ago | (#29328979)

The idea of saving an animal based on its appearance is one of the reasons why many animals receive a disproportionate amount of funding. There are some species of animals that have more money diverted to them than hundreds of other species combined for no other reason than they are more marketable.

If pandas go extinct, what effect would it have on the ecosystem? Almost none. It eats bamboo for 99% of its diet and I doubt it eats enough to be a source of control on the growth of bamboo. However, pandas are one of the most iconic and most fiercely protected animals. Why? Because they're cute. Not because they're useful to the ecosystem.

Screw plumage, I'm tired of hearing from bleeding hearts over cute, useless animals. I want to see protection of animals that mean a damn to the ecosystem, not for animals that look good on kid's folders and as plush toys.

Re:Importance (1)

Onymous Coward (97719) | about 5 years ago | (#29330185)

The plumage comment was a joke, sorry. I was trying to be ludicrously shallow, but the truth is that beauty actually does count for something.

The value of life is not simple, so it's not easy to put it simply. For example, it's not clear to me what "good for the ecosystem" means. It sounds like maybe it means "tendency to preserve the extent (quantity?) of food/consumer relationships" or maybe "tendency to preserve maximal living mass" or maybe "tendency to promote diversity". This is real philosophical stuff.

My preference for value is "the experience of sentience". To the degree that things are aware and experiencing reality is the degree to which they should have their experience cared for. But it's virtually unpossible to gauge degree of awareness. And what makes for a good experience for any known kind of sentience is a vastly complicated thing.

Still, gotta try. Be well.

PigeonRank (2, Funny)

FooAtWFU (699187) | about 5 years ago | (#29320479)

I would have thought that an animal-based algorithm such as PigeonRank would be more applicable to this problem.

Re:Importance (4, Informative)

Hadlock (143607) | about 5 years ago | (#29320625)

NO! Page Rank is not named after webPage. It's named after Larry Page who created it. Arrrgh.
 
http://en.wikipedia.org/wiki/PageRank
 
http://en.wikipedia.org/wiki/Larry_Page

Re:Importance (1)

Atario (673917) | about 5 years ago | (#29328695)

Huh -- I never realized poor Sergey Brin got screwed on that deal.

Very helpful for Endangered Species Act (2, Interesting)

Kligat (1244968) | about 5 years ago | (#29320285)

I've often been annoyed by the excessive focus on the iconic [washingtonpost.com] and popular species in many endangered species awareness campaigns. It is easy to say "we are spending a million dollars on protecting a worm?" in Congress, but when more renowned species like a hammerhead shark variety are endangered, they will naturally get more attention. Now scientists can defend their case for funding by pointing to this algorithm.

Or... (1)

PC and Sony Fanboy (1248258) | about 5 years ago | (#29320459)

That's interesting, because most americans don't care about preservation.

My proof?
Wal-mart (and the associated industries that support low prices).

Sure, save the whales/sharks/pandas/worms. But I better get my tampico for 0.34$/bottle and jeans for $4.99 so I can afford to help out.

Re:Or... (1)

timmarhy (659436) | about 5 years ago | (#29320537)

whats wrong with low prices? would you prefer high prices so people can't invest in cleaner technology eg. i can't afford that prius because the cost of living means i'm JUST scraping by. i think there is a hole in your thinking there.

Low prices = low wages (0)

Anonymous Coward | about 5 years ago | (#29322701)

Where do you think low prices come from? Minimum wage in countries like china is pennies a day. Exploitation, really. And encouraging exploitation of people leads to exploitation of other resources. I think there is a hole in your thinking. Or maybe you've never thought about why walmart can sell things so cheap.

Re:Very helpful for Endangered Species Act (0)

Anonymous Coward | about 5 years ago | (#29320517)

I've often been annoyed by the excessive focus on the iconic [washingtonpost.com] and popular species in many endangered species awareness campaigns. It is easy to say "we are spending a million dollars on protecting a worm?" in Congress, but when more renowned species like a hammerhead shark variety are endangered, they will naturally get more attention. Now scientists can defend their case for funding by pointing to this algorithm.

Oh joy, more hippies wasting stimulus money. Take as many DNA samples as we can, freeze them, store them, and be done with it until we have solved all of humanity's issues.

Re:Very helpful for Endangered Species Act (2, Insightful)

icegreentea (974342) | about 5 years ago | (#29320917)

People generally don't want to spend their money saving some worm. As it's been suggested before, the focus on megafauna partly exists just because they are charismatic. Panda bears are fricking cute. And people will donate money to save panda bears, their habitat, and everything else living there. It's unfortunate, but it's just facing the reality of the situation. Being able to identity the real keystone species would be great for the actual scientists, conservationists, and policy makers. But when its time to get funding, donations and support especially from the public, you can bet it'll be some megafauna. I mean, look at that cute widdy tiger cub. Worm eggs? UGH.

Pagestank (-1, Flamebait)

syousef (465911) | about 5 years ago | (#29320471)

Pagerank is one of the most overblown "algorithms" ever. The way people talk about it you'd think it ranks up there with Fourier analysis or orbit determination. Pagerank is little more than a popularity contest - American Idol phone voting on steroids. If you need a general idea of what's going on, searching on Google's okay. If you want more substance better go for a specialist search engine.

Applying this to food I expect McDonalds to be ranked very high and fine dining to be ranked as rubbish.

Yeah go on mod me as troll, because *sarcasm* a rational person couldn't possible hold this opinion...

Re:Pagestank (0)

Anonymous Coward | about 5 years ago | (#29320573)

Did you even read the fine summary? It does not rank the food we eat everyday (well, at least not directly). It is to determine the importance of each species so that we can better spend our effort in preserving them. This has the helpful effect of keeping ecosystems intact.

I am not new here, and I know a fair amount of people here don't RTFA but seriously, do you people now just read the headlines and start making useless comments?

Re:Pagestank (1)

Atario (673917) | about 5 years ago | (#29320761)

Do you have a point? Or did you just use the mention of the term "Pagerank" to come in here and randomly slag off Google?

Re:Pagestank (1)

invalid_user (253723) | about 5 years ago | (#29320855)

Do you have a point? Or did you just use the mention of the term "Pagerank" to come in here and randomly slag off Google?

The poster has a point, and is certainly not slagging off Google.

The point is that the mathematics of Page Rank is not very deep. A fact which can be asserted.

Re:Pagestank (0, Troll)

syousef (465911) | about 5 years ago | (#29321301)

Do you have a point? Or did you just use the mention of the term "Pagerank" to come in here and randomly slag off Google?

Apparently the point - that pagerank stinks and is not something I want to pay attention to if used to rank food - was too subtle for you. I don't know if you're a Google employee or just a run of the mill sock puppet but I did not go into a tirade about Google teh company so stop trolling.

Re:Pagestank (1)

Atario (673917) | about 5 years ago | (#29328675)

<eyeroll />

Ok, Captain Expert. Pagerank is awful, and that's why Google is not useful to anyone. And these people trying to apply it to what organisms eat other organisms -- not, as you seem to think, to what restaurants are better than others -- is completely moronic as well, since the quality of the organisms' meals are more important than what organisms depend on what other organisms and to what extent, which these poor mislead people are paying attention to.

In short, gosh, I guess I'm the troll and you're the poor victim. Gee whiz, sorry for tricking you like that.

Re:Pagestank (1)

Ambvai (1106941) | about 5 years ago | (#29321133)

I'd expect McDonald's to be ranked very high based on importance to the diets of people around the world while the importance of, say, filet mignon to be comparatively negligible. There are times where a popularity contest works: "Hey, people are getting fat. What food should we make healthier? Well, people seem to be eating a lot of hamburgers, so lets see if we can make those leaner!"

Re:Pagestank (1)

jpmorgan (517966) | about 5 years ago | (#29321139)

Pagerank isn't an important algorithm, it's an application of an important mathematical concept. Pagerank is just computing the limiting distribution of a specially constructed Markov chain, which is very important and has many applications beyond pagerank and 'popularity contests.'

Re:Pagestank (1)

chthonicdaemon (670385) | about 5 years ago | (#29321341)

At the heart of Pagerank is the idea that, if one has a connection matrix between 'things' and these connections are related to the scoree, one can pose the problem as an eigenvalue problem [wikipedia.org] . That's a pretty cool insight, and is applicable to many more fields than internet searches, for instance: ranking articles due to citations, teams based on wins and losses, and now finding important species based on their genetic connections.

I would imagine that the many places Pagerank has found application would count for something when you figure the significance.

Re:Pagestank (1)

martin-boundary (547041) | about 5 years ago | (#29327725)

It's a pity that this insight isn't Google's insight. It's been known for a hundred years, and goes back to the works of A.A. Markov, G. Kirchhoff, O. Perron and F.G. Frobenius (look them up on wikip).

The *only* thing worthy of note with PageRank is the humongous size of the graph that is being modeled. This could never have been attempted until the 1990's because computers weren't powerful enough before (and the few that were just weren't going to be used for "silly" things like web search).

Needs more verbs. (0)

Anonymous Coward | about 5 years ago | (#29321829)

NO SHIT!
That is the whole damn point of this analysis, to determine popular food chains between all the animals to see the ones that would cause the largest impact in all the species.

If McDonalds suddenly died, the reverberations it would cause in the human food chain would be crazy!
Yes, the humans will just start targeting Burger King more, but they will end up going through a horrible time as well as they are filled to capacity and end up running out of stock quicker.
By the time they gather enough monies to either build new buildings or buy more stock, a significant amount of their regular customers would probably be pissed off by them running out of stock so much.
Pizza hut doesn't even come in to the argument, it is already dead. (in your average MKer or BKer, "pizzas, ewck")
Sure, "fine dining" might gain some popularity, but it would be very low percentage, like less than 10% increase on average.

There is absolutely nothing wrong with using what is basically a popularity algorithm to determine links like this.
But i can certainly see your criticism since it doesn't show the most information when it comes to how important a species is.
It could be improved to the point where it isn't so much as a food chain, but a verb chain, THIS would be a million times more useful, there are many verbs that animals do that can heavily influence other species, like bees as the best example i can think of.
Also, i hate DFDs...

This begs the question (1)

RCourtney (973307) | about 5 years ago | (#29320555)

In the context of being an important part of the web, what is the page rank for the species homo sapiens?

Re:This raises the question (0)

Anonymous Coward | about 5 years ago | (#29323453)

Corrected that for you

Re:This begs the question (1)

mhotchin (791085) | about 5 years ago | (#29324271)

"Raises", damn-it, "This RAISES the question".

"Begging the question" is more like circular reasoning - you assume that which you are trying to demonstrate.

Eigenvector Centrality Measure (2, Insightful)

sugarmotor (621907) | about 5 years ago | (#29321081)

The pagerank algorithm is better understood as a kind of Eigenvector Centrality Measure.

See http://en.wikipedia.org/wiki/Eigenvector_centrality#Eigenvector_centrality [wikipedia.org]

Meaning it is not new as a method by itself, but applying it to the linking-structure of the WWW in order to produce
relevant documents for a query, was new. I think it is fair to say that the Google Pagerank matters very little, outside of being able to rank otherwise
  not-comparable search results.

And so it is better to state that "a specialized Eigenvector Centrality Measure can predict with great accuracy which species are vital to the existence of others" instead of "a modified version of PageRank can predict with great accuracy which species are vital to the existence of others". One can see that also when one realizes that these biologists have no query, no search, no equivalent of search keywords.

On the other hand, when the post says "Co-author Dr. Stefano Allesina realized he could apply PageRank to the problem when he stumbled across an article in a journal of applied mathematics describing the Google algorithm." -- I guess he might have found the method through the Google name.

Stephan

Useful (1)

mqduck (232646) | about 5 years ago | (#29321211)

Awesome, now we know which species we can let go extinct!

Other utility (1)

rafaelolg (1248814) | about 5 years ago | (#29322263)

This could be used to predict which projects are essential to open source and free software.

Gaia (1)

Karl Capek (776807) | about 5 years ago | (#29322409)

Certainly this is an additional tool that can be used to explore Lovelock's Gaia hypothesis. If other elements were included in the web of interactions such as atmospheric and dissolved CO2, the actions of rocks it might provide a further insight into global warming and what we should be looking at the mitigate it.

Let me get this staight (1)

JAlexoi (1085785) | about 5 years ago | (#29322933)

I am a representative of an important species and if I point to a web page it becomes important?
How long do I have to point at a certain page to put it on top of Google search results.

So what happens when... (1)

partypants69 (1294046) | about 5 years ago | (#29327797)

So what happens when this algorithm determines humans are the least important species to the ecosystem?
Check for New Comments
Slashdot Login

Need an Account?

Forgot your password?