Field of Science

Highlights from the Year in Ideas

The New York Times Year in Review section always has some good ones. Some highlights for me from this year:

  • Does feeling like a fraud make you act like one? Researchers gave experiment subjects designer-style sunglasses from boxes marked "authentic" or "counterfeit". They then put the subjects in situations with an incentive to be dishonest; far more of the subjects who were told they were wearing counterfeit designer glasses acted in a dishonest manner. Possible conclusion: wearing the "counterfeit" glasses (in reality all the glasses were authentic) made people feel like they were dishonest, and they acted accordingly.

  • Battle-bots with a moral compass: A roboticist is collaborating with the US army on combat robots (e.g. predator drones) that can weigh military objectives against civilian harm, and adhere to codes of international law. Personally, I'd rather trust human beings with moral decisions, but seeing as we have robots fighting our wars already, putting some safeguards in them is better than nothing.

  • Proof by blog: Fields medalist mathematician Timothy Gowers decided to run an experiment on his blog by challenging his readers to collaboratively prove a mathematical that he himself could not. Six weeks and hundreds of collaborators later, the theorem was proven, and is planned for publication under the name DHJ Polymath. This success inspired the creation of the polymath project, which aims to advance mathematics through "massively collaborative mathematical research programs".

  • Conditional microfinance: The website matches prospective philanthropists with artists, journalists, inventors, and others needing funding for their projects. The twist: unless a project attracts enough funding to meet its needs, no one pays a dime. So you don't need to worry about throwing money at something you're not sure anyone else will invest in; just pledge and see what happens!

  • SmartTrash Here's a case where I'm not so excited by the invention itself (a garbage can that scans barcodes items as they go in to see if they can be sold for money) as with the general idea it portends: I've always thought of our trash system as one of the worst inefficiencies in our society, in both economical and environmental terms. Outfitting garbage cans with microchips is a possible first step in designing a waste management system that isn't actually wasteful.

Finally, there's one "idea" that involves a complete misunderstanding of evolutionary game theory, as far as I can tell. I'll give this one a separate post when I get around to it.

Book Review: LOGICOMIX

We are living in an age of, amongst other things, excellent graphic novels. One shining example, which I have just finished reading, is LOGICOMIX, a graphic novel biography of mathematician and philosopher Bertrand Russell. (Side note: can a biography still be called a graphic novel? Our terminology may need an update.)

Seeking an escape from his authoritarian religious upbringing, young Bertrand turned to mathematics as the one source of absolute certainty in his life. But the more he studied mathematics, the more he realized that underlying all the sophisticated theories of the time were arguments based more on intuition than full rigor. Driven by his quest for absolute truth, Russell embarked on a project to rebuild mathematics from the foundations up, and thereby establish its status as absolute truth.

Unfortunately, his project ran into major difficulties of the mathematical/philosophical variety (to say nothing of his equally great personal difficulties) including the famous paradox of Russell's own invention, the arguments of his student Wittigstein that logic was merely a tool for generating tautologies, and finally, Godel's proof that even in the self-consistent world of mathematics, there must always be true statements that cannot be proven.

In the end, though Russell and his contemporaries eventually succeeded in placing mathematics on a rigorous footing, the dream of a logically grounded "universal truth" had to be abandoned. Mathematics is only as true as the assumptions it rests on, and cannot even prove all that is true in its domain.

While the mathematical and philosophical ideas are well-illustrated for a lay audience, the heart of LOGICOMIX is Russell's personal struggle, first to find the universal truths in mathematics and then to accept their nonexistence. Like others engaged in this project, Russell's struggle with logic occasionally veered into a struggle with sanity. Through a meta-narrative of the book's creation, the authors debate the "logic and madness" theme, and ask whether some amount of detachment from reality a prerequisite for one who spends his or her life searching for its foundations.

This narrative of Russell's quest had personal resonance for me: I went through my own late-high-school/early-college phase of viewing mathematics as a bastion of truth in an illogical world. I wonder if many of my mathematical colleagues' careers had their genesis in the same yearning for certainty. I imagine we all eventually come to the same realization as Russell: that mathematics is a powerful tool for clear thinking, but the only "truth" it contains is ultimately tautological.

Disillusioned by his self-described "failure" but ultimately freed from his need for unblemished truth, Russell turns to more worldly concerns, including pacifist activism and the founding of a school with no rules (spoiler: it doesn't go well). The book ends on a bittersweet note as Russell encourages students to accept their lives in an uncertain world.

I had great pleasure following Russell's journey, and the many ideas and people encountered along the way. If anyone is interested in what really drives mathematicians, this book is heartily recommended.


The following question was given as a homework problem in a course I'm TAing:

CNBC had an interesting program on the current financial crisis. They located one investor who noticed that since the late 1990's housing prices have been growing 10 percent every year (that is, each year, the average home price is 1.1 times the average price in the previous year) while income was only increasing by 5 percent each year (that is, each year, the average income was only 1.05 times the average of the previous year).

Explain why it is "absolutely clear that this situation could not go on forever", in the words of the investor (who made over a billion dollars because of this observation).
This simple question goes right to the heart of the financial collapse. I would only add that, not only did this particular investor make billions off this observation, but our whole economy lost trillions, because the vast majority of financial decision makers were either unable or unwilling to make this same observation.

(Anyone who needs help with the mathematics of this problem can meet me in the comments.)

Human Cultural Transformation Triggered by Dense Populations

Biologically,modern humans first appeared 160,000 to 200,000 years ago. But the transition to complex human societies, with art, music, advanced tools, occurred a good deal more recently, and moreover, occured at different times in different parts of the world. An article in June's Science magazine (see a less technical write-up here) argues, based on historical evidence and computer simulations, that in each case the transition was triggered once the population density had reached a critical threshold. At this threshold, there is sufficient interaction to allow for complex ideas to be passed down through generations, enabling rapid cultural evolution.

This highlights an interesting evolutionary tension: as I've written before, evolutionary theory tells us that cooperative behaviors are more likely to evolve (biologically speaking) in populations that are dispersed over space rather than densely packed. But I'm beginning to think that cultural evolution may be different enough from biological evolution to require its own body of theory.

Inferring Social Security Numbers from Birth Data

An article in July's PNAS investigates the possibility of predicting a person's Social Security number from their birth date and place. Exploiting patterns in how SSN's are assigned, authors Alessandro Acquisti and Ralph Gross developed an algorithm which could correctly predict the first 5 digits of a social security number 44% of the time, for people born after 1988 (older SSNs are significantly harder to predict). The accuracy varied from state to state; for smaller states and recent birthdays, the algorithm could sometimes predict an entire SSN on the first try.

Think you're safe?

The Quandaries of Quantifying Complexity

My good friend and computer scientest Kyle Burke has recently started a highly interesting blog on his research field: combinatorial game theory. The idea of this field is to use games as a tool for studying issues of complexity. Though his blog is only a month old, some important foundational ideas have begun to rear their heads, one of which I'll explore in this post.

Understanding complexity is important for almost any human endeavor, but defining it in rigorous terms is notoriously difficult. For example, which is the more complicated game, chess or tic-tac-toe? Almost anyone would say chess, but suppose you had a computer that was designed only to play chess. In fact, this computer has no capacity for calculation; it simply has the best move for any given chess position hardwired into its architecture. To get this computer to play tic-tac-toe, you would have to program it to translate each tic-tac-toe position into an analagous chess position, so it could then find the best chess move and translate this move back into tic-tac-toe. This computer would certainly find chess an easier game to play.

Computer scientists have a way around this paradox: instead of looking at individual games or problems, they look at classes of problems. Each problem in the class has a certain size, and they look at how complexity increases in relation to size.

For example, you could easily imagine playing tic-tac-toe on boards of various sizes. Computer scientists can analyze how the complexity of tic-tac-toe varies with the size of the board. (Chess, on the other hand, doesn't generalize as easily to larger sizes, which makes it difficult to talk about its complexity.)

Unfortunately, if we are faced with a real-world issue (such as how to provide for the needs of a large population), we will want to know the complexity of the specific problem at hand, not how the complexity might theoretically scale with problem size. Part of the reason that complexity issues are so often ignored (to the detriment of many well-meaning policies and programs) is that defining and quantifying complexity is so unavoidably slippery.

Further reading

The Criminalization of Poverty

Barbara Ehrenreich had an excellent article in yesterday's New York Times on the many ways that being poor can land you in trouble with the law. One striking example:

In just the past few months, a growing number of cities have taken to ticketing and sometimes handcuffing teenagers found on the streets during school hours.

In Los Angeles, the fine for truancy is $250; in Dallas, it can be as much as $500 — crushing amounts for people living near the poverty level. According to the Los Angeles Bus Riders Union, an advocacy group, 12,000 students were ticketed for truancy in 2008.

Why does the Bus Riders Union care? Because it estimates that 80 percent of the “truants,” especially those who are black or Latino, are merely late for school, thanks to the way that over-filled buses whiz by them without stopping. I met people in Los Angeles who told me they keep their children home if there’s the slightest chance of their being late. It’s an ingenious anti-truancy policy that discourages parents from sending their youngsters to school.

The column was based on a report by the National Law Center on Homelessness and Poverty, which finds that the number of ordinances passed and tickets issued for crimes related to poverty has grown since 2006.

Hey, no one likes poverty, right? Let's pass a law!

The Evolution of Bad Ideas

It is by now common wisdom that our current financial crisis is due in large part to misplaced incentives in our financial system. Analysts and fund managers were rewarded for short-term thinking and risk-taking. If we can rework our financial system to reward long-term, careful planning, it is often argued, we can avoid collapses like this in the future.

While I agree that misplaced incentives were a fundamental problem, the question of how to change this is rather more deep and complex than I think many people realize.

Our economy is, of course, an evolutionary system. Successful businesses grow in size and their practices are imitated by others; unsuccessful businesses vanish. This process has led to many good business practices, even in the financial sector.

However, evolution does not always yield the best outcomes, in biology or in economics. Our recent crisis illustrates two key limitations of evolutionary systems, limitations which allow bad ideas to evolve over good ones.

The first problem has to do with time lags. Suppose Financial Company A comes up with an idea that will yield huge sums of money for five years and then drive the company to bankruptcy. They implement the idea, obfuscating the downside, and soon the company is rolling in cash. Investors line up to give them money, magazines laud them, and other companies begin imitating them.

Not so Company B. Company B believes in long-term thinking, and can see this idea for the sham it is. They persue a quiet, sound strategy, even when their investors begin pulling money out to invest in A.

We would like to think that in the end, Company B will be left standing and reap them benefits of their foresight. But there is a fundamental problem of time-scales here: by the time A folds, B may already be out of business, due to lack of interest from investors. In theoretical terms, there is a fundamental problem when the evolutionary process proceeds faster than the unfolding of negative consequences. In these situations, good ideas never have a chance to be rewarded, evolutionarily speaking.

One might argue that investors, not to mention government regulators and ratings agencies, should have forseen the flaw in A's plan. But this highlights a second limitation of the evolutionary process: it favors complexity. Simple bad ideas can be detected by intelligent agents, but complex ones have a chance to really stick. If Company A's idea was so complicated that no one aside from a few physicists could figure it out, investors and regulators could easily be fooled.

It's not clear to me how to patch these flaws in the evolutionary system. Increased transparency and oversight will help, but unless we can somehow cap the complexity of financial instruments (difficult) or slow down the evolutionary process (impossible), I'm not sure how we'll avoid similar crashes in the future.

Biodiversity and Entropy

On Tuesday, my Erdos number dropped from infinity to four. That's right: after four years of grad school, I am now officially published!

The article, “A New Phylogenetic Diversity Measure Generlizing the Shannon Index and Its Application to Phyllostomid Bats,” by Ben Allen, Mark Kon, Yaneer Bar-Yam, can be found on the American Naturalist website or, more accessibly, on my professional site.

So what is it about? Glad you asked!

Protecting biodiversity has become a central theme of conservation work over the past few decades. There has been something of a shift in focus from saving particular iconic endangered species, to preserving, as much as possible, the wealth and variety of life on the planet.

However, while biodiversity may seem like an intuitive concept, there is some disgreement about what it means in a formal sense and, in particular, how one might measure it. Given two ecological communities, or the same ecological community at two points in time, is there a way we can say which community is more diverse, or whether diversity has increased or decreased?

Certainly, a good starting point is to focus on species. As the writers of the Biblical flood narrative were in some sense aware, species are the basic unit of ecological reproduction. Thus the number of species (what biologists call the "species richness") is a good measure of the variety of life in a community.

But aren't genes the real unit of heredity, and hence diversity? Is the number of species more important than the variety of genes among those species? Should a forest containing many very closely related tree species be deemed more diverse than another whose species, though fewer, have unique genetic characteristics that make them valuable?

And while we're complicating matters, what about the number of organisms per species? Is a community that is dominated by one species (with numerous others in low proportion) less diverse than one containing an even mixture?

There is no obvious way to combine all this information into a single measure for use in monitoring and comparing ecological communities. Some previously proposed measures have undesirable properties; for example, they may increase, counterintuitively, when a rare species is eliminated.

In this paper we propose a new measure based on one of my favorite ideas in all of science: entropy. You may have heard of entropy from physics, where it measures the "disorderliness" of a physical system. But it is really a far more general concept, used also in mathematics, staticstics, and the theory of automated communication (information theory) in particular. At heart, entropy is a measure of unpredictability. The more entropy in a system, the less able you will be to accurately predict its future behavior.

The connection to diversity is not so much of a stretch: in a highly diverse community, you will be less able to predict what kinds of life you will come across next. Diversity creates unpredictability.

To be fair, we weren't the first to propose a connection between diversity and entropy. This connection is already well-known to conservation biologists. But we showed a new and mathematically elegant way of extending the entropy concept to include both species-level and gene-level diversity. It remains to be seen whether biologists will take up use of our measure, but whatever happens I am happy to have contributed to the conversation.

A Middle/High School That Teaches Complex Systems Through Games??!

A new school is opening in New York for grades 6-12 that completely blows my mind. The Quest to Learn school combines games and complex systems in a way that pretty much would have made my life as a teenager. Hell, I wouldn't mind going back to high school now if I got to go here. I'll let them describe it:

Mission critical at Quest is a translation of the underlying form of games into a powerful pedagogical model for its 6-12th graders. Games work as rule-based learning systems, creating worlds in which players actively participate, use strategic thinking to make choices, solve complex problems, seek content knowledge, receive constant feedback, and consider the point of view of others. As is the case with many of the games played by young people today, Quest is designed to enable students to “take on” the identities and behaviors of explorers, mathematicians, historians, writers, and evolutionary biologists as they work through a dynamic, challenge-based curriculum with content-rich questing to learn at its core. It’s important to note that Quest is not a school whose curriculum is made up of the play of commercial videogames, but rather a school that uses the underlying design principles of games to create highly immersive, game-like learning experiences. Games and other forms of digital media serve another useful purpose at Quest: they serve to model the complexity and promise of “systems.” Understanding and accounting for this complexity is a fundamental literacy of the 21st century.
Elsewhere they go into a bit more detail about how games are used to teach different subject areas:

At Quest students learn standards‐based content within classes that we call domains. These domains organize disciplinary knowledge in 21st certain ways—around big ideas that require expertise in two or more traditional subjects, like math and science, or ELA and social studies. One of our domains— The Way Things Work—is an integrated math and science class organized around ideas from design and engineering: taking systems apart and putting them back together again. Another domain—Codeworlds—is an integrated ELA, math, and computer programming class organized around the big idea of symbolic systems, language, syntax, and grammar. A third domain—Being, Space and Place—an integrated ELA and social studies class—is organized around the big idea of the individual and their relationship to community and networks of knowledge, across time and space. Wellness is the last of our integrated domains, a class that combines the study of health, socio‐emotional issues, nutrition, movement, organizational strategies, and communication skills.

One of my favorite aspects of this school is that they have a separate staff of game designers working together with their teachers. As a former teacher I can tell you that designing good, creative lessons is a relatively different skill-set from actually implementing these lessons in front of a class and following up with your students, and that doing both well requires more time than is physically possible without traveling at relativistic speeds. So having designers who are there at the school and understand the teachers' needs, and who have the time to make great lessons, is a really really good idea.


This is just a brief note to let everyone know I'm spending the summer at IIASA, a scientific policy research institute located just outside of Vienna. IIASA focus on systems analysis of global problems such as climate change, land use, demographic changes, public health, ecology, and energy. They don't seem to use the phrase "complex systems" much, but they're clearly talking about the same thing.

I happen to be one of 53 lucky graduate students to be selected for this year's Young Scholars Summer Program, meaning I get to paid to live in Vienna and do research. Can't really complain about that. Tomorrow I get to hear mini-presentations on everyone's research proposals, which should be very interesting. My own project will be on the long term, gradual evolution of cooperation in spatially structured populations, using a mathematical framework known as adaptive dynamics.

I'm expecting to learn a lot here, and I'll share as much as I can with you readers. Looking forward to it!

Nature Minus Humans?

From the "nothing is quite so simple" department, a Boston Globe article this week points out a hidden legacy of the conservation movement: The expulsion of native peoples from their land.

Starting with Yosemite in the late 19th and early 20th centuries, the pattern of forcing indigineous civilizations from their ancestral land in order to create wildlife reserves and national parks has been repeated across the country and the world.

The conflict is... compelling the conservation movement to grapple with the effects of its own century-long blunder, and with its origins as an American movement driven largely by nature romantics and aristocratic men determined to protect their hunting grounds. Not only has it dispossessed millions of people who might very well have been excellent stewards of the land, but it has engendered a worldwide hostility toward the whole idea of wildland conservation - damaging the cause in many countries whose crucial wildland is most in need of protection.
The article describes how indigineous peoples threatened with displacement across the globe have begun to band together to force a change in the conservationist mindset that humanity and nature are antithetical.

Reporting like this is why the Boston Globe needs to stay in business.

The Human Dimension of Climate Change

A New York Times Magazine article raises an issue I've been thinking a lot about lately.

If you are, as I am, a scientist concerned about global climate change, you may find yourself asking, "What kind of research could I be doing to best contribute to a solution?"

According to some, it may not be to study the climate itself. We may not know enough to predict exactly what will happen when, but we do know that drastic changes are coming whose magnitude will be determined by the actions we take now. It may not even be to study technologies such as alternative energy or policies such as cap-and-trade that can help combat global warming. Because while these policies and technologies are surely necessary, global warming is a problem created by human behavior, and our behavior will need to change if we are to make the individual and group decisions necessary to mitigate it, including the implementation of these policies and technologies. It may therefore be that the most important scientific questions in the fight against global warming are questions about humans, human behavior, and what we can do to change it.

The climate change puzzle presents a number of interesting questions about human behavior. The global environment is the ultimate "commons" game: We have a shared resource, and we can individually decide how much effort to put into preserving it. Only, we don't see the fruit of our individual efforts directly; only the sum total of everyone's efforts determines how well the resource is preserved. In the case of climate change, there are further complications: the effects of our actions now may not be seen for another fifty years, and some argue that the entire problem was fabricated by misguided scientists. Combining these factors, it is not hard to understand why many people feel little incentive to take action against global warming.

The article focuses on Columbia's Center for Research on Environmental Decisions, which performs experiments on people's decision-making processes. One finding jumped out at me as interesting and perhaps counter-intuitive: we tend to make better decisions as groups rather than as individuals. For example, one researcher studied decisions made by farmers in Southern Uganda as they listened to rainy-season radio broadcasts. If they listened to it in groups, they would typically discuss it afterwards and come to consensus on the best planting strategy in response to the weather. They ended up more satisfied with their yields than other farmers who listened to the broadcasts individually.

Our response to climate change will obviously involve a great variety of individual and group decisions, but it may be that if we can force more of the critical decisions to be made in group settings, where participants have not made up their minds beforehand (research shows this is crucial) we may find ourselves more able to put aside the parts of our human nature that would impede progress, and make the decisions that are in all of our best interests.

Gangs and Homeostasis

"To live outside the law you must be honest"
-Bob Dylan

I just finished "Gang Leader for a Day", a memior in which sociologist Sudhir Venkatesh recounts his days as a University of Chicago graduate student, most of which were spent hanging out in the Robert Taylor Homes with one of Chicago's most successful crack selling gangs.

My personal interest in gang culture began with my teaching days on the west side of Chicago. Over the course of my first year I gradually realized the extent to which gang affiliations were affecting the culture of my classroom and the school at large. Four sesasons of The Wire widened my interest by showing how the drug trade intersects with every other aspect of city life.

Venkatesh's story starts with an ill-advised trip to a local housing project as a first-year sociology student, in which he tries to get anyone to answer the asanine survey questions he has prepared (question one: "How does it feel to be black and poor?") He is detained overnight and nearly killed by the local gang members on suspicion of being a scout for a rival gang. But their leader, J.T., recognizes Venkatesh for the naive outsider he is, and advises him to dispense with the surveys. "With people like us, you should hang out, get to know what they do, how they do it."

The rest of the book, and indeed Venkatesh's entire graduate research, is predicated on the unlikely interest J.T. takes in Venkatesh and his project. He believes Venkatesh will write his biography (Venkatesh does little to contradict this misconception) and gives him guided tours on nearly every aspect of the gang's operations, often trying to cast himself as a philanthropic community organizer. In time, Venkatesh's research branches out to other forces in project life: prosititutes, odd-job hustlers, community workers, religious leaders, CHA (Chicago Housing Authority) representatives, and police, each playing complex and often morally ambiguous roles.

There is much of interest here from a complex systems perspective, but the place to start is probably the multiple roles the gang plays in project life.

First and foremost, the gang is a business. It exists to make money, most of which goes to the upper management. In the case of the Black Kings gang that ran the towers in this story, the business was primarily crack cocaine, though they also extorted "protection" money from other formal and informal businesses in and around the towers.

However, because of the nature of the business, it wouldn't do to have cops, social workers, and other civil servants roaming around the projects. The gang was largely effective in keeping these unwanteds out, but this meant there was a vacuum in terms of keeping order, resolving disputes, and looking after children. The gang stepped in to fill part of this vacuum. They helped negotiate conflicts between tenants, and mete justice when it seemed necessary. Sometimes they even helped clean the tower hallways. And J.T. instituted a rule that no one could join the gang unless they had graduated high school.

Despite J.T.'s talk of helping the community, the primary reasons for this behavior were financial, not altruistic. Any violence in the building would attract the attention of the cops, which in turn would disrupt operations and scare away customers. It was therefore in their interest to resolve disputes peacefully, or to administer punishment so that a wronged party would not take matters into their own hands. Keeping teenagers in school would also cut down on unwanted violence, and produce workers better able to handle money.

The relevant complex systems principle here is homeostasis: the regulation of one's internal environment. In order to compete effectively against other forces (gangs, police, etc.), the Black Kings had to reduce competition and discord within their own gang and the community in which they operated.

There's so much more to Venkatesh's story than I could possibly relate here, so I'll end by giving the book a full-throated recommendation. Although his naivite is often cringeworthy, his experiences provide a window into a complex world that operates so differently from the societies most of us inhabit.

Freeman Dyson on Climate Change

The New York Times has an article on eminent physicist Freeman Dyson's skepticism of climate change arguments. Several passages struck me in particular:
Dyson agrees with the prevailing view that there are rapidly rising carbon-dioxide levels in the atmosphere caused by human activity. To the planet, he suggests, the rising carbon may well be a MacGuffin, a striking yet ultimately benign occurrence in what Dyson says is still “a relatively cool period in the earth’s history.” The warming, he says, is not global but local, “making cold places warmer rather than making hot places hotter.” Far from expecting any drastic harmful consequences from these increased temperatures, he says the carbon may well be salubrious — a sign that “the climate is actually improving rather than getting worse,” because carbon acts as an ideal fertilizer promoting forest growth and crop yields. “Most of the evolution of life occurred on a planet substantially warmer than it is now,” he contends, “and substantially richer in carbon dioxide.” Dyson calls ocean acidification, which many scientists say is destroying the saltwater food chain, a genuine but probably exaggerated problem. Sea levels, he says, are rising steadily, but why this is and what dangers it might portend “cannot be predicted until we know much more about its causes.”
Beyond the specific points of factual dispute, Dyson has said that it all boils down to “a deeper disagreement about values” between those who think “nature knows best” and that “any gross human disruption of the natural environment is evil,” and “humanists,” like himself, who contend that protecting the existing biosphere is not as important as fighting more repugnant evils like war, poverty and unemployment.
His basic argument seems to be that, yes, human activity is causing global temperatures to rise, but this may not be a bad thing. Life, and humanity, will adjust to life in the new climate through adaptation and evolution, and may even emerge richer and stronger.

In a long-term sense, he is completely right. Life on earth has survived much greater shocks in the past and will likely continue to adapt and evolve as long as the sun is shining. We humans are a particularly adaptable bunch; we don't need to wait for genetic evolution to change our behaviors. We have devised ingenious solutions to our problems in the past, and we could probably think of something to carry us through whatever changes may come.

But the problem with this argument is the short-term. Humanity and life in general may be infinitely adaptable, but the fact is that, for the moment, we have adapted to life on the planet the way it is. We depend on certain plants and animals for food. These plants and animals in turn depend on other plants and animals, as well as certain chemicals and climate conditions. Every step in this chain is, for the moment, perfectly adapted to the climate of the present. Nature has even devised its own mechanisms to keep the current climate in place: for example, ocean bacteria help regulate the earth's temperature and atmosphere. We are, at present, in a state of equilibrium.

Massive increases in carbon dioxide, leading to rapid temerature growth, would push us out of equilibrium. Nature's homeostatic (equilibrium-maintaining) mechanisms would be insufficient to maintain our current climate, and large changes would occur. Food chains would have to be restructured as intermediate links go extinct. Some species would win and some would lose in the scramble to adjust to the new status quo.

Ecologists know that an ecosystem pushed out of equilibrium will eventually reach some new equilibrium state. But the details of this new state are impossible to predict ahead of time. Which species will dominate? What new food chains will form? This is the big question of climate change; no one can really say.

As far as we humans are concerned, the odds that this new state will be better for us are pretty low. Consider, for example, that the typical American diet is built from a relatively small variety of fruits, vegetables, grains, and animals. And the genetic variety within these crops is decreasing as breeds become standardized within the agriculture industry. It's unlikely that the specific plants and animals we depend on will be winners in the new equilibrium, since they, like us, are adapted to what we have now. We will have to scramble to change how we eat, as well as where we live, thanks to sea level changes. Millions of lives will be disrupted in this change. We have to ask ourselves, as a society, if we this disruption is an acceptable tradeoff to maintain our current energy habits a little longer.

As mathematician and ecologist Simon Levin said, “Nature is not fragile... what is fragile are the ecosystems services on which humans depend."

Reader Show-and-Tell

One of the joys of writing a blog like this is receiving comments from people I've never met in real life, but who have stumbled upon my blog from somewhere in webland, and found something on it worth responding to. It's really great to know my ideas are bubbling out and reaching people.

So this time I'd like to put aside my usual format and get to know some of my readers a little better. If you don't mind, I'd be very grateful if you can drop a comment answering these:

1. Who are you? (student, researcher, generally interested person, ...)

2. How did you find this blog?

3. What topics interest you most within those I've discussed?

4. What else interests you, either within or outside of the complex systems field?

Those who I do know in real life are also quite welcome to respond!

Two great links about the economy

1. Eduardo Porter has an excellent Op-Ed in the New York Times comparing the evolution of huge bonuses for bankers to the evolution of excess blubber on bull elephant seals--good for the individual seal (bank) but bad for the species (financial sector.) I couldn't agree more.

2. The collaboration between This American Life and NPR news that brought us the excellent show about the mortgage meltdown are back again with the clearest explanation I've heard to date on how our banking system is screwed.

On the Definition of Life

Last post we discussed a theory for the origin of life on earth, and we found that a proper definition of life is necessary to even begin addressing the question. This post, I'd like to dig deeper into the definition issue.

I strongly feel that life is a process, and should be defined in terms of what it does, not what it's made of. But adopting a process-based definition of life means we must consider whether our definition applies to entities that we think of as non-biological. For example (as my dad pointed out upon reading my previous post) crystals replicate their structure. Should they be considered alive? Computer viruses reproduce en masse; are they alive? Are "25 things about me" Facebook posts alive?

The example of crystals, more than anything else, convinces me that although reproduction is the central feature of life, it is not sufficient for defintional purposes. Crystals have not changed their nature since they first appeared on the earth. Their abitily to "adapt" is limited to conforming to the shape of their environment; they have produced no novelty in their billions-year history.

A glance at the wikipedia page on this subject gives us several other criteria we may wish to include, such as homeostasis (the ability to regulate one's internal evironment), and metabolism (the ability to convert raw materials to energy.) But these also seem peripheral to what I would consider the principal feature of life: its abilty to create new innovations in the world. These innovations are the product of evolution, so (as faithful reader samineru suggested), we should focus on entities that don't just reproduce, but evolve.

Evolution requires that:
  • Entities compete for the chance to reproduce, based on their characteristics.

  • Whenever an entity reproduces, its characteristics are passed on to its offspring, with slight variation.

These requirements rule out crystals: It would be hard to say that crystals are competing in any meaningful sense, and variations in the structure of a crystal are not (as far as I know) passed down onto other crystals seeded by it. "25 things about me" posts also don't compete, and small innovations in one post are not typically passed down into the other posts inspired by it. So neither crystals nor facebook memes are alive by this definition.

Computer viruses are more tricky. I don’t know of any viruses that mutate and pass mutations on when they spread. But one can imagine this happening in the near future: viruses producing their own innovations and finding ever more devious ways to infect other computers. If they did, would we call them alive? By this definition, we would.

Such questions are central to the field of artificial life. Artificial life (or “alife”) researchers write computer programs in which entities compete and evolve according to abstract sets of rules. There is debate in this community over whether they are actually creating life with these programs, or merely simulating it.

Many other intelligent people have written on the definition of life; I recommed these articles for further reading.

On the origin of life

First of all, you may have notied something a little different here. I am now a member of Field of Science, a new network of science blogs. You can investigate the other blogs in this network through the links at the top and bottom of this page. All the content from the original blog has been imported here (including your lovely comments), and the original address redirects here, so no need to update your links. At the moment, we're looking a little plain in the visual department, but some massive redecoration plans are in the works.

On to today's topic: life. How exactly did a collection of random chemicals give rise (eventually) to sentient beings? Where did it start?

This question supposes that at some point, a collection of chemicals that were "not alive" found a way to organize themselves into an entity that was "alive." But we immediately run into another, more fundamental issue: what, exactly, is life? How can we distinguish life from whatever came just before it?

Some researchers (see this Wikipedia article, for instance) consider chemicals such as DNA or RNA to be the distinguishing feature of life, and reduce the question of life's origin to looking at how these chemicals were synthesized.

But this perspective, in my opinion, misses the point. Life is a process, not a chemical. The distinguishing feature of life is not what it's made of but what it can do: namely, it can reproduce itself. More precisely, we can define the process of life by this picture:

Or in words:

An entity is alive if it can produce copies of itself using the free energy and materials that are available in its environment.

There are other caveats we may want to add, such as that living entities can tolerate a certain amount of mutation or environmental change without losing their reproductive ability. But self-replication is a good starting point.

Now the question becomes, how could such a process have arisen? Scientists have managed to synthesize a few self-replicating molecules, but the sponaneous formation of such molecules from inorganic matter seems highly unlikely.

On the other hand, nature is full of chemicals that do this:

In this diagram, A plays the role of a catalyst, helping to synthesize B from other chemicals in the environment. The ubiquity of catalysts led Stuart Kauffman to hypothesize that life may not have started with a single self-replicating molecule, but with a collection of catalysts, each catalyzing another in a cycle:

or in a more complex network:

Kauffman called such collections autocatalytic sets. If such a set of chemicals were able to surround themselves with a membrane, and eventually produce enough of themselves so that the membrane would split in two, we could have our very first example of a living cell.

This idea has a number of interesting implications, which I intend to explore in the very near future. In the meantime, enjoy the new site!

Why Darwin?

Charles Darwin turns 200 today. His birthday is the occasion for worldwide celebrations by scientists, and also a few protests by those who still dispute the theory of evolution. 150 years after this theory was published in "Origin of the Species," it remains the primary flashpoint of what some call a war between science and religion. I'd like to take this day to explore exactly why evolution has sparked such a passionate debate, and why even those of us who have no use for the concepts of creation or God might find value in considering the philosophical implications of evolutionary theory.

First, why is Darwin such a hero to the world of science? Before Darwin, biologists could only describe the "what" of nature. Evolutionary theory provided them with the tools to ask "why?" The whole nature of biological inquiry was changed. Beyond that, he showed how every living thing on Earth is connected by a common heritage. Evolutionary ideas have found application in almost every other area of science. An argument could be made that no other single idea has had such an impact on the history of science.

Secondly, why exactly is evolutionary theory so threatening to those who take the Bible literally? It's hardly the only scientific theory to contradict the literal truth of the Bible: scientists knew for decades before Darwin that the earth must be much older than 4000 years. The Big Bang theory has generated much less controversy than evolution, despite its obvious differences from the biblical creation story.

I think that the hidden thread underlying the evolution/creation debate is the question of meaning. Genesis doesn't just give a story for how the earth started, it gives humans a special place and purpose on the earth. It tells us that we are made in God's image, and that we are to fill the earth and be its stewards. Evolutionary theory upends this picture, saying instead that we are the product of a random process, following our genetic impulses, whose only purpose is to ensure the survival of our species.

Of course, it is not the role of science to provide meaning in people's lives. But I do think scientists should ackowledge the philosophical implications of their work, if for no other reason than that it significantly affects how that work is recieved. Having deflated the Judeo-Christian idea of meaning in life, can scientists, in their alternate roles as human beings, help provide an alternative?

My life partner is taking a class at Harvard Divinity School, taught by complex systems guru Stuart Kauffman and theologian Gordon Kaufman, exploring this very idea. Kauffman holds that notions of the "sacred", and even "God" itself, can and should be reclaimed without any reference to the supernatural, that the natural word itself can be our source of spirituality and meaning.

I won't say any more now about Kauffman's ideas because I haven't read his book yet. But I will over the course of the semester, and I'm sure I'll have much more to say about it soon.

Brits and Yanks on the Titanic

Discovery News Top Stories: Manners Lowered Brits' Chances of Survival on Titanic, said my Gmail ad banner. Intrigued, I clicked the link.

It seems behavioral economists David Savage and Bruno Frey, looking through historical records, found that Britons had the highest death rate of any nationality aboard the Titanic, even though the ship's crew was British. There is anecdotal evidence that British politeness contributed to their mortality: Witnesses heard the captain saying "Be British, boys, be British!"--meaning for them to "queue up" and wait for women and kids. Meanwhile, Americans, whom some saw elbowing their way forward to board the lifeboats, had the highest survival rate of any nationality.

Behavior in all animals reflects a delicate balance between cooperative and selfish instincts. Human history, in particular, shows extreme examples of both greed and selflessness. These behaviors, like all others, are evolved; and reflect the multilayered incentives for selfish and altruistic behavior that run throughout evolutionary history.

Assuming Savage and Bruno are correct, it appeared the jerks took the day in this instance. If we suppose that evolutionary history contained many such "Titanic moments", in which the self-interested could elbow out the polite in the struggle for survival, one might conclude that only the selfish would emerge from evolution unscathed.

But there's more to the picture. We'll never know if more could have survived the Titanic had everyone on board worked together. Certainly fewer would have survived had everyone been fighting for a spot on the lifeboats. If we imagine many Titanics sinking in simultaneous, independent events, it's possible that more altruists would survive overall, because boats of mostly altruists would save a higher percentage of passengers than boats filled with arseholes. So there is a sense in which, while selfishness works on an individual level, cooperation may do better on a large scale. (This is essentially the group selection argument I refered to in this post--one of many explanations for why both altruism and selfishness are seen in the products of evolution.)

One can also ask how the social norms in America and Great Britain evolved to be this way. British and American people separated far too recently to have diverged genetically, but the two nations have certainly evolved culturally along different paths. An argument could be made that America, with its vast expanses of open (except for Native Americans) land and looser socioeconomic hierarchy, rewarded bold and individualistic behavior more than old, statified Britain.

Neither British nor American social norms were evolved specifically for the Titanic. Behaviors adapted for one context played out in another, resulting in a higher proportional survival for Americans, perhaps a lower total survival than if all the passengers were British.

In considering the behaviors we'll need to survive in a world of global interconnection and environmental fragility, it's important to remember that behavior evolves in context. If we can anticipate the kinds of behaviors we'll need in the future, can we also anticipate the changes we'll need to make to start evolving these behaviors now?

Update: The Emerging Field of Cultural Evolution

In my last post I asked how a society that evolves through its ideas would differ from one that evolves through its genes. Today I came across a cache of Wired Science blog posts highlighting recent efforts to address this very idea, in a new field that is being called "cultural evolution."

  • Paul Ehrlich studied the evolution of canoe design in Polynesia, as a model system for how cultural evolution works in general. He found, not surprisingly, that artistic variation occurred rapidly, whereas variation in the the canoes' functional design was slower (due to the need to be sea-worthy.) (blog post,journal article)

  • Simon Kirby et. al. simulated the evolution of a new language. Human subjects were shown a collection of nonsense words, and a picture associated to each word. They were then asked to recall these word-picture associations. Whether or not these recollections were correct, they were used as the basis for a new set of words-picture associations, which were then shown to a new set of subjects. As the associations changed each round based on what people could remember, a structred language began to develop.

    In other words, human memory was the environment in which the language was evolving. The more structure in the language, the easier it was to remember, and therefore the more it got passed on. Very cool! (blog post, journal article)

  • Arne Traulsen et. al. (the et. al. includes Nowak) found that if you assume a much higher rate of "mutation" in ideas than in genes (a reasonable assumption), you get qualitatively different results. For example, cooperation can become viable in situations where it wouldn't otherwise be. (blog post)

The Future of Human Evolution

For much of the history of life, evolution worked a certain way. Organisms competed for the chance to reproduce. An individual with an advantageous mutation would produce more offspring, which would inherit the advantageous gene, and in this way life continually improved upon itself.

But I would argue that for humans, in the world as it is today, this process is more or less defunct. We are not, by and large, competing with each other to produce more offspring. It's true that some people lack reproductive ability or die before their time, but most people who reach adulthood with their health intact can have as many babies as they want. It is a matter of choice more than a competition. Furthermore, people with genetic defects, who may never have survived in times past, can now (sometimes) lead healthy procreative lives thanks to modern medicine.

This means that the best genes no longer produce more copies. There is no longer a way for advantageous mutations to spread through the population. If these trends continue, we can expect that our gene pool will no longer improve, and may even degrade a bit thanks to advanced health care. The human body and mind are currently as good as they will ever get.

So have humans stopped evolving? As individuals, I would say yes. But our society is clearly still evolving, due a mechanism we evolved in the past million years (back when we were still evolving the normal way): language.

Language allows for the evolution of ideas rather than genes. A person with a good idea can communicate it to others, who, if they like it, can communicate it further. In this way good ideas, rather than good traits, spread through the population.

Here's another way of seeing the difference: for conventional evolution, DNA carries information about traits that successfully spread themselves. For this new form of evolution, language (both oral and written) carries information about ideas that successfully spread themselves.

I don't think any of the above ideas are terribly original. But it occurred to me today that while there are many mathematical models for genetic evolution, I don't know of any good models for the evolution of ideas. And more generally, how does a society that progresses by idea-based evolution differ from one that evolves genetically? The question is so vague I can barely conceive of how to frame it, but it seems very important to the study of humanity's future.