Evolutionary Dynamics

Nice to see an excellent science writer, Carl Zimmer, write about an excellent mathematical biologist, Martin Nowak, in an article in the New York Times (via The Loom).

Here is a non-technical lecture on evolutionary dynamics by Martin Nowak.

I also look forward to reading his most recent book, Evolutionary Dynamics: Exploring the Equations of Life.

Harvard’s Program for Evolutionary Dynamics was established by Harvard’s then President Larry Summers as a way of using the theory of evolution as a common foundation for biology and economics (I am not sure that he took the other social sciences seriously). Judging from the website, the program’s current mission is now somewhat less ambitious. 

Bernd Heinrich’s new book

On Radio Open Source, Christopher Lydon interviews Bernd Heinrich. This is one interview that didn’t work. Christopher Lydon is all over the place, and he comes across as someone with a serious attention deficit problem. However, after listening to the interview, one thing is clear in my mind. I want to read Heinrich’s new book, The Snoring Bird: My Family’s Journey Through a Century of Biology.

I have previously read his Why We Run: A Natural History. It was excellent.

What we need now is an interview with Bernd Heinrich without so many interruptions, e.g. following the format on BBC’s The Interview.

Natural-born runners

Several blogs have linked to this article about Daniel Liberman’s argument that about 2 million years ago our ancestors evolved physical characteristics that have no impact on walking, but make humans better endurance runners, presumably because of a shift in food consumption from scavenging to hunting.

Speaking about running, if you are a runner, 2PEAK is the best web-based training program I have seen. It dynamically adjusts your training program, and you can upload data from Garmin, Polar, and Suunto watches. It is, however, somewhat pricey.

Here is what Owen learned from running the London Marathon.

The Quartenary Conundrum

The Quartenary Conundrum is this: While current empirical and theoretical ecological forecasts suggest that many species could be at risk from global warming, during the recent ice ages surprisingly few species became extinct.

In a recent paper in BioScience, Forecasting the Effects of Global Warming on Biodiversity (pdf), Daniel Botkin et al. state that

Fossil evidence and recent ecological and genetic research, along with specific problems with present forecasting methods, lead us to believe that current projections of extinction rates are overestimates. Previous work has failed to adequately take into account mechanisms of persistence. [...]

Until recently, it was thought that past temperature changes were no more rapid than 1 degree Celsius (°C) per millennium, but recent information from both Greenland and Antarctica, which goes back approximately 400,000 years, indicates that there have been many intervals of very rapid temperature change, as judged by shifts in oxygen isotope ratios. Some of the most dramatic changes (e.g., 7°C to 12°C within approximately 50 years; Macdougall 2006) are actually of greater amplitude than anything projected for the immediate future. [...]

What, then, is the answer to the Quaternary conundrum? The answer appears to lie in part with the ability of species to survive in local “cryptic” refugia, that is, to exist in a patchy, disturbed environment whose complexity allows faster migration than forecast for a continuous landscape, within which species move only at a single rate. The answer also lies in part with greater genetic heterogeneity within species, including local adaptations,which allows rapid evolution. For example, populations close to latitudinal borders are likely to be better adapted to some environmental changes than the average genotype. However, the conundrum is not completely solved, and some important genetic research suggests that species are more vulnerable than the fossil record indicates. A fuller solution to the conundrum will be important for improving forecasts of climate change effects on biodiversity.

HT Carl Zimmer.

Note that this is not a call for complacency, it is a call for better models of climate change effects on extinctions.

Accelerating human evolution

The concept of the EEA, the Environment of Evolutionary Adaptedness, never made much sense. In its strong form it is based on the misunderstanding that we evolved during the Stone Age, and then we more or less stopped evolving.

World Science reports on a study by Greg Cochran and John Hawks,

The tra­di­tion­al pic­ture of hu­mans as a fi­n­ished prod­uct be­gan to erode in re­cent years, sci­en­t­ists said, with a crop of stud­ies sug­gesting our ev­o­lu­tion in­deed goes on. But the new­est in­vest­i­ga­tion goes fur­ther. It claims the pro­cess has ac­tu­al­ly ac­cel­er­at­ed.

It al­so down­plays the im­por­tance of a much-scru­ti­nized era around 200,000 years ago, when hu­mans con­sid­ered “ana­tom­i­cally mod­ern” first ap­pear in the fos­sil rec­ord. In the stu­dy, this ep­och e­merges as just part of a vast arc of ac­cel­e­rat­ing change.

“The or­i­gin of mod­ern hu­mans was a mi­nor event com­pared to more re­cent ev­o­lu­tion­ary chang­es,” wrote the au­thors of the re­search, in a pre­sent­a­tion slated for Fri­day in Phi­l­a­del­phia at the an­nu­al meet­ing of the Amer­i­can As­so­ci­a­tion of Phys­i­cal An­th­ro­po­l­o­g­ists. [...]

Hawks and Coch­ran said some of the most no­ta­ble phys­i­cal changes in hu­mans have been ones af­fect­ing the size of the brain case.

A “thing that should prob­a­bly wor­ry peo­ple is that brains have been get­ting smaller for 20,000 to 30,000 years,” said Coch­ran. But brain size and in­tel­li­gence aren’t tightly linked, he added. Also, growth in more ad­vanced brain ar­eas might have made up for the shrinkage, Coch­ran said; he spec­u­lated that an al­most break­neck ev­o­lu­tion of high­er fore­heads in some peo­ples may re­flect this. A study in the Jan. 14 Brit­ish Den­tal Jour­nal found such a trend vis­i­ble in Eng­land in just the past mil­len­ni­um, he noted, a mere eye­blink in ev­o­lu­tionary time.

Research pub­lished in the Sept. 9, 2005 is­sue of the re­search jour­nal Sci­ence by Lahn and col­leagues found that two genes linked to brain size are rap­idly evolv­ing in hu­mans.

Harpending on McKinnon on Evolutionary Psychology

Henry Harpending reviews Susan McKinnon’s book Neo-Liberal Genetics,

…She does not complain that evolutionary psychology is bad science according to standard criteria for evaluating science: Instead she dislikes the “rhetorical structures and strategies of the texts.” She deplores the “narrative” of evolutionary psychology because it “severely constricts the kinds of questions we can ask and the kinds of social worlds we can possibly imagine and endeavor to create for ourselves” (p. 152). In other words McKinnon dislikes the implied constraints on her political fantasies.

Everyone understands and deals with evolutionary psychology. We understand why our cat was easier to toilet train than our baby was: One has the brain of a denning predator and the other of a mobile and occasionally arboreal ape. We also understand that there is no “should” implied in this: No one thinks that children should not be toilet trained. MacKinnon, by contrast, attributes to evolutionary psychologists the belief that saying something “is” is the same as saying that that it “ought” to be. Here, for example, is her notion of what genetic individualism means: “that the ‘public good’ should be replaced by individual responsibility and social services privatized; that profit and capital should be maximized through the deregulation of markets - that is, that competition should run its course unchecked - in a ‘race to the bottom’ - regardless of the social consequences” (p. 44). Notice the “shoulds”, none of which are appropriate…

Despite an occasional interesting insight, most of this book reads like a clone of the dreadful wrong-headed ramblings that were the “sociobiology debate” of the 1970s.

Bob Trivers gets the Crafoord Prize in Biosciences

We are a bit late, but here is the announcement from the Royal Swedish Academy of Sciences,

… Robert Trivers, is one of the small group of pioneering scientists who began to ponder on the social behaviour patterns of animals and how they might have arisen through evolution. Between 1971 and 1976, he launched five ideas that have been of the greatest importance for the development of sociobiology. They have inspired many behavioural ecologists, who have to a large extent confirmed Trivers’s ideas.

Science writers: two of the best

Edward O. Wilson and Steven Pinker are excellent science writers. Both are arguably better science writers than scientists. E.O. Wilson’s work on insects was really good, but his sociobiological ideas are less original than the ideas of e.g. Bill Hamilton or Bob Trivers (a talk by Trivers here). Steven Pinker’s ideas can be summarized as Chomsky plus Tooby & Cosmides; he stands on their shoulders but it it not clear that he sees a whole lot further than they did.

As writers both Wilson and Pinker are prolific, clear, readable, and mostly right. Their books are widely read. Those are great accomplishments.

The person who has done more than anybody else for building the market for science writing is John Brockman, who is a very successful literary agent. He correctly describes himself as an impresario. By creating hype and hoopla around a bunch of nerdish scientists he has promoted the public understanding of science and provided a real public service (see his Edge website, profile in The Guardian (pdf)).

The evolution of altruism

One of the most important 2006 papers in the behavioral sciences is Sam Bowles’ Group Competition, Reproductive Leveling, and the Evolution of Human Altruism (Science vol 314, p 1569). He demonstrates that genetic differences between early human groups are likely to have been great enough so that lethal intergroup competition could account for the evolution of altruism. Crucial for his argument are distinctive human practices such as sharing food beyond the immediate family, monogamy, and other forms of reproductive leveling.

Comment by Yann Klimentidis here.

Here is an article in New Scientist about the paper,

Humans may have evolved altruistic traits as a result of a cultural “tax” we paid to each other early in our evolution, a new study suggests.

The following points are made in Science Week by Robert Boyd,

Market fundamentalism, statism, and community governance

Brad DeLong writes,

How economists use the neoclassical benchmark:

• At Chicago: Assume that the economy is at the neoclassical benchmark, and demonstrate that whatever exists is, in some subtle sense, constrained Pareto-optimal efficient–except where ham-handed government intervention has caused messes.

• At Berkeley: Investigate the deviation from the neoclassical benchmark that can be caused by one single but significant market failure, demonstrate that this deviation matches up to some important feature of the real world, and demonstrate that a clever, subtle, and strategic government intervention can move us to a situation that is constrained Pareto-optimal.

If we were to be unkind, we would call these the market fundamentalist and the statist approaches (in Brad DeLong’s case, a social democratic statism). We can add a third approach, community governance.

• Investigate the deviation from the neoclassical benchmark, demonstrate that this deviation is causes by badly designed government and market institutions that have crowded out community governance. To address this failure, develop institutions and property rights that support community governance as a complement to markets and governments. Note, however, that effective community governance is usually based on insider-outsider distinctions, between Us and Them.

For an introduction to community governance, see

Ostrom, Elinor. Governing the Commons : The Evolution of Institutions for Collective Action. Cambridge: Cambridge University Press, 1990.

Ellickson, Robert C. Order Without Law : How Neighbors Settle Disputes. Cambridge: Harvard University Press, 1994.

You may also want to take a look at

Boehm, Christopher. Hierarchy in the Forest: The Evolution of Egalitarian Behavior. Cambridge: Harvard University Press, 2001.

For researchers doing interesting related work, see the list of network members from the Norms and Preferences Network.

Charles Darwin, natural novelist

From Adam Gopnik’s essay in the New Yorker, now online (via Afarensis),

Darwin’s strategy was one of the greatest successes in the history of rhetoric, so much so that we are scarcely now aware that it was a strategy. His pose of open-mindedness and ostentatiously asserted country virtue made him, in his way, as unassailable as George Washington. The notion persists to this day that Darwin was a circumspect observer of animals, not a confident theorist of life…

Darwin was humble and modest in exactly the way that Inspector Columbo is. He knows from the beginning who the guilty party is, and what the truth is, and would rather let the bad guys hang themselves out of arrogance and overconfidence, while he walks around in his raincoat, scratching his head and saying, “Oh, yeah—just one more thing about that six-thousand-year-old Earth, Reverend Snodgrass . . .” Darwin was a civil and courteous man, but he was also what is now polemically called a Darwinian fundamentalist. He knew that he was right, and that his being right meant that much else people wanted to believe was wrong. Design was just chance plus time, greed not a sin from the Devil but an inheritance from monkeys…

Darwin was a Darwinian fundamentalist. But he was not a Darwinian absolutist.

Clever Brain Parasite

Toxoplasma gondii is in the news again. It is a really interesting brain parasite. It lives in the guts of cats. Eggs are shedded with excrement, and inhaled by animals that are eaten by cats, e.g. mice and rats. T. gondii then form cysts in their brains. And here is the clever part. When a mouse or rat is infected, it is no longer afraid of the smell of cats, and it is therefore more likely to be caught and eaten.

Toxoplasma also infects people, and therefore pregnant women are adviced not to handle cats or cat litter.

Fuller Torrey has been saying for years that schizophrenia may be caused by toxoplasmosis, e.g. in this paper and in his book Beasts of the Earth: Animals, Humans and Disease.

Carl Zimmer has a number of really interesting posts about toxoplasmosis.

Now an article in the Guardian reports that pregnant women with high levels of infection by the T. gondii parasite are more likely to give birth to boys. The parasite infects around 15% of Britons, but up to 80% of the population in some countries. Women whose antibody count is high - suggesting a substantial infection - has a much higher chance of having baby boys. In most populations the birth rate is around 51% boys, but women infected with toxoplasma had up to a 72% chance of a boy.

Indigenous People as Natural Conservationists

Are indigenous people natural conservationists? Is there a mysterious connection between indigenous people and the natural world?

If you think that people are natural conservationists, then human prehistory is not encouraging. Expansion of modern humans into new regions were accompanied by the disappearance large animals in those regions, megafauna extinctions (see e.g. Paul Martin’s Twilight of the Mammoths, and this paper).

Large animals became extinct up to 50,000 years ago in Australia and New Guinea, around 11,000 years ago in North America, about 1500 years ago in Madagascar, and between 900 and 600 years ago in New Zealand. This pattern closely follows the current chronology of human expansion around the world.

What about present day indigenous people? Natalie Smith has written a paper, Are Indigenous People Conservationists? Preliminary Results from the Machiguenga of the Peruvian Amazon. She writes,

“Contrary to the widespread belief that indigenous peoples are adept managers of their natural environments, preliminary research from the Machiguenga of the Peruvian Amazon indicates this may not be the case…

The data that I and others have acquired about the Machiguenga do not provide empirical justification for the presence of conservation in this cultural group. Given the structural difficulties that would hinder conservation (open-access resources), as well as the particular history of this group (lowdensity, semi-nomadic, family-level society), it should not be surprising that no evidence of conservation was found… In fact, I expect that it would be rare to find conservation in any group given that the emergence of such practices requires, among other things, cooperative norms, punishment of norm breakers, and renewable resources that have restricted access so that consumption by non-group members can be prevented… Instead of assuming that groups do or do not conserve, we need to identify the circumstances under which conservationist norms can evolve. And then, if the group does in fact conserve, investigate the social mechanisms that enable prosocial behavior.”

There are practices that lead to conservation of wildlife as an unintended consequence. Tribal warfare may have been an important factor in wildlife conservation. Constant tribal warfare and raiding lead to buffers zones between tribes in North and South America and in Africa, and presumably in other places as well. Wildlife thrived in these zones, much like wildlife has been thriving in the DMZ, the demilitarized zone, between North and South Korea, or along the Wall between East and West Germany.

Discrimination and Ethnic Nepotism

We all discriminate all the time. As Walter Williams says (via Stefan Karlsson),

“When I married Mrs. Williams, I discriminated against other women. Even though I occasionally think about equal opportunity, Mrs. Williams demands continued discrimination.”

Chris Dillow asks, “Why do people identify so much with their ethnicity?”

One argument is that a bias in favor of one own’s ethnic group is an example of kin selection. A map of a person’s ancestors is not a tree, but a bush, where everyone in an ethnic group is related to everyone else, possible on average as closely as first cousins. Identification with one’s ethnic group is therefore rational and makes perfect sense in evolutionary terms.

Another argument is that it is more efficient to work with someone belonging to your own ethnic group. If you share a common language and a common set of values, it is much easier to evaluate how far you can trust another person.

Here is a report in ScienceNOW Daily News on a recent study,

“When it comes to nepotism, people from indigenous tribes are not so different from you and me. Given the choice between punishing a fellow tribesman or a member of a neighboring tribe for the same crime, New Guinea natives protect their own, according to new research. The study suggests that favoritism knows no cultural boundaries.

Economic Man and Economic Monkey

But men and monkeys have a sense of fairness and an aversion to inequity. In a fascinating study, Sarah Brosnan and Frans de Waal showed that capuchin monkeys react negatively when another individual gets a better reward for the same or less effort on a specific task.

Pairs of brown capuchin monkeys (Cebus apella), were placed next to each other and trained to exchange a token with human handlers to receive a reward, in most cases, a piece of cucumber. Partners of capuchins who made the swap either received the same reward (a cucumber slice), or a better reward (a grape, a more desirable food), for the same amount of work or, in some cases, for performing no work at all. Capuchins who witnessed unfair treatment and failed to benefit from it often refused to conduct future exchanges, would not eat the cucumbers they received for their labors, and in some cases, threw food rewards at human researchers.

Like the Ultimatum Game in experimental economics, this experiment demonstrates inequity aversion. In the Ultimatum Game two parties interact anonymously and only once. The first player proposes how to divide a sum of money with the second party. If the second player rejects this division, neither gets anything. If the second accepts, the first gets what he proposed and the second gets the rest. Low offers are often rejected by the second party. Since an individual who rejects a positive offer is choosing to get nothing rather than something, that individual is not acting to maximize his economic gain.

In a study by Joseph Henrich et al., In Search of Homo Economicus: Behavioral Experiments in 15 Small-Scale Societies the researchers reported,

Recent investigations have uncovered large, consistent deviations from the predictions of the textbook representation of Homo Economicus: in addition to their own material payoffs, many experimental subjects appear to care about fairness and reciprocity and reward those who act in a cooperative manner while punishing those who do not even when these actions are costly to the individual…

We can summarize our results as follows. First, the canonical model is not supported in any society studied. Second, there is considerably more behavioral variability across groups than had been found in previous cross-cultural research, and the canonical model fails in a wider variety of ways than in previous experiments…

“Economic man” doesn’t exist. Neither, it seems, does “economic monkey”.

Update: See Joseph Henrich’s critique of Brosnan and de Waal here.

Economic Man is a Straw Man

People wanting to criticize economics often set up a straw man, “Economic Man”, a purely rational and selfish creature who can easily be knocked down. However, economics has moved beyond this caricature (well, maybe business school economics hasn’t, you still get a Panglossian “Greed is Good” triumphalism in B schools). Read e.g. this paper in Science,

When Does ‘Economic Man’ Dominate Social Behavior?,
Colin F. Camerer and Ernst Fehr

The canonical model in economics considers people to be rational and self-regarding. However, much evidence challenges this view, raising the question of when ‘‘Economic Man’’ dominates the outcome of social interactions, and when bounded rationality or other-regarding preferences dominate. Here we show that strategic incentives are the key to answering this question. A minority of self-regarding individuals can trigger a ‘‘noncooperative’’ aggregate outcome if their behavior generates incentives for the majority of other-regarding individuals to mimic the minority’s behavior. Likewise, a minority of other-regarding individuals can generate a ‘‘cooperative’’ aggregate outcome if their behavior generates incentives for a majority of self-regarding people to behave cooperatively… Recently developed theories of other-regarding preferences and bounded rationality explain these findings and provide better predictions of actual aggregate behavior than does traditional economic theory.

See also the papers on the websites of these very good scientists,

Colin Camerer

Ernst Fehr

Herbert Gintis

Top 10 Ideas in the Behavioral Sciences

Here is a list. All “Top 10″ lists are somewhat absurd, but they are useful for keeping a perspective on what is important and what is not. Let me know if you have any candidate ideas that are better and should replace one or more of the ideas on this list.

Year		Person	Idea	Publication
1748		Montesquieu	Separation of Powers	The Spirit of the Laws
1759		Adam Smith	Invisible Hand	The Theory of Moral Sentiments
1786		William Jones	Comparative Linguistics	The Sanscrit Language
1817		David Ricardo	Comparative Advantage	Principles of Political Economy and Taxation
1859		Charles Darwin	Natural Selection	Origin of Species
			Sexual Selection
1860s		Louis Pasteur	Germ Theory of Disease	Anti-spontaneous generation experiments
1865		Gregor Mendel	Mendelian Inheritance	Experiments on Plant Hybridization
1944		Von Neumann & Morgenstern	Game Theory	Theory of Games and Economic Behavior
1964		Bill Hamilton	Inclusive Fitness	Evolution of Social Behaviour, 2 papers