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:: By Carrie M. Golus, AB’91, AM’93

:: Photo by Dan Dry

:: Syllabus

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Investigations ::

Course Work

Unit Costs

Philosopher Bill Wimsatt helps Biological and Cultural Evolution students see change through the sum of its parts.

It’s 1:25 p.m., five minutes before PHIL 225 Biological and Cultural Evolution is scheduled to begin, but Bill Wimsatt can’t wait. His laptop is booted up, the first slide is on-screen, and he’s telling 12 punctual students about a luncheon he recently attended on energy problems. A speaker from BP, Wimsatt says, discussed how different cultural institutions respond to issues like global warming, in the process offering an “interesting classification” about the rate of change. Wimsatt quickly outlines the speaker’s scheme on the blackboard: scientific change is the fastest, followed by business and market response, then government, and finally—the most conservative—law and religion.


At 1:30 Wimsatt’s co-instructor, Salikoko Mufwene, PhD’79, takes a seat in the front row of the lecture hall, BSLC 205. Wimsatt, Peter B. Ritzma professor in philosophy and evolutionary biology, and Mufwene, the Frank J. McLoraine distinguished service professor in linguistics and a professor in evolutionary biology, have team-taught the course every other year since 1999. Mufwene takes off his trench coat and brown fedora to reveal an equally dapper suit. Wimsatt wears baggy khaki pants, a blue button-down with rolled sleeves, and glasses perched on his head.

“We’re switching back to cultural evolution today,” Wimsatt begins, then corrects himself: “not cultural, but technological evolution.” It’s week eight, and the students have been through a lot: two and a half weeks of evolutionary theory and genetics, followed by the evolution of language, evolution of other elements of culture, and the spread of Christianity.

The subject of the day’s lecture, according to the brightly lettered title slide, is “The Evolution of MOD-U-LAR-IT-Y in Biology and Culture.” The slide also reveals its first audience: the annual meeting of the ISHPSSB (International Society for History, Philosophy, and Social Studies of Biology) at the University of Exeter last July.

“Modularity is in some sense inescapable and particularly interesting,” says Wimsatt, lecturing with his arms crossed. (Modularity, as the class learned earlier in the quarter, is fundamental to evolutionary biology. Put simply, it’s the notion that complex systems are made up of modules, or quasi-independent, pre-assembled components.) “It’s interesting in two ways,” he continues. “One, the issue of units. You want to find units to analyze.

“And when you have the right kind of modules, they can provide a kind of combinatorial alphabet. You can put together a variety of different technological things in much the same way that you can assemble words and sentences out of letters.”

Wimsatt paces and fiddles with a piece of chalk. “So if you want to look for analogs of cultural genes,” building blocks of cultural evolution that spread ideas much as genes act as units of biological evolution, “you ought to look for these kinds of modules. What are the parallels between standardized nuts and bolts, say, and the amino acids that make up a protein?” He flips on the next slide. “As always, stop me as we go along if something is as clear as mud.”

Over the next few minutes, ten more students drift into the room. It’s the week before Thanksgiving break, the weather has turned wintry, and the energy level in the room—with the notable exception of Wimsatt—is a little low.

“So where does modularity come from? For systems that are self-reproducing, it’s inevitable,” Wimsatt says. He’s paraphrasing the sentences on the first slide, which is crammed with text.

“The very act of reproduction makes modules, or quasi-independent entities,” he says. “If you have a bacterium and it divides into two bacteria, you have two modules.” Modularity is common to technology too, he says, “except that technological parts don’t grow themselves.”

The next slide is even more dense. Most students have notebooks open, but they seem to be processing rather than scribbling. A hand goes up in the second row. “I have a quick side question,” says a woman with a smooth chestnut ponytail. “Is this going to be online? Because I don’t think I’ll be able to write it all down.”

Wimsatt nods: “I should have said that.”

Slide six brings up the lecture’s first image—an iconic Pointillist painting. “Some surprising things are modular,” Wimsatt says. “How many of you have seen Seurat’s Sunday Afternoon on the Island of La Grande Jatte downtown at the Art Institute?” A few hands go up. “His paintings were composed of little dots of color”—that is, modules. “He’s actually responding to the dominant theory of sensory perception at the time, that sense data were point-like.”

Next Wimsatt turns to the reading for the day, “The Architecture of Complexity,” written in 1962 by Herbert A. Simon. Simon, AB’36, PhD’43, who won both the Nobel Prize for economics and the American Psychological Association’s award for lifetime contributions to psychology, is one of Wimsatt’s major influences. At this point, the lecture shifts to technological evolution—in particular, the development of standardized parts.

With standardization comes entrenchment, explains Wimsatt, whose engineering background becomes more apparent as the lecture continues (he started as an engineering major at Cornell, worked as a designer with NCR, then returned to graduate in philosophy; he earned a PhD in the philosophy of science at Pitt). “For example, a mechanic in the United States or England can’t easily switch over to the metric system. Even now, after “the so-called metric conversion, they just give the metric equivalents of measurements in the English system,” he says. “They didn’t change the nut and bolt sizes. You still need two different sets of socket wrenches” to fix American and European cars.

The ponytailed woman raises her hand again. “That’s why we missed Mars,” she says, explaining how, in September 1999, the Mars Climate Orbiter, a joint project between NASA and the European Space Agency, went wrong when navigation software used imperial (pound-second), instead of metric (newton-second), units.

“That’s right!” says Wimsatt. “That’s a lovely example. I’ll have to remember that.”

Wimsatt’s next slide, “Genesis of Modularity for Technology,” begins with stage 0: “non-interchangeable parts.” His example is the Brown Bess musket used by the British during the American Revolution. Although the muskets used the same design, their parts were not interchangeable: “The threads didn’t quite fit,” he says.

“With higher accuracy, you began to get interchangeable parts”—stage 1 on his list—“but only within manufacturers,” he says. Stage 2 is standardized parts. “The more people use them, the more everyone who uses them benefits,” he says. “And if you start out with two standards, sooner or later one of them will knock out the other.”

The march of technology continues. Stage 3 is the distribution of standardized parts. At stage 4, parts become polyfunctional—and entrenched. In an Erector Set, for example, standardized parts can be put to a multitude of uses. “How many of you have kid brothers with Erector sets?” Only two hands go up. Wimsatt is aghast. “Wow,” he says. “There are going to be no mechanical engineers in the next generation.”

A disadvantage to entrenchment is that  “backwards compatibility” becomes a potential problem—new technology won’t work with the old. “I have Word 1.1 on an old Mac Plus,” Wimsatt says. It still works fine, “but I can’t port anything I write on that computer to anything else.” One student cracks up. “It uses diskettes that are not compatible. I can’t download it to a hard drive, because the connectors are different.”

On goes technological evolution. Stage 8 in Wimsatt’s progression is “black boxing,” which takes away the ability to disassemble modules. The black box, first developed for World War II aircraft, was a sealed piece of equipment, Wimsatt explains. “You didn’t have to look inside,” he says, “you just used it.” In 1970, Wimsatt says, he was able to have a car generator rebuilt. Today, with component parts no longer available, he would have to replace it completely.

The final stage, number 11, is “training for modularity”—much more fun than it sounds. What he means is playing with modular toys such as Legos, Lincoln Logs, and Erector sets. Wimsatt ends his lecture with an exhortation: “Buy your kid brother a Tinkertoy set for Christmas,” he says, “and play with it.”


To quote the syllabus’s page-long course description, “Cultural evolution is often described as ‘merely analogical’to biological evolution. We believe stronger claims are justified. … We seek a two-way street between biology and culture, enabling findings in either discipline to question assumptions and inspire models in the other.” Initially created as a Big Problems course, Biological and Cultural Evolution is cross-listed in seven departments, including biological sciences, linguistics, and philosophy.

Two books are required: Evolution in Four Dimensions by Eva Jablonka and Marion J. Lamb (2005) and Genes, Peoples and Languages by Luigi L. Cavalli-Sforza (2000). Four texts are “STRONGLY” recommended—Thought in a Hostile World: The Evolution of Human Cognition by Kim Sterelny (2003), The Evolution of Technology by George Basalla (1988), The Rise of Christianity by Rodney Stark (1997) and Guns, Germs, and Steel by Jared Diamond (1997). Other readings are available on Chalk, the U of C’s online course site.

Students write an end-of-quarter paper (12 to 15 pages for undergrads, 16 to 20 for grad students) on a topic approved by at least one instructor, “though we encourage you to consult with all three of us [Mufwene, Wimsatt, and TA Christopher DiTeresi, AB’99, AM’07].” True to the course’s interdisciplinary, team-taught nature, students are also encouraged to collaborate on larger topics, “with suitable discounts on total length.” One student planned to write about the evolution of ideas of abstraction; another was analyzing different manuals for bird watchers; and several students, working independently, had chosen to explore the evolution of religion.—C.G.