Canoe evolution
Like owning a VW Bus, when you own your scientific knowledge, you’re comfortable hacking it: painting flames on the front, replacing the engine with pedals, converting it into a submarine.
For decades now, anthropologists have tried (with varying success) to apply quantitative methods from evolutionary biology to explain and predict cultural change. The most compelling of this work has addressed language, a cultural feature that’s almost DNA-like in its structure: linear strings of sound-symbols which can be substituted in and out, etc. Now here’s a study of a cultural feature that’s not at all DNA-like: canoe design. It’s a very cool hack. They code the canoe designs in such a way that a computer can analyze patterns of similarity and infer relatedness. They then build something that looks like a phylogenetic tree:
The resulting cultural tree suggests that New Zealand was at least partially settled from Hawaii, a hypothesis that fell from favor in the early 20th century. It also suggests a course of Polynesian settlement that started in the far western islands, jumped to the far eastern, then worked backwards to the original point of origin.
The study uses a novel method and therefore won’t by itself resolve any debates about the history of Polynesian migrations. That’s of course how science moves along: small steps.
Learning as protein folding
A polypeptide is a lot of amino acids strung along together in a chain. It’s not particularly interesting: a bunch of identical aminos and carboxyls, with a bunch of different R-groups hanging off the sides. It’s not until the carboxyl oxygens start forming H-bonds with the amino hydrogens that you start getting loops, helices and sheets. And it’s not until the R-groups get involved — bonding, attracting, hiding from water, etc. — that you get actual proteins, with all their bumps and grooves and nooks and crannies. And from there you can do just about everything that proteins do.
A course outline is a lot of terminology strung together. It’s not particularly interesting: a bunch of words with some definitions attached. It’s not until the structures connect to the functions, and the functions to the processes, that you’re learning instead of just memorizing. And it’s not until you connect structure-function complexes to patterns, principles, and theories that you’re thinking like a scientist. At that point you’re building intuition, making predictions, hacking together theories to meet your needs. From there you can go just about anywhere science can take you.
One trick to building connections among concepts is to go beyond the sequence of materials presented in the book or in class. Like bonds between amino acids dozens of peptides away from each other, there’ll be similarities, causalities, even just resonances between mechanisms or structures separated by entire textbook chapters. Or even in different courses or departments. Use these linkages! The more ways you can connect things together, the fewer separate concepts you have to learn. And anyway, nature’s truths aren’t compartmentalized or linear, so there’s no reason for our understanding of it to be, either.
An example. Phosphoglucose isomerase (PGI) is an enzyme involved in glycolysis. It is highly conserved (that is, it’s important enough that natural selection tends to minimize change in its structure), but there is some variation — among species and even among populations — in its kinetics. What this means is that different PGI variants function best in different temperature ranges. These different performance levels in different environmental conditions make PGI interesting for people who study the ecology and evolution of insects (which, as you remember, don’t regulate their internal body temperatures — at least not physiologically). Every year, a few more papers are published that examine variation in PGI kinetics and this variation’s role in determining the geographic range of some species of beetle or butterfly. (Here are two: 1, 2.) What are the authors of these papers doing? They’re skipping all over any traditionally organized biology curriculum. They’re making connections between ecology and metabolic biochemistry. They’re doing enzyme kinetics at the same time that they’re doing population genetics. In the morning they’re tromping around the mountains with butterfly nets, and in the afternoon they’re at the bench running gels.
And of course they’re not creating the links among their science’s subdisciplines; they’re discovering them. Or following them or respecting them, whatever — and these connections are what make the study of nature coherent and useful and fun.
