Evolution, Constraints, and Legos.

I spend a lot of time teaching my undergraduates about how constraints in the environment influence biological processes. From an evolutionary perspective we can call these constrains "selective pressures." In class I ask the students to brainstorm what these selective pressures might be. In students' minds it pretty much boils down to the availability of resources, through there are many other environmental constraints as well, such as climate, pathogens, and symbionts. 

But what bothers me about this exercise is that it's all pretty abstract. We can talk about resources and even think of examples. But it remains a kind of thought exercise without a compelling hook into the reality of biological systems. 

So the other day I picked up some Legos and started to model a termite mound, which incidentally is my favorite example for discussing environmental constraints with students. What looked like thousands of blocks began to appear quite inadequate by the time I had started an outer chamber to surround the inner chamber of my termite mound. I realized I would have to build more efficiently or much, much smaller as my supply of lego bricks dwindled. What would a termite colony do?

Aha! A way to teach about how constraints limit biological processes! Maybe I shouldn't order all those extra bricks after all. 

My barely started termite mound model. About at this point I ran out of bricks. 

Looking up into my termite mound, visualizing air flow.