This old piece of pine lumber (the stub end of a two-by-four) has been devoured by termites. The rest of our garage has been spared their attentions, so far.

A weighty block has turned to crumbly paper. The insects responsible for this impressive work were scurrying nervously in the too-bright light of day, each one looking like a fat grain of rice from a milk pudding. Add sugar and I’m ready to become an myrmecophage (yes, anteaters love termites).

Termites are like cows, they graze on plant material that is completely indigestible to them. Only by harboring an internal band of helpers can termites (and cows) free the nutrients and energy locked in woody tissues. The termites’ helpers are in the hind part of the gut. Here single-celled protists (relatives of “amoebae”) engulf small wood particles and digest them. But these protists are cows too…they have within their cells a peculiar group of bacteria, the critters that do the actual work of making wood-destroying enzymes. So helpers live within helpers.

The fact that only a few obscure groups of bacteria can digest cellulose (the main component of “wood”) explains a lot about our world. If more creatures could digest wood, then trees likely could not exist (their trunks would be gobbled up in short order), wooden structures would last about as long as gingerbread houses (which are, I’m told, digestible, explaining perhaps their limited popularity outside of confectioners), and our great stockpiles of coal (old compressed wood) would not exist. No forests, no houses, and no industrial revolutions (at least not coaly ones…and what other kind has there been?).