These changes will happen at evolution’s grindingly slow pace, but by the time these creatures have gotten used to life in vast ecosystems of garbage, a future researcher will marvel at how readily and how ingeniously these creatures have adapted — and continue to adapt — to their befouled environs.

This week’s entry discusses the myriad mammals that are able to live in a landfill, from small rodents to upper-echelon predators to human beings. But this is a Pyrrhic victory, as they are subject to the same hazards that afflict any creature searching its way through a dump.

Insects are important to the decomposition of garbage because they eat a lot of trash and tunnel their way through it, which mixes and aerates it. Some insects find their way to the trash, while some are inadvertently brought to it. In interesting case of filth in reverse, cockroaches are often found in landfills, as they hitch a ride in the belongings humans have discarded.

The smallest layer of life in a landfill — a “robust set” of microscopic bacteria, fungus, yeast, and protozoa — consumes and digests organic materials in garbage, breaking it down like an enormous compost pile and producing huge amounts of methane gas as a byproduct of their activities.