Your Building's Roach Problem Is a Family Affair

Dogs may be man’s best friend, but we are the cockroach’s. A new study concludes that the ubiquitous German cockroach (the kind likely skittering across your sidewalk or kitchen last night) spreads most actively within apartment units and complexes, and that those roach populations have closely linked genetic structures. (Think of it as a culture that values intergenerational living.) Roach populations that have spread between one city and another or between continents, on the other hand, share a lot less DNA.

That makes sense. But what's interesting is how the study relates to the way these guys travel. The flightless insects are so finely adapted to city life as to be virtually incapable of existing in any natural environment. So for a roach to get from Raleigh, North Carolina, to Gary, Indiana—or, heck, to Paris—it must do so through human means, hitching a ride in a car, on a ship, or on a plane. Roaches trek those great lengths less often and in lower numbers, and so tend to reproduce with partners with little genetic similarity when they arrive at their new homes.