Reinventing the beehive has been an impulse of beekeepers for centuries, and bees have managed to tolerate most of their tomfoolery, more or less. The beehive that I use has been the standard for most beekeepers worldwide for more than 160 years. It's the Langstroth hive, patented way back in 1852.
The hive is boxy, but also elegant in a completely utilitarian sense. The elegance of the hive came from an amateur's scientific observation and the desire to do as little damage to the bees and their work as possible. Its inventor was a Congregationalist minister in Philadelphia, the Rev. Lorenzo Lorraine Langstroth, who took up beekeeping as an antidote to severe bouts of depression. Building on the work of others, he discovered the concept of “bee space,” which is remarkable in its simplicity. If presented with surplus space narrower than one-quarter inch, the bees will fill it in with propolis, the sticky tree sap they collect for filling nooks, cracks, and crannies; if wider than three-eighths inch, they'll fill it with honeycomb. Of course, honeycomb is preferred. Knowing that, Langstroth built hives like top-hanging filing cabinets, in which frames hung with precise gaps between them, which encouraged the bees to fill combs in the right places and not gum up everything with propolis. That allowed each comb to be lifted out of each box “like pages in a book,” meaning less damage and fewer bees killed during hive inspections and honey harvesting. That said, there are some problems with the Langstroth hive, especially among farmers of the developing world and hipster urban farmers of the post-industrial West. Foremost is that they are relatively expensive, requiring precision-cut lumber shapes and patterned sheets of beeswax. So some people took what looked like several steps backward and began championing the top bar hive.
The main benefit of top bar hives is that they're easy and cheap to make out of whatever materials are available. They resemble Langstroth hives in that the combs hang from supports on the tops of the boxes with “bee space” in mind. They are different in that, unlike Langstroth hives, top bar hives are only one box and are not built to one standard size. The guides for comb building in a top bar hive are not frames with thin sheets of wax stretched across them, as is the case with the Langstroth hive, but just a bar with a small strip or smear of wax so that the bees will (hopefully) build unsupported hanging combs straight across them.
But no matter. The benefits of top bars over standard Langstroth hives are their cheapness, use of recycled material, lightness (only individual frames are lifted, not the wooden boxes that hold them) and their funky-pretty style. Disadvantages, though, are pretty substantial. For one, you don't get nearly as much honey. You also can't add additional hive boxes on top to accommodate a growing hive (often inspiring half the bees to leave the hive in a swarm). Finally, you can't empty the unsupported combs in a centrifuge extractor, so harvesting honey means breaking the comb into bits, which means the bees have to build new combs after every harvest. (Langstroth combs, supported by wood on all four sides instead of just one, can be emptied of honey and replaced unharmed for immediate refilling by the bees.) You might consider top bars as a cheap way to try out the hobby before investing in Langstroths.
HISTORY OF THE TOP BAR HIVE
Top bar hives are sometimes called Tanzanian or Kenyan top bar hives. From this, many Westerners (especially those who treasure the wisdom of faraway tribal societies over their own) assume that they are an ancient invention by indigenous people in those two countries. It turns out that this is not true.
The real story is that the top bar hive was invented in the 1970s by Westerners from the Peace Corps and Canada. Their aim was to end the traditional method of harvesting honey, which was finding a bee tree and chopping it down, destroying the hive and killing the tree. The idea was to reduce the destruction in wildlife preserves by convincing the locals to raise bees instead of hunting them.