Says a study published in the journal PLOS ONE, researchers used archaeological evidence of lighting remains found across several Paleolithic caves featuring cave art in Southwest Europe to experimentally replicate the artificial lighting systems presumably used by the original human cave dwellers. It included five replicated torches (made variably from ivy, juniper, oak, birch, and pine resins), two stone lamps using animal fat (bone marrow from cow and deer), and a small fireplace (oak and juniper wood). Wooden torches made of multiple sticks worked best for exploring caves or crossing wide spaces, since they projected light in all directions, were easy to transport, and didn’t dazzle the torchbearer. In contrast, grease lamps worked best for lighting small spaces over a long period but weren’t well-suited for transit.