[Warsaw, November 27. Image via Getty]

Two volunteers, a 18-year-old woman (L) and a 24-year-old man, dressed as cavemen are pictured in a cage of the Warsaw on November 27, 2009. Warsaw's zoo has opened a new display where two volunteers dressed as cavemen will spend time in a former monkey-cage, to remind visitors that humans are animals too, organisers said today. Dressed in animal skins, the 24-year-old man and 18-year-old woman will while away their time grooming each other, keeping a fire burning, and watching visitors who look in through the bars, the zoo's deputy director Ewa Zbornikowska said. AFP PHOTO / JANEK SKARZYNSKI (Photo credit should read JANEK SKARZYNSKI/AFP/Getty Images)