Controversial research published in New Scientist, demonstrating that apes suffer self-doubt, has given scientists an important clue into how religion may have originated in our early hominid ancestors.
In the research, apes first watched a human researcher place food in one of two covered plastic pipes. After a delay, giving the apes time to forget which pipe the food was in, they were allowed to check the pipes before opening one and claiming the food reward. The longer the delay the more often the pipes were checked before a decision was made.
"This behaviour clearly shows they are expressing self-doubt, something we thought was a purely human trait." remarked Joseph Call of the Max Planck Institute for Evolutionary Anthropology in Leipzig where the research was carried out.
To test the hypothesis in more detail, the animals were taught a rudimentary sign language so they could communicate with researchers. The results astounded everybody by clearly showing that apes have developed a rudimentary and primitive religion.
The clearest link, not surprisingly, was found amongst bonobos, the closest evolutionary relatives of humans. After one particularly long delay a young bonobo called Baa-baa showed particularly strong signs of self-doubt by signing, "Why I here? What it all mean?"
At that point an older Bonobo known as Papa, who had until then been sitting on his own wearing a funny hat, came over. He made signs meaning, "Man feeder too clever. We not know what he want." before mounting Baa-baa in a simulated sex act, a typical dominance display in this species.
Following this activity, baa-baa retreated into a corner where he sat playing with his favourite toy, a string of beans, whilst continuously signing "Guilt, guilt, guilt".
Papa, unmoved by Baa-baa's obvious distress, signed, "What man feeder want. I not responsible. You not tell." He then set about building a large construction out of cardboard boxes before demanding that the other bonobos bring him bananas.
"Other species of ape have shown less obvious displays of 'religious' behaviour." said Mr Call. "One particularly interesting example was a chimpanzee named Malik. When he opened the pipe to get his reward he signed 'Ugh! Bacon. Kill infidels.' then went on a violent rampage and mercilessly attacked other chimpanzees who didn't share his aversion to pig products."
The much more docile Orang-utans were the most disappointing subjects according to researchers. "They simply sat cross-legged in their cages, constantly repeating, 'Ohmmm, Ohmmmm.' for hours on end."
According to Mr Call, the strangest bahaviour was observed in gorillas. "They love to dress up in a type of 'underwear' they have fashioned from old pieces of material and which seems to have an almost 'magical' fascination for them. Particularly irritating is their habit of getting up early on a Sunday morning and knocking on the glass of their enclosure until they get our attention. I really hate getting dragged out of bed at the weekend."
"We're not quite sure where this research will end but so far the results have been unbelievable. We can't wait to see what happens next."