麻豆传媒

鈥淗ERE and now鈥�, 鈥淏ack in the 1950s鈥�, 鈥淕oing forward鈥濃�� Western languages are full of spatial metaphors for time, and whether you are, say, British, French or German, you no doubt think of the past as behind you and the future as stretching out ahead. Time is a straight line that runs through your body.

Once thought to be universal, this 鈥渆mbodied cognition of time鈥� is in fact strictly cultural. Over the past decade, encounters with various remote tribal societies have revealed a rich diversity of the ways in which humans relate to time (see 鈥淎ttitudes across the latitudes鈥�). The latest, coming from the Yupno people of Papua New Guinea, is perhaps the most remarkable. Time for the Yupno flows uphill and is not even linear.

Rafael N煤帽ez of the University of California, San Diego, led his team into the Finisterre mountain range of north-east Papua New Guinea to study the Yupno living in the village of Gua. There are no roads in this remote region. The Yupno have no electricity or even domestic animals to work the land. They live with very little contact with the western world.

N煤帽ez and his colleagues noticed that the tribespeople made spontaneous gestures when speaking about the past, present and future. They filmed and analysed the gestures and found that for the Yupno the past is always downhill, in the direction of the mouth of the local river. The future, meanwhile, is towards the river鈥檚 source, which lies uphill from Gua.

This was true regardless of the direction they were facing. For instance, if they were facing downhill when talking about the future, a person would gesture backwards up the slope. But when they turned around to face uphill, they pointed forwards (Cognition, ).

鈥淚f they were facing downhill and talking about the future, the person would gesture backwards鈥�

N煤帽ez thinks the explanation is historical. The Yupno鈥檚 ancestors arrived by sea and climbed up the 2500-metre-high mountain valley, so lowlands may represent the past, and time flows uphill.

But the most unusual aspect of the Yupno timeline is its shape. The village of Gua, the river鈥檚 source and its mouth do not lie in a straight line, so the timeline is kinked. 鈥淭his is the first time ever that a culture has been documented to have everyday notions of time anchored in topographic properties,鈥� says N煤帽ez.

Within the dark confines of their homes, geographical landmarks disappear and the timeline appears to straighten out somewhat. The Yupno always point towards the doorway when talking about the past, and away from the door to indicate the future, regardless of their home鈥檚 orientation. That could be because entrances are always raised, says N煤帽ez. You have to climb down 鈥� towards the past 鈥� to leave the house, so each home has its own timeline.

鈥淭his study is an important landmark,鈥� says Pierre Dasen, an anthropologist at the University of Geneva in Switzerland who was not involved in the work. 鈥淚t demonstrates both universality of cognitive processes and a fascinating cultural difference.鈥�

Lera Boroditsky of Stanford University in California agrees. 鈥淓ach one of these discoveries isn鈥檛 just telling us something about other people, it鈥檚 telling us something about us,鈥� she says. 鈥淎 lot of English speakers think that it鈥檚 natural to think of time as a straight line. But that鈥檚 an illusion. It doesn鈥檛 have to be that way.鈥�