Metaphors are cultural

• When English speakers use hand gestures to talk about the past and the future, they thrust a hand over the shoulder for the past and put a hand forward to indicate the future. English speakers also talk of the past as "leaving behind" and the future as "looking forward."
• The Yupno people of Papua New Guinea don't think of the future as before you, but as uphill. Their concept of time is not anchored in the body, but to the world and its contours.

Humans are different from animals in that we don't sense time only as passing. We dice time into units or think of time to go beyond our lifespan, such as millennia. We rely on time concepts that allow us to make plans, follow recipes, and discuss possible futures.

Recent research suggests that across all cultures, the concept of time depends on metaphor, known as a conceptual metaphor. We build our understanding of duration and sequences of events out of familiar spatial ideas such as size, movement, and location.

But the "time is like space" metaphor takes on very different forms from one culture to the next.

Time is difficult to explain, yet we deal with it every day. All people talk of time as "motion on a space," and think of time as linear.

• Durations are talked about using size ("a short weekend").
• The passage of time is treated as a movement. ("the week flew by").
• We think of events as located at different positions on a path - internally as "the week ahead of us" and externally as "a reception follows the ceremony."

People of all cultures lean on spatial concepts for understanding time, but exactly which spatial metaphors they use can vary.

• The English may speak of "a long time ago," while the Aymara from the Andes refers to "a lot of time in front."
• The Pormpuraaw, and Aboriginal Australian community, refer to the past as "to the west" and future as "to the east," while we refer to the past as "behind" and the future as "in front."

The parts of the brain used for thinking about space are also used for thinking about time.

• Studies reveal that people with damage to space-related brain areas also have trouble thinking about time.
• In English and many European languages, we often think of past events to the left and future events to the right. One study found that people with disrupted spatial abilities of their left side had trouble remembering past events and even confused past events for future ones.

Time as space metaphor shows up in our language and gestures, but also in depictions of external sequences of events.

• Histories are laid out on timelines.
• The human evolution is shown creature by creature, proceeding rightward.
• The calendar shows the days arranged from left to right and the weeks from top to bottom.
• Latin script proceed from left to right.
• If you lay out three ordered images, - a banana in its peel, the banana partially peeled and the banana half eaten - English speakers will lay them out from left to right.but Hebrew speakers will lay them out from right to left.
• Mandarin Chinese speakers refer to "last week" as above and "next week" as below. since Mandarin is written vertically, from top to bottom.

The concept of time reveals the human's capacity for abstract thought. But time is not the only abstract domain, nor the only one we understand through metaphor. Spatial metaphors are very common, structuring how we think about kinship, politics, and power. ("She has the upper hand.")

The particular metaphors we use, however, rely on our culture, not biological evolution.