Why do people in deprived areas live life in the fast lane? It may be because of the age of people they observe in the street, according to a new study by Daniel Nettle and colleagues from Newcastle University in the UK.

Their work suggests that because fewer older people are seen out in the street in deprived neighborhoods, younger generations assume that people die young.

As a result, they may be adapting the speed at which they live their lives accordingly - for example, by having children earlier in life. Nettle and team's work is published online in Springer's journal Human Nature.

The researchers looked at the 'social diet' - or the daily distribution of types of people to whom one is exposed - in two neighborhoods in Newcastle.

One neighborhood was affluent, the other was poor.

They walked through the main streets of both neighborhoods six times, recording the estimated ages of every man, woman, and child they passed.

They then compared their recordings with census data, to establish how closely what people witness in the street reflects the actual age distribution of the population in these two neighborhoods.

They found that in the affluent neighborhood, more people over the age of 40 - and over 60 in particular - were seen than in the deprived area. In contrast, more young adults were observed on the streets in the poor neighborhood.

However, this was not an accurate picture of the actual age distribution of residents in the two neighborhoods. In reality, more residents over 60 were living in the deprived area than in the affluent one.

The authors comment that this discrepancy between what people see and the reality of who lives where is not a reflection of the different age profiles of people who live there, but rather of differences in the ways in which residents use the streets.

The authors conclude: "Chronic exposure to a world where there are many visible young adults and few visible old ones may activate psychological mechanisms that produce fast life-history strategies."

Nettle D et al (2012). No country for old men: street use and social diet in urban Newcastle. Human Nature. DOI 10.1007/s12110-012-9153-9