The aim of our study was to be able to attach a number to human traveling behavior. If you want to understand how modern epidemics spread, you need to make some assumptions about how humans spread.

I think the greater significance of this is that human travel ... obeys some quite simple, independent rules.

If you want to understand how disease spreads, you need to understand how humans travel, because a lot of the time humans carry the disease from one place to the next. It's clear people travel long distances less often, but make a lot of short trips, but what are the details? How often are trips of a certain distance made?

This study is the first to assess which types of behavior contribute most to crashes and near crashes.

We can now plug in the parameter ranges that we think will apply to influenza and then simulate a pandemic that runs through Europe and see what happens.

This is a very good estimate of how humans travel.