New York, Feb 26 (IANS): Our ability to respond to the challenges of the fast-changing world comes from our brains' ability to flexibly combine and repurpose the neural resources that evolution has provided us, researchers report.

Online dating, chatty smartphones and social media played no role in the evolution of our ancestors, yet humans manage to deal with and even exploit these hallmarks of modern living, they noted.

"This repurposing allows us to do a lot with a little. Our brains have the flexibility to form new combinations of pre-existing computations and deploy these computations rapidly and flexibly in new contexts," explained study co-author Thalia Wheatley from the Dartmouth College in New Hampshire, US.

Wheatley and her team described three kinds of repurposing, each happening at three distinct timescales.

The first - evolutionary repurposing - is exhibited in all animals and it describes how evolution "uses what's in the room" to solve a novel problem.

It happens slowly, across lifetimes, through natural selection.

The other two forms of repurposing that are found in humans rely on social cognitive abilities.

Cultural repurposing refers to the process by which cultural inventions such as reading, musical forms and belief systems are acquired in a lifetime by co-opting pre-existing brain circuits.

"For example, we did not evolve to read. Instead, a growing body of research suggests that we read by repurposing neural machinery that evolved to process faces and objects," the authors explained.

Finally, instrumental repurposing happens not only within a lifetime but on the fly.

It is how we intentionally and creatively push our old evolutionary buttons to influence our own and others' behaviours.

"Understanding what is in our cognitive toolbox is a first step to understanding how we can most effectively use these tools to address modern problems that our brains did not evolve to solve," Wheatley concluded.

The study appeared in the Cell Press journal Trends in Cognitive Sciences.