Although you may no longer be in touch with your first love, it's highly likely that if you caught a hint of their perfume you would be transported back to those exhilarating first months or painful last nights.

Scents can stir in us dormant images and scenes that we didn't even know we had stored in our minds. Although we may pour over letters and photos of loved ones long gone, there is no other sense that can create the vivid and often tactile memories that odours do.

Many people have experienced the powerful memory tug brought on by a scent, but few understand what causes it.

According to scientists, this powerful phenomenon originated as a survival strategy - but has developed into something much more complex.

Dr Warrick Brewer, Associate Professor of Psychiatry at the University of Melbourne, was so intrigued by the connection that olfaction has with the brain that he has dedicated his career to understanding it.

He explains that scents can bring up memories that we didn’t know we had ever stored because the emotional attachments to them are so strong.

“Some memories are stored and we’re not that conscious of them because we don’t need to use them,” he explained. He said memories were like dreams, which we have every night but only remember if they stir strong emotions inside of us.

“It’s like a solar flare on the sun. The memories are there, usually burning away, but sometimes recognising a scent can cause them to flare up. Sometimes these flares never reach our consciousness. But when you get a big flare of emotion, then it impacts upon our awareness.”

These flares are what cause long-buried memories to unfurl in front of you, like sets from a play.

According to scientists, smells bring up the oldest, rarest and most vivid memories. Although scent memories are not any more accurate than those brought on by sight or sound, research has found they include a depth of emotion that no other sense can evoke.

Dr Brewer explains that this is because of our sense of smell's origins. It was developed to bring on a fight or flight reaction, to initiate quick decisions that would save an animal’s life.

This means that smells bypass consciousness and goes straight to the emotional part of the brain.

This allows a gazelle that picks up the scent of a lion on the wind to run into the shelter of the undergrowth before it even realises it has smelt anything or what the smell means.

For humans today it means that we cannot select what we do and don’t smell. We cannot filter our sense of smell or the response it evokes, it is pure. A scent reaches the limbic system and brings up a memory that is linked to it without us consciously deciding which ones are relevant or recent. Our brain simply picks the memory with the strongest emotional attachment to it, because in the animal world this would be the memory that causes a fast reaction from us.

The work that scientists have done on olfaction and memories won the Nobel Prize in 2004 and has explained much of how the process is regulated. But there is still much that is unknown.

“We’ve only scratched the surface of the brain’s potential,” said Dr Brewer. He is currently working on the link between mental illness and the ability to distinguish scents from one another.

It has been found that schizophrenia can be predicted by a poor ability to tell one smell from another. This may present ways to diagnose the disease early. He is also investigating the power of aromas to evoke painful memories in sufferers of Post Traumatic Stress Disorder.

Today the digital world is so obsessed with capturing moments and storing memories. We take photos, record ourselves and make videos to leave to people after we’re gone, but it is perhaps our smell that will leave the most lasting impression on the world.

Maybe this has lead to our obsession with fragrances. Perfumes cost more per gram than gold – but in certain scents we know that we can find something that digital cameras and videos cannot capture, the smell of lost time.

Fiona MacDonald is sub-editor at ScienceAlert. She completed honours in reproductive zoology at The University of Melbourne and has just finished studying journalism.