NEXT time you walk into a room and completely forget why you’re there, take it as an evolutionary compliment.

It’s a sign your survival instincts are finely attuned to the dangers of your new environment, even if you can’t remember why you’re holding an empty tea cup.

That’s according to Australian pop-science guru Dr Karl Kruszelnicki who said the evolutionary quirk is triggered by walking into a new space.

“The doorway is a killer,” he said as human brains can only focus on an area “the size of your thumbnail at arm’s length.

“Subconsciously you’re checking out the killer toaster.”

It’s just one of a handful of facts the ABC and BBC presenter gave an audience in London ahead of his Royal Institute live shows. Here’s some more mind-blowing trivia you never knew you needed to know.

WHY DIET COKE WILL MAKE YOU MORE DRUNK

A rum with diet coke will make you significantly more drunk than a rum with regular coke, Dr Karl explained.

This is because the energy from the sugar in the real Coke means it will take longer for the alcohol to be pushed into your system. It’s thought this is because the body will treat a sugary drink like food, and it will sit in your stomach longer to be broken down by acids.

WHY YOU (PROBABLY) KISS TO THE RIGHT

Two thirds of people lean to the right when going in for a kiss, according to some not at all creepy research carried out by Onur Gunturkun while hanging around airports and watching couples kiss each other without baggage or any other obstruction in the way.

That makes five out of the possible nine combinations potentially good, and four out of nine kisses a “terrible situation”, Dr Karl said.

DR KARL’S WIFE MAKES HIS SHIRTS

True story.

AN AUSSIE ON THE LOO HELPED SHORTEN WORLD WAR ONE

Australian-born William Bragg was stationed in France during World War I when he noticed that he was lifted off the seat of the otherwise-sealed toilet, when a large artillery gun nearby was fired.

He figured out, along with a friend, that the gusts of winds were due to a low frequency sound produced by the gun.

The discovery led to a way to locate enemy guns during the war — a major advantage to the allied forces — and eventually won him the Nobel prize.

THE OUTBACK HAS ‘UPSIDE DOWN’ RIVERS

Australia’s outback is home to one of the world’s oldest, the Finke River, parts of which are “upside down” meaning there is sand on top and freshwater underneath, according to Dr Karl. “Literally people have died within a metre of water, because of thirst,” he said, adding that the red soil gets its colour from huge quantity of iron ore.

“You can run electricity through the dirt of Australia, it’s that conductive.”

‘SELFIE’ IS AN AUSSIE INVENTION — OR IS IT?

Take a bow, Australia. The first recorded use of the world “selfie” seems to be a drunk Aussie at a mate’s 21st, who smashed his face and posted it online.

Nathan Hope, aka, Hopey, put a picture of himself with a huge fat lip on Dr Karl’s forum in September 2002.

He said he “tripped ofer [sic] and landed lip first (with front teeth coming a very close second) on a set of steps …. sorry about the focus it was a selfie”.

It’s commonly reported as the first usage of the term however Hopey himself later said “It was not a word I coined. It’s something that was just common slang at the time, used to describe a picture of yourself. Fairly simple.”

THE ODDS OF GETTING A DOUBLE YOLK EGG

Are around 1000 to 1, but they can be reduced by factors like buying large eggs which are more likely to contain the double yolk ones.

The odds of getting four in a row are around one in a trillion, so make sure you buy a Lotto ticket that day.

‘THERE IS NO DEBATE’

When asked about the Australian education system and its emphasis on science Dr Karl said it’s geared for the elites and advocated a greater emphasis on STEM subjects, arts and trades.

“[I come from a time] when education was seen as an investment in future rather than an intolerable burden on society,” he said.

“The best predictor of how many prison cells you will need is the illiteracy levels for 10 and 11 year olds.”

“Our education system in Australia, despite being horrendously expensive is also …. geared for the top 5 per cent of students. The other 95 per cent are left feeling bad.”

On the Brexit quagmire the UK finds itself in as politicians squabble over the terms, he compared the economic consequences to the climate change and vaccination.

“There is no debate about vaccination or climate change … if you’re in a restaurant and you’re the chef and you suddenly have a case of diarrhoea and you come out and say I have two choices, I have faeces on my hands, shall I wash them or not? Well there are two choices, obviously, but are both of them equally good in terms of health? No! You wash your hands. Really really thoroughly! There are arguments where the weight is all on one side.”