David Attenborough: In a lifetime spent observing Nature, nothing has been more rewarding to me than the time I have spent studying reptiles at the BBC. These cold-blooded creatures can seem so exotic – even off-putting to some – but, at the same time, strangely familiar.

[Image of large lizard with half a small lizard dangling from its mouth.]

David Attenborough: But where did they come from? What are they doing here? And what should we be doing about it?

1^st scientist (Ken Rice): Only a few decades ago, the number of known planetary systems in the universe was just one. We have now identified over two thousand, and new ones are coming to light all the time.

[image of planet revolving in a gaudy galactic broth resembling a pub doorway on a Saturday night, from NASA’s inexhaustible stock of What Space Looks Like from the Porthole of Flash Gordon’s Atomic Rocket]

2^nd scientist (Charles Darwin): If you’re looking for a class of beings capable of evolving over hundreds of millions of years in extreme conditions, gifted with the patience and tenacity necessary for undertaking the perils of interstellar space travel, then Reptilia, and more particularly Squamata, is your only man.

[Image of Professor Stephan Lewandowsky staring fixedly at the camera, his hands splayed on the desk before him, elbows out.]

Ken Rice: As we discover more and more exoplanets, the chances of there not being one out there inhabited by an invasive reptilian species is becoming vanishingly small.

3^rd scientist (Stephen Hawking): Hominids have been evolving for millions of years, yet it was only five minutes ago, mathematically speaking, that we learned to beat each over the head with a bit of wood.

[Image of Michael Mann holding the twisted trunk of a strip bark pine in a threatening manner]

Historian (Naomi Oreskes): ..then in short order we invented the bronze sword, the cooking pot, and methods of establishing scientific truth by the statistical analysis of word searches in abstracts of the peer reviewed literature.

4^th scientist (Matt Ridley): Everything we do, we get better at doing – every day, in every way. Sorry, did I say something wrong?

David Attenborough: The time taken to evolve from the age of crude bronze weaponry and interminable epic poetry recited to the sound of a five stringed harp to the age of the modern TV documentary is a mere blinking of an eye in evolutionary terms.

Stephen Hawking: If you take the length of time to develop modern human amenities and divide it by the total time we’ve been evolving to where we are, you get a figure so vanishingly small you might as well toss it into the waste paper basket. And yet here we are. (Well, I’m not, but you are.)

David Attenborough: Who is to say that the humble lizard might not have achieved as much and even more on another planet, unhindered as he might be by rapid asteroid-induced climate change?

Ken Rice: An extraterrestrial, viewing our planet from afar, couldn’t help but notice that it is three quarters covered in water. This would be an irresistible attraction to an aquatic race.

David Attenborough: Were our first extraterrestrial visitors amphibians, as suggested in ancient Babylonian texts? Creatures with short fin-like arms, pointy heads, and scales?

[Image of Professor Stephan Lewandowsky being dowsed by a strange unearthly creature carrying a bucket]

Naomi Oreskes: Did the arrival of these amphibian invaders spell doom to the highest civilisation then present on earth? Does this explain why we have found no trace of Atlantis?

David Attenborough: The first aim of such an invading reptile species would be to insinuate themselves surreptitiously into the ruling élite. But are there tell tale signs, visible to the observant eye, that they are already among us?

[Image of President Macron staring unblinkingly into the camera, his tongue flicking nervously from between his lips]

David Attenborough: The gait of the lizard is highly distinctive, characterised by sudden twitches of the pelvis as it swiftly shifts position in order to confound its predators.

[Image of a gecko’s bottom as it disappears up the wall. Cut to Theresa May crossing the floor of the EU Commission in a nifty pencil skirt.]

(Where was I?)

Ken Rice: The controversy over President Obama’s place of birth is noteworthy in this context. Nothing would be easier than to lay an egg on one continent and hatch it on another.

David Attenborough: Despite the evidence, there are still those would deny reality, or seek to twist it to their own ends..

[Clip of President Trump: “We’re gonna drain the swamp…”]

David Attenborough: …But their anti-bactrian diatribes will come to nothing. The evidence is there.

Naomi Oreskes: Of ten thousand articles in the New York Times about Russian interference in the US presidential election, the number denying that President Putin is an iguana was precisely zero.

[She stares meaningfully at the camera from under her hooded eyelids, then with a flick of her tail disappears under a stone.]

David Attenborough: So what is to be done in the face of this undeniable reality? Should we give up in despair, stop paying our licence fees, and go to live on a remote island in the Pacific?

Charles Darwin: Well, it worked quite well for some. You see…

David Attenborough: Time is too short for learned argy bargy. But we can all do our bit. Change our eating habits for one thing.

[Clip of cool young people eating locust fritters in a smart London pavement bruncherie.]

Ken Rice: We must accept limitations on our freedom of movement. Flying must be kept to a minimum if we are to survive..

[Clip of a chameleon tongue-swatting a passing fly]

David Attenborough: But hope for the future lies with the upcoming generation. They will have to learn to suppress old-fashioned instincts and desires inherited from their warm-blooded mammalian past, and adapt to a radically new lifestyle. Already there are hopeful signs that young people are adapting; learning how to stay cool; how to respond to binary stimuli in a predictable fashion (to the delight of cognitive psychologists); and how to remain in a comatose state for months on end.

It is on the young people that we must depend to lead us out of the past, past the present, into the future that presents itself; a cooler, more cold-blooded future.

[Close up of an egg cracking, out of which emerges a tiny pale creature with hair in plaits. It stares fixedly at the camera. Freeze.]