ideas such as a colourless, soundless, odourless world, but I urge you to reflect that a colourless world is incompatible with natural selection, because you have left yourself no way to account for the survival of the chameleon – unless you also believe in the existence of extremely patronising birds of prey. How kind of nature to select for hawks and shrikes prepared to humour the chameleons’ pathetic attempt at camouflage! Yet how wasteful of nature to select for chameleons with subcutaneous photonic crystals! All the energy that the male adult panther chameleon (Furcifer pardalis) spends on lugging these photonic crystals around is energy wasted, because in a colourless world they confer no selective advantage whatsoever.
If Eagleman is right and it is indeed a colourless world, then the whole science of co-evolution must be wrong, everyone from Darwin first observing the selective advantage of a scarlet throat pouch for the Great Galapagos Frigate Bird, down to and including a 2016 Nature article headed ‘Lizards Tailor Tails For Local Predators’. The article was about how, in three different areas of Japan, the same species of skink lizard, Plestiodon latiscutatus, has evolved a different coloured tail in response to different predators: for weasels a blue tail, for snakes an ultraviolet tail, for birds a brown tail. There was an interview with the project’s chief scientist Dr Takeo Kuriyama, who said:
When I first told my colleagues that I’d discovered a link between the blue-tailed lizard and the weasel they were frightened for their very lives, or pleasantly surprised. Hard to tell. One or the other.
Brightly coloured Plestiodon latiscutatus tails evolved to attract snakes and weasels to the one disposable part of its body. The lizard can shed its tail with the snake’s fangs still in it, scuttle away and grow a new one. Ditto weasel. But birds have such sharp sight they are less likely to fall for this misdirection trick. If they see a lizard’s tail they’ll see its head and belly too. Against birds, the lizard’s only hope is not to be seen in the first place, and so the brown tail has evolved as simple, old-fashioned camouflage. It’s the least likely colour to be seen among the sticks and twigs littering the forest floor.
Imagine an organism that actually had to live in Eagleman’s nuclear winter wonderland. In a colourless, odourless world, how could the orchid attract the bee it needs for pollination? You might argue that all that is needed for pollination to occur is for just one bee to land on one orchid however accidentally. Maybe it just lands on the orchid for a rest. Once the bee has found the orchid’s pollen, it would then return to its hive, perform its waggle dance to inform the other bees where the pollen is at, and the other bees will follow it back to the orchid. To this argument I say: Prasophyllum fimbria.
The orchid Prasophyllum fimbria offers nothing but colour. From a distance Prasophyllum displays what looks like a pollen-spattered anther. But there is no pollen, no food reward for the bee at all. The blotchy yellow splodges are a 2D trompe l’oeil. The bee gropes around for ages, trying to find something that lives up to the tasty promise of the picture that drew him in, like someone eating in Harry Ramsden’s, which has created a Pavlovian connection in the human brain between tartar sauce and regret.
Or consider the monarch butterfly. The monarch’s colouring is what’s called aposematic, warning predators ‘TOXIC! DO NOT EAT!’ In a world of austere monochrome, the monarch has no warning signal with which to deter hungry frogs and birds. Instead its only hope of survival is to blend in with all the other graphite butterflies, slate-grey macaws, and pumice parakeets flitting through electrostatic skies that fizz like out-of-tune TV sets. Safely camouflaged in this way, the monochrome monarch may survive, but I fear for the scarlet kingsnake and all other practitioners of Batesian mimicry.
Batesian mimicry is a twist on aposematic colouring, by which edible snakes and frogs deter predators by mimicking toxic snakes and frogs. The edible non-toxic scarlet kingsnake, for example, copies the patterns and colours of the poisonous and venomous coral snake. The kingsnake’s life depends on falcons, weasels and monitor lizards falling for the bluff.
‘What these astounding phenomena teach,’ the great art historian E. H. Gombrich wrote,
is precisely that there is a limit to perceptual relativism. What looks like a leaf to modern European must also have looked like a leaf to predators in fairly distant geological epochs. Likeness is not only in the beholder’s eye.*
* E. H. Gombrich, Art and Illusion, 2002.
But colour, for Eagleman, is only in the eye of the beholder. ‘Colour,’ he says, ‘is an interpretation of wavelengths, one that only exists internally.’
How could there be colours in our head if there were none in the world? From where would we get the concept? And why is colour the illusion rather than, say, colour-blindness? Why is the one supposed to happen only in the head but not the other?
In 1894 Arthur König demonstrated the fovea to be blue-blind. Does this mean the fovea is one step closer to seeing reality-as-it-really-is than the rest of the eye? Only the fovea has been able to rid itself of the blue delusion. It alone has escaped the shackles of blue to see the sky for the fizzing Alka-Seltzer electrostatic it really is. Now we just need to figure out how to communicate the fovea’s disillusion to the rest of the eyeball.
The fact that the human brain perceives only one ten-trillionth of the spectrum of electromagnetic radiation is evidence enough for Eagleman to declare that ‘in the outside world colour doesn’t actually exist.’ Shouldn’t the fact that we can only see a narrow band of broader spectrum, suggest that the world is more colourful than we can possibly imagine, not less? That would be the logical conclusion, wouldn’t it? And it would be consistent with zoology, too.
In 2016 it was discovered that reindeer not only see ultraviolet light but, in stark contrast to other mammals, their eyes have evolved to resist the damage caused by UV. This resistance allows them to spend longer staring at snow for any clues of food or foe, without becoming snow blind. It enables them to do better than humans or pine martens at discerning patches of hollow snow, which will give way if stepped on.
Reflectance spectrophotometry has revealed that blue tits ought really to be called ultraviolet tits, since females prefer males with the most dazzlingly UV crests. All this dazzle passes us by. Human eyes can’t see it, but blue tits are not making it up. Their eyes just have different cones to ours, cones which are ‘visually sensitive to wavelengths in the near-ultraviolet.’*
* S. Hunt et. al., ‘Blue tits are ultraviolet tits’, Proc. Biol. Soc., 1998.
We cannot hear the high-end kilohertz laughter of tickled rats, nor the deep clicking of long-tusked narwhals echolocating their way through the black depths of the Arctic Ocean.
All of which goes to show only that there are biological constraints to what different animals can discover in their environments. Eagleman himself puts it very clearly when says that ‘each creature picks up on its own slice of reality.’ That is absolutely right. But it is not very melodramatic or spooky. It doesn’t have the macho tone of ‘can you handle reality as it really is?’ And so Eagleman cannot stop there, but goes on to commit himself to the disastrous doctrine that animals have no access to reality at all:
In the blind and deaf world of the tick, the signals it detects from its environment are temperature and body-odour … No one is having an experience of the objective reality that really exists.
If ‘no-one is having an experience of the objective reality that really exists’, then what is this temperature and body-odour that the tick thinks it detects? And didn’t Eagleman just now say that the world was odourless? Or did I only imagine he said that. Did you imagine it too? If we both imagined it then maybe it is an objective reality that really exists. If so, then how can the deaf-blind tick detect body-odour? To detect means ‘to discover or identify the presence or existence of.’ But in an odourless world odour has no presence or existence. You can’t detect odour in an odourless world.
Then