The Second Book of General Ignorance (41 page)

It gave Sir Christopher Wren the opportunity to rebuild St Paul’s Cathedral. What it didn’t do was clear the city of plague.

No one knows what stopped the Great Plague of 1665–66, but despite what generations of schoolchildren have been taught, it definitely wasn’t the Great Fire of September 1666.

The plague flared up in early 1665, probably carried on ships bringing cotton from Amsterdam. It was the first major outbreak in thirty years but, by the beginning of the
following year, it had already begun to die out. In the last week of February 1666 there were only forty-two plague deaths reported in London, compared to more than 8,000 in each week of September 1665. The king had returned to London on 1 February 1666. Although it killed an estimated 100,000 people (20 per cent of London’s population), the plague crisis was over six months before the Great Fire in September.

Also, the areas of London that burned down in the fire – the City, mainly, where 80 per cent of property was destroyed – were not the areas where the plague had been at its worst, which were the suburbs to the north, south and east.

No one really knows why the plague stopped. Perhaps it was spontaneous. That’s how epidemics often end: by burning themselves out because they spread so quickly, and have such a high mortality rate, that they have nowhere left to go. It’s one of the reasons the Ebola virus hasn’t killed more people in Africa: a high (99 per cent) mortality rate means a quicker burn out.

Another possible reason for the disappearance of the plague in London was that the ancient method of barring the houses of known victims was policed much more aggressively. Doors were locked from the outside for twenty to twenty-eight days and guarded by watchmen. It’s a fate that doesn’t bear thinking about.

Even more difficult to comprehend is the story of the small hamlet of Eyam in Derbyshire. In September 1665 a bundle of infected cloth arrived from London for the local tailor. He was dead within a week. As the plague began to rage, the villagers (led by the Anglican vicar and the Puritan minister) voluntarily cut themselves off from the rest of the world so that it wouldn’t spread elsewhere. When the first visitors were finally allowed to enter a year later, they found that three-quarters of the inhabitants were dead.

The disease had struck viciously, but apparently at random. Elizabeth Howe never became ill, despite the fact that she had buried her husband and their six children. Another survivor, against all probability, was the man who helped her do it – Marshall Howe, the unofficial local gravedigger.

Yes.

Introducing the Immortal jellyfish …

The adult form of the species
Turritopsis nutricula
looks like any other small jellyfish. It has a transparent bell-like body, about 5 millimetres (⅕ inch) wide, fringed with eighty or so stinging tentacles. Inside is a bright red stomach, which forms the shape of a cross when seen from above.

Like most of the
Cnidaria
family (from
knide
, Greek for ‘stinging nettle’), the tiny
Turritopsis
is predatory, using its tentacles to first stun plankton and then waft them up through its mouth-cum-anus. The females squeeze their eggs out through the same passage, after which the males spray them with sperm. The fertilised eggs fall to the ocean floor where each one attaches itself to a rock and starts growing into what looks like a tiny sea anemone: a stalk with tentacles called a
polyp
(from the Greek
poly
‘many’ and
pous
‘foot’).

Eventually these polyps form buds that break off into minute adult jellyfish – and the whole process starts all over again.

Reproduction by budding occurs in thousands of species – including sponges, hydras and starfish – and has gone on with few modifications for half a billion years. What makes
Turritopsis nutricula
so special is that it has evolved a skill unmatched, not just by other jellyfish, but by any other living organism.

Once the adult
Turritopsis
have reproduced, they don’t die but transform themselves back into their juvenile polyp state. Their tentacles retract, their bodies shrink, and they sink to the ocean floor to restart the cycle. Their adult cells – even their eggs and sperm – melt into simpler forms of themselves, and the whole organism becomes ‘young’ again.

Newts and salamanders can grow new limbs using this cell reversal process, but no other creature enjoys an entire second childhood. Among laboratory samples, all the adult
Turritopsis
observed, both male and female, regularly undergo this change. And not just once: they can do it over and over again.

So although many
Turritopsis
succumb to predators or to disease, if left to their own devices, they never die. And, because individual specimens haven’t been studied for long enough, we have no idea how old some of them may already be. What we do know is that, in recent years, they have spread out from their original home in the Caribbean to all the oceans of the world, carried in the ballast water discharged by ships.

It’s an extraordinary thought. All other living things on earth are programmed to die. What does the future hold for a species that isn’t?

A life-form in which each individual has the potential to found colony upon colony of fellow immortals …