The Second Book of General Ignorance (26 page)

Surprisingly, it is possible for a living person to donate their heart to someone else and survive the experience – provided they get another heart in exchange.

This happens when someone with severe lung disease but a healthy heart is assessed as having a better chance of survival if they receive a heart-and-lung transplant. In return, they can donate their heart to someone who needs only a
heart transplant.

The cardiac surgeon Magdi Yacoub (now Professor Sir Magdi Yacoub) carried out the first of these so-called ‘domino’ transplants in the UK in 1987. We don’t know the patients’ names because they requested no publicity. Later that year a cystic fibrosis sufferer called Clinton House became the first US donor of a living heart. He donated his to John Couch, while he received a new heart and lungs from an unidentified car accident victim.

The first successful transplant of any kind made by a living donor took place in Boston in 1954, when one identical twin brother donated one of his kidneys to the other, both of whose kidneys had failed. In theory, everyone can survive perfectly well on one kidney, one lung, one of the two lobes of the liver and only parts of the pancreas and intestines. The liver, uniquely among such organs, has the capacity to grow back almost completely.

In 1896, the English surgeon Stephen Paget (1855–1926) wrote the standard textbook
Surgery of the Chest
, in which he predicted that it would always be too difficult and dangerous to operate on a human heart. But, later that very year, a German surgeon, Ludwig Rehn (1849–1930), successfully repaired the left chamber of a young man’s heart after he had been stabbed in the chest. It was the first case of a surgeon operating on a heart and the patient surviving, and Rehn didn’t dare try it again. Even in wartime, conventional surgical wisdom stated that shrapnel lodged in the heart should be left there and heart surgery for any reason was almost unheard of before the Second World War.

Things improved rapidly after the war. The South African surgeon Christiaan Barnard (1922–2001) performed the first heart transplant in Cape Town in 1967. Although his patient only lived for eighteen days, two-thirds of transplant patients now survive for more than five years. The longest recorded is Tony Huesman, a sporting goods retailer from Dayton, Ohio who lived for thirty-one years with a transplanted heart until he died of cancer, aged fifty-one, in 2009.

In the UK, these advances have led to a change in the legal definition of death. Until the 1970s, death was considered to have occurred when the heartbeat stopped. After the first heart transplants, death was redefined as the absence of brain function. This gave surgeons the chance to remove a donor heart before it stopped beating.

Thanks to medical science, we do.

Large mammals have slow heartbeats and long lives and small ones have short lives and fast heartbeats. Because of this, no matter what size a mammal is, it has the same average number of heartbeats in a lifetime – about half a billion. This is known as ‘the rate of living hypothesis’ and it applies to all mammals except humans. Improvements in medicine and hygiene have extended our life expectancy so that we now get through more than five times as many heartbeats in a lifetime than all other mammals.

The world’s smallest mammal is the Etruscan shrew (
Suncus etruscus
) of southern Europe, which weighs 2 grams (0.07 ounces) and is 3.5 centimetres (just over an inch) long.

Its heart hammers away at an average 835 beats per minute but it only lives for a year, just enough to allow it to reproduce before being eaten.

At the other end of the scale is the Blue whale (
Balaenoptera
musculus
), which can reach 30 metres (100 feet) long and weigh 150 tons (thirty times more than an African elephant). It has a heart the size of a small car, which thumps out its stately cadence just ten times a minute for eighty years.

The beats-per-life of the two species are remarkably similar: 439 million for the shrew; 421 million for the whale. In contrast, the average human heart, at seventy-two beats per minute spread over sixty-six years, will beat 2.5 billion times.

The US astronaut Neil Armstrong was so taken by the idea of having a finite number of heartbeats that he joked that he was going to give up exercise because he didn’t want to use up his allocation too quickly. But it doesn’t quite work like that: though strenuous exercise makes the heart beat faster in the short term, the resultant fitness
decreases
the heart rate in general.

An even better way to slow the heart rate is to take up yoga. Research conducted over thirty days in 2004 in Bangalore, India, showed that yogic breath control and meditation led to an average reduction in the heart rate of 10.7 beats per minute. The control group, who attempted to reduce their heart rate by other means, didn’t manage any lasting improvement at all.

A macabre experiment to record the effect of fear on the heart rate was conducted in 1938, when convicted murderer John Deering donated his body to science while he still was alive. Sentenced to death by firing squad in Salt Lake City, Utah, he allowed Dr Stephen Besley, the prison doctor, to wire him to an electrocardiograph. Beneath Deering’s calm exterior, Besley recorded his heart rate rocketing from 72 to 120 as he was strapped down, and reaching 180 at the moment of impact. His heart stopped 15.6 seconds later.

Besley commented that, despite having ‘put on a good front’, the machine had confirmed what he’d expected: Deering ‘was scared unto death’.

The one thing ‘everybody’ knows about mayflies is that they only live for a day – but their lifetimes are much longer than that.

Depending on species, the adult lives from less than a day to a week, but this is only the final stage of a much longer life-cycle. Most of the mayfly’s existence is spent as an aquatic nymph, a period lasting from a few months to four years.

There are 2,500 species of mayfly, fifty-one of which live in the UK. They fly all through the summer – not just in May – and they are not actually ‘flies’. True flies belong to the order
Diptera
(Greek for ‘two wings’), whereas mayflies belong to the order
Ephemeroptera
(Greek for ‘short-lived wings’). Mayflies are much older than true flies. They were one of the first flying insects: there are mayfly fossils that are 300 million years old. Their closest relatives are dragonflies and damselflies – neither of which are ‘flies’ either.

Mayflies are unique among insects, in that their final skin-shedding takes place after their wings have formed. On first
emerging from the water, the immature adult, or nymph, moults and becomes a ‘dun’, so-called because of its small, dull-coloured wings. It flies a short distance from its pond, and rests for a while on vegetation. Then it undergoes its ultimate transformation, sloughing its final skin and emerging as the much shinier ‘spinner’.

Adult mayflies never eat: their only interest is sex. Vast swarms of males take to the air simultaneously and the females fly among them to pick a partner. Mating takes place in flight, and as soon as the deed is done, the male drops to the water, dead. The female immediately lays her eggs in the water – and
then
drops dead. One species –
Dolania americana
– dies within five minutes of its final moult. In that tiny window of time, it has to dry its new wings, fly, select a partner, mate, and – if it’s a female – lay its eggs. A day is a long, long time in the life of a mayfly.

In some countries, it’s not only fish that benefit from these huge clouds of protein from the sky. Along the Sepik River in New Guinea, villagers skim masses of post-copulatory mayflies from the surface of the water and cook them in sago pancakes. Apparently, they taste a bit like caviar.

Not butterflies. But most moths do – and so do fleas, bees, worms and spiders.

A cocoon is a kind of silken changing room where a creature metamorphoses into a different stage of its life – such as a spider’s egg into a baby spider or a caterpillar into a moth. The word comes from
kokkos
, Greek for ‘berry’.

Silkworms are not worms but caterpillars. At about a month
old, they spend three days carefully winding a mile-long thread of their own saliva round their bodies that dries into a casing to keep them safe during their transformation into a silkworm moth. Unfortunately for them, it is at this stage that they are picked up by silkworm farmers and shipped off to the factory. It takes 3,000 cocoons to make a pound of silk.

Baby bees develop inside a cocoon made of royal jelly. They eat themselves out of it. Flea larvae become adults inside cocoons. They can remain in that state, buried in your carpet for months, until vibrations caused by movement nearby announce that a host animal is available for them to jump on.

After mating, an earthworm secretes mucus that hardens into a loose girdle around its body. This sheath slowly slides along the worm’s length, collecting eggs and sperm from its genital openings as it goes, finally sliding off its head like a vest, where the ends seal up and it becomes a lemon-shaped cocoon. Inside the cocoon, the eggs and sperm merge into embryos. Spiders, too, place their eggs in a silken sack to hatch. They spin their thickest grade of silk for this purpose. Peasants in Romania use it as an antiseptic wound dressing.

Butterflies don’t make cocoons; instead they form chrysalises (from the Greek for ‘golden sheath’). A cocoon is an external structure, designed to protect the creature within, whereas the chrysalis
is
the creature. The hard exterior of the chrysalis is the final skin of the caterpillar before it becomes a butterfly.

For many centuries butterflies and moths were thought to be completely unrelated to caterpillars. Then in 1679 the German naturalist and illustrator Maria Sibylla Merian (1647–1717) published a book called
The Caterpillar: Marvelous Transformation
and Strange Floral Food
which meticulously detailed the life-cycle and metamorphoses of 186 species of butterflies and moths. Because she published it in German, rather than Latin, it became one of the most talked about science books of the age.

Maria’s organised approach to scientific observation and recording was far ahead of most of her contemporaries. Despite this, her discoveries were used by other scientists to justify the old theory of ‘preformationism’ – the idea that all life was created simultaneously at the beginning of time. They argued that, because the makings of the adult butterfly existed within its pupa form, so Adam and Eve had contained within themselves all the humans who came afterwards, already formed, like a set of smaller and smaller Russian dolls.

No, it’s not ‘soup’ or ‘dribble’ or anything like that. It may surprise you to learn that some amoebae live in houses they design and build themselves.

Amoebae (from Greek
amoibe
, ‘change’) are minute single-celled organisms. No one knows how many countless thousands of different species there are: anywhere that’s damp will provide a home for them – as we know to our cost. The species that causes amoebic dysentery kills over 100,000 people a year and lives in the intestines and livers of 50 million more.

Living beings don’t get much simpler than an amoeba: they’re just an outer membrane full of a watery fluid surrounding a nucleus containing genetic material. They have no fixed shape, but they do have a front and back, and move by squeezing bits of themselves forward in the direction of food. They eat by surrounding smaller bits of algae or bacteria and
absorbing them, and they reproduce by splitting themselves in two.

Which makes it extraordinary that one branch of the amoeba family is able to build themselves portable shelters. They do it by swallowing microscopic granules of sand. Once they have enough on board, they start to glue them together by secreting a form of organic cement. As no one has ever observed this process, we have no idea how they do it.

Each species creates its own distinctive style of home. The des res of
Difflugia coronata
is a globe, with a scalloped entrance at the front, and eight points like the fins of a 1950s spaceship at the back.
Difflugia pyriform
constructs a pear-shaped urn;
Difflugia bacillefera
, a cigar-shaped tube. None of them is bigger than a full-stop.

As with so many domestic arrangements these days, inevitably the time comes to split up. The parent amoeba gets to keep the house; the offspring inherits whatever spare building material is left lying around so it can start knocking up one of its own. How is any of this possible without a brain, or even a nervous system?

In 1757 an Austrian miniature painter and naturalist called Johann Rösel von Rosenhof (1705–59) described and drew an amoeba for the first time. He called it Proteus after the Greek god who could change his shape at will. Since that time, the word ‘amoeba’ has become universal shorthand for something basic or unsophisticated.

Maybe it’s time to revise our ideas. We have recently learnt that the genetic information packed into the single nucleus of
Amoeba proteus
is 200 times greater than our own.

They may be brainless, but you can hardly call an amoeba ‘simple’.