Over the centuries, the most common causes of death have changed dramatically. What are we most often dying from now and how could that change in the future?
Biochemistry professor Andrew Doig put four decades of research into his new book This Mortal Coil: A History of Death.
Photo: Marcus Ganahl / Unsplash
Doig tells Kathryn Ryan he presumed the history of death would be largely a story about the evolution of medicine but it turned out good governance and innovations in other fields have just as much influence on how we die.
It was engineers who first designed systems for clean water which is, with hand-washing, one of the most powerful ways in which we can help eliminate infectious disease, Doig says.
Doctors and nurses not washing their hands was a big reason so many women who gave birth in the maternity hospitals picked up deadly bacterial infections known as childbirth fever.
Infectious diseases will always come and go, he says - "Covid is a blip" - but in the last century, smallpox, typhoid and measles have faded as leading causes of death.
Famine is killing much fewer people, too - probably the lowest percentage of people than ever before in history.
Deaths by famine now aren't simply the result of food scarcity, Doig says, politics is to blame.
"Even though there are 7 billion people [on Earth], we can feed the world, we have got enough food out there… where we do have famines it's due to the failures of politicians, it's due to wars and misgovernance.
"We have famine at the moment in places like Sudan - civil war, Yemen - civil war, North Korea - the world's worst government."
Back in 1315, no governor could assist when one of the worst famines in history struck Europe.
"At the time, if you had a bad harvest [but] you had a decent ruler… a king, probably… he could try to go to a neighbouring country and say 'can you help us out, we've had a bad harvest?' but in 1315 everyone from Ireland to Russia was having that.
"Starving people go to extreme measures … if somebody was being hanged, people would hang out and pounce on the body and they would eat it afterwards… people would murder each other for any kind of food."
Hans Christian Andersen's story of Hansel and Gretel - in which a brother and sister abandoned by their father are kidnapped by an old woman who wants to eat them - is thought to have been based on the shocking reality of that time, Doig says.
"People were abandoning their children because they couldn't afford to feed them anymore and children were getting eaten."
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What now kills Westerners in far greater numbers than cannibalism are so-called lifestyle diseases, he says.
As life expectancy jumped up from 50 to over 80 in "rich countries like New Zealand", heart disease, stroke, cancer and dementia are the most common causes of death.
Nowadays, medical scientists are "getting a good grip" on treating cardiovascular disease and improving cancer treatment but dementia is taking more and more lives, particularly in women.
Dementia rates will continue to grow and a cure would be one of the "revolutions in science" required to slow down its escalation, Doig says.
He predicts genetic sequencing technology will play a role in the decades to come.
"Everyone's DNA is going to be sequenced so we can understand why people are different, how they respond to diseases in different ways and we can look at the best drug for a particular person depending on their DNA.
"[We will have a lot of] data on bodies we can use for diagnosing things like cancer at the molecular level before we have symptoms."
Organ transplants will also look very different in the future, Doig says.
"Instead of waiting for a donor, we'll get skin cells and turn them into stem cells and then we'll grow replacement organs for our own bodies… the organs will be genetically the same as us so they won't be rejected by our bodies."
