YOLO

YOLO. True. But as we move further into the Anthropocene, we are living much longer than our ancestors did a few thousand years ago. This definitely warrants a few minor diversions:

- a music video 

- 'How Long Will I Live?' a website where you can calculate how many years you have got left

- an insight into the use of the acronym on twitter

Let's get back to life expectancy. My post will talk about the general upward trend of life expectancy, what that means for population and explore reasons why we are living longer.

What's trending?

A trend in the life expectancy of humans during the past thousand years has been characterised by a slow and steady increase. Epidemics, famines and warfare were to blame for frequently upsetting this upward trend with volatile death rates however this curtailed in the mid-19th century. Why? Due to improved living conditions, advances in public health and medical interventions. 

The figures below suggest the changing picture of mortality. It is crystal clear that life expectancy is climbing and projections suggest that this trend will continue to increase. Only 50 years ago, life expectancy was just 68 years of age, now we can expect to live past 79. That's an increase of about 16%. A key indicator of the dramatic change in life expectancy is the growth of people aged over 100 in our society. In terms of centenarians per million, by 2030 estimates predict anything between 515 and 3,500. Now that's a LOT of letters from the queen. 

Figures 1 and 2 use data taken from RMS

We must be careful however when generalising life expectancy across the globe, as it can be different within the same city. Places just a few miles apart geographically have life expectancy spans varying by years. The diagram gives an example of a small area in London along the Jubilee Line. It suggests that men living in Westminster can expect to live at least 4 years longer than those in Canning Town!

Why the upward trend?

The greatest advance of medical science in history has helped to push life expectancy through the roof. Let's break this down and look at the major social changes year by year: 

	Lifestyle	Medical	Health Economics
1950	Two thirds of adults smoke; smoking linked to cancer proved in 1954	Discovery of structure of DNA. Penicillin in mass production	Healthcare insurance offered by US employers. Universal health services set up in Europe
1990	Tobacco companies settle law suit for $206 bn; tobacco advertising banned. Food calorie labelling	Clinical trials prove statins cut heart deaths, 5% of adults take statins by 1998; heart attack mortality rate 80%	Healthcare expenditure averages $2000 per person. Consolidation of drug industry into giant pharmaceutical companies
2010	A quarter of adult population smokes; smoking bans in many countries	Lipitor becomes world’s best-selling drug; stem cell transplants; heart attack mortality rate 40%	Health expenditure 9% of GDP (average $3000 per person)
2030 – What If?	Nobody smokes; obesity wave halted; fitness levels higher than today	Cancer becomes managed disease	20% of GDP spent on medicine

This obsession with longevity feeds into our every day lives. Headlines such as 'sex adds years to your life' this century, have triggered a mad outburst in people searching for activities, foods, diets and wild and wondrous ways to live longer. wikiHow gives you an opportunity to live a very long life just by having a read of this article.  

Shocks to the system?

The last 20 years have seen unprecedented mortality improvement. Medical advances have been fundamental in this undeniable upward trend in life expectancy, however there have been numerous 'mortality shocks' which work against this trend. 

• Asian Flu pandemic 1957/8 kills up to 4 million people worldwide 
• HIV/AIDs emerges in 1980s, reaching 8 million cases by 1990
• SARS emerges as a new infectious disease in 2002
• Terrorist attack 2001 kills 3000
• Avian flu outbreaks from 2006 puts world on pandemic alert

Pandemics are a threat to life expectancy now, but will they always be? Will technological fixes make us immune to pandemics in the future? What type of mortality shocks will gain momentum in years to come? What impact will climate hazards have on life expectancy? The recent Philippines typhoon alone is expected to have claimed approximately 2000 lives. 

The 5 'catastrophe perils' in the diagram below are shocks which have the potential to cause excess mortality in the future. Infectious diseases have featured throughout history, however natural hazards and mass-casualty terrorism are factors which have merely been considered as a threat to life expectancy in the past.

RMS include 'natural hazards' in their life-risk models, a factor which could start to gain momentum. Unprecedented urbanisation to coastal areas (explored in a previous post) means thousands of people are vulnerable to the increasing frequency of climate hazards. Do climate hazards have the capacity to reverse the upward trend of life expectancy? That is the question.