The Hong Kong Hypothesis

Explaining the city with the longest lives.

Trevor Chow

For those who don’t know me, I’m from Hong Kong. I think it’s a great city, and one of the things that confirmed this for me was the fact that life expectancy in Hong Kong was the highest in the world. And so Tyler Cowen posed the question: why is life expectancy so long in Hong Kong, when it isn’t the wealthiest or environmentally friendliest place? I’m not sure myself - but here are a few ideas. I’d love to hear from anyone if they have a better angle on this!

Before we begin, I will note that of the top 5, 4 are reasonably wealthy places that are primarily ethnically East Asian: Hong Kong, Japan, Macao and Singapore. Are there commonalities here? I suspect so - and the hypotheses below regarding Hong Kong will be somewhat applicable to the other 3.

It’s the economy, stupid

Although it is true that Hong Kong doesn’t have the highest per capita GDP in the world, it does rank as 12th in the world and is a comfortably wealthy place. A high level of material living standards means access to nutrition, medicine, shelter and all sorts of useful things. It also means that there is a well-funded healthcare system, which is able to prevent the big traditional killers of childhood mortality, infectious diseases and old-age chronic diseases. Economic prosperity in Hong Kong is driven by a service-based economy, which means that there is a low chance of a high-risk job. But there are plenty of prosperous countries without the commensurate life expectancy, so this can’t be the only factor when it comes to longevity.

The revenge of geography

Is Hong Kong somehow suited in an geographical and environmental sense for maximising lifespans? By and large, it faces few natural disasters - and it has a moderate temperature, which prevents deaths caused by extreme-heat or extreme-cold. It further allows people to walk outside for most if not all of the year, maintaining a level of exercise. However, Hong Kong is quite a polluted city - inevitably, the diminished air quality must have a detrimental effect.

What it lacks in clean air due to being a packed city might be made up for by the benefits of urbanisation. A concentrated urban environment where shops are proximately connected to residential areas via footbridges and open-air escalators, coupled with a well-developed public transport system, affordable taxis and limited parking space, results in citizens spending a lot of time on their feet walking to various places, instead of driving. It also means that people will have opportunities aplenty to buy fresh food and socialise with each other in open-air markets or parks, improving their physical and mental health. Finally, the proximity of most things means that medical attention is available at a moment’s notice - not only does this make visits accessible, it can help reduce mortality rates for time-sensitive issues like strokes and such. Although all of this helps build a clearer picture, Hong Kong ranks well even among cities - so it’s not just the physical setup that determines health.

The rise and fall of institutions

Institutions come in various flavours, and Hong Kong has well-designed cultural and political institutions. The diet in Hong Kong is such that there is lots of steamed foods, seafood and vegetables, while keeping sugar, alcohol and drug consumption fairly low. The prevalence of extended families and the cultural norm of filial piety means large family units, allowing for collective care, respect for elders, reduced financial stress and healthier cooking at home. This is buttressed by the wide availability of communal events, such as mahjong, taichi, qigong calisthenics and various celebrations, providing an avenue for the elderly to exercise and avoid isolation. As for political institutions, the Hong Kong government provides a nearly universal level of access to medical treatment and public education, as well as investing in public health measures like sanitation and clean water. The result is that most people have fairly accommodative environments within which they can live.

Ultimately, I think all of these play a role - I’m planning on posting an update at some point with some preliminary findings based on a bit of exploratory data analysis, but as before, I’d love to hear if people have other suggested factors or good methodological suggestions, like possible instrumental variables or diff-in-diff ideas.