I have recently been looking into the topic of mortality by sex/age groups and have come to some interesting conclusions. The data analysis is based on UK (England and Wales) statistics. I think it should be representative to most developed countries, but I will try to confirm the findings with sources from other countries.Despite the historic increase in human longevity in the 20th century (from less than 40 years to above 70 years in many developed countries) there are still skeptics as to whether we are able to further increase human longevity. An argument is brought forward that most of the increase has been coming from reduced infant mortality and not from extended lifespan. While this has been the case especially for the past two centuries this is not necessarily the case now.
I have looked at the multi-year changes in mortality rates for different age groups and found out that for the most recent 10 year period (1996 to 2006) the group with the highest decrease in mortality rate were the 65-74 year olds – both men and women!
Table 1 Groups with highest improvement in mortality rates:
...............MEN........................................WOMEN
Age group........Change in................Age group.....Change in
........................Mortality rate...............................Mortality rate
65-74...............-3.9%.....................65-74..............-3.3%
1-4...................-3.2%.....................15-19..............-2.7%
55-64...............-3.0%.....................55-64..............-2.3%
75-84...............-2.7%.....................75-84..............-2.0%
15-19...............-2.6%.....................10-14..............-1.8%
Source: UK National Statistics Online, author's calculations
These are annual changes in mortality rates: 65-74 year old men's mortality rate went down from 34.5 per 1000 to 23.2 per 1000 persons in this age group. This represents a drop of 33% over 10 years, or 3.9% annually.As one can see the infants (age <1) are nowhere near the top in decrease in mortality for the past 10 years. The reason probably is that the mortality rate went down to a low level and simple reserves were exhausted in advancing progress further at a fast pace. Also, more resources might have been devoted to combating the diseases of the middle and old age.The spreadsheet with calculations is in the attachment.There are some implications from these findings. Strong and sustained decrease in mortality rates for people in older groups indicate that the life expectancy can be expected to grow healthily for the years to come. The decrease in mortality is substantial at 2-4% and it is accelerating! For the age/sex group I'm most interested in (males 65-74) the annual drop in mortality rate was 1.6% between 1976 and 1986, 2.1% between 1986 and 1996 and 3.9% for the period of 1996 to 2006. Similar pattern exists for males 75-84 (-1.4%, -1.7% and -2.7% for the respective decades) and for women (-1.0%, -1.3%, -3.3% for the ages between 65 and 74 and -1.8%, -1.1% and -2.0% for those aged 75-84).Is Kurzweil's law of accelerating returns applicable to this phenomenon as well?
Let's now spend some time understanding what life expectancy really is. Most will know that it is currently calculated to be around 70-80 years (at birth) with women life expectancy several years longer than men's. So is this really the lifespan that you can expect? In short – no! There are at least 4 factors that may indicate most of us will live longer than the life expectancy for a given country and gender.
1) You have already lived for a couple of decades, and life expectancy at your age is higher than at birth.
2) Life expectancy calculations do not take past progress (scientific, technological) into account.
3) Life expectancy calculations do not take future progress (scientific, technological) into account.
4) You can increase your life expectancy by changing your lifestyle.
Let's look at these points one by one.
1) This is fairly simple and coming from the way life expectancy is calculated. There is some risk of dying even if you are a child. So, if you lived to being 30, 40 or 50 years old this means you have avoided bad luck that sometimes happen to young people or to those in the middle age. As life expectancy is a certain average, you are lucky to be above it and, therefore, your expected life expectancy is higher. For example, in the US in 2004 the life expectancy at birth was 75.2 for males and 80.4 for females, but if you were 50 years old, you could be expected to live to 78.8 years (males) and to 82.7 years (females).
2) While calculating life expectancy the demographers look at mortality rates for different age groups. However, even if all progress – medical, technological, scientific stopped as of today, you could reasonably expect to live longer than the calculated life expectancy. How's that possible?
Let's assume that among people that died within the last year there are some unlucky souls that were exposed to asbestos during their lives. This exposure has negatively impacted health during their lifetimes, shortening their lifespan. Therefore we can expect to live longer than them, as our health would not be compromised. Or, within the group that has died there is a person who suffered from an illness that could have been cured if a therapy for it was available just a year earlier. It wasn't, so the condition of this person passed point of no return and, unfortunately, he or she was doomed to die. We will be spared this fate, as the cure is already available for all of us to use at the early stages of illness.
3) Obviously life expectancy doesn't take future progress into account. The impact of future discoveries and inventions is impossible to quantify in detail, so only some approximations can be made. But, up to now progress has been leading to extended human lifespan and, barring a global catastrophe, we can expect this trend to continue.
4) This point is also rather obvious and widely discussed. Quitting smoking, drinking alcohol in moderation, avoiding drugs and other risky behavior, exercising more and many other changes in behavior have been shown to have positive impact on health and longevity.
So, taking it all together – what can be my life expectancy? The fact that I have already lived to 35 adds 2 years to life expectancy at birth. I have seen no data concerning the impact of past progress on life expectancy, but I do not believe it will be more than a year or two. Changing one's behavior can have a tremendous impact on life expectancy – it can increase your lifespan by 10 or even 15 years. However, I do not smoke, don't eat fast foods, don't take drugs, have an optimal weight (or, maybe, 2-3 kilos too much;) ), etc. I could exercise a bit more (who couldn't?) and eat a bit less of sweets, but otherwise there's little I could do to improve my longevity. Yes, I do drink a lot of green tea and eat a lot of low-mercury fish, so this out of To-Do list as well.
So my bet must be on future progress – as most of us here concluded long time ago. I do not know how much we can add, but I do think I can achieve Longevity Escape Velocity and cancel the appointment with the Grim Reaper!
Maciek Kolodziejczyk
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Mortality.xls 27KB
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