Wednesday, September 23, 2009

The Folly of our Times (Part Two)

This is a continuation of the themes from this previous post.

Of all the incredible things that humans have accomplished, our ability to think rationally and consistently about an uncertain and unpredictable long-term future is not one of our strongest attributes. For the vast majority of human history we had a short life expectancy (under 30 years) and thus the cognitive capacities we have inherited from our Darwinian past reflect the reality that, historically, it was much more important to think clearly about short-term goals (like finding food and a mate) than the complex long-term goals facing societies in the 21st century.

This situation thus creates a real pickle for us once we attempt to tackle very complex, long-term challenges.

Perhaps one of the sagest insights from the history of moral philosophy, which can help us out in such cases, is Jeremy Bentham's "calculus of happiness" (see my previous posts on Bentham here and here). Today I don't want to invoke all of Bentham's calculus, but just 3 important components of rational, long-term priority setting.

(1) We have to come up with some criteria for determining what makes an issue a "BIG" issue. So let's say that "harm", generally construed, helps determine the magnitude of a particular problem. So harm could be disease, death, poverty, etc.

If the harm of A is 10 times larger than the harm of B (say A =10 cancer deaths and B= 1 cancer death), then (all else being equal) A is a much bigger problem than B. Or if the probability of X occurring is only 0.0001% and the probability of Y occurring is 50% then, even if the magnitude of Y is half that of X, Y is a much bigger problem as the expected disutility of Y outweighs that of X. This provides us with a "rule of thumb" by which we can determine what the biggest problems are: the larger and more probable the harm in question, all else being equal, the stronger the imperative to mitigate it (i.e. the higher up on the list of priorities it should be).

(2) Once we have come up with the list of "The Biggest Problems", that is only have the battle. A big problem that you cannot do much about is not a problem worth worrying about too much. So the other important issue to bear in mind when thinking about priorities is the likelihood of success. All else being equal, the greater the chances are that you can actually mitigate the harms in question the greater the case for making the issue in question a higher priority. So if the harms of Y outweigh the harms of X on both the magnitude and certainty criteria, but you can't do anything about Y but could do something about X, it would be irrational to prioritize Y over X.

(3) You must also consider the cost trying to realize the benefits of the intervention in question. Spending all available resources on trying to mitigate the harms of X means you have no funds left for tackling Y and Z and Z'. But if the good realized in mitigating Y, Z and Z' are larger than the good realized in X, it would have been more prudent to tackle less major harms (but more of them) for lower cost.

These three issues- (1) the magnitude and certainty of the harm in question, (2) the probability of a successful intervention and (3) the cost of the intervention- ought to be the central considerations at play in determining societal priorities.

Of course the devil is in the details. It is notoriously difficult to estimate what the long-term consequences of something might be. And there are issues of discounting: do we give equal weight to the interests of those alive now and those that will follow us in a century or millenia from now?

When I reflect upon the issues of what constitutes a harm for humans (as both individuals and collectively as a society), and what it may be possible to do this century if we invest in certain areas of knowledge and innovation, one particular issue stands out far above the rest--- global aging. Why not climate change, the threat of terrorism or an asteroid hitting the planet, you ask? Let me tell you why (though I'll only focus on climate change as that dominates the news today).

(1) First let's take stock of the harms of biological aging. The inborn aging process is the leading cause of disease and death today. But to see that we need to focus on the ultimate (rather than proximate) causes of disease and death. Disease and death are bad for an individual as they jeopardize or remove the opportunities for flourishing. Disease and death are also bad for societies. Dramatic rises in chronic diseases like cancer, heart disease and stroke present enormous challenges to the economic prosperity of a country.

So the magnitude of the harms of senescence are unprecedented in human history (in terms of the number of people negatively affected by it).

Furthermore, these harms are a 100% certainty if we do not modify the aging process. We don't need computer models to accurately predict that middle aged people today will age and become frail. Unless an infectious disease comes along and kills today's young and middle aged, they will live to be tomorrow's aged persons and they will suffer the same chronic diseases of late life that killed their parents.

Contrast this with the magnitude and certainty of the harms of climate change. The climate is of course always changing. But unlike biological aging, that leads to an exponential increase in risk of morbidity and mortality, when the climate warms or cools a few degrees it brings a complex mix of harms and benefits. Warmer temperatures could boost agricultural production in certain regions of the world (like Russia), but harm agricultural production in other areas. With respect to infectious diseases like malaria (see here), warmer temperatures will result in lower risk of malaria for some areas as temperature fluctuation around means >21°C slows parasite development, whereas fluctuation around <21°C speeds development. So changes in climate are not "unconditionally" good or bad. There are some good things for some people, and some bad things for others. And it is immensely difficult to anticipate what any of these will be 50 or 100 years from now.

And observing temperatures is not like observing biological changes in a mammal. We can accurately predict what will happen to most humans after the age of 80 (they will become more frail and suffer one of the diseases of aging and most likely die before age 100). But the climate? Predictions are on much, much more precarious grounds. Even though we still have a lot to learn about human biology, we are light years ahead in our understanding of human biology than we are with understanding what influences global temperature (humans are complex, but the not as complex as all of the external enviroment). There is no climate science equivalent to Darwin's Origins of the Species that was published over 150 years ago and has withstood more than a century of rigorous scientific testing. So climate science is an infantile science. To say that is simply to state a fact (so critics who claim it is "anti-scientific" don't understand what science actually is). The main reason climate science enjoys the popularity and influence it now enjoys is because it has become policitized. It is not because of major scientific breakthroughs in our knowledge of the workings of the climate.

This is not to say there are no important issues worth investigating here and that these insights shouldn't inform policy. I believe there are. But the confidence many have in the magnitude and certainty of the potential harms in question are unfounded and are simply scare tactics that, like the "war on terrorism", people use to persuade people to accept when they have little else to invoke. Taken in the abstract, the harms of climate change might appear enormous and probable. But when placed in the context of all the other things that can occur this century, they are less prominent and concerning.

But perhaps the greatest contrast between prioritizing the effort to retard global aging rather than global warming concerns criteria (2) and (3) noted above. Let's start with (2). Is there reason to believe we could retard aging, thereby increasing the human healthspan and compressing morbidity and mortality at the end of life? Yes. Since the 1930's we have known that calorie restriction extends the lifespan of a variety of different organisms (e.g. yeast, fruit flies,), including mammals. More recently "longevity genes" had been identified. And the first human clinical trials involving anti-aging molecules are already under way.

How many experiments have we done to see if humans can control global temperatures? 0.

Now consider (3). How much would it cost to make serious headway on aging? Proponents of the "Longevity Dividend" campaign recommend a $3 billion investment. Slowing aging by just 7 years would reduce the risk of disability, disease and death by 50% at every age in adulthood. Whereas the Stern Report recommends spending 1% of global GDP each year to reduce greenhouse gas emissions. Looking up the global GDP for the year 2008, that would put the investment for 2008 at $600 billion dollars. And this would of course rise over the next two decades as the global GDP rises. So advocates of tackling climate change are proposing we (including poor countries, I might add) spend much, much more money trying to mitigate smaller and less certain (and immediate) harms that are premised on a more imcomplete observational science. Such a project would amount to the most expensive scientific experiment in human history. And it would be the first time any such "climate experiment" would be pursued.

So the way I see it, we face a choice. Those that want to create the greatest good for those alive today and those to come in the future can champion one of two causes as the defining cause of our times:

Cause #1 Slowing global aging
Cause #2 Slowing or reversing climate change

The certainty and magnitude of the harms of permitting the status quo with respect to aging far outweigh what will occur with respect to climate change. Secondly, as both an observational and experimental science, biogerontology is much, much further advanced than climate science. And so the likelihood of the benefits of doing something about #1 is much higher than #2. And the magnitude of the potential benefits are also much higher. And finally, in terms of cost-- reprogramming the human metabolism via a drug that mimics the effects of CR will cost a lot less than aspiring to control the climate.

So the real debate we need to have today is this: Which cause ought to be the greater priority- decelerating human aging or trying to control global temperatures. For me at least, the choice is clear.