What causes ageing?

It's attractive to think of ageing as the accumulation of damage (like a car or washing machine) at a cellular level (e.g. reactive oxygen species damage). However, there has been a turn away from the idea of death through the accumulation of cell damage due to the lack of experimental evidence that shows any benefits when changes are made to reduce this damage.

Recently, there has been a trend of thought that says simply turning down those pathways associated with growth may make the body work better for longer.

When doing research its useful to look at exceptions to the rule.

For ageing, the Marine Hydra is very interesting as it seems to be immortal (this paper did a statistical analysis of mortality over a 4 year period of a population of marine hydra:

However, a problem with studying them for the purposes of tackling human-related ageing is that you can't make a change to make them live longer.


Studies in comparative ageing (i.e. animals of the same species) on the other hand are very interesting. E.g. worker ants have a lifespan of several weeks but the queen ant can live for years. And there are clams that have similar properties.


One factor in ageing seems to be telomere shortening (ends of chromosomes – the idea is that they get so short that you can't function) however this varies in animals. But flies don't have telomere shortening and still age. Also mice have ridiculously long telomeres and age. More on telomere shortening in this TED talk:

Another factor is diet. Calorie restriction (e.g. a reduced daily calorie intake of 2/3 your normal calories such as around 1600 to 2000 calories for male adults – or a 5:2 diet (i.e. intermittent fasting (aka IF)) where you have 600 calories (or 500 calories for women) for 2 days of the week) can have an impact on life duration and cognitive ability. The NHS has a page on the diet, originally written in Jan 2013 but updated in May 2013, here: Briefly:

Does IF increase life span? This study, whilst a small sample, would indicate it does:

Does IF improve cognitive ability? This study, whilst limited to mice, is also affirmative:

Does IF prevent diseases? This 2007 clinical review on IF (specifically alternate day fasting) indicates it does have a preventative effect on heart disease, type 2 diabetes and cancer in animals but says further studies are necessary for humans:

Aubrey de Grey claims that someone may already be alive today that could live to 1000 due to the bridge to a bridge effect of solving sufficient age-related diseases now to get to the stage where the really difficult age-related diseases are solved. More on him here:

And a Royal Society discussion on “Is Growing Old An Illness” here:


Ageing gracefully


In 1981, Ellen Langer and her Harvard colleagues took two groups of men in their seventies and eighties to an old monastery which was set up to appear as in 1959 with 1950s issues of Life magazine and the Saturday Evening Post, a black-and-white television and a vintage radio.

The first group were asked to pretend they were young men, once again living in the 1950s. The second group, who arrived the next week, were told to stay in the present and simply reminisce about that era.

In studies with colleagues at Yale, Langer had already shown that memory loss—a problem often blamed on aging—could be reversed by giving elderly people more reasons to remember facts; when success was rewarded with small gifts, or when researchers made efforts to create personal relationships with their subjects, elderly memory performance improved.

In another study, she and Yale colleague Judith Rodin found that simply giving nursing-home residents plants to take care of, as well as control over certain decisions—where they would meet guests, what activities to do—not only improved their subjects’ psychological and physical health, but also their longevity: a year and a half later, fewer of those residents had died.

Before and after the experiment, both groups of men took a battery of cognitive and physical tests, and after just one week, there were dramatic positive changes across the board. Both groups were stronger and more flexible. Height, weight, gait, posture, hearing, vision—even their performance on intelligence tests had improved. Their joints were more flexible, their shoulders wider, their fingers not only more agile, but longer and less gnarled by arthritis.

But the men who had acted as if they were actually back in 1959 showed significantly more improvement. Those who had impersonated younger men seemed to have bodies that actually were younger.

More here:

Another amazing story of old age is that of Dr Charles Eugster, a 93 year old bodybuilder.


Work on things that are hard

Tim O’Reilly puts the point eloquently in his talk on why Idealism is the Best Marketing.

With Delacroix’s painting of Jacob wrestling with the Angel in the background he reads Rilke’s poem:

What we fight with is so small, and when we win, it makes us small. What we want is to be defeated, decisively, by successively greater things.

The point being that even if we lose we make the world a better place. So, go out there and find hard problems.


Defaults and Path of Least Resistance

Really interesting point about Defaults and Path of Least Resistance in the Behavioural Economics course from Duke.

People were given a course of branded medication. During the course they were offered generics – the same drug but substantially cheaper. The take up rate was practically 0%. So, it appears people prefer branded medication.

However, if people were told they would not receive any further medication until they made a choice then there is a drastic change. Now, 82% chose generics.

People generally avoid changes, even if they are minor and even when another path is clearly better.

Another case run in a shop selling jams.
One day, it had 6 jams on display and another day it had 24 jams on display. People were given coupons with money-saving offers on the jam.

Unsurprisingly, 60% went to the 24 jam booth – it’s more exciting. And more people were willing to try from this booth.

However, from which booth were people more likely to purchase jam?

The answer? 30% bought from the 6 jam booth, 3% bought from the 24 jam booth.

Why? Some people had jam as their default – it was on their shopping list. So, you see many, you see few, you will buy some jam. However, for many people jam is not on their shopping list. So, it’s not part of the default.

So, what’s the percentage of people having jam on their shopping list (i.e. the Default)? It’s around 3%.

So, how did the 6 jam booth get so much action on jam? People are overwhelmed by choice. The complexity of the 24 jam booth overwhelmed their desire to buy jam.