[36.The Benefits of Marriage]
Being sociable looks like a good way
to add years to your life.
Relationships with family, friends, neighbours, even pets,
will all do the trick,
but the biggest longevity boost
seems to come from marriage or an equivalent relationship.
The effect was first noted in 1858 by William Farr,
who wrote that widows and widowers
were at a much higher risk of dying
than their married peers.
Studies since then
suggest that marriage could add
as much as seven years to a man's life
and two to a woman's.
The effect holds for all causes of death,
whether illness, accident or self-harm.
Even if the odds are stacked against you,
marriage can more than compensate.
Linda Waite of the University of Chicago
has found that a married older man with heart disease
can expect to live nearly four years longer
than an unmarried man with a healthy heart.
Likewise, a married man
who smokes more than a pack a day
is likely to live as long as a divorced man
who doesn't smoke.
There's a flip side, however,
as partners are more likely
to become ill or die in the couple of years
following their spouse's death,
and caring for a spouse with mental disorder
can leave you with some of the same severe problems.
Even so, the odds favour marriage.
In a 30-year study of more than 10,000 people,
Nicholas Christakis of Harvard Medical School
describes how all kinds of social networks have similar effects.
So how does it work?
The effects are complex,
affected by socio-economic factors,
health-service provision, emotional support
and other more physiological mechanisms.
For example,
social contact can boost development of the brain and immune system,
leading to better health
and less chance of depression later in life.
People in supportive relationships may handle stress better.
Then there are the psychological benefits of a supportive partner.
A life partner, children and good friends
are all recommended if you aim to live to 100.
The ultimate social network is still being mapped out,
but as Christakis says: "People are interconnected,
so their health is interconnected."