Will I live longer with more social contact?
More social contact is linked to a longer life, but the effect is far more specific than you might think: the type of contact and your sex make the difference, and quality counts more than quantity.
More social contact is on average linked to a lower chance of dying early. But the picture is more nuanced than the familiar message suggests. Many studies combined showed that people with less social contact had a 13% higher chance of dying than people with more contact. That applied only to women, however, and only to contacts outside the family. For men, and where contact was limited to family members, no clear link was found.
Whether the feeling of loneliness itself shortens your life is less certain than is often assumed. An Israeli long-term study following people aged 70 to 90 for seven years found no link between feeling lonely and dying sooner or declining faster, even after accounting for depression.
What you count as 'social contact' also matters a great deal. People followed for many years showed that most ways of measuring your social network said almost nothing about how long you live. Only the quality of your network, assessed by an outside observer, reliably predicted lifespan. Notably, the feeling of loneliness in men was linked to a higher rate of death from heart and blood vessel disease. That is almost the opposite of what had previously been found in women.
A larger network also has downsides. Research in two hunter-gatherer populations showed that women with a more central position in the network had more living children. But in one of the two groups, that same central position was linked to more illness, probably because of greater exposure to infections.
Finally, the Georgia Centenarian Study found that centenarians with more social resources more often lived independently rather than in a nursing home. Whether this extended their lifespan itself cannot be determined from that study. The effect also depended on which measuring tool was used.
Five studies using long-term follow-up of people over time; no controlled experiments. The findings reflect associations, not cause and effect. Populations, outcomes and measurement methods vary considerably, which makes direct comparison difficult.
Will I live longer if I have a sense of purpose in life?
A strong sense of purpose in life is associated with a lower risk of premature death, but whether the relationship is also causal is not yet known. Still, there is no reason to avoid cultivating a sense of purpose: the association is consistent and robust.
Does having a pet benefit your health and longevity?
A pet can contribute to more physical activity, less loneliness, and a better sense of wellbeing, but whether it also extends your lifespan has not yet been demonstrated. If you are considering a pet primarily for your health, a dog is the best-supported choice, but weigh the practical burdens as well.
Do your eyes age faster than the rest of your body?
The lens of the eye ages noticeably early and quickly, but whether your eyes as a whole age faster than the rest of your body has not been demonstrated. The retina actually reveals a great deal about your overall health, so the two track more closely together than you might think.
Does exercise help with Parkinson's disease?
Exercise demonstrably helps with Parkinson's disease: motor symptoms decrease and quality of life improves. Dance and aquatic exercise have the strongest evidence base; flexibility training offers little benefit. Discuss with your healthcare provider which form best suits your situation.
Do screens and too little outdoor light cause short-sightedness?
Screens are probably not the main culprit; too little time outdoors and academic pressure are better-supported causes. Make sure your child spends enough time outside every day, especially at a young age.
How do I keep my kidneys healthy as I age?
The two best-supported steps to limit kidney damage as you age are keeping your blood pressure under control and exercising regularly. Moderate salt intake and a healthy weight demonstrably contribute to both.