Humans are social animals. That means that our friendships, family, and other social networks are not just pleasures; they're also essential to our survival. New research presented at the 125th Annual Convention of the American Psychological Association finds that loneliness and isolation may be bigger public health issues than previously realized.

"Being connected to others socially is widely considered a fundamental human need—crucial to both well-being and survival," psychologist Julianne Holt-Lunstad of Brigham Young University said in a statement.

"Extreme examples show infants in custodial care who lack human contact fail to thrive and often die, and indeed, social isolation or solitary confinement has been used as a form of punishment."

A 2010 AARP study of adults aged 45 and up found that more than one-third of respondents felt lonely, and that loneliness and poor health went hand in hand.

To quantify the impact of loneliness and isolation, Holt-Lunstad conducted two separate meta-analyses of the scientific literature, reviewing a total of 218 studies. Her first analysis found that higher social connectedness is linked to as much as a 50 percent decrease in risk of early death.

The second, which included data from more than 3.4 million people in North America, Europe, Asia, and Australia, suggests that social isolation, loneliness, and living alone can be as bad for a person's health as other common risks. (The AARP study also concluded that prolonged isolation carries the same health risks as smoking 15 cigarettes per day.)

"There is robust evidence that social isolation and loneliness significantly increase risk for premature mortality, and the magnitude of the risk exceeds that of many leading health indicators," Holt-Lunstad said.

"With an increasing aging population, the effect on public health is only anticipated to increase. Indeed, many nations around the world now suggest we are facing a 'loneliness epidemic.' The challenge we face now is what can be done about it."

To combat loneliness, experts recommend strengthening existing relationships, scheduling regular phone dates with friends, and signing up to volunteer or otherwise help build community.

Carla Perissinotto is a geriatrician and researcher at the University of California, San Francisco. "Maintaining connections, that touchy-feely thing, is actually really important," she told NPR. "It's hard to measure, it's hard to quantify, but there is something real."