Christian O'Hara thinks endlessly about bullets.
The 11-year-old says that when he hears gunshots in Fairhill, North Philadelphia, he feels painful pressure in his belly. "And," the soulful, dark-haired boy adds, "I know if a bullet hits me, it will feel worse than my stomach does.
"I feel stressed and scared, always. It needs to stop."
His life depends on it.
Children born today can expect to live only to an estimated average age of 71 in Fairhill, part of what outsiders call the Badlands, a study released earlier this month predicts.
It's the poorest community in America's poorest big city. And life expectancy there isn't as high as it is in Syria and Iraq (both over 74 years), research by the CIA shows. Overall U.S. life expectancy is 79 years.
Life is shorter still in the North Strawberry Mansion/Swampoodle area, Philadelphia's most violent place. On average, a child born there today couldn't count on living beyond age 68.
But five miles south, in Society Hill and Old City, newborns today in the city's most prosperous zip code could expect to see the year 2104, 88 years from now. That, the World Health Organization says, exceeds life expectancy in Japan by four years, the country where people live longest.
In a city of stunning inequality, neighborhood becomes destiny. Dan Taylor, a pediatrician at St. Christopher's Hospital for Children in North Philadelphia, says his work proves that daily:
"Health has a lot less to do with your genetic code and a lot more to do with your zip code."
While it may be of little surprise that life in a leafy locale lasts longer than in the distressed precincts of North Philadelphia, the 20-year life-expectancy gap still startles.
"People are taken aback by it," says Derek Chapman, associate director of research for Virginia Commonwealth University's Center on Society and Health. Chapman was the principal investigator on the study, supported by the Robert Wood Johnson Foundation.
"Where you live really impacts your health."
The pressures of life in North Philadelphia assail body and brain, releasing stress hormones in children as damaging, some experts say, as lead in the water.
Battered residents weather toxic squalls of bad times, and live in an adrenalized, near-constant state of disaster readiness akin to that of ancients compelled to scout the camp perimeter for lions, researchers say.
Over the years, that tension ravages skin, sickens organs, stunts brain growth, and hastens ambulance rides to crowded hospitals for heart disease, diabetes, and more.
In shorter-life communities, smoking is common while broccoli is not.
Meanwhile, homicides and overdoses linked to the active drug trade fill funeral homes. Even children untouched by bullets pay a price: Kids who live in an area where homicides are committed have lower reading and verbal test scores, social scientists say.
"It all adds up to stress," says Mel Wells, president of One Day at a Time, a Strawberry Mansion agency that helps people with addictions and HIV. "Our kids grow up depressed. This area is a walking, living nightmare."
Ever-anxious Christian O'Hara would agree: "Here, there's just too much to worry about."
Tucked into a quiet Society Hill street is Little Angels Learning Center Academy, a child-care and education center. It sits blocks from where America was born, itself aging well.
In a darkened room, hovering caregivers eye sleeping infants, their projected 88-year lives beginning with burps and yawns in a safe and pretty place.
It's Fairy Tale Week here, and the older children hear stories about magical kingdoms where dreams come true.
"This neighborhood is a breath of fresh air," says Anna Marie Kambouris, the center's assistant director. "People in the parks that we take the kids to are smiling."
In Society Hill/Old City, there's a veneration of old times that compels people to live like folks did 100 years ago, says Stephen Klasko, president and CEO of Thomas Jefferson University, and an area resident.
"My wife and I transport ourselves that way - walking, biking, running, and rarely using our car," Klasko, 62, says. "It's so much healthier."
Good food is close by, he says, with expensive but salubrious choices that can prolong life.
As a doctor, Klasko is aware that this is a privileged enclave with wholesome options, the virtual antithesis of North Philadelphia. "If you grow up in a place where you worry about getting shot," he says, "you're less concerned about what you're eating for breakfast."
That perspective isn't lost on Society Hill resident Sara Caselle, 37, a Philadelphia schoolteacher who has two children, ages 10 and 5, in Little Angels' after-school program.
"We're not watching over our shoulders here," she said. "We pay a lot to live here so our kids won't have to worry."
What would it take to lengthen North Philly life?
The city has already tried, lowering the obesity rate by 6 percent between 2006 and 2013 in 5- to 18-year-olds in people of color, Chapman says. It's also expanded bike lanes, and made corner stores healthier.
Little things can help. At Penn, epidemiologists cleaned and greened vacant lots in poor areas, and residents reported feeling less stress.
Experts say the city needs higher wages and more buy-in from corporations. That's a problem, according to Don Hinkle-Brown, president and CEO of the Reinvestment Fund, which uses investment strategies to revitalize neighborhoods.
"The Philadelphia corporate sector has been disengaged," he says. "It's so easily within its means to contribute more" to poor areas, but it doesn't. Plus, the city suffers from the exodus of middle-class jobs that aid the suburbs to Philadelphia's detriment, he says, adding, "Places like Conshohocken shouldn't even exist."
Meanwhile, in Fairhill, the hard life grinds on. Aisha Morales, 12, a classmate of Christian O'Hara's at Julia De Burgos Elementary School, says she fears for the lives of her siblings, ages 6 and 4.
Aisha and Christian are among a group of kids being helped by nearby Providence Center, a nonprofit that builds social skills. Aisha remembers being in lockdown at the school last fall five times in seven weeks because of nonfatal shootings.
"It's too much stress," Aisha says. If a bullet were to hit her siblings, "It's going to have me thinking it's my fault."
Kids always speak that way, says Maura Bernt, director of youth programs for Providence: "I can't think of a student not dealing with trauma."
That worry can't lead to a long life. And even a child understands that.
"I would move to a calmer place if I could," Aisha says. "Here, it's just too much to handle."