You can tell sweeps are over when TV’s IQ rises by about 50 points. Gone are the Rob and Amber wedding specials and “American Idol” exposes. Tonight, both ABC News and PBS offer sobering documentaries about one of America’s nagging social problems: Just who is raising our kids?

Cynthia McFadden hosts a “Primetime Live” (9 p.m., ABC) report on the growing and troubling trend of grandmothers, great-grandmothers and even great-great-grandmothers – some well into their 80s – caring for infants and young children abandoned by parents lost to drugs, prison, street violence and gang warfare.

McFadden reports from Newark, N.J., a city that has often been a bellwether of urban social ills. According to “Primetime,” grandmothers and elderly relatives take care of more than 10 percent of Newark’s youth. Many of these children were born to drug-addicted mothers and suffer from severe physical and emotional handicaps.

And while “Primetime” and McFadden show nothing but appreciation and admiration for the devotions of Newark’s elderly caregivers, many of the women are clearly overwhelmed and no longer fit to raise young children. A scared and emotionally distant woman keeps her grandson as a virtual prisoner. She shuts him away so he doesn’t fall prey to the streets that took his parents and her other children. But his social isolation and need for affection may leave him emotionally scarred for life.

¢ Adam West narrates the three-part series “Ultimate Super Heroes, Ultimate Super Villains, Ultimate Super Vixens” (9 p.m., Bravo). The show will interview more than 50 comic book experts and artists, including George Lucas, Steven Spielberg and Stan Lee.

Tonight’s other highlights

¢ Born Marion Michael Morrison in Iowa on May 26, 1907, John Wayne would be 98 today. Encore Westerns celebrates with a 24-hour movie Duke-a-thon. Check cable listings.

¢ A new look at an activist’s murder on “Cold Case” (7 p.m., CBS).

¢ On back-to-back episodes of “The O.C.” (Fox), Julie’s big day (7 p.m.), Summer’s end (8 p.m.).

¢ The documentary “Slave Catchers, Slave Resisters” (7 p.m., History) looks at the elaborate and organized efforts by 19th-century slaves to escape their masters.