John Perry Barlow

SAN FRANCISCO (AP) - John Perry Barlow, an internet activist and lyricist for the Grateful Dead, has died.

The digital-rights group Electronic Frontier Foundation said Barlow died early Wednesday in his sleep at home in San Francisco. He was 70. The cause of death was not immediately known.

Barlow co-founded the EFF in 1990 to champion free expression and privacy online. In a 1996 manifesto, the "Declaration of the Independence of Cyberspace," he argued that the U.S. and other governments shouldn't impose their sovereignty on the "global social space we are building."

"He always saw the internet as a fundamental place of freedom, where voices long silenced can find an audience and people can connect with others regardless of physical distance," Cindy Cohn, the EFF's executive director, said in a statement.

Barlow was born in rural Sublette County, Wyoming, in 1947 and grew up in Pinedale, where his parents were ranchers.

Barlow has said he grew up as a devout Mormon before leaping into the counterculture of the 1960s. He befriended Bob Weir, one of the Grateful Dead's founding members, when they were boarding school classmates at the Fountain Valley School in Colorado. Barlow graduated from Wesleyan University in 1969.

He later returned to Wyoming, where he ran a cattle ranch for nearly two decades and dabbled in Republican politics. He had been battling a variety of debilitating illnesses since 2015, according to supporters who organized a benefit concert for him in October.

Barlow co-wrote several songs for the Grateful Dead with Weir, including "Mexicali Blues," Black Throated Wind," Bombs Away," Heaven Help the Fool," Cassidy," I Need a Miracle," Lazy Lightnin'," Looks Like Rain," Lost Sailor," Money Money," My Brother Esau," Feel Like a Stranger," Saint of Circumstance," Supplication" and "This Time Forever." With keyboardist Brent Mydland, Barlow wrote "Blow Away," Just a Little Light" and "We Can Run." He also wrote songs for String Cheese Incident and Burning Spear.

"John had a way of taking life's most difficult things and framing them as challenges, therefore adventures," Weir said in an online post Wednesday. "He was to be admired for that, even emulated. He'll live on in the songs we wrote."

His survivors include three daughters and a granddaughter.