LONDON (AP) — Literary biographies vie with explorations of extremism, slavery and European wolves on the shortlist for Britain’s leading nonfiction book prize.

The six finalists announced Thursday for the 50,000 pound ($67,000) Baillie Gifford Prize include “The Boundless Deep,” a biography of poet Alfred, Lord Tennyson by Richard Holmes, Frances Wilson’s “Electric Spark,” about Scottish writer Muriel Spark, and acclaimed Australian writer Helen Garner’s diaries, “How to End a Story.”

Also in the running are Jason Burke’s book about 1970s anti-capitalist militants, “The Revolutionists”; Justin Marozzi’s history of slavery in the Muslim world, “Captives and Companions”; and Adam Weymouth’s “Lone Wolf,” which traces a wolf’s 1,000-mile (1,600-kilometer) journey across the Alps in search of a mate.

Journalist Robbie Millen, who is chairing the prize jury, said the six books displayed “candor and courage” in exploring “formidable female novelists, ghastly literary men, a faith-shaken poet, eunuchs, pirates, horny wolves (and) international terrorists.”

The winner will be announced Nov. 4 at a ceremony in London.

Founded in 1999, the prize recognizes English-language books in current affairs, history, politics, science, sport, travel, biography, autobiography and the arts. It has been credited with bringing an eclectic slate of fact-based books to a wider audience.