SACRAMENTO, Calif. (AP) — Gov. Jerry Brown has signed a landmark bill adding lessons about gay history to social studies classes in California's public schools.Brown, a Democrat, signed the bill Thursday, making California the first state in the nation to require public schools to include the contributions of gays and lesbians in social studies curriculum.The Democratic-majority Legislature passed the bill last week on a largely party-line vote.The bill has drawn criticism from some churches and conservative groups that argue such instruction would expose students to a subject that some parents find objectionable.Democratic state Sen. Mark Leno of San Francisco, the bill's author, has said that teaching gay history in public schools will teach students to be more accepting of gays and lesbians.