Announcing the shortlist, Alex Farquharson, Tate Britain's director, says: "The upper age limit originally helped the prize define itself as an award for a breakthrough moment in a more emerging artist's career".
Pethick said: "I think we are living in serious times and we felt this needed to be reflected in this years shortlist".
Finalists announced Wednesday are British painter Hurvin Anderson, whose images often draw on his Caribbean heritage; Lubaina Himid, one of the U.K.'s leading black female artists; German-born multidisciplinary artist Andrea Buttner; and Palestinian-English artist Rosalind Nashashibi, whose work includes the film "Electric Gaza".
Himid, 62, makes paintings, prints, drawings and installations that celebrate black creativity and challenge institutional invisibility.
She has been shortlisted for two paintings, Invisible Strategies and Navigation Charts, as well as her participation in the group exhibition The Place Is Here.
Himid claims the Guardian, "no doubt in the interests of good design and witty narrative", uses black people in a subtle way, "which could be said to undermine their identity". In the 1990s, it became dominated by the Young British Artists (YBAs) such as Damien Hirst and Anish Kapoor, and memorably made headlines for Tracey Emin's My Bed, which was nominated in 1999. They said her work was both "visually arresting and critical".
Anothr black British artist recognised after the rule change is 52-year-old Hurvin Anderson. He is shortlisted for solo exhibitions at the New Art Exchange in Nottingham and the Art Gallery of Ontario, Canada.
Tate Britain said that "the jury was impressed by the depth and maturity of Nashashibi's work, which often examines sites of human occupation and the coded relationships that occur within those spaces - whether a family home or garden, a ship or the Gaza Strip".
The Turner Prize judges praised her for "addressing pertinent questions of personal and political identity".
The fourth artist is Stuttgart-born Andrea Büttner, 45, who lives and works in London and Berlin. "They show how the intimate and everyday collide with issues of surveillance and control".
The jury chose Buttner because of her unique approach to collaboration and her exploration of religion, morality and ethics, articulated through a wide range of media including printmaking, sculpture, video and painting.
William Hill bookmakers have deemed Himid the 6/4 favourite to win and Büttner a 4/1 outsider.
The four artists' work will be displayed in an exhibition at the Ferens Art Gallery in Hull as part of the UK City of Culture celebrations from September 26 2017 until January 7 2018.