It is an awful, uncomfortable yet indisputable truth that we, as societies and individuals, often treat differently those who look or love or sound or worship differently than we do. We don't always become suspicious, but too often we do. We don't always feel threatened, but too often we do. We don't always respond with violence, but too often we do.

Sometimes these contrasts come purely from hatred. We need only tune into the news to be bombarded with plenty of examples. But humans are complicated, and often the reasons for their actions are complicated, too. Not necessarily more justifiable, just less tidy, less easily dismissed.

Karen Jennings' "An Island" probes the roots of why we treat others with such reductive inhumanity, even at times against our rational intentions or interests. The novel, which was long-listed for the 2021 Booker Prize, is set in a fictional African country — Jennings is South African — whose past includes periods of colonization, independence, dictatorship and popular uprising, periods that stoke division, fear and aggression.

This history is outlined through the recollections of Samuel, a septuagenarian lighthouse keeper who lives alone on an island. During the 23 years he's held his position, he has never returned to the mainland, interacting only with the men from the supply boat every couple of weeks. Samuel sought the job shortly after being released from prison, where he was held for more than two decades, during which he was isolated as a known informant.

When the novel opens, a body has washed ashore, but unlike the others that have done so during his stint on the island, this one is not a corpse. Samuel has company. The two men, who don't share a common language, must coexist. And Samuel must confront who he has become in the face of "These memories, these memories, hunting him down, taking possession of him."

Colonizers drove Samuel's family out of the "green and warm" valley where he grew up. In the city his family lived on the streets, where he and his sister begged for scraps. As a teen, Samuel was not interested in the independence movement that enticed his father, and instead "loitering became his daily habit." Rarely does Samuel become an active participant in any event, content to observe, to react and to be acted upon. When he counters his inclinations, he finds only shame or worse.

Much of the story reads like an allegory, but Jennings, despite her insight, never implies that Samuel's actions are generalizable to a nation. This is simply how isolation, humiliation and disappointment at the hands of friends, family and institutions crafted one man.

Samuel is resilient, too, but not in an up-by-your-bootstraps way familiar to U.S. audiences, though he aspires to that at times: "Who didn't want to be more than they were, who didn't want to rise up out of the dirt and be something?" But those memories haunting him won't let him rise up, and when you have been alone for so long, sometimes memories are your only guide.

Cory Oldweiler is a freelance writer.

An Island

By: Karen Jennings.

Publisher: Hogarth, 224 pages, $25.