On The Agent Intellect, the latest from Detroit-based post-punk quartet Protomartyr, singer Joe Casey continually returns to the idea that everything is in a constant state of flux, be it gentrifying hometown watering hole Jumbo's Bar or the human mind.

On The Agent Intellect, the latest from Detroit-based post-punk quartet Protomartyr, singer Joe Casey continually returns to the idea that everything is in a constant state of flux, be it gentrifying hometown watering hole Jumbo's Bar or the human mind.

"Nice thought, and I'm never gonna lose it," the frontman deadpans on "Why Does it Shake?," a song that wrestles, in part, with the impermanence of memory.

Though Casey has gradually come to terms with the concept of transition - "There's no use being sad about it/ What's the point of crying about it?" he counsels on "Pontiac 87" - the singer admitted change has never come easily to him during an early January phone interview from his home in Detroit.

"I have this thing of maybe sticking with something too long," said Casey, who joins his bandmates for a concert at Ace of Cups on Wednesday, Jan. 20. "For instance, I was a Boy Scout until our troop folded. I played Little League when I was in grade school, and usually people move up to the CYO level and stop playing Little League, but I stayed in Little League for a couple more years. By the end I was the best player, but it was because everyone was much younger. I worked at a summer camp until it closed. So it's mostly me trying to talk myself into the idea that change is OK."

This idea, as with everything else in the musician's life, has taken on greater import with each passing year.

"It means a lot more when you break up with somebody and you're my age than if you break up with somebody and you're 22," said Casey, 38. "I was telling someone the other day, when I was in my 20s it was like, 'Oh, someday when I have kids, blah, blah, blah.' I'm at the age now where it's like, 'If I have kids.' 'Oh, when I get married.' Am I going to get married? I have no idea now.

"Before it was always like, 'Sometime in the future these things will happen.' But you get to a certain age and it's like, 'Some of these things might not happen,' or they might have already happened and it fell apart. Without being too morbid about it, there is an extra weight to almost everything."

Rather than moping, Casey and Co. continually mine dark humor and deeply human truths from these heavier transitions, swinging from unexpectedly gorgeous love songs ("Ellen," named for and written about Casey's mother, burns a slow comet trail across the night sky) to wordy, angular diatribes like "I Forgive You," driven by Alex Leonard's machinelike drums and Greg Ahee's relentless guitar chime.

Throughout, the focus remains on the everyday rather than on broad, worldly concepts, and songs are awash in mentions specific to Casey's Detroit, including local business magnate Mike "the Pizza King" Ilitch, Jumbo's Bar and personal injury lawyer and enduring billboard presence Joumana Kayrouz.

"I think everybody knows globally what is annoying and what should be changed, but it's the death of 1,000 cuts. It's the little things that start to add up," Casey said. "Being on the road so much, I'm amazed because every single time I use the bathroom somebody had pissed all over the seat. Have we not taught people how to use the bathroom? What the hell has happened? We already know the upper classes and the global corporations and everything is conspired against us, but it's when a guy pisses on the seat that you know every layer of society is out to get you."

The singer attributes his well-documented gallows humor (see "Tarpeian Rock" from the 2014 album Under Color of Official Right, where Casey updates a growing list of annoyances he'd like to hurl off a cliff, including "gluten fascists," "internet personas" and "adults dressed as children") to some combination of genetics and upbringing. "I don't know if it's a Midwestern thing or a Detroit thing or an Irish-Catholic thing," he said. "It's probably a little bit of everything. That's the way I was baked. Those are the ingredients that went into this."

These are the same ingredients that Casey credits with keeping the Protomartyr mates grounded in the wake of the unexpected success of Under Color of Official Right, which landed on a number of critic's Best Of '14 lists, and increased the sense of expectation as the band entered into recording sessions for The Agent Intellect at Key Club Recording Company in Benton Harbor, Michigan, in February 2015.

Sold-out concerts and critical accolades did little to alter the singer's deeply engrained pessimistic streak, however - "It's my nature to err on the side of being too depressing," he said - and he still approaches band operations with the idea each record or tour could be the group's last.

"Anything can go away at any point, so it's a challenge to try and enjoy the good times as they're happening," Casey said. "I think ultimately that feeling of not being satisfied until it's over will continue, and then you can look back like 'I guess we did accomplish something.' Until then you just keep greasing the wheels and hope things keep moving forward."