You might think a guy with a master’s degree in biology and a built-in future in science would be an unlikely candidate to head down the creative and uncertain singer-songwriter path. But Mark Erelli says it’s really not a far-fetched stretch. And as his songs gather increasing critical support, and tunes from his second CD “Compass & Companion” are added to more radio playlists, who’s to say he’s wrong? For Erelli, there are parallels between science and art, whether you wear a lab coat or strap on an acoustic guitar. “It [success] requires … a lot of luck. You have to be creative, be persistent and have wide-open eyes. You also have to know who’s before you and what’s been done,” the 26-year-old folk-scene newcomer explains by phone from his western Massachusetts home. “It never struck me as odd as it did a lot of people.” In fact, his musical aspirations struck him as such a natural that Erelli had his song-writing future well planned even as he headed off to grad school at the University of Massachusetts at Amherst in 1997. He’d already fallen deeply under the blues spell of guitarist Chris Smither in high school. During his years at Bates College in Maine, Erelli had started writing songs, polishing them in the dorm stairwell. Friends encouraged him, and with a borrowed guitar, he started playing the local coffeehouses. “People like totally reacted,” Erelli remembers. “I figured I should buy a guitar.” Heading off to grad school with guitar and songs in hand, Erelli told his adviser he could both study his course load and push his music. Touring the Northeast on weekends, Erelli found fans that took to his urgent baritone and honest heart songs. Soon the small but respected label Signature signed him, and his first CD was released two weeks before he finished graduate school. To top off this burgeoning good fortune, Erelli was also accepted to compete at the prestigious Kerrville Folk Festival in Texas immediately after his 1999 graduation. “I defended my thesis … finished my revisions and left [for Kerrville],” Erelli laughs. Much to his pleasure, Erelli took first in the new-folk category at the festival. He returned to Massachusetts and entered the music world full time. In the ensuing short two years, the young writer has found critical acceptance that draws on both luck and undeniable talent. His CD, “Compass & Companion,” includes one tune featuring Kelly Willis, which should bring him wider recognition. This young performer may not have years of experience under the belt, but his deft touch with words belies youth and vouches for estimable talent. As Erelli prepares for a short tour that includes a stop in Richmond Saturday with accompanying guitarist Kevin Barry, he acknowledges he’s had a crash course in making a living on the road. But he sounds like a fellow who has the gig figured out. “Everyone wants a kind of angle,” Erelli says of songwriters who often rely on hard times for inspiration. “I finally just realized that’s not the issue. The issue is communicating with people.”