Looks like Taylor Swift is taking her hair evolution back to her roots.

The 26-year-old singer has been leaving her hair in curls lately, a look that has us reminiscing about when she first burst onto the scene in 2006. Of course, Swift's hair is now a much shorter bob instead of her longer ringlets, though it's safe to say she's still looking fantastic in the more mature style. Swift hit the gym in New York City on Monday, looking fresh in minimal makeup and an artfully messy hairstyle.

PICS: Taylor Swift's 'Hair-Story': From Curly to Chic

Swift also sported the new look over the weekend at a birthday party for her bestie, Karlie Kloss, and oil heir pal Mike Hess in the Hamptons. The "Shake It Off" singer looked happy and relaxed during an impromptu duet with Nelly -- when the rapper brought her up onstage to sing Kelly Rowland's part in his 2002 hit "Dilemma" -- showing off her flat abs in an off-the-shoulder crop top, a matching black skirt and comfy white sneakers.

Swift's been rocking a variety of different looks lately, from bleach blond to back to an ashy blond after splitting from Calvin Harris in June. Still, she's kept it primarily pretty straight for a while now.

... Perhaps she's been influenced by her best pals, Selena Gomez and Gigi Hadid? Just last week, 24-year-old Gomez debuted her voluminous new curls during her Revival tour stop in Kuala Lumpur, Malaysia.

And last month, 21-year-old Gigi showed off her perfect ringlets with her Instagram followers.

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Watch the video below for more on Swift's cute duet with Nelly!

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Taylor Swift's 'Hair-story': From Curly to Chic!