It's only a recent development, but for the first time, rap doesn't seem so scared of age anymore. Maybe it's because the genre itself hasn't even been around for four decades, but as hip-hop's lifespan grows, so does its tolerance for older rappers.

There was a time when turning 30 pushed MCs into "old man" territory, but that's changed. As evidenced by our list of the best rappers in their 30s, many of the most popular hip-hop artists of the moment fall into that category. Instead, it's the age of 40 at which a rapper is now considered "old."

What's most remarkable is that, these days, so many MCs remain relevant well into their 40s. Jay-Z got his first No. 1 song at 40. Raekwon is doing songs with Justin Bieber, and he's 42.

To commemorate Eminem's 40th birthday, which fell yesterday, we're taking a look at other rappers who, like him, are still killing it. The list's rank and selection are wholly dependent on relevance at this very moment. That means legends like KRS-One and Rakim, bosses like Birdman, and guys who don't dabble in rap much anymore, like Ice Cube, aren't included.

Read on for our breakdown of The 15 Best Rappers in Their 40s Who Are Relevant Right Now.

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