Bad news: You’re not just getting older—you’re getting dumber.

Yep, according to a new study published in the journal Trends in Genetics, humans have lost the smarts they once had in the days of fending off saber tooth tigers and seeking refuge in caves.

See, the stakes just aren’t the same as they used to be, the study authors argue. They write that while our ancestors lived and died by the ability to find food and shelter, those processes simply don’t require as much brain power in today’s world. The other side: Humans have simply evolved to do tons more cool things—way better than the cavemen could have.

While the jury’s still out, there are plenty of things you do every day that certainly don’t help your noggin—like these five.

1. You Abuse Google
Why rack your brain for the name of that great Chinese restaurant downtown when you can just Google it? Having a search engine in your pocket 24/7 makes things super convenient—but it also makes you super forgetful, according to a 2011 study from Columbia University.  When you’re constantly Googling things, you’re not helping yourself remember stuff—just where to find it, the study’s researchers say. A better approach: When you want to remember something, repeat the information a few times aloud. You may sound crazy, but rehearsal is one of the best tricks for memory. (Keep your mind in tip-top shape with these 27 Ways to Power Up Your Brain.)

2. You Drive Everywhere
If a caveman skipped his cardio, he likely made up for it walking those long miles home from work at night. Meanwhile, you hop in your car. The problem: Falling short in the fitness department hurts more than just your physique. A 2011 study found that the brain’s striatum—an area associated with executive function and working memory—was smaller in non-athletes than in basketball players. But there’s hope: A year of regular aerobic exercise can up the size of an adult’s hippocampus by 2 percent, according to research from the University of Illinois at Urbana-Champaign. Experts believe that exercise can balance the chemical cocktail in your brain, strengthening connections and boosting brain power.

3. You Go With the Fries Instead of the Salad
Obesity rates are up since ancient times—so much so that more than two-thirds of Americans are now overweight, according to the Centers for Disease Control and Prevention. That’s bad news for your brain: The brains of obese people work harder than those of normal weight people to achieve the same results, according to researchers at Carnegie Mellon University. See, high blood pressure and inflammation—both of which strike obese people hard—irritate your brain’s communication networks, which makes it more difficult for your brain to receive messages. (For smart nutrition suggestions, stock up on these 125 Best Foods for Men.)

4. You Stay Cooped Up in the Office
In a recent study of 22 people, researchers gave participants a decision-making test while pumping the room full of carbon dioxide. (Normal levels of carbon dioxide are about 600 parts per million, and the study raised levels up to almost 2,500 ppm.) They found that at as the levels of carbon dioxide increased, people’s focus and ability to strategize plummeted. It could be that excess CO2 in your blood leads to a lack of oxygen in the brain. Some plants, like peace lilies and lady palms, have been found to remove air pollutants, according to research at NASA. But the best option is fresh air—15 minutes or so can help level out the amount. (Are harmful chemicals lurking in your cube? Learn Why Your Office Is Making You Dumb.)

5. You Travel for Business All the Time
Different time zones aren’t just messing with your sleep patterns—they’re messing with your smarts. Researchers at Cal Berkeley changed hamsters’ sleep schedules—the equivalent of traveling from New York to Paris—every 3 days for a month. They found that the jet-lagged hamsters weren’t as smart: They produced 50 percent fewer neurons than they did when they were sleeping normally. Researchers speculate that the production of the sleep hormone melatonin, stress, and an increase of cell deaths from lack of sleep could be to blame. (Trouble hitting the sack? Here’s How to Snooze Like a Baby—No Matter Your Age.)

Additional research by Bari Lieberman, Scott Rosenfield and Denny Watkins.