In an era where all it takes to get a party pack of tacos delivered to your front door is a credit card and an app, it can be difficult to imagine a time when humans had to rely on hunting and gathering for every meal they ate.

There were no 7-Eleven’s for cavemen where they could pick up a soda and a bag of chips, and no school cafeteria serving up a hot lunch every day. There weren’t fridges to store meals they’d prepped for the week, and no microwave to heat up yesterday’s leftovers.

You might think that sounds like a nightmare. But there are people who want their diets to look more like the way humans ate back then. In fact, there’s an entire style of eating built around it called the Paleo Diet. It encourages people to eat foods like meat, fish, eggs, seeds, oils, fruits and vegetables, and avoid anything that a cavemen probably wouldn’t have been able to find or prepare, like food with added sugars and high-fructose corn syrup, processed foods and grains like bread, that would have had to have been made in a way that cavemen just couldn’t do yet.

One small hole in paleo-style eating is that ancient people didn’t conform to one style of eating. They couldn’t! After all, they lived all across the globe. What was available to a small community of hunters and gatherers in a jungle near the equator would look a lot different than what ancient people on the chilly island of Greenland had access to, in the same way that diets worldwide still differ today, even as new farming methods, global shipping and food preservation has made it easier to access a wider variety of foods.

In places like Greenland and Scandinavia, ancient diets include tons of fatty fish, including animals as big as seals and dolphins, as well as some local foods like nuts and starchy root vegetables. In areas like tropical grasslands and deserts, hunters and gatherers consumed a lot more carbohydrates, including wheat and barley, though what they ate looked a lot different than the slice of bread or bowl full of piping hot steamed barley that you might be used to.

One study on prehistoric people in what’s now Israel found that cavemen also liked to have a little backup meal on hand. They saved animal bone marrow, the tissue inside of bones, for as many as nine weeks before snacking on it. The researchers of the study likened it to the way that humans have a can of soup in the pantry they can pull out when they need.

Throughout the globe, these meals started with the more easily accessible foods like nuts, seeds, fruit and meat they had scavenged from animals already dead. Their diets became more complex and varied as people developed tools like sharpened stones, axes, fish hooks and the controlled use of fire, which allowed them to better hunt and cook new food sources.

Well, the truth is, we don’t know that much. One issue with trying to eat like a caveman is that we don’t have much data to go off of about what the bulk of their diets looked like. One of our sources is the frozen body of the guy now known as Ozti the Iceman, who was extraordinarily preserved in a glacier for more than 5,000 years. Research revealed that his last meal has a mix of goat, venison and wheat.

But not everyone from back then is as well preserved as Otzi. Researchers have to go off ancient samples of teeth and bones, and while they can pick up traces of different proteins, though it can be tough to determine whether those proteins came from animal or plant sources after so much time has passed.

And even if we could eat just like cavemen, who knows if we should? There’s not a ton of evidence to suggest they were super healthy – many died young, had hardened arteries and may have been eating fish with a high level of harmful metals.

One of the biggest arguments that advocates make for eating like a caveman (or at least, what people think all cavemen at like) is that our bodies are genetically the same as they were back in Fred Flintstone’s day. They figure that our bodies were designed way, way, way back in the day to only be able to process those types of foods, and that putting other things in them will send them all out of whack.

But that’s completely wrong.

Human bodies, and the genes inside of them, are wildly different from thousands of years ago. Sometimes genetic mutations that impact important things about our anatomy can happen within a single generation.

One of the biggest indicators that are bodies are built to change and adapt to new environments is the gene that partially determines how your body reacts to milk, or lactose. Ancient people didn’t have much tolerance for milk after they were older than about a year, because the gene that would help humans digest the lactose in milk “shut off” after they went from baby to kid.

But when dairy became a part of people’s diets in some parts of the world started developing a gene mutation that didn’t switch off that mutation, meaning that they could digest it into adulthood – and get all the nutrients, vitamins and healthy fats that come with it, allowing them to grow stronger. But dairy didn’t become a diet staple throughout the globe, so there are still people from some global regions who are more likely to grow up and still have that mutation “shut off.”

That’s one of the many examples that shows our bodies learn and grow with us, both during our lifetimes and over generations. The cavemen ate what they had to to stay alive. Now, armed with a lot more knowledge and options, you can figure out the kind of foods that make you feel strong and smart, and continue to pump your body full of that good stuff.