Hey, smart people, Joe here.

My last name comes from Norway, where the national dish is something called farikal-- boiled lamb, cabbage, some salt, pepper... Well, that's it, actually.

I've never tried it.

Compare that with one of my favorite dishes, delicious Indian curry.

Full of spices, and so, so good.

Why do people in different places prepare the things they eat so differently?

Well, there's a lot of reasons, from traditions, what flavors we like, or simply what foods we have around us.

But cooking with spices may have been crucial for human survival.

Don't "bay-leaf" me?

It's "thyme" for some "sage" wisdom.

"Cumin" a little closer; I'm about to get "jalapeño" bra-- [intro music] blast!

When we talk "spices," we're talking more than just hot things.

Culinary spices include dozens of aromatic plants and their seeds.

Compare the number of spices in recipes far from the equator to ones close to it.

People in warm climates use way more spices, even though northern countries have access to just as many herbs and veggies they could cook with.

It's something any food lover sort of intuitively knows, but have you ever wondered why people near the equator think spice is so nice?

The history of spices extends far beyond the kitchen.

To many peoples, they came to hold monetary and cultural value.

When Alaric, leader of the Goths, besieged Rome in 408 BC, he demanded 3,000 lbs of pepper as ransom.

Neolithic graves have turned up with spices in tow, and Egyptian scrolls from 1555 BC describe adorning the deceased with aromatic plants.

Caring for the dead was thought to discourage spirits from sticking around, and a lot of those plants happened to preserve the bodies.

The oldest example of spice use in cooking is 6,000-year-old pottery found with traces of garlic mustard-- a plant with otherwise little to no nutritional value.

But beyond the interesting smells and rich history, there's a hugely important use for spices that might surprise you-- they kill bacteria.

Plant tissues, including those we use for spices, are full of phytochemicals-- compounds which give many plants their flavor.

Plants manufacture numerous chemicals to defend themselves from insects and microbes by poisoning or ripping apart foreign cells.

When these flavorful phytochemicals hit our food, they can have the same microbe-killing effects.

The most commonly used spices from recipes around the world all inhibit growth of some kind of bacteria, often the same ones that cause food-borne illnesses.

Uncooked meats and cooked meat dishes stored at room temperature build up massive bacterial populations in just hours.

Places where food spoils faster use more bacteria-killing spices per recipe.

And the spices used most often turn out to be the ones that are the strongest bacteria killers.

There are exceptions to the geography-spice rule.

Some neighboring countries, like Japan and Korea, can have wildly different spice habits despite having similar climates.

Traditional Japanese recipes date back to a time when much of the meat and fish consumed in Japan was fresh and local, making the preservation properties of spices less essential.

As a result, Korean meat recipes today typically call for more spices than Japanese ones.

Some theories point to spice use in hot climates to increase perspiration and cool the body by evaporation.

If you're about to leave that comment, spoiler alert--very few spices actually make us sweat.

And it's probably a myth that people use spices to mask the smell and taste of spoiled meat before refrigeration because these anti-microbial spices really only work their magic by keeping fresh meat fresh for longer.

Before modern awareness of chemistry and microbiology, spices may have seemed downright magical.

And that "magic" might be why many of these spices are ingredients in witch's brews.

"Eye of newt" is just another name for mustard seed.

"Tongue of dog" refers to an herb called hound's tongue.

And "lion's hairs" are just turnip leaves.

Combining modern scientific knowledge with historical spice traditions has led to some interesting recent discoveries.

Doctors have used a compound from cinnamon bark to ward off bacterial infections like MRSA.

And in another experiment, rosmarinic acid added to hamburger meat reduced the level of carcinogens after cooking.

We may be entering a renaissance of plant-inspired medicine, but just like the actual Renaissance, there's plenty of bad science alongside the good stuff.

So take outrageous spice claims with a grain of salt because that essential oil could really just be snake oil.

Without a "recipe" for a time machine, it's hard to pin down exactly why we started to use spices.

The dishes we eat are part of local traditions that today are spreading around the globe.

Recipes have often been passed down for so long that no one quite knows how or why they originated.

But whether we were driven by taste, tradition, medicine, or all of the above, we stumbled upon some delicious knowledge along our evolutionary history.

"Those who control the spice control the..." mi-microbes?

Pretty sure that's how that goes.

Stay curious.