This is a story about the fundamental underpinnings of biology, but it starts with a story about baking brownies. What do brownies and biology have to do with one another you ask? Well, let’s begin.
First, I must introduce you to my dad, the World’s Best Brownie Eater. He’s the kind of guy who would choose to eat vegetables over cake, and his dessert is more commonly a bowl of Cheerios than a bowl of ice cream. However, his weakness is homemade brownies. Bake a pan of brownies and within 24 hours, he (yes, with a little help from the rest of us) will be finishing off the last brownie. So, it’s a given that when we visit each other (he lives in Oregon, I in Indiana), I bake brownies for him.
During his last visit, we stepped up our baking game a notch. Flipping through a used cookbook, dedicated entirely to recipes for brownies, our science brains started churning (did I mention my dad is also a biologist?). My dad and I have long sought for the perfect brownie: fudgy and rich, just a tad bit gooey with creamy chocolate. We thought: somewhere in this brownie bible must lay the answer to such perfection!
For those not familiar with brownie baking (what a travesty!), the delicious, edible product is, in short, the sum of just a few essential ingredients: flour, sugar, fat (usually butter or oil), eggs and chocolate. The ratios of these ingredients hold the key to the perfect brownie. With a plethora of recipes at our fingertips and inspiration in our bellies, my dad and I began to compare different recipes and ratios of these ingredients. We quickly recognized this to be a more challenging task than we had presumed. Not all recipes used the same units of measurements; in one, flour was measured in cups, in another, ounces. Some used (a lot!) of white sugar, while others combined white, brown and powdered sugar together to make our beloved sweet concoction. Determined to find the perfect brownie recipe, we went to the drawing board – literally.
On my whiteboard (you, too, have a whiteboard in your house, right?), we drew up our Brownie Ratio Table: each of three basic brownie recipe names listed by column and essential brownie ingredients in rows. Then we went to work filling in the table to ultimately calculate the flour: sugar: fat: chocolate: egg ratio for each recipe. To do this, we first had to convert each ingredient to a common unit (e.g. convert all flour measurements to cups). From there on, we could compare across recipes. This conversion to a common unit makes for easy comparisons among things, be it among brownie recipes or the chemical composition of different living organisms.
So, back to the original question: what do brownie ingredient ratios have to do with biology? Just like baking in the kitchen, biology relies on just a few key ingredients to create an impressive diversity of organisms. All of life on Earth — from single-celled bacteria invisible to the naked eye to the largest animal on earth, the blue whale (Balaenoptera musculus)– is composed of a relatively short list of essential elements (e.g. carbon, nitrogen, phosphorus) that combine together to form the carbohydrates, proteins and fats. While many factors lead to Earth’s impressive biodiversity, one of the underpinnings of biodiversity is simply the vast array of different ratios of these few essential elements.
After my dad and I had calculated our brownie ingredient ratios for different recipes, we noticed two things. One, there was definitely variation among recipes – for example, one recipe had a lot more sugar than the other two while another had more flour but also more eggs. We could think of this as analogous to an example of intraspecies variation in biology: while all these recipes produced brownies (i.e. the same species), they had slightly different chemical ratios. But, we also recognized there were limits to this variation; no recipe had a flour: egg ratio of more than 1 cup : 5 eggs. Sure, we could combine these ingredients and pop it in the oven but we would probably end up with something more akin to chocolate cake than to brownies. In effect, we would have baked up a different species. Comparing chocolate cake to our brownies is like examining interspecies variation, or variation between species.
So, the real take-home here is that you should feel no guilt in taking a break from studying your biology textbook to head to the kitchen to bake up a batch of brownies. While you are baking up this delicious concoction, think about how you really are experimenting with the fundamentals of biology. After all, biology is simply the products (i.e. the brownies) of similar chemical compounds (the ingredients) mixed together using different recipes.
Acknowledgements: Thanks to my awesome dad, a great friend and the perfect accomplice in brownie consumption.
Edited by Riddhi Sood and Emily Byers