In today’s society, the word “steroid” conjures up images of hulking body-builders and sheepish forfeitures of Olympic medals. What most people don’t realize is that steroids actually play a role in all of our lives. In fact, right now there are a whole host of steroids performing the very important role of keeping you alive. Whether we’re pumping up or vegging out, we’re all chock full of steroids. What might be even more amazing is that in addition to keeping animals, plants, and fungi functioning like they should, steroids may also be able to tell us a bit about how and when such multi-celled beings came to be.
As I alluded to above, steroids aren’t just for greased-up gym junkies. On the contrary, they are enormously prevalent substances produced by all kinds of plants, animals, and fungi. Steroids are molecules made of four rings of carbon fused together in a bent line. This basic structure contains 17 atoms of carbon, and modifying this welded-ring core with additional carbon or oxygen atoms makes hundreds of different steroids. The central steroid in human biology is cholesterol, and it is a vital component of every cell in your body. We also use it to make other steroids like the dreaded hormones that complicate adolescence and control much of our development and body maintenance. While fruit bats, magnolias, and button mushrooms don’t have the same type of awkwardness during puberty, they also produce a preponderance of different steroids nonetheless critical for their own lifestyles.
While cholesterol is indeed present in your hamburger, your body also makes it from the simpler molecules you get from digesting all kinds of food. There are three major atomic ingredients in the cholesterol recipe: carbon, hydrogen, and oxygen. The first two come from the food-begotten hydrocarbon building blocks. The necessary oxygen comes from the O2 in the air we breathe. Like so many things our body makes, the real construction workers are our enzymes. There are many enzymes involved in making steroids, some of which are dedicated to incorporating oxygen from O2 into the steroid being produced. These enzymes are aptly named “oxygenases”. The job of an oxygenase is not an easy one, and the reaction between O2 and the hydrocarbons is incredibly slow if no oxygenase is around to speed it along. Many oxygenases use tools like metals and vitamins to manipulate the oxygen into reacting with the carbon in order to come up with the final steroid product.
Steroids, produced with the help of oxygenases, are one of the major things separating multi-cellular plants, animals, and fungi from life forms made of a single,simple cell, like bacteria. While all “higher” life forms produce steroids, as a rule, bacteria don’t. In fact, steroids are so important to the membranes of more complicated organisms that evolution of everything from venus flytraps to the mailman may not have been possible if our common ancestors couldn’t make steroids. When it comes to steroid production, we need a lot of oxygenases and a lot of oxygen. Way back in the history of life on earth, however, there wasn’t much oxygen floating around in the air like there is today. When there was no oxygen, there were also no steroid-producing oxygenases. As oxygen levels rose, these enzymes evolved, steroids were produced, and in a few hundred million years you were born, went through puberty, and learned all about it. Because of this necessary sequence of events, scientists are able to look at the emergence of steroid production and make connections with changes in the earth’s atmosphere and the evolution of the earliest common relative we share with the coconut.
Studying modern biology can not only help us understand how we are now, but give us insight into where we came from. As for me, the next time someone questions whether an athlete is on the ‘roids, I’ll turn to them and ask, “Isn’t everyone?”