Credit: (AP Photo/Bullit Marquez) 

Doctor Randi Hutter Epstein likes to compare human hormones to the internet. And if you think about it, it makes sense. The brain sends messages to the testes in the same way that someone in Paris can send an email to someone in Tokyo. There’s no apparent infrastructure that connects the senders and receivers. Just a message floating out there, knowing what its target is. But it took a very long time before we had this kind of basic understanding of hormones. And, even today, most people doesn’t understand the power of these chemicals. We talk to Epstein, author of, “Aroused: The History of Hormones and How They Control Just About Everything,” about how we came to understand the endocrine system. 

Three Takeaways:

• We traveled a long, strange road before we started understanding hormones. One scientist, Arnold Adolph Berthold, removed rooster testicles to gauge how hormones affect behavior. The experiment found that roosters lost interest in hens once their testicles were removed. But once they were put back in, even if they were inserted in the rooster’s belly, the rooster started to act like its old self. 
• What did this experiment prove (other than that Berthold had some weird ways of killing time)? Most 19th-century medical experts believed that hormonal messages traveled along tiny nerves we just couldn’t see. But that turned out to be wrong. Think about diabetics. They don’t need to inject insulin directly into the pancreas for it to work. The rooster’s belly testicle could communicate messages even though it was technically out of place. 
• Most people associate hormones with puberty or pregnancy. But they do so much more than that. Epstein points to the hormone leptin as an example, which rises after you eat so that you feel full. People with a leptin defect are constantly hungry, which can lead to higher calorie consumption and weight gain. 

More Reading:

• Epstein writes in The New York Times that we should stop calling women hormonal, especially when it’s being used as a synonym for going off the rails. 
• Want to know more about farm animals and testicles? The Daily Beast goes into the life of John Romulus Brinkley - who almost became Governor of Kansas - and his odd hormone experiments with goats.    
• U.S. News & World Report explores why more older men are bailing on testosterone therapy.