The Dutch undertake the best research. I’m always on the lookout for studies about improving leadership – since I coach leaders on how to do their jobs better – and by extension that important form of leadership known as public speaking. So naturally I was fascinated when I saw a study from that wonderful country promising to answer the age-old question, do you prefer your leaders to be intelligent or healthy?

Now, if you ask people logically which would make for better leadership, most people would surely pick intelligence. After all, whenever we here in the United States have suffered through a relatively dim-witted President, the press writes stories about how important intelligence is to the modern presidency, and we Americans dutifully elect a smarter one the next time around.

But our unconscious biases push us in a different direction. When we’re simply asked to pick who would be the better leader of an organization under various scenarios (intense competition, new markets, and so on) we reliably pick the healthier leader more than two-thirds of the time. Not the smarter one.

Now, this seems to me to make sense in an evolutionary way. We certainly couldn’t afford to have a scrofulous-looking leader of our tribe, could we? Imagine how quickly the germs would spread around the cave!

But time has gone by since we lived in caves, the demands on our intelligence have become more abundant, and the wonders of medicine more impressive. Surely intelligence is more important in leaders than healthiness.

Tell that to the unconscious mind. It has not kept pace. We still shun the scrofulous and cleave to the healthy. Smart is nice, but healthy is better.

What does this mean for the leader – and the public speaker? Eat your vegetables. Take care of yourself. Get fit. If you champion the weedy-but-intelligent look it doesn’t mean that you can’t be successful. But it’s going to be harder. It’s just one more unconscious, unfair strike against you.

The playing field is never level and life is never fair. It is therefore important for someone who wants to be a successful leader and public speaker to understand the forces at work governing his or her success or failure. In this case, you now have research that suggests you need to be doing what your commonsense already told you was a good idea: get healthy.

In my recent book, Power Cues: The Subtle Science of Leading Groups, Persuading Others, and Maximizing Your Personal Impact, I ask several key questions that leaders need to answer for themselves in order to be successful:

• How do you show up when you walk into a room?  You need to take control of your presence and change both your thinking and the messages you send to those around you.
• What emotions do you convey for important meetings, conversations, and presentations? You need to share your focused emotions and control the emotional tenor of your tribe.
• Do you have a leadership voice? You need to tune your voice to automatically lead your peers.

Each of these tasks is easier to complete successfully when you’re healthy – and infinitely harder when you’re not. Once again the Dutch point the way forward for success in leadership and public speaking in 2015.