Looking back, the most surprising thing about Robert Wadlow was his normal height and weight at birth. When he was born on February 22, 1918, Wadlow weighed 8 lbs 6 ounces (3.8 kg) and was 20 inches tall (0.51 m).

There was nothing normal about what happened next.

Within six months, Wadlow had doubled in height and quadrupled in weight. As a one-year-old, he was over 3 feet tall and weighed the same as the five-year-olds in his neighborhood. By the age of five, Wadlow had exploded to 5 feet 6 inches tall. On his first day of kindergarten he wore clothes made for a seventeen-year-old.

Wadlow suffered from an overproduction of human growth hormone caused by hyperplasia of his pituitary gland. To put it more simply: most humans have an internal …show more content…
These systems can be very effective at both moderating bad habits and kickstarting good habits.

Here’s a common example:

Let’s say you are driving just a little too fast and you pass a digital radar sign that says, “Your Speed Is…” and displays the current speed of your car as you pass.

You might not expect it, but these signs are incredibly reliable and effective ways to change the behavior of drivers. On average, “Your Speed” signs decrease the driving speed by 10 percent. Not only that, but drivers continue to drive more slowly for miles down the road. 1

These signs are one example of a balancing feedback loop. The output of your current behavior (driving too fast) becomes the input for your new behavior (slowing down).

The thermostat is another example:

Imagine that you set your thermostat to 68 degrees Fahrenheit (20 degrees Celsius). When the temperature of the room dips below your setting, the heater comes on and warms up the room. When the temperature rises above your setting, the air conditioning kicks on and cools the room. The thermostat acts as a balancing feedback loop and keeps the temperature oscillating between a narrow