The Evolution of Anxiety: Why We Worry and What to Do About It Worry is a problem for humans, but not animals. Read on to find out why.

Let's pretend for a moment that you are a giraffe.

You live on the grasslands of the African savannah. You have a neck that is 7 feet long (2.1 meters). Every now and then, you spot a group of humans driving around on a safari taking pictures of you.

But it's not just your neck and their cameras that separates you from the humans. Perhaps the biggest difference between you and your giraffe friends and the humans taking your picture is that nearly every decision you make provides an immediate benefit to your life.

• When you are hungry, you walk over and munch on a tree.
• When a storm rolls across the plains, you take shelter under the brush.
• When you spot a lion stalking you and your friends, you run away.

On any given day, most of your choices as a giraffe -- like what to eat or where to sleep or when to avoid a predator -- make an immediate impact on your life. You live in what researchers call an Immediate Return Environment because your actions deliver immediate benefits. Your life is strongly oriented toward the present moment.

The delayed return environment

Now, let's flip the script and pretend you are one of the humans vacationing on safari. Unlike the giraffe, humans live in what researchers call a Delayed Return Environment.

Related: 7 Times a 'Thank You' Is the Best Response

Most of the choices you make today will not benefit you immediately. If you do a good job at work today, you'll get a paycheck in a few weeks. If you save money now, you'll have enough for retirement later. Many aspects of modern society are designed to delay rewards until some point in the future.

This is true of our problems as well. While a giraffe is worried about immediate problems like avoiding lions and seeking shelter from a storm, many of the problems humans worry about are problems of the future.

For example, while bouncing around the savannah in your Jeep, you might think, "This safari has been a lot of fun. It would be cool to work as a park ranger and see giraffes every day. Speaking of work, is it time for a career change? Am I really doing the work I was meant to do? Should I change jobs?"

Unfortunately, living in a Delayed Return Environment tends to lead to chronic stress and anxiety for humans. Why? Because your brain wasn't designed to solve the problems of a Delayed Return Environment.

The evolution of the human brain

The human brain developed into its current form while humans still lived in an Immediate Return Environment.

The earliest remains of modern humans -- known as Homo sapiens sapiens -- are approximately 200,000 years old. These were the first humans to have a brain relatively similar to yours. In particular, the neocortex -- the newest part of the brain and the part responsible for higher functions like language -- was roughly the same size 200,000 years ago as it is today.

Related: The Reason We Don't Follow Through on What We Set Out to Do

Compared to the age of the brain, modern society is incredibly new. It is only recently -- during the last 500 years or so -- that our society has shifted to a predominantly Delayed Return Environment. The pace of change has increased exponentially compared to prehistoric times. In the last 100 years we have seen the rise of the car, the airplane, the television, the personal computer, the Internet, and Beyonce. Nearly everything that makes up your daily life has been created in a very small window of time.

A lot can happen in 100 years. From the perspective of evolution, however, 100 years is nothing. The modern human brain spent hundreds of thousands of years evolving for one type of environment (immediate returns) and in the blink of an eye the entire environment changed (delayed returns). Your brain was designed to value immediate returns.

The evolution of anxiety

The mismatch between our old brain and our new environment has a significant impact on the amount of chronic stress and anxiety we experience today.

Thousands of years ago, when humans lived in an Immediate Return Environment, stress and anxiety were useful emotions because they helped us take action in the face of immediate problems.

For example:

• A lion appears across the plain > you feel stressed > you run away > your stress is relieved.
• A storm rumbles in the distance > you worry about finding shelter > you find shelter > your anxiety is relieved.
• You haven't drank any water today > you feel stressed and dehydrated > you find water > your stress is relieved.

This is how your brain evolved to use worry, anxiety, and stress. Anxiety was an emotion that helped protect humans in an Immediate Return Environment. It was built for solving short-term, acute problems. There was no such thing as chronic stress because there aren't really chronic problems in an Immediate Return Environment.

Wild animals rarely experience chronic stress. As Duke University professor Mark Leary put it, "A deer may be startled by a loud noise and take off through the forest, but as soon as the threat is gone, the deer immediately calms down and starts grazing. And it doesn't appear to be tied in knots the way that many people are." When you live in an Immediate Return Environment, you only have to worry about acute stressors. Once the threat is gone, the anxiety subsides.

Related: Lessons From Sun Tzu: How to Use Military Strategy to Build Better Habits

Today we face different problems. Will I have enough money to pay the bills next month? Will I get the promotion at work or remain stuck in my current job? Will I repair my broken relationship? Problems in a Delayed Return Environment can rarely be solved right now in the present moment.

What to do about it

One of the greatest sources of anxiety in a Delayed Return Environment is the constant uncertainty. There is no guarantee that working hard in school will get you a job. There is no promise that investments will go up in the future. There is no assurance that going on a date will land you a soulmate. Living in a Delayed Return Environment means you are surrounded by uncertainty.

So what can you do? How can you thrive in a Delayed Return Environment that creates so much stress and anxiety?

The first thing you can do is measure something. You can't know for certain how much money you will have in retirement, but you can remove some uncertainty from the situation by measuring how much you save each month. You can't be sure that you'll get a job after graduation, but you can track how often you reach out to companies about internships. You can't predict when you find love, but you can pay attention to how many times you introduce yourself to someone new.

The act of measurement takes an unknown quantity and makes it known. When you measure something, you immediately become more certain about the situation. Measurement won't magically solve your problems, but it will clarify the situation, pull you out of the black box of worry and uncertainty, and help you get a grip on what is actually happening.

Furthermore, one of the most important distinctions between an Immediate Return Environment and a Delayed Return Environment is rapid feedback. Animals are constantly getting feedback about the things that cause them stress. As a result, they actually know whether or not they should feel stressed. Without measurement you have no feedback.

Related: Determining How Much Your Time Is Really Worth

If you're looking for good measurement strategies, I suggest using something simple like The Paper Clip Strategy for tracking repetitive, daily actions and something like The Seinfeld Strategy for tracking long-term behaviors.

Shift your worry

The second thing you can do is "shift your worry" from the long-term problem to a daily routine that will solve that problem.

• Instead of worrying about living longer, worry about taking a walk each day.
• Instead of worrying about whether your child will get a college scholarship, worry about how much time they spend studying today.
• Instead of worrying about losing enough weight for the wedding, worry about cooking a healthy dinner tonight.

The key insight that makes this strategy work is making sure your daily routine both rewards you right away (immediate return) and resolves your future problems (delayed return).

Here are the three examples from my life:

• Writing. When I publish an article, the quality of my life is noticeably higher. Additionally, I know that if I write consistently, then my business will grow, I will publish books, and I will make enough money to sustain my life. By focusing my attention on writing each day, I increase my well-being (immediate return) while also working toward earning future income (delayed return).
• Lifting. I experienced a huge shift in well-being when I learned to fall in love with exercise. The act of going to the gym brings joy to my life (immediate return) and it also leads to better long-term health (delayed return).
• Reading. Last year, I posted my public reading list and began reading 20 pages per day. Now, I get a sense of accomplishment whenever I do my daily reading (immediate return) and the practice helps me develop into an interesting person (delayed return).

Related: Here Is How to Effectively Manage Your Stressful and Busy Schedule

Our brains didn't evolve in a Delayed Return Environment, but that's where we find ourselves today. My hope is that by measuring the things that are important to you and shifting your worry to daily practices that pay off in the long-run, you can reduce some of the uncertainty and chronic stress that is inherent in modern society.