The mad rush of the holidays can stress out the sunniest soul, and yet somehow, beneath it all, we remain cheerfully optimistic.  We look ahead, make New Year’s resolutions and generally believe next year will be better than this one and the year before. Why? Tali Sharot, who spoke at TED2012, says we homo sapiens are genetically predisposed to look on the bright side. In her new TED ebook, The Science of Optimism: Why We’re Hard-Wired for Hope, Sharot explains why we’re biologically tuned to be positive.

In your book you note that people are genetically predisposed to be optimistic. What advantage does that provide?

Overall, optimism is a good thing. We now know that underestimating the obstacles life has in store lowers stress and anxiety, leading to better health and well being — this is one reason why optimists recover faster from illnesses and live longer. For example, a study of cancer patients revealed that pessimistic patients under the age of 60 were more likely to die within eight months than non-pessimistic patients of the same initial health, status, and age. Optimists are also more likely to take actions that promote health. Researchers studying heart attack patients have found that optimists were more likely than non-optimistic patients to take vitamins, eat low fat diets and exercise, thereby reducing their overall coronary risk. Also, believing that a goal is attainable motivates us to execute actions that will help us get closer to our dreams. Optimism increases explorative behavior and innovation, which is why so many entrepreneurs are on the optimistic side.

Why do people maintain this rosy bias even when information challenging our upbeat forecasts is so readily available?

Our brain tends to engage more in positive thoughts of the future than negative. This is the result of an interaction between deep structures in our brain that process emotion and motivation (such as the amygdala and striatum) and parts of our frontal lobes that modulate them (frontal lobes). Most importantly, when people learn what the future may hold, our neurons efficiently encode unexpectedly good information, but fail to incorporate information that is unexpectedly bad — rendering us more optimistic.

Are there disadvantages to being optimistic?

Yes, making assumptions that are too positive can lead to disastrous miscalculations.

If we underestimate our risks we might be less likely to take precautionary actions; less likely to get health checkups, apply sunscreen or open a saving account. Optimism can also results in bad planning — we tend to think projects will take less time to complete and cost less than they end up. Think house renovation or planning a wedding.

Can this form of inherent optimism help breed success?

Optimism pushes us to take chances — attempt a new job, a new relationship. It also acts as a self-fulfilling prophecy, as believing a goal is attainable makes it more likely to be. This is why optimism has been related to success in many domains including sports, academia, business, politics. However, there are pitfalls — for example, the optimism bias is thought to be a leading cause for the 2008 global economic collapse.

The Science of Optimism is available for the Kindle and Nook, as well as through the iBookstore. Or download the TED Books app for your iPad or iPhone..

Neuroscientist Tali Sharot comes on stage to discuss the “optimism bias.” It’s a topic that she’s been studying in her lab and she claims that 80% of us experience it. “It” being the tendency to overestimate the likelihood of good things happening to us. As she puts it: “we’re more optimistic than realistic, and we’re oblivious about it.” An example: Divorce rates in the western world weigh in at about 40%. Yet when you ask newlyweds to rate their own likelihood of divorce, they more than likely put the figure at, yes, 0%.

Similarly, many of us are uniquely biased toward the fabulousness of our own families. Sharot’s statistics show that three-quarters of people are optimistic about the future of their own families; yet only 30% said families are doing any better than they were a few generations ago. In other words, “We’re not so optimistic about the guy sitting next to us.”

So the real question here: is the widespread optimism bias good for us? Some say no, believing that low expectations mean we won’t be disappointed when things don’t work out — and yet pleasantly surprised if they do. This, says Sharot, “is a good theory that’s wrong for three reasons”:

1. Interpretation matters: Whatever happens, whether you succeed or fail, people with high expectations always feel better. That’s why optimists who get a poor result in an exam will blame the exam; they’ll nail it next time. Pessimists who get a good result in an exam will consider it a one-off.

2. Anticipation makes us happy: The thrill of the wait matters. That’s why people tend to prefer Friday to Sunday. On Friday we’re looking forward to the weekend ahead; on Sunday, the only thing to look forward to is the work week.

3. Optimism changes (objective) reality: It is not only related to success, it leads to it. If you expect to do well, you will put more effort into making it so.

But there are also pitfalls to the optimism bias. Sharot shares an email from a fire team captain who told her that fire teams often make mistakes even when all the necessary information is there to make safe decisions. The British government acknowledged the optimism bias can make individuals more likely to underestimate the cost and duration of projects — and so they adjusted the 2012 budget for the Olympic Games.

The key, she concludes, is to learn how to protect ourselves from dangers of optimism while also benefiting from its fruits. And the first step is to understand that the bias exists. Once we take that on board, we can work towards striking a balance and protecting ourselves from unrealistic optimism while remaining hopeful.