The taller you are, the more you earn and the more satisfied you are. Flickr/dougwoods If there was ever a tall tale, it's this: People of different heights have equal opportunities to achieve success in life.

Instead, scientific research seems to suggest that tall men and women have a significant advantage over their shorter counterparts.

One 2004 study found that the taller you are, the more you earn. In fact, according to that study, a person who is 6 feet tall would be predicted to earn nearly $166,000 more over the course of a 30-year career than someone who clocks in at 5 feet 5 inches. (The researchers observed those results even when they controlled for gender.)

Perhaps even more importantly, recent research found that taller people are more satisfied with work and with life in general.

As for why exactly taller folks should have an edge over the rest of us, researchers have proposed a few fascinating theories, several of them cited in The Atlantic. These theories aren't mutually exclusive, so it's possible that they all could help explain tall people's relative success.

1. They picked up more social skills as teens.

Scientists at the University of Pennsylvania and the University of Michigan found that your height in adolescence is much more meaningful for your adult career than your current height.

They drew their data from Britain's National Child Development Survey (NCDS) and the National Longitudinal Survey of Youth (NLSY, which took place in the US). To make sure professional success couldn't be explained by gender or race, the researchers focused specifically on white men, about 4,000 of which reported their height at different ages throughout childhood, adolescence, and adulthood. They were also asked to report their wages in their 30s.

When the researchers analyzed all the data, they found that, for the NCDS participants, only height at age 16 predicted wages in the 30s; for the NLSY participants, only height between ages 16 and 23 did. In order to figure out why, the researchers ruled out a number of possibilities by controlling for variables such as family background and health.

Instead, they determined that the link between teen height and adult success has to do with the fact that taller teens are more likely to participate in social activities such as athletics, school clubs, and dating. In doing so, the authors write, they accumulate "productive human capital such as social adaptability" that will help them achieve success down the line.

2. They're smarter.

Princeton scientists found that height predicted success even among three-year-olds taking tests of cognitive ability. In other words, they hypothesize that taller people are inherently more intelligent than shorter people.

The researchers drew their data from a number of British and American longitudinal surveys, including the Fragile Families and Child Wellbeing Study, which includes nearly 5,000 participants born in big US cities between 1998 and 2000. When the researchers looked at data from that particular study, they found that taller boys and girls performed significantly better at age 3 on a test in which they had to point to pictures of different words.

According to the paper, one possible explanation for the link between height and cognitive ability is that certain biological growth factors, like the thyroid hormone, simultaneously stimulate growth and neural development. Similarly, the paper says, mothers who smoke during pregnancy may end up stunting their baby's growth and cognitive development. (Of course, other factors such as family environment could influence a person's intelligence at a young age.)

One theory is that tall people were better fed as kids, which aided their cognitive and non-cognitive development. Shutterstock

3. They were better fed as kids.

Earlier this year, economists at the FDA and Ohio State University published a paper positing that the key factor linking above-average height and professional success is good nutrition.

These researchers also looked at the National Childhood Development Study and found that, when they controlled for cognitive and non-cognitive skills, the relationship between height and wages disappeared. Because nutrition affects how tall you grow, as well as the development of your cognitive and non-cognitive skills, the researchers believe it's the key factor linking height and success.

People who had healthier diets as kids, they say, demonstrate higher cognitive ability as well as better social skills — both of which are useful among adults in the workplace.

4. We're biased to see tall people as more leader-like.

As Malcolm Gladwell writes in "Blink," "No one ever says, dismissively, of a potential CEO candidate that 'he's too short.'"

And yet "we have a sense, in our minds, of what a leader is supposed to look like." Presumably, that's why the majority of Fortune 500 CEOs are taller than the average man. (The majority of Fortune 500 CEOs are men.)

Other researchers say it all comes down to evolution. Back in our caveman days, we would have been wise to select tall, strapping people to lead the tribe because they'd be able to physically defend us — and that preference prevails even today.

Alternatively, the researchers say that tall individuals may be more likely than shorter folks to put themselves forth as leaders.