After U.S. President George W. Bush held a joint press conference with Mexican President Vicente Fox in 2005, there was some speculation that the American leader had stood on a hidden stool to make himself look taller. In photos at the podiums, the two men appear to be the same height. But in other pictures of them standing next to each other, Fox towers over Bush.

At 6’0’’, Bush is no shorty, but Fox is a lofty 6’4”. Still, everyone acknowledged Bush as the leader of the free world, so why should he care if Fox was taller than him. The reasons are primal.

Throughout the natural world, animals use relative size to express dominance and submission. You can even see vestiges of this in your pet dog’s behavior, as for example when she raises her hackles to intimidate the neighbor’s cat. And when you come home from work, she bows down before you, submitting to the leader of the pack.

Just like other animals, humans also equate size with dominance and submission. The priest stands at the altar before a kneeling congregation. The orator struts upon a dais before a seated audience. And the king sits on his raised throne before his prostrate subjects. These are all ancient practices, but there’s also a modern ritual in which people try to manage other people’s impressions of how tall they are—the selfie!

If you hold your camera straight out, you’ll take a selfie that accurately represents what you really look like. But what if you hold the camera above or below face level? When you take a selfie from above, you make the face and eyes look larger, so you appear shorter and younger. And if you photograph yourself from below, you emphasize your jaw, making yourself look taller and more dominant.

Florida State University psychologist Anastasia Makhanova and her colleagues tested the hypothesis that people would manipulate camera angle when taking selfies as an impression- strategy. The rationale for this idea is derived from evolutionary theory.

In the mating world of Bob and Carol and Ted and Alice, two processes are at play, intersexual and intrasexual . Intersexual attraction refers to the set of strategies that people use to arouse the interest of members of the opposite . Bob brings Carol an extra-large piece of meat from the hunt to show he’s a good provider. Meanwhile, Ted shows his thoughtfulness by bringing Alice an animal skin to keep her warm on a chilly night. Likewise, Carol and Alice are flaunting their youth and fertility to garner the of Bob and Ted.

At the same time, Bob and Ted are in intrasexual competition with each other as they vie for the ladies’ attention. To do this, Bob and Ted jockey for a position of dominance amongst themselves, since the more powerful male will likely attract the sexier female. Women are attracted to men who dominate other men, but they also expect those same men to be supportive toward their spouses. Likewise, women rely more on social influence than physical size or strength to establish their position in the pecking order.

Thus, Makhanova and colleagues argue, people will manipulate the camera angle of their selfies depending on their intended audience. In one study, they examined self-portraits posted by men and women on and professional-networking sites. In this case, the internet dating sites were viewed as contexts for intersexual attraction, and the professional-network sites as contexts for intrasexual competition.

Specifically, they made the following predictions:

Men will take selfies from below when their audience is other men (to show dominance).

Men will take selfies straight on when their audience is women (to show supportiveness).

Women will take selfies from above when their audience is men (to show submission).

Women will take selfies straight on when their audience is other women (to show supportiveness).

This is exactly the pattern of results that Makhanova and colleagues obtained. But this was just an observational study, and the researchers wondered if they could produce these effects experimentally. So they approached students on campus, handed them a camera and asked them to take a selfie. Half of the participants were told their picture would be viewed by members of the same sex, and the other half were told it would be shown to members of the opposite sex. Again, the results patterned as predicted.

So, people really do manipulate the camera angle of selfies to create an impression of dominance or submission. But are other people actually influenced by camera angle? To explore this question, the researchers took pictures of men and women, each from all three camera angles—above, straight on, and below.

Another set of participants then viewed these photos and rated them on a number of characteristics related to dominance and submission. They also rated the and other physical characteristics of the person in each photo. As predicted, the men were perceived as taller and rated as more dominant and attractive when the camera angle was from below. And conversely, the women were perceived as younger and rated as more submissive and attractive when the camera angle was from above.

These results show that people really do manipulate their perceived height to indicate dominance or submission. Furthermore, people actually are influenced by these attempts at . But what’s the take-home message?

Here’s the advice for men: If you’re trying to impress other men in a professional context, take your selfies from below. This will signal your dominance. But if you’re trying to impress women in a romantic context, take your selfies straight on. This will show your supportiveness.

And here’s the advice for women: If you’re trying to impress other women in a professional context, take your selfies straight on. This will demonstrate your social . But if you’re trying to impress men in a romantic context, take your selfies from above. This will make you look younger and more attractive.

Despite our modern beliefs about equality, the dynamics of intersexual attraction and intrasexual competition are still deeply engrained within us. However, this doesn’t mean we’re powerless pawns of our evolutionary past. Rather, it means that if we understand how these dynamics work, we gain power over them and can wield them to our own advantage.