"Sexting" has become a favorite celebrity pastime, with more photographs of naked celebrities having been leaked over the last two years than over the previous centuries. 

Everyone from Scarlett Johansson to Congressman Anthony Wiener has been caught in the act and sometimes even gotten into trouble because of sexting, but scientists are now saying that people may be predisposed to show naked pictures of themselves.

Researchers are saying that the primal urge to sext can be attributed to the design of the sexual brain, rather than modern celebrity culture or technology.

New research has revealed two distinct "primal" explanations for female and male exhibitionism. Researchers said that women sext to get attention and feel desired, whereas men texted to show off.

"Being desired is very arousing to women," said clinical psychologist Marta Meana, president of the Society for Sex Therapy and Research, according to Ogi Ogas from Wired magazine. "An increasing body of data is indicating that the way women feel about themselves may be very important to their experience of sexual desire and subjective arousal, possibly even outweighing the impact of their partners’ view of them."

Past studies have shown that more than half of women’s sexual fantasies involve the desire to be sexually irresistible to men, and in one recent survey nearly 47 percent of women report the fantasy of imaging themselves as a striptease dancer, harem girl, or other performer.

Half of the women in the survey fantasized about pleasuring more than one man. 

However, male exhibitionism is motivated by something entirely different.

Like male monkeys and apes that routinely present their penises to females to signal their sexual interest, men, too, show pictures of their manhood to show off. 

"Since bonobos can sheath their penis, nothing is visible most of the time. When the organ does appear, however, it is not only impressive in size, but its bright pink color makes it stand out against the dark fur. Males invite others by presenting with legs wide apart and back arched, often flicking the penis up and down — a powerful signal," Primatologist Frans de Waal wrote in Peacemaking Among Primates.

Researchers said that this type of behavior also appears in men, and some experts believe that men may have inherited their urges to show their penises from their primate ancestors. 

Recently, a plethora of websites showing amateur self-portraits have taken over the internet and become a huge success around the world, with the majority of them being of penises rather than vaginas.

"At any given moment, one in four cameras on the webcam network ChatRoulette are aimed at a penis. On the adult networking site Fantasti.cc, 36 percent of men use an image of a penis as their avatar; only 5 percent of women use a vagina," Ogas wrote. "On Reddit’s heterosexual Gone Wild forum in 2010, where users were free to post uncensored pictures of themselves, 35 percent of images self-posted by men consisted of penises."

Meana who did the research said that more was needed to determine female and male eroticism, according to the Daily Mail.

"The little data we have indicate that eroticism just will not be told what to do," she said, according to the UK paper. "Consequently, research and clinical forays into eroticism may go a long way toward facilitating inclusiveness and considering the diversity and full range of women’s sexual desires."