Of the 7 billion people on Earth, roughly 6 billion own a cellphone, which is pretty shocking, given that only 4.5 billion have access to a working toilet.
So how are cellphones changing us? On average, people spend 4. 7 hours a day looking at their phone. Combined with the length of time spent in front of computers, this has led to an increase in the nearsightedness. In North America, in the 1970s about 1/4 of the population had nearsightedness, where today nearly half do; and in some parts of Asia, 80 — 90% of the population is now nearsighted.
And it can be hard to put your phone down, take for example the game Candy Crush. As you play the game, you achieve small goals causing your brain to be rewarded with little bursts of dopamine, and eventually, you are rewarded with new contents of the game. This novelty also gives little bursts of dopamine, and they together create what is known as a "compulsion loop", which just happens to be the same loop responsible for the behavior associated with nicotine or cocaine. According to a recent study, 93% of young people aged 18—29 report using their smartphones to avoid boredom. Without their phones, they may suffer "nomophobia"—the fear or anxiety of being without their phones.
Your smartphone can also disrupt your sleep! The screen produces a blue light which has been shown to change our biological clock, reducing the time spent in deep sleep, which is linked to the development of diabetes, cancer, and obesity.
Of course, smartphones also completely change our ability to access information, most notably in poor and minority populations. 7% of Americans are entirely dependent on smartphones for their access to the Internet.
So while phones are in no way totally bad, and have been a part of positive change in the world, there's no denying that they are changing us.