Japan is dealing with what economists call a "demographic time bomb."

Through a vicious cycle of low fertility and low consumer spending, the country's economy has gradually shrunk over the last 25 years.

People are living longer, and they're heaping greater social-security costs onto younger generations who aren't having kids to replace them — thereby furthering the cycle.

Here are some of the most visible signs in daily life that the time bomb is ticking.

There are now 68,000 people over 100 years old

To put Japan's widespread aging in perspective, 2017 marked the 47th straight year that the country has broken its own record for the number of centenarians, or people living past their 100th birthday.

In 2016, there were roughly 65,000 centenarians out of the total population of 127 million. The new total for 2017 stands at 67,824, The Asahi Shimbun reported in September.

Japan has the highest rate of centenarians out of any country, with 4.8 per 100,000 people. The US, the country with the most overall, has 2.2 per 100,000.

Adult diapers outsell baby diapers

Ever since 2011, sales of adult diapers in Japan have outpaced those of baby diapers.

The trend reflects just how big the cohort of senior citizens is: People over 65 make up a larger demographic than any other in Japan. Of the 127.11 million people, about 26.7% of them are seniors.

That proportion is up 3.7 percentage points from six years ago.

2016 marked a 117-year low for fertility

Ever since 1899, the annual number of births in Japan had exceeded one million — until 2016.

When government officials conducted a tally of total births last year, they counted about 20,000 shy of the benchmark. The death count, meanwhile, fell at around 1.3 million.

Young people have started "granny dumping"

The word ubasute is an old Japanese word that translates to "granny dumping," and according to Japanese news sources, it's making a comeback.

It describes the unfortunate practice of younger citizens bringing their senile elders to hospitals or charities and essentially abandoning them — generally because they can't afford care anymore.

The trend still isn't widespread yet: One social worker estimates the total number of cases is in the low hundreds each year.

Prisons are turning into nursing homes

About one-fifth of all crime committed in Japan is done by the elderly. Most of it is petty theft and shoplifting.

As crime rates among the elderly rise, prisons have effectively turned into nursing homes. Guards are made to bathe the inmates and help them get dressed, and experts say living conditions are too good to keep recidivism rates down.

Normally, younger relatives would take care of the inmates once they're released. But in some cases the costs (and loneliness) are simply too much to bear in a troubled economy, and seniors look to prison as the better alternative.

A doomsday clock counts down the seconds until extinction

Over time, low, unchanging fertility rates (without additional immigration) could mean actual extinction for an entire country.

In the short term, that could mean losing 34% of the country's population by 2100.

Taking a longer view, Japanese researchers recently pinned down the expected date of extinction with a doomsday clock. The date, according to the latest fertility rates, is August 12, 3776.

Friends are getting married out of desperation

One of the main traits of the demographic time bomb is that young people focus a lot of their time on work instead of socializing, largely to keep up economically.

They still want to get married, however, so the compromise they're making is just partnering up with friends.

It's a real-life version of that game "If we're both not married by the time we're 40..." — except people are playing it in their late 20s.

Employees are succumbing to 'death from overwork'

Long work hours are leading to a rise in cases of karoshi, or "death from overwork."

A report from October, which examined karoshi and its cause of death, found more than 20% of people in a survey of 10,000 said they worked at least 80 hours of overtime a month — a signal of just how desperate young people are for extra income.

Japan's government is taking steps to encourage people to leave work on time or take off one day entirely.

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