As Japan’s birthrate plummets, pets are increasingly replacing children as members of the family. The country has 22 million pets, compared to 17 million kids under the age of 15. (Photo: Ruth Evans)

Jonathan V. Last is a senior writer at the Weekly Standard. He’s also written for the Wall Street Journal, Los Angeles Times, Washington Post, The Week, Salon and Slate. He is not particularly fond of children or pets, but argues they are both players in a potential global population crisis. He blogs at .

Journalist and new dad Jonathan Last has no illusions about starting a family.

“God help me. I have 3 children under the age of4,I don’t know who’s idea that was,” he tells weather.com. “Most of the time, I’m covered in vomit and poop ... It’s an enormous amount of work and I am totally unsentimental about children and child-rearing," Last tells weather.com

So why then is he warning Americans -- and for that matter, the world -- that unless women start having more babies, humankind is headed for big trouble?

It’s all about fertility rates worldwide, especially among the educated and middle-class, Last writes in his new book: . Worldwide, birth rates are declining at an alarming rate and that has serious consequences for the future.

“The age profile inverts so there are more old people than children. The economy stagnates because there are too few innovators and entrepreneurs and there isn’t enough investment capital. The entitlement state teeters on collapse because there aren’t enough workers to support all of the retirees,” he writes.

The Numbers Tell a Scary Story

For years, demographers, policy-makers and environmentalists warned that overpopulation -- and not underpopulation -- was driving the human race toward doom. The overpopulation problem would cause widespread hunger, economic, social and environmental disaster as more and more people competed for limited resources.

That threat was wildly exaggerated, and in fact, the opposite happened, Last argues.

Last is obsessed with demographic data and proudly declares himself a numbers nerd.His book contains nearly 500 source footnotes and in total, they paint a very scary picture:

In 1970, the global total fertility rate (average number of children born to a woman over her lifetime) was 6.5.Today, it’s 2.5.In the U.S., it’s only 1.9.The replacement level -- defined as the average number of children a woman needs to have to keep the population from shrinking -- is 2.1.

"Whether you think it’s a good thing or bad thing ... where we’re heading towards in the next 60-70 years is a peak population of 9 Billion or so and then we’re going to begin contracting ... and that is a VERY BAD THING," Last says.

Japan: The Demographic Death Spiral Has Begun

As a microcosm of the consequences, Last points to Japan, where the demographic death spiral has already begun.

According to the Ministry of Health and Welfare, Japan’s population will go from 128 million to 87 million as the aging adult population continues to live longer and the .

The birthrate for the average Japanese woman in 1950 was more than 6 children. Today it’s one of the lowest in the world -- 1.39.

In 2012, for the first time, sales of surpassed those for babies. Currently, the elderly make up 23 percent of the population. But the Ministry of Health and Welfare projects that people age 65 and older will account for nearly 40 percent .

With fewer sons and daughters there won’t be as many future working adults to support the economy and take care of the elderly.

Japanese Increasingly Replacing Children With Pampered Pets

Another bellweather of how society is changing, Last points out, is that Japanese are increasingly choosing pets -- and not children -- as family members. Official estimates put the pet population at 22 million or more, but there are only 16.6 million children under 15.

"In Japanese society, it's really hard for women to have a baby and keep a job ... so my girlfriend decided against having a baby, and that's why we have a dog instead,” one Tokyo pet owner .

The Japanese lavish attention and money on their pets with the latest grooming products and designer outfits, expensive treatments at hot-springs resorts and pricey dinners at upscale restaurants where Fido is invited to dine alongside his human “parents.”

Many people spare no expense, even in death. For about $8,000, , complete with a monk officiating.

The Trend Continues in the U.S.

Pets are fast-becoming replacements for children

“Pets have become the fuzzy, low maintenance replacements for children in other countries, like Germany, Italy and the U.S." Last writes.

Americans who’ve opted out of the parenthood club complain that it’s just too expensive and stressful (easily costing over $1.1 million to raise a child -- including college tuition and lost parental wages). But the fact that Americans spent more than $50 Billion on their pets in 2011, doesn’t seem to faze them, Last says.

“You look around, we have car insurance for pets, we have medical insurance for pets. We spend more and more money on them.

“Pets are in many ways like kids but easier and they make you happier than kids do. They don’t cost as much as kids do. You can board them for a week and go to Paris. But I’ve found, much to my chagrin, that people frown when you try to board your children to take a vacation ... It’s certainly a new phase in American cultural development,” he tells weather.com.

So Last talks the talk. But does he walk the walk? Is the Last family doing its part to reverse the declining birthrate trend by choosing to have more human kids rather than pets as replacements? The jury is still undecidedon that question.

“We don’t have any (pets) and I want to get my children out of diapers before we consider it ... I would say this isn’t a subject of intense conversation right now (between my wife and I) ... If you’re on the fence and if it’s a close call between a dog and baby, you should get the dog!”