It was, after all, only 12 years since the global population hit six billion, and, as the Viictorian doomsayer Thomas Malthus put it, "the perpetual tendency of the race of Man to increase beyond the means of subsistence" has historically brought nothing but pain and hunger to the world's poorest people.
But "Seven Billion Day", and its attendant hype, disguised another, contradictory trend that threatens the wellbeing not of the poorest nations of the world, but the richest. For, far from exploding, the populations in the developed world, particularly Europe and east Asia, are rapidly ageing.
In Japan, the ratio of people under 20 years old to those over 65 has plummeted from 9.3 in 1950 to a predicted 0.6 in 2025. In Italy, which has seen its birth rate crash in recent years, there are now only 1.3 taxpayers to every pensioner. And in Britain, there are now more pensioners than children. By 2028, demographers predict a quarter of the nation's adult population will be over 65.
There's nothing wrong with people living longer, of course; it's what we all want, provided we can remain healthy. But the way countries treat their elderly populations varies enormously. Too often, in Britain, old age is spent in fear and dread. Patients - like those who were so badly neglected at Stafford hospital between 2005 and 2008 - find themselves dying of thirst because nurses can't be bothered to refill their glass, or developing bedsores because soiled sheets haven't been changed.
Less conspicuously, ageist attitudes - completely alien to some cultures - permeate day-to-day life. Our national broadcaster still seems hypnotised by the spectacle of youth, removing presenters (like Strictly Come Dancing's Arlene Phillips) from our screens as soon as their skin starts to sag.
Advertisers, too, carry on as if nobody above the age of 30 watches TV or reads a magazine.
Our nursing homes are staffed by carers, some of whom are oblivious to the needs of their elderly patients and every winter we have the inevitable reports of pensioners so poor, frail and isolated from friends and family that they've frozen to death in their own homes.
However, some progress has been made. Mandatory retirement is now illegal in Britain, meaning that businesses can no longer force employees to stop working when they reach 65. And a recent 'triple-lock' pension guarantee means pensions will rise in line with inflation.
But there is still a long way to go. In particular, Britain is yet to grasp the most painful nettle of all: funding care for the elderly. To put the issue at its plainest, it's impossible for a country like Britain, which has an increasing number of old citizens and a decreasing number of young people, to pay for the long-term care of all those who need it.
The systems for providing the care that older people need are broken, not fit for purpose and hugely overdue for reform. Public policy has entirely failed over the past 60 years to create proper and effective systems to deliver care. Currently, there is no limit on the costs that individuals can incur and an estimated 20,000 people are forced to sell their homes to pay for residential places each year. One in 10 pensioners faces care bills of more than £100,000.
So, what's the answer? Perhaps a system in which the individual is asked to pay the first £35,000 towards his/her care, with the state paying any charges after that. Recently a report commissioned by the department of Health suggested almost doubling that amount to £60,000, but it's far from certain that the government will adopt either proposal.
The demographic shift, after all, is not confined to Britain. According to the OECD*: "Any discussion of care has to start with the family: family carers remain the backbone of any long-term care system, even in countries which have a very developed, formal arrangement. We should never forget about them. Governments want people to continue to provide care because, if they don't it would simply be financially unsustainable."
Anyone who has had to look after an elderly parent knows what hard work it can be. There's an endless round of shopping, cooking and cleaning to do, as well as helping them to dress and undress, take a bath or go to the lavatory (and also possibly dealing with someone who feels rather down because of having to ask for help - Ed)
If you're trying to hold down a full-time job at the same time, the pressure can be intolerable.
In Britain, one has to rely on an understanding boss. But other countries have recognised this situation as a serious problem and introduced new laws to make is easier for carers to take time off. In Australia, there is a statutory entitlement to "carers' leave" which applies whenever an employee needs to care for a member of their immediate family. And in the US, the 1993 Family and Medical Leave Act entitles employees to take up to 12 weeks of unpaid, job-protected leave per year for 'specified' family reasons.
Other countries here in Europe have even passed laws stipulating what a son or daughter is obliged to do for their parents. When 15,000 mostly elderly people died in a heat-wave in 2003 in France, many were not discovered by their families for weeks. People were so shocked by the news that new legislation was drawn up soon afterwards, holding children 'legally responsible' for their parents' care.
No such legislation is in force here in Britain. No yet, anyway. But we are hardly models of filial devotion. for that, you have to go to Japan. The longest-lived race in the world (the country boasts nearly 48,000 people aged 100 or over) Japan holds its elderly citizens in high esteem.
Respect for the elderly is drummed into children from a young age. Families stick close together and older members of the family come to live with their children in their later years. It's the done thing.
That makes care cheaper, of course, but Japan was also one of the first countries in the world to introduce a universal system of funding, by which the entire population contributes to a pool of money that is ring-fenced for long-term care. Statistically, there are plenty of people who pay into this pool who will never need to draw out from it, but nobody would ever dream of complaining, such is the value placed on old age.
And the result? A well-training phalanx of professionals who administer high-quality care both in a person's own home and in well-resourced nursing homes. A lot of them actually tell their families that they want to move to a residential home because there are so many amenities.
Three or four years ago this was a problem because too many people wee going to nursing homes. This was proving very costly for the government so they then put more of an emphasis on day-care centres and community-based solutions so people would receive the same type of amenities without going into a residential home.
Being Japan, there are all sorts of futuristic gadgets to ease people into their twilight years. For instance, a robot has been invented which boasts 320 pressure points on its arms and chest and is designed to carry patients and take over many of the other tasks normally carried out by a carer.
In Japanese life, there is an unmistakable vibrancy among the old. Gyms are filled with yoga and weightlifting classes for the elderly, millions play sudoku and other brain-training games to keep their minds sharp - and many older men continue to work after they retire, often as taxi drivers or private security guards or traffic wardens.
There's a sense of needing to have something to do. If they're not working, most get involved with local volunteer activities (such as picking up litter) or join sports clubs to play games like gateball (which is similar to croquet, see: http://www.youtube.com/watch?v=PL6rC4hEvPk).These are the signs of a nation that truly values its older citizens.
Populations around the world are rapidly ageing, but when people talk about that they often talk about it as if it were a problem. Although there are challenges with ageing, there are also many opportunities. Older people are a very big resource for society, their families and the voluntary sector and what needs to happen, to liberate that resource is, first, encourage good health in old age and, second, make sure people live in a society that allows older citizens to contribute. In other words, putting an end of age discrimination (but see: http://tx.english-ch.com/teacher/shelle/level-c/the-lonesome-life-of-japanese-senior-citizens/).
Of course, Japan doesn't have a monopoly on respect for the elderly. The same values apply in many east Asian countries. In South Korea, for example, a sense of duty towards the old is at the root of a highly successful volunteer scheme which trains thousands of young people to care for elderly people whose friends and family have either died or moved away.
The volunteers are determined to do whatever they can to ensure their clients stay in their own homes for as long as possible, rather than being transferred to an institution.
And in Scandinavian countries, too, a high priority is placed on providing care for people in the last years of their life. Sweden, where one in six citizens is 65 or over, is widely regarded to have the best long-term care in the world, funded by general taxation. Those with a pension make a contribution but it's not that high; the most anyone pays is around £90 a month, and if you have a low pension you don't pay anything.
The care market is also heavily regulated, so all care providers are paid the same rate and therefore have to compete on quality, rather than price. Homes typically put on a whole range of exercise classes pay for a yoga teacher to visit the home once a week, and organise swimming trips. In some cases, the local church will hold its weekend service at the home, encouraging its congregation to get to know the residents.
Perhaps the worst indictment of Britain is that far fewer older people, proportionately, die from cold weather in Finland (where temperatures can go as low as -10C (14F) in winter) than do here. Why?
Because they live in better insulated houses. Improving the housing stock in Britain is, of course, an expensive endeavour, but there are examples from all over the world of schemes that have improved the lives of old people cost next to nothing to implement. In New York, school buses that were sitting idle all day while the children were in classes, are now being used to transport people to community centres, shops or museums.
In Peru and Bolivia, older citizens join 'white brigades' (so-called because most people have white hair) to help prepare their local communities for natural disasters, such as earthquakes and floods.
And in Thailand, elderly people run farms where they raise chickens and ducks, breed frogs and crickets (both of which they eat) - and cultivate mushrooms.
It may sound a world away from our lives in Britain, but the idea behind it can apply to almost anywhere. The members do it, they say, to stave off their loneliness and to boost their self-esteem,
at a time in their lives when they feel nobody values them any more.
And many old people in Britain can relate to that.