There is a rather unsettling but believable theory that the people of the industrialised world are evolving into one and the same person.
That the globalising forces of international trade, cheap travel and the internet are gradually ironing out our differences.
Global advertising has grown hand-in- hand with this idea. The more we have in common, the more sense it makes to choose a single, consistent approach.
For no creature, it would seem, does global advertising make better sense than for the business traveller, perhaps the most homogenised of any of us. But, even for a group of people who have all seen the world, know their vintage clarets and could tell you who has the flattest beds in business class, it's never as simple as one size fits all.
For a start, don't assume that wherever you go, executive lounges will be filled entirely with men. Only in Asia is this likely to be the case.
In Japan, only 16 per cent of business travellers are women. In China, where the number of female travellers has actually dropped (by 12 per cent) since the turn of the millennium, the figure is just 20 per cent.
But go to South Africa, and you'll find that almost half of all business travellers are women. Even in traditionalist Germany, your business traveller is no longer predictably male. There are now 17 per cent more female business travellers in Germany than there were four years ago.
Nor can business travellers be neatly defined by age. The internet economy flooded airports with bright young things looking to make their mark on the global business stage. But that was in 2000. These days, the group known as "mid-youths" - 35- to 44-year-olds - provides the bulk of business travellers in most markets.
In Canada, 40 per cent fall into this age bracket. In Japan, though, they're a lot older. Twenty-seven per cent of business travellers are aged between 45 and 54, and almost a fifth are over 55. But go to Saudi Arabia and it's clear why advertisers are so keen to build relationships with its business community. Almost a quarter are fresh-faced, iPod-obsessed 18- to 24- year-olds.
One place these diverse people do converge is the media they use. For this on-the-go, time-pressured lot, there is no more suitable medium than the internet. In Canada and the US, business travellers are more likely to use the web than any other group, a pattern mirrored elsewhere. In China, where demand for the internet is growing faster than they can build internet cafes, 57 per cent of business travellers say the web is the first place they go for information.
The business community is famous for its "it doesn't work on me" attitude to advertising. But this varies enormously too. In Saudi Arabia, more than half of them say that they find advertising a complete waste of their time.
But in Brazil, where a career in advertising can land you celebrity status, business travellers are more ad tolerant. In fact, they're less likely to reach for the remote than any other group.
So what's the best way for advertisers to talk to these people? In the UK, look no further than a taxi. More than half of British business travellers are more likely than your average Joe to notice ads plastered on the cabs they're chasing. In the US though, the reverse is true. Subtler methods such as word-of-mouth, viral or "buzz" marketing would work better - more than half of American businesspeople say they ask for advice before buying new things.
The key to creating that stunning, transcendent global campaign is to find connections that anyone, anywhere can relate to. And for all their differences, there are some consistent attitudes among the business traveller set.
As one might expect, they are prepared to splash out a bit more on quality products than the average person. More than 80 per cent of both British and Brazilian business travellers think "it's worth paying extra for quality goods". That said, they are a conscientious bunch: most are far more likely to buy environmentally friendly brands.
Regular exercise is important to them too, regardless of how little time they spend outside the office or the airport. In the US, Britain and Saudi, nearly two-thirds say that they do some form of exercise at least once a week. Probably golf, but still.
They are also an adventurous, trend-setting bunch. South African, American and Mexican business travellers are more likely to indulge in foreign cuisine than their average countrymen, and all (Canadians especially) enjoy blowing their cash on the latest gadgets. For the group who seem to live to work rather than the other way round, money isn't everything.
Only a small proportion believe that "money is the best measure of success". Many more, particularly the Chinese, believe that "it's important my family thinks I'm doing well".
Business travellers have enough in common to suggest that single, global messages can work - think HSBC or IBM. But for a campaign to stand the test of time, the "think global, act local" mantra, which may seem as dusty and dated as an old briefcase these days, is clearly as pertinent as ever.
This article was first published on Campaign