I don’t know if it’s a human nature thing or a Western civilization thing, but it seems a lot of the time we focus on winners, damn the rest, and assume that when one supplants the other the other drones on eternally in obscurity rather than the two coexisting. We do this even though Coke and Pepsi, McDonald’s and Burger King, Wal-Mart and Target all coexist in free market bliss.

So why do we fixate on whether Yahoo will ever get over on Google, or announce the death of LinkedIn, Bebo, and MySpace when Facebook suddenly has its day in the sun?

Maybe it’s fun to think of the world in boxing terms. Maybe it’s a side effect of the masculine society, but that’s a whole other topic.

At the beginning of the week Jeff Pulver – you should know him, he’s kind of a big deal – was published in BusinessWeek. In his column, Pulver said he’d abandoned LinkedIn for Facebook and advised the entire literate business world to do the same.

And thus begins speculation of the demise of the now (supposedly) former business-geek-network darling. This pronouncement mere months after Guy Kawaski, another kind of a big deal guy, proclaimed LinkedIn as an essential business tool.

Hitwise’s Sandra Hanchard provides a nice little case study – a case study in that Hanchard’s “beat,” so-to-speak, is the Asia-Pacific market, primarily Australia – that shows Facebook has indeed surpassed UK-preferred Bebo in terms of traffic in July.

There has also been a spike, she says, in LinkedIn referral traffic to Facebook, while referrals from LinkedIn to MySpace and Bebo “have either trended down or remained stagnant.”

Does that mean MySapce and Bebo are doomed? Doubtful.

“I would begin to speculate that users are a) looking-up the professional details of friends and acquaintances from Facebook on LinkedIn or b) business-oriented in visiting both networks concurrently.”

She also “wouldn’t go so far as to back up” Pulver’s position that Facebook would replace LinkedIn entirely.

And that does seem more rational to me, not just that they will coexist, but that professionals would be silly to limit their networks. In fact, it’s probably a good idea to have a presence on all four of the aforementioned networks, just to maximize your reach.