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Frank,

I believe you're investing more power in microbes than they have,
when you state that the absence of Eurasian diseases in Australia or
the Americas prior to their "discovery" by Europeans is evidence for
no prior contact.  Microbes are usually very inefficient at spreading
from one host to another, and tend to rely strongly on close contact
and huge numbers.  The probability of becoming infected over some
time period given an infectious individual is usually quite low for
most diseases.  One indication of this is that most diseases usually
do not reach 100% of the potential hosts.

The infectious potential of an individual changes with time, and is
oftentimes zero except for small windows of a few weeks duration.
Thus a sailor with smallpox would not be infectious except if a
lesion were oozing.  Then, I would guess for smallpox, the ooze from
an active lesion would have to be transferred to the recipient's
skin, perhaps by exchange of clothing and blankets or perhaps by
direct contact.  If populations of Eurasians and Australians were
living side-by-side for years, then infection of the Australians with
smallpox would be guaranteed.  But there are no guarantees for
crewman from a few ships trading for a few months, and the sailors
perhaps sleeping on board.  There's an excellent chance that no
sailors would be infectious, even though several had had smallpox.

One would actually have to analyze this question separately for each
disease due to differences in pertinent epidemiological factors, and
also consider the living arrangements of the victim population; more
communal habits might be more conducive to epidemics.  However, my
experience (for plant diseases) is that limited contacts of
relatively few individuals would not result in a 100% chance of
transmission.

Fred

On May 13, 2009, at 10:20 AM, 
 wrote:

>
> Peter, you wrote:
> "By their own accounts, the contact was typically brief, ephemeral,
> and hardly conducive to the transmission of diseases"
>
> Yes, sure. So for example the Norse in Newfoundland, which I
> mentioned as a counter-example, probably did not infect any of the
> locals since boths groups stayed as far from the other as they
> could (or so the saga says). But you do agree that some of the
> fanciful stories of Norse expeditions penetrating deep into North
> America are effectively ruled out by this, right? If the contact
> was anything but "brief and ephemeral", the European diseases would
> have left an earlier record and would have been common in the
> Americans by the time the Spanish arrived.
>
> And you wrote:
> "Nothing like a long sea voyage as a useful spell of quarantine."
>
> Yes, but that only gets you so far. The diseases DID cross the
> oceans, and they arrived with some of the earliest Spanish
> expeditions.
>
> In your second message, you wrote:
> "People from the now Indonesian islands to the north of what is now
> the Australian Northern Territory visited the Australian northern
> coast on a semi-regular basis over several hundred years before
> European settlement"
>
> Ah, but was it "several hundred years" or only 75? The consensus
> (for whatever that's worth) appears to be that this trade began
> around 1720. That's not much before the main European settlement. I
> understand that there are some folks who want to push the contact
> back earlier, but if so, then why no plagues among the Native
> Australians?? Or maybe there were, and they simply didn't travel
> far because of the low population density...
>
> And you wrote:
> "Much later it was speculated that infectious diseases in general
> and Smallpox in particular was introduced to indigenous Australians
> by these Moluccans (one of the Indonesian islands).  Quite recently
> researchers focusing on this question have showed conclusively that
> this contention is incorrect."
>
> Conclusively, eh? That's a pretty good trick. Myself, I would be
> willing to entertain the model that "some" smallpox infection came
> from the Moluccans while the devastating infections occurred in the
> more densely populated areas of European settlement. If you choose
> to believe otherwise, then you would have to propose that the
> Moluccan traders somehow avoided diseases which were endemic in
> their own islands. How would this miracle occur??
>
> -FER
> PS: you wrote: "beche de mer (sea slugs)". Do folks in Australia
> still call these 'sea slugs'? They're sea cucumbers by modern
> terminology, distantly related to the starfish and sea urchins, but
> I understand that they used to classed with the true sea slugs --
> which are shell-less snails (mollusks) like land-bound slugs.
> Understand, I'm not objecting to whatever terminology is considered
> normal down there. Do you call sea cucumbers "sea slugs"? And if
> so, is there a different name for true sea slugs?
>
>
>
> >


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