[extropy-chat] Bowhead Whales May be the World's Oldest Mammals
robert.bradbury at gmail.com
Tue Mar 27 18:50:35 UTC 2007
On 3/27/07, Damien Broderick <thespike at satx.rr.com> wrote:
> At 05:00 AM 3/27/2007 -0400, Robert wrote:
> >Longevity evolves along various vectors given the minimization of
> >the external hazard function which seems associated with in a shift
> >from R-selection to K-selection.
> Do marine and aerial critters suffer to the same extent as land
> beasties from infection by microorganisms?
Ah, that reminds me of the 4th (or part of the 3rd) criteria for
They are: intelligence, size, extreme defenses and flight.
(Flight could be considered a form of an extreme defense although the
prototypical example is shells).
I don't know the answer with respect to water vs. air transmission rates for
microbes. There oceans are teaming with microorganisms that more or less
peacefully coexist (and in some cases, e.g. coral & tube worms) are
synergistic with their hosts). It is a general principle in biology that
the war between hosts and parasites tends to evolve towards "mutual
coexistance" as any extremely pathological organisms that prey upon and kill
their hosts will soon go extinct as well. Usually one has to adopt a
strategy of evolving towards peaceful (or productive) coexistence, or being
a minor annoyance (mosquitoes?).
It is true that a number of major human diseases tend to be water borne
rather than air borne (cholera for example). The nasty part generally
occurs when an organism migrates from its natural host (which may have
defenses) to an unnatural one which may not. I think for example that one
working hypothesis for things like Ebola viruses is that bats may serve as
the normal reservoir for them.
I know nothing at all
> about this, but it occurs to me that disease vectors might be far
> more ubiquitous in oceans, since there'd be fewer "natural barriers"
> such as mountains and other land interruptions to easy migration.
Not really, the above argument says that one evolves towards relative
coexistence between host and hosted.
I wonder if whales that spend their lives moving vast distances north
> and south might have already developed early immunity to many
> diseases that might clobber more territorial and hence immuno-naive
The limit on the evolution of the "size" vector is the requirement for the
consumption of massive quantities of food to sustain oneself. So elephants
eat all the plants in sight and whales eat all the plankton or all of the
squid (or in the case of killer whales all of the seals). The long
migrations of whales are generally due to the fact that the seasonal changes
(esp. sunlight and micronutrient availability) significantly changes the
quantity of food available in specific parts of the ocean. And the
elephants and whales have large enough memories and long enough lives to
know exactly where the abundant resources may be. It is perhaps true that
large migrations might have exposed one to a greater variety of
microorganisms (and thus promoted immune system development) but I have to
think that microorganisms and their hosts in the ocean evolved to a relative
standstill long ago.
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