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From the Encyclopedia Britannica on Vampire bats:
"Weight is variable owing to the large volume of
blood that the bat ingests. A 57-gram (2-ounce) specimen, for example, can double
its weight in one feeding. Its fur is short, ranging in colour from brown to
reddish orange; its wings are long and pointed; and the first segments of the
thumb are exceptionally long, enabling it to hop and creep in a strangely agile,
yet froglike manner along the ground. The common vampire bat is the only bat
capable of taking off from the ground, using its long thumbs to leap a metre
(three feet) or more into the air before flying off.
What would vampire bats benefit from this behavior
of regurgitation to feed their neighbors?
Vomitting keeps the hungry bats from attacking them.
It takes a lot of energy (food) to fly, and a lot
of energy to keep warm, the smaller you are.
Whales keep warm easily.
Add to the bat's energy cost to fly, the loss of
body heat from huge blood-supplied wing membranes that act like a car's radiator,
and.... throw those cookies, quick! My cave mates look hungry!
If you read the following excerpts, it suggests
that this particular experiment's two male bats might be "special" = behaviorally
"economic girly-men" as Ah-nold Schwartzenegger says (from either or both environment
and genetics).
Four female and Two male bats, at least one married
couple (Aggressive interactions between male-female *pairs* were much more common),
subjected to experimental manipulations (unpublished data) intended to promote
blood-sharing behaviour and 'cheating' (i.e. nonreciprocation or recipient's
non-upchuck later, to return the favor).
Possible manipulation: they denied food to some
of them each night, overfed others.
"We observed blood-sharing regurgitations between
males on three occasions, twice from 35R to 32L and once from 32L to 35R.
"35R never regurgitated to the females in the colony,
even when solicited, and 32L regurgitated only once to a female"
"Association time between the two males, defined
as the total time a pair of bats were observed in close proximity (less than
one body length) as a percentage of the total observation time, was high: 28%
of 32L's total association time was with 35R, compared with as little as 1%
for some female pairs.
"Mutual social grooming between males, not previously
reported, was relatively common.
"Also, male-female association and non-aggressive
social interactions were much higher than previously reported.
"The prevailing paradigm in which vampire bat society
is dominated by strong resource defense polygyny and strong male-male dominance
hierarchies may need to be re-examined."
Where did those bats come from? San Francisco? (Joke,
just kidding. Could as easily come from Austin... or your closet.)
Vampire Regurgitators Maybe vampire bat donor-regurgitators,
who's stomachs get "hugely full" with their own weight in blood, might have
genetic influences to feel something akin to heartburn that further helps a
process of "Selection" or Natural Filtration. The compelement = the agonistic
behavior of the skinnier, more agile, and very hungry bat that might attack,
and possibly kill, the gorged and selfish bat, what some might define as a pre-emptive
Virtue of Selfishness (Ayn Rand) behavior that demands democratic and Catholic
acts of Altruism from others (Socialism or Christian Communism?)
So these complementary genes, which enhance reciprocal
behaviors, improve both bat's probability of offspring = evolution " selected
for" these behaviors.
_____________________________
"I regret to inform you that news of my death
"in as little as" 48 to 72 hours due to lack of food have been greatly exaggerated."
(From a Real Vampire Bat)
All vampire bats in Central America
would be wiped out in one three-day hurricane.
Ha ha ha. These scientist can really get you going sometimes, until
you think about it a minute...
Unless they really do get wiped out, and have to fly in relatives
to restock the area...
____________________________
Vampire Woos With Vomit
Whine, whine, whine....
"I was surprised that the males did not regurgitate
more frequently for the females."
They obviously have homosexual tendencies, compared
to other Vamps in other studies... Lab rats... Must be environment... Liberal
academic environment... commie lefties...
And how would a Vampire bat detect lazy Cheaters
who take undue advantage of this altruitic vomitting?
Look for the fat ones that no one ever sees fly....
Some might think "male vampires give investments
to sisters' offspring more than their own, because of the possibility that their
own might not be theirs. So they invest in the genetic sure thing, their sister's
kids."
Take ducks, for example...
I see helper behavior as a tradition, a learned
behavior that itself constitutes a way for an immature non-reproducing helper
to learn the habits of parenthood (and the parent - helper relationship, which
also teaches the chicks to grow up and become helpers!!) for later (sometimes
from five to fifteen years, I think the book said) reproductive activity from
"matured helpers", as it also would for newly-Alpha pack animals, mammals especially
and specifically.
Bird helpers delay breeding so that they can invest
in the offsprings of relatives, which unfortunately might promote a higher mortality
rate within their gene pool. Scientists anthropomorphize too much, and imply
that the birds logically decide to help relatives raise kids, in the hope that
non-relatives die, even though non-relatives ARE the "gene pool."
Pretty dang lucky for relatives, but not so good
for the gene pool over the long haul.
Maybe that's what saves them. The geographic distribution
of birds makes it likely that their genes will mix with non-relatives.
This work is licensed under a Creative
Commons Developing Nations license.
E-mail: Mark Plimsoll