X-Message-Number: 24018
Date: Thu, 29 Apr 2004 20:48:40 -0700 (PDT)
From: Doug Skrecky <>
Subject: 134'th update on fly longevity experiments
This is the 134'th update of my fly longevity experiments. Average
temperature was 21.1 C during this run. Estimated maximal longevity using
the formula (363 - T*11.2) is 127 days.
Several records were set in this run. The maximum control longevity of
113 days eclipses the previous record of 95 days set back in run #89.
Marmite yeast extract at the 1/2 tsp dose also set an all-time record of
129 days, which beats the previous record of 124 days set by pomegranate
syrup in run #87. Marmite is being retested in run #148.
I attribute both of these records partly to improved pathogen control
in the breeding bottle used to supply the flies for this run. I had been
"rotating" breeding bottles more often of late, and this change may be
reducing pathogen load.
For some time I had been thinking that the primary pathogen(s) killing
most of my flies before they can get "old", were viruses. However many of
the supplements I have been feeding to flies in these experiments had
documented antiviral effects, yet failed to significantly increase
survival. The benefit in the present experiment of both fructose and the
probiotic lactobaccilus makes me think that it is bacteria, and not
viruses or other pathogens that are the primary threat. Some previous
tests of glucose, and sucrose also pointed in this direction.
For some time I have been adding 1/8 tsp citric acid to all bottles,
despite previous tests indicating that higher doses were more beneficial.
This has resulted in some false positive results, when an added supplement
provided addition acid. I had been concerned that many phytochemicals
would be less stable at acid pH, hence the conservative use of citric
acid. However I have since learned that some plant phytochemicals are
more, not less stable at acid pH.
In update #139 I will be reporting on further tests on sugars, and
there are a number of other, later experiments in progress testing the
effects of other interventions targeting bacteria. Ultimately, I hope to
eliminate most deaths due to infection, so that longevity is then largely
determined by the rate of motor neuron degeneration. This is the main
limiting factor in fly longevity found in high quality experiments
published in medical journals. If pathogen mortality were to be avoided in
my own fly experiments, then these experiments too might become a straight
forward series of battles against age-associated motorneuron degeneration.
Although the motor neuron is not a major factor in human mortality,
central nervous system health does appear to be important. Fly supplements
with significant neurotropic effects might reduce dementia risk in humans,
and thereby possibly exert at least some salutary effects on maximum human
lifespan.
Run #134 Percent Survival on Day
supplement 48 55 62 70 80 86 92 97 108 113 120 129 130
_____________________________________________________________________
control one 25 17 8 4 0 - - - - - - - -
control two 42 17 17 8 4 4 4 4 4 4 0 - -
box phorn 2% 52 42 29 26 7 7 3 3 3 3 0 - -
box phorn 10% 46 35 35 27 19 12 8 4 0 - - - -
brewer's yeast 1/2 tsp 33 29 24 19 10 5 0 - - - - - -
brewer's yeast 2 tsp 25 14 7 4 0 - - - - - - - -
engivita yeast 1/2 tsp 38 29 24 5 5 0 - - - - - - -
engivita yeast 2 tsp 30 26 13 9 9 4 0 - - - - - -
fructose 1/2 tsp 64 43 36 7 0 - - - - - - - -
fructose 2 tsp 71 62 24 19 5 5 0 - - - - - -
lactobacillus 1/2 billion 44 28 24 12 0 - - - - - - - -
lactobacillus 2 bil cells 50 28 28 22 17 6 0 - - - - - -
marmite yeast ext 1/2 tsp 56 33 22 22 11 11 11 11 6 6 6 6 0
marmite yeast ext 2 tsp 17 6 6 0 - - - - - - - - -
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