Re: News: Is Aging an Accident of Evolution?

On Aug 6, 5:58 pm, Vend <ven...@xxxxxxxxxxx> wrote:
On 6 Ago, 16:17, John Harshman <jharshman.diespam...@xxxxxxxxxxx>
wrote:





Ernest Major wrote:
In message <9kZlk.20563$N87.2...@xxxxxxxxxxxxxxxxxxxx>, John Harshman
<jharshman.diespam...@xxxxxxxxxxx> writes
r norman wrote:
On Mon, 04 Aug 2008 06:45:13 -0700, John Harshman
<jharshman.diespam...@xxxxxxxxxxx> wrote:

Ron O wrote:
On Aug 3, 11:07 am, John Harshman <jharshman.diespam...@xxxxxxxxxxx>
wrote:
Ron O wrote:
On Aug 1, 8:35 am, John Harshman <jharshman.diespam...@xxxxxxxxxxx>
wrote:
Ron O wrote:
On Jul 31, 8:51 pm, John Harshman
<jharshman.diespam...@xxxxxxxxxxx>
wrote:
Ernest Major wrote:
In message <Isrkk.16904$mh5.12...@xxxxxxxxxxxxxxxxxxxx>, John
Harshman
<jharshman.diespam...@xxxxxxxxxxx> writes
SNIP::

Only if you also gather data on humans kept under optimal living
conditions. But at least you have gone from assertion to
agnosticism.
That's progress.-
This is a sort of strange thing to say for someone that probably
knows
that they are holding the short end of the stick.  I made an
assertion
based on what I had heard and read about lifespans of birds.  It
turns
out that the data was real.  Not only that, but we are talking about
limited populations under study and likely unsatisfactory
environments
that these animals lived in  most of their lives, simply out of
ignorance.  Just 40 years ago animal breeding in zoos and
aviaries was
pretty much in its infancy.  They likely didn't even know what a
good
diet for a lot of these animals was.  The were treated as disposable
display objects until things like the endangered species act limited
their supply.
How long was the expected lifespan of those poor red eared turtles
that used to be ubiquitous in pet shops in the 1960's and early
1970's?  Probably months, but we had one that just died two years
ago
and lived for around 40 years in a decent sized goldfish pond.  How
many had that chance?  This turtle would hibernate in the winter
even
in Southern California.  It would disappear every winter and
reappear
in the spring.
These animals were not treated this way out of a vindictive
nature it
was out of ignorance.
Given this reality, my bet is that estimated livespans for these
animals will increase significantly.  You might say that human
environments haven't been the best, and modern medical technology is
lengthening lifespans, but it isn't the same deal.  We are talking
about comparing mostly solitary confinment with inadequate
housing and
diet to adequate living conditions.  Something that middle class
humans would have been enjoying for well over 100 years to get that
estimate for humans.
You have no estimate for average lifespan of any bird that's
longer than
for humans. You have no stated maximum age for any bird that's longer
than the maximum age for humans. You in fact have nothing other
than a
belief that if we knew much more than we know now it would turn
out the
way you want.

I still don't understand why you are so frantically defending this
claim, since it has nothing to do with your initial point.
Beats me what has gotten you so bent out of shape.  If there is anyone
frantically defending their position it is you.  Just the fact that
you have to stoop to such verbage should say something.

I simply stated what I had heard, and it turned out to be fairly
accurate.
But it didn't. You have no support for this claim. A list of web
sites  is no support. Look at them closely and you will find mostly
undocumented claims, and the documented ones are extremes for single
individuals.

I have admitted that we don't have the data yet, so I don't
know what is your complaint about that.  You seem to be stuck on
something, but I don't know what it is.  From my point of view, any
bird that lived over 100 years under the conditions that they were
likely raised during that time is pretty good evidence that the
original assertion is true.  Do you have any type of counter?
Yes. I deny that your evidence is evidence. It's anecdotal at best,
web  hearsay at worst.

I
haven't seen it.  Just the fact that we don't have an accurate
estimate for these birds average lifespans should tell you something,
but it obviously can't for some reason.
Yes, it tells me that we don't have an accurate estimate. That
doesn't  mean you get to project your favorite belief onto our lack
of knowledge.

Frantic, read your own posts.  What was frantic about my reply?  I
just recapped the current situation.  Just because you don't like
where it leads, doesn't make it frantic.
We can agree that some large birds have lifespans comparable to
those of  humans. I don't see any data that let you make a stronger
claim than  that. I have no particular ax to grind here, just a
respect for evidence.
 Aren't extreme examples for specific individuals more indicative of an
overall "life span" than averages?  The extreme should be a limitation
of the kind, the average is more an expression of environmental
limitations.

If so, then shouldn't one compareparrotextremes with human extremes,
not (as Ron is doing)parrotextremes with the human mean?

The extreme figures (assuming that they can be verified) are suggestive,
rather than probative. However, it should be noted that the larger a
sample the greater the expected difference between the mean and the
extreme measured value. (But questions of variance muddy the water.) As
sample sizes for humans are much larger than for parrots, which we
expect, for equal mean lifespans,parrotextremes to be significantly
lower than human extremes.

Now, given the correlation between size and lifespan, and that
observation that human lifespan lie well above the trendline, it would
be contrary to expectation for any bird to have a longer lifespan to
humans. But if the reported figures are accurate the situation in
reality looks too close to call.

There is a correlation between size and lifespan, but it seems to be
different for birds and mammals. And it's not an extremely good
correlation either, at least for birds.

I was wondering, what is the average age of sexual maturity and
reproductive lifespan of these long living birds?-

According to the web Amazon Parrots are sexually mature at 4-5 years
of age.

There probably is some correlation of age at sexual maturity and
expected lifespan, but I don't know how good it is.

Japanese Quail are used in research as a short lived (probably around
5 years for a really old bird) avian species, but it is sort of
unfair. They have a fairly high genetic load (estimated at 8, humans
have one of about 2.5), and were likely derived from a fairly small
initial population. Their short lifespans are also a function of
their reproductive activities. You can literally go from egg to egg
in less than 10 weeks for a generation. The domestic birds are egg
factories. The females will keep laying eggs from around 6 weeks of
age, and pretty much burn out. Their eggs are larger in proportion to
their body size than a chicken egg and some of them can lay one just
about every day. They have study populations where they have selected
for mating behavior in males and these guys will literally kill
themselves and their mates with their constant activity. In the wild
they were colony mating flock birds and migratory in a fashion. They
do not pair up and males are pretty much hyperactive breeders. They
literally would breed as they moved from Asia to Africa. Probably as
long as there was food they would reproduce. I don't know how you
migrate and breed at the same time, but the eggs hatch in around 18
days and in 6-8 weeks the chicks would be sexually mature.

Parakeets are used as a longer lived species (they live from 10-15
years), but you can burn them out reproductively too. The females are
sexually mature at 1 year of age, and the pet books used to advise
that you use an older male to mate with them. The male is important
in the breeding. He has to be a good provider and delivers the food
to the female in the nest box. I used to raise parakeets, and in
California they would breed as long as they had food in front of
them. The books would tell you to limit their breeding to two batches
of chicks a season, but there was no season. I would have a nesting
cage and a flight cage. You had to remove the birds from the mating
cage with the nest boxes in order to get them to stop breeding. I've
seen breeding operations where they just let the birds breed until the
production fell below a certain level and then replaced the flock. In
the wild they can reach pest levels and will breed throughout the
season as long as they have food and water. So the estimated lifespan
is likely for well managed birds.

My guess is that if you could limit the quail reproduction to around
12 eggs a year and have the males only mate for a few weeks out of the
year that they would live longer than they do, but genetically they
aren't geared that way.

.

Relevant Pages

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