> Erik Moeller <flagg@oberberg-online.de> writes:
>
> > Maybe it would be helpful to create a detailed table/overview of species
> > which do not age, including their habitat. Parallels?
>
> I'll post one tomorrow (promise) when I get to my office and can look
> it up in Hayflick. I recall that most of the apparently "immortal"
> species were aquatic, and most were "primitive".
OK, here it is, from chapter 2: "Some Animals Age, Some Don't" of
Leonard Hayflick's _How and Why We Age_.
"But some animals do not seem to age at all, even when
protected by humans. If they do age, it occurs at such a slow
rate that their aging has not been demonstrated
convincingly. These animals increase in size indefinitely;
their growth may slow as the years go by but, apparently, it
does not stop.
Nonaging animals tend to be more primitive species. Typical
examples are lobsters and many, but not all, fish (sturegons,
sharks), amphibians (alligators) and reptiles (the Galapagos
tortoise). Nonaging animals do experience a peak in their
physiological functions at some point after their sexual
maturation, but as they continue to grow those functions do
not seem to decline. The classic example of indeterminate
growth associated with lack of aging is the fish called
flounder in the United States and plaice in England. The
female grows indefinitely and does not show age changes, but
the male reaches a fixed size and ages. The reason for this
difference is a mystery."
The list I was referring to was unfortunately a list of records for
various species, and not a list of whether they age or not. Still, it
is clear that reptiles and amphibians at least have a maximum lifespan
of several decades, while there is a great variability among mammals
(humans are of course the longest-lived mammals). Fishes has great
variability, but ages such as 75 for beluga, 82 for syuregon and 60
for catfish clearly hint that they do not age. The same goes for
invertebrates, bivalves can get 116 years old (Margaritifera
margaritifera) or 220 (Arctica islandica), lobsters 50, Nautilus
pompilus 20 and ant queens 27 years. In general we need more data here.
So it seems that immortality (or at least extreme life spans) is
physically possible in some groups of species. Unfortunately we do not
have any mammals that do not age, so we don't know if it is applicable
to us.
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