Re: great chain of being

Geoffrey Norman Watson (
Thu, 26 Oct 1995 13:11:42 +1000

On 25 Oct 1995, Alex Duncan wrote:

> In article <> H. M. Hubey,
> writes:
> >The degree to which PC has invaded science never ceases to amaze
> >me. What now? Am I being accused of being racist toward bacteria
> >and fish?
> The recognition that it is impossible to claim that one organism is more
> advanced than another is not PC. It's just a recognition of reality.
> For example, we can claim that humans are more intellectually advanced
> than other animals (and some would question this: see Douglas Adams), but
> does that mean we are "more highly evolved"? Virtually all modern
> biologists would deny this possibility. Sure, we may be able to do
> "human-things" better than other animals, but how good are we at
> "cat-things" or "fish-things"? The answer is: not very good at all.
> From a cat's perspective, we're primitive. Evolution has probably been
> occuring for ~4 Byr here on earth. IOW -- ALL organisms on earth belong
> to lineages that have been evolving for 4 Byr.

I realise that this is a reply to H.M. Hubey, so I have not read the original
post :), but I think that this response is a little confusing.

In arguing that " A is more highly evolved than B" is nonsense it seems to
imply that "A is more evolved than B" is nonsense and simply to equate
evolution with the elapsed time for which a lineage has been extant.
However this would seem to render the concept of differential rates
of evolution nonsensical too. Evolution involves change but the rate and
consequent degree of change is variable.

I think there is also a grain of truth in the "great chain of being" idea
too :). Considering the evolution of life on this planet as a system in
its own right, this system is capable of producing *complex* organisms.
We tend to think of this in terms perhaps of behavioural complexity,
with ourselves as the oustanding example. But there is also structural
complexity. And complexity in diversity - the insects, flowering plants.
And relational complexity - between organisms which depend on one another.
Since evolution proceeds in small steps from a simple base-line, complexity
can only be achieved over time, so the more complex products can ONLY be
produced by more mature evolutionary systems.

IF you accept that not all evoutionary change generates more complexity,
then, for example, a system that has been evolving for 1Byr can have generated
products of at most "1Byr's" worth of complexity, but will also have objects
with complexities of 0.5Byrs, 50Kyrs etc. The underlying assumption is that
evolution is "skewed" in respect to complexity, often being neutral, sometimes
generating more and seldom reducing it.

So there are "great chains", but lots of them "heading" in different directions.
However, I also think that the mammal-primate-human one towards behavioural
complexity and consciousness is the most important.

Geoffrey Watson
(Note: I am a Computer Scientist, not a Biologist !!)