Fwd: Re: Real Species

[pierre deleporte]

>At 10:11 26/04/2004 +0200, Zdenek Skala wrote:
>>From: pierre deleporte
>> > A species is simply not an individual. [snip]
>> > What a human being decides to put in the same class is not >equal to a 
>> concrete system. It may be the same, and may not.
>> >[] I think "individual" should mean a highly cohesive system at least.
>>
>>Zdenek: Well, a ("natural", not "taxonomic) species *is* cohesive and 
>>*is* interacting.

No, the dead don't interact with the living (if yes, where and when?). The 
"cohesion" comes from our biological, evolutionary explanation of 
similarities between specimens, i.e. common descent.

>>Z: At least, here is only a negligible difference between the (many) 
>>species and populations.

I admit that populations may not be genetically highly cohesive (perfect 
panmixy is rarely the case, and what should we say of non-sexual 
"populations"). But the dead still don't interact cohesively with the 
living, even for populations.

>>Z: Anyway, the concept of "connection" or "interaction" as something 
>>(roughly) spatially and temporally close is indefensible, IMHO. Any 
>>communication have a temporal dimension (the signal needs to be sent 
>>before it is received; the time lag between these two events is a pretty 
>>quantitative thing).

Sorry for my incomplete formulations. The concept of a social group as a 
concrete whole of living, socially interacting individuals, is highly 
defensible in my view. But of course I should have specified that I meant 
biological interactions (e.g., social ones), and thus spatio-temporal 
proximity is a necessary, but not sufficient, condition to make a concrete 
biological system.
The same way a physical system requires physical connections and 
interactions, and a chemical etc.

>>  Z: Consequently, I would argue that hereditary and generally 
>> parent-offspring relations

Even this (hereditary versus parent-offspring) is not the same. Living 
parents and their living offspring can interact (socially, for instance). 
But this is social interaction, this is not "hereditary relation", which 
does not exist between living individuals (not after the genetic process of 
mitosis-meiosis; the embryo does not "interact hereditarily" with its parents).
[ I'm not playing the smart and original here, I pick everything to Bunge, 
a consistent materialist philosopher of science ].

>>Z:  (including cultural phenomena, BTW)

Even here, Aristotle and Darwin are quite dead. There is no present 
aristotelianism or darwinism outside brains of living human beings. 
Ideas-in-themselves existing independent of thinking brains is a Popperian 
myth.

>>Z: are a kind of connection/interaction and so qualify even dead members 
>>of a lineage as parts of a species.

There is strictly no populational interaction between dead and living.
Now, as for "connection", common descent qualifies as members of a same 
class defined by common ancestry, not as parts of a concrete whole. The 
"connection" is our classificatory criterion, not effective biological 
interactions.

>>Z: Any individual has its history and would we call the dead parts as 
>>"members" or "traces" or anything is really playing with semantics only. 
>>The only important thing here is that the current individual (Curtis, Zea 
>>mays...) is the same individual as was 10 years ago.

Sorry, I don't mean playing at all...  ;-)
I agree that we may think of "individual" as either:
- a concrete whole (myself as a living organism now, or myself as a living 
organism yesterday)
- a historical sketch of myself in successive states from birth to present.
This is not the same. The material "me" in all its successive states taken 
together is not a consistent whole. One consistent whole constantly chases 
the other through time. Much more for individuals of successive generations 
in a "same species" through time.
What would you think of a geologue or geomorphologist considering that the 
sandstone in the mountain up there, and the pebbles in the river down 
there, and the sand on the beach far away, constitute a geologically 
"consistent whole"? Because they were once part of the mountain? But at 
this time they were a consistent whole, no more today. Even if we can 
figure out the whole story of orogenesis and erosion.

>>Z: Speaking about dead cells or fossil plants we are mismatching the 
>>whole (a man, a species) with its parts (no matter if dead or living).

Cast away dead cells cannot be part of a concrete living whole. A living 
individual cannot be said to constitute a concrete biological whole with 
some decaying has-been parts of it rotting on a refuse pile down there. 
What is a concrete whole?
Neither can dead individuals be part of a concrete population, much less a 
"concrete species" if any.
Dead or living really matters if we talk of concrete biological wholes.

>>Zdenek:
>>Here is some misunderstanging, probably. You, Pierre, are an individual 
>>(I believe!); the Homo sapiens *can* be individual, too - simply 
>>individuality can be hierarchically arranged.

Effectively I admit that all things, including biological things, come into 
concrete systems, embedded in systems, in even larger systems... Hence a 
hierarchy of systems of increasing complexity.
But a whole species is not materially, hence not biologically, cohesive. It 
is a historical explanation of biological similarities between specimens, 
which may be a true account of past reality (but don't call it a concrete 
thing).

>>pierre:
>> > I completely agree that even our daily trivial "observations" are
>> > theory-loaded some way. [snip]
>> > I see no difficulty here for distinguishing an observable self-coherent
>> > concrete individual from a human-conceived class of living objects.
>>
>>Z: The individual/class distinction is more a matter of the angle of view 
>>than of what is in "reality".

I see your point, I can't agree. A class may correspond to a concrete 
system, or not.
- It may, if defined accordingly, e.g. the class of all the cells sharing 
the property "living cells being parts of a living individual". Note that 
this class contains no dead cells.
- And it may not, if not defined accordingly, e.g. the class of all the 
cells sharing the property "cells dead and alive being parts or having 
being parts of a living individual from birth to present state". Note that 
this class contains dead cells which cannot be parts of the concrete system 
"present living individual", and some living cells which were not part of 
the concrete individual in any of its early states.
The class "same species" much less corresponds to a concrete system 
(because even at a given time its living members are much more loosely 
materially connected than an individual's cells are).

>>Z: With a huge simplification: we can class all the Zea mays plants 
>>according to some set of characters (and we get a "taxonomic species")

[[Please note that even a phylogenetic species is a taxonomic species 
(classified under the taxonomic criterion of inferred common ancestry). 
Were you right: no more phylocode dispute!]]
But I understand that you mean: a non-phylogenetic "species".

>>Z: or we can see it as an interacting whole (and we get a "natural 
>>species" see above for the historical aspect of interaction).

Note that I can figure out the ongoing evolutionary process of apparition 
and replacement of individuals and "species"... figure out the process and 
the history of it...
But species, a concrete interacting whole? In no ways.
Phylogenetic species, a biologically meaningful explanation of biological 
similarities? Yes, this kind of "whole" if you like, which we better call a 
human-conceived explanation and corresponing class).

>>Z: To summarize: I am not saying that species (or even all species) are 
>>individuals; only that the arguments of Pierre are not very relevant to 
>>this problem - sorry.

No offense, you're welcome.

I think that part of the difficulty is semantic (slippery acceptions of 
"real", "natural", "individual", even "taxonomic"...).
But beyond words, there is the notion of a concrete whole (you can have a 
glance at it out there) versus a historical fresk (you will never can, even 
if this historical inference is highly plausible).

The implication is that a species is not 
real-as-an-observed-concrete-whole, it is only 
highly-plausible-as-the-best-evolutionary-explanation-of-observations-on-available-specimens.
This is what phylogenetic systematics is all about: historical explanation 
of life, not observation of taxa-as-concrete-wholes, not even for species.

Many thanks for thoughtful hints.
Best, Pierre


Pierre Deleporte
CNRS UMR 6552 - Station Biologique de Paimpont
F-35380 Paimpont   FRANCE
Téléphone : 02 99 61 81 66
Télécopie : 02 99 61 81 88