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Darwin-L Message Log 4:22 (December 1993)

Academic Discussion on the History and Theory of the Historical Sciences

This is one message from the Archives of Darwin-L (1993–1997), a professional discussion group on the history and theory of the historical sciences.

Note: Additional publications on evolution and the historical sciences by the Darwin-L list owner are available on SSRN.


<4:22>From princeh@husc.harvard.edu  Wed Dec  8 14:20:51 1993

Date: Wed, 8 Dec 1993 14:15:03 -0500 (EST)
From: Patricia Princehouse <princeh@husc.harvard.edu>
Subject: Re: extinction & splitting heirs
To: darwin-l@ukanaix.cc.ukans.edu

On Wed, 8 Dec 1993, Terrence Peter McGlynn wrote:

> There is a definite analogy between linguistics and evolution regarding
> the types of extinction.

Definite, perhaps, but very superficial.

> it looks like fossilized organisms are called different species when there
> is a significant enough structural change.

Yes, fossil species are based primarily on morphological differences
(Steven Spielberg notwithstanding).

> slow change from one species to another is probably much less common from
> the "branching" evolution, because usually new species arise in very small
> populations that are isolated from a larger one...

I understand you to be saying here that anagenesis is much less common
than cladogenesis -a view which has become very popular in the past 10
years, but is problematic for analogy with language since languages are
never "reproductively isolated" (so to speak) from each other, while
species are seen as "temporally bounded entities" (to cite the litany).

> In short, when did homo erectus become homo sapiens?  That's
> probably an equivalent question to when did Latin become Spanish.

I see at least 3 important differences here:

1) We know that Latin is ancestral to Spanish, but we do NOT know that
_Homo erectus_ (especially in the strict sense - the Indonesian fossils)
is ancestral to _H. sapiens_

2) Even if _H.e._ is ancestral, that doesn't necessarily mean that a large
erectus population somehow magically turned into a large population of
_H.sapiens_. Erectus (especially in the broad sense) was a fairly long
lived species and might have given rise (by branching) to _Hs_ at any
time, only to die off later and have its range overrun by the younger
species (producing a continuous fossil record in that range but not one
reflecting evolutionary history).

3) As mentioned above, Spanish could have been formed by crossing Latin
with other languages (surely there was influx to some extent), but a
daughter species arises from only one parent (with very minor exceptions
of very special cases of retro-virus insertion of functional gene
sequence).

The analogy would kind of work for tracking morphological change between
subspecies, but if one finds that microevolution =\= macroevolution, then
it doesn't work so great for species change.

-Patricia Princehouse, Princeh@Husc.Harvard.Edu

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