Species

The Species Problem Arises 193

George Romanes, who coined the term “neo-Darwinism” to sneer at the extreme

selectionist views of Wallace and Weismann,^10 in his Darwin and after Darwin gave

ve denitions of species:^11

1. “A group of individuals descended by way of natural generation from an
   original and specially created type.”
   He calls this “virtually obsolete.”


2. “A group of individuals which, while fully fertile inter se, are sterile with
   all other individuals—or, at any rate, do not generate fully fertile hybrids.”
   Romanes calls this the “physiological denition” and claims that it is not
   entertained by any naturalist at that time, as it is incomplete.


3. “A group of individuals which, however many characters they share with
   other individuals, agree in presenting one or more characters of a peculiar
   kind, with some certain degree of distinctness.”
   Romanes claims this is practically followed by all naturalists. But it is
   insufcient to enable a uniform standard of specic distinction, and so he
   adduces two more denitions, “which will yield to evolutionists the steady
   and uniform criterion required.”


4. “A group of individuals which, however many characters they share with
   other individuals, agree in presenting one or more characters of a peculiar
   and hereditary kind, with some certain degree of distinctness.”
   This merely adds hereditary characters to the previous denition.
   And nally, he adds one for the “ultra-Darwinians” who insist that spe-
   cies are formed through natural selection.


5. “A group of individuals which, however many characters they share with
   other individuals, agree in presenting one or more characters of a peculiar,
   hereditary, and adaptive kind, with some certain degree of distinctness.”

These are the “logically possible” denitions of species, meaning by this that
they include all the differentiae of the thing dened. Romanes presents something
rather similar to some versions of the modern phylogenetic species concepts, but
the “degree of distinctness” is still relatively vague, and relies on the judgment of
the specialists. He rejects absolutely the idea that the characters that mark species
from each other must or even can be adaptive, and a discussion he instigated in the
Biological Section of the British Association ended in

... as complete a destruction as was possible of the doctrine that all the distinctive

characters of every species must necessarily be useful, vestigial or correlated. For it

became unquestionable that the same generalization admitted of being made, with the

same degree of effect, touching all the distinctive characters of every “snark.”^12

(^10) Although Gould 2002, 198 ascribes this to Spencer in 1893, Romanes claimed the honor in his 1895
as an earlier coinage of his own.
(^11) Roma nes 1895, vol. II, 229–234.
(^12) Roma nes 1895, 235.