Many proteins (and structural RNAs as well) are conserved throughout the entire history of life as we know it (not just older than species that cannot even be meaningfully defined in prokaryotes and viruses).
This state cannot even be changed by an external stimulus.
Otherwise competition and extinction, or even identity, cannot be defined as a replicator.
Family relationships cannot be ordered, they cannot be defined in court papers.
This value is complex and can only emotionally be grasped but it cannot be defined, nor even propositionally characterized.
Another member of the biochemistry department, N.W. Pirie, tackled the question of defining life and concluded that it could not be adequately defined by a list of qualities nor even processes since life "cannot be defined in terms of one variable" (Pirie 1937, p. 21 22).
However, they admit the term cannot easily be defined.
ACOS cannot yet be defined.
Thus biological species cannot currently be defined for cercomonads.
However, the two combinations cannot strictly be defined as "bioequivalent".
"Our community cannot be defined by one group.
