In cases where human traits are acknowledged to be variants of traits shared with other animal species, the human variant is sometimes used as the standard by which to assess the non-human version. This practice can be understood as an example of (human) interpersonal consistency — but interspecies inconsistency — overriding ideational consistency, as will be explained below.
(1) Ideational Inconsistencies
To judge nonhuman traits by comparing them with the human version is to privilege the human and ignore the fact that each variant has evolved because it has been of value to the species in question in the context in which it has had to function. What has been of value in the evolution of humans may not have been of value in the evolution of another species, and what has been of value in the evolution of another species may not have been of value in the evolution of humans.
If the traits in question are defined narrowly enough, so as to refer only to the variant specific to humans — privileging the human variant as the standard — then demonstrating that another species lacks the human-specific trait is merely (and trivially) demonstrating that it is not human. An example of this is demonstrating that another species lacks (human) language — instead of investigating language and the communicative interactions of other species as comparable variants of the more inclusive category of social-semiotic systems.
(2) Interspecies Inconsistencies: Separatism And Triumphalism
The interpersonal function of assessing other species by criteria thought to be uniquely definitive of humanity, such as by reference to the human version of semiosis or intelligence[1], is to demarcate a boundary between humans and other species, and so to separate ‘them’ from ‘us’ and ‘us’ from ‘them’, continuing a regional lineage of ancestral modelling that evolved in the Bronze Age, or before.
Demonstrating the inability[2] of other species to perform acts of evolutionary value to humans but not to the species in question has the interpersonal function of judging the other species to be inferior to humans[3] (because they are not human), and so, judging that humans are superior to other species (because we are human).[4]
This triumphalism is the interspecies variant of intraspecies racism (“they are inferior because they are not us”) and nationalism (“we are superior because we are us”). It is no accident that the measure of intelligence is a strategy common to both versions of the practice: the interspecies and intraspecies varieties. The dismissal of the value of the semiosis of other animal species by humans is the interspecies version of the dismissal of the value of the languages of indigenous people — “jabbering” — by the people invading them, stealing their land and destroying their livelihood.
Footnotes:
[1] The identification of‘intelligent’ with ‘human’ is demonstrated by the self-selected species name: Homo sapiens sapiens.
[2] Note also the potential modality error of mistaking (dis)inclination for (in)ability. Conditioning experiments demonstrate the importance of motivation for behaviour, and alert us to what we interpret as a matter of ability in other species may instead be a matter of inclination.
[3] Consider the quickness of humans to delimit the possibilities of other species, in the absence of any evidence whatsoever, including all the false claims about other species — eg no brain lateralisation, no tool use, no toolmaking — based only on preconceived assumptions.
[4] This species “cheerleading” might be seen as evidence of the interpersonal damage caused by the proposition that humans are animals of this world, rather than eternal beings of some imagined one.