It has traditionally been believed that the cognitive abilities of humans differentiates them and makes them superior to other animals. Charles Darwin is often credited with reducing the notion of human superiority by identifying the mechanisms of biological evolution (Erdos, 2020). However, this is somewhat overstated; for example, although Darwin believed that humans had evolved biologically in the same way as other animals, he also held the view that humans had risen to the summit of the organic scale (Darwin, 1871) and are, therefore, superior. Furthermore, the idea that humans have reached the pinnacle of intelligence infers a single evolutionary chain of events towards perfection (orthogenetic view) (Grehan and Ainsworth, 1985); however, intelligence has evolved independently in other vertebrates, for example, corvids have evolved greater cognitive abilities than most other bird types (Seed et al., 2009).
Robin (1973) postulates that there is no absolute measure of superior traits over inferior traits. However, it is widely accepted that evolution involves the process of favouring superior (more beneficial) traits and rejecting inferior traits (Riechmann, 2001). This acceptance may be somewhat misleading because any trait (including cognitive ability) which improves fitness for a particular species at a particular time may have no fitness benefit (or become maladaptive) at another time due to continuous environmental change. Therefore, intelligence, as a superior trait, is relative.
The idea of intelligent superiority has resulted in considerable human suffering; for example, eugenics policies of the Nazi regime led to the forced sterilisation of German citizens for ‘feeble mindedness’ (Seeman, 2005) and culminated in the systematic murder of six million Jewish people during the Holocaust (Robinson et al., 1990). It may also be argued that intelligence measuring is biased towards humans, or skills which are most valued by humans. Cetaceans are often considered highly intelligent due to abilities associated with human abilities, for example, complex social lives, vocal communication, and self-recognition (Grimm, 2011). However, the macrosmatic ability of many mammalian species may not be valued so highly due to humans being microsmatic and therefore lacking in appreciation or conceptual ability (Nielson et al., 2015). This postulation is supported by the lack of animal olfactory research compared to that of other sensory modalities (Campbell-Palmer and Rosell, 2011).
It is widely accepted that all extant animals are genealogical descendants of a common ancestor (Sober and Steel, 2002). This is evidenced by each sharing detailed and complex genetic coding (Vetsigian et al., 2006) and supported further by computer modelling of ubiquitous proteins (Theobald, 2010). Therefore, different species may represent divergence, but all carry the genetic code of a single ancestor. Considering that life is dependent on generational transfer of genetic coding, it may be considered that no animal is superior to any other, but that divergence into different phenotypes (including cognitive abilities) secures continued transfer following extinction of any particular species, order, or class. Humans have unique abilities, for example, language; however, this is judged as superior intelligence from a human perspective. Other species have abilities that humans do not share, for example, bats have the ability to use echo location (Jones and Teeling, 2006) and many birds have the ability to use the earth’s magnetic field to navigate migration flights (Wiltschko et al., 2009). It would not be unreasonable for these species (if they were setting the standard) to consider their smaller brains superior to humans. From an evolutionary perspective, there may also be benefits to having a smaller brain, for example, smaller brains are lighter and require less energy (Wang et al., 2008). So, is human intelligence superior, or just different?