Darwin and Intelligence / Aristotle's Scala Naturae

Intelligence and consciousness can be viewed as dynamic phenomena that have evolved over time. Darwin's theory of evolution by natural selection and the more modernly refined synthetic theory of evolution can provide a sound scientific explanation for why an animal's behavior is usually well adapted for survival and reproduction in its environment. Similarly, Tinbergen's question of adaptation addressed how a species trait evolved to solve a reproductive or survival problem in the ancestral environment. Intelligence is clearly a trait that is functional to the survival and reproductive success of the organism. In fact, it is most likely the unique ways of thinking that have allowed humans to adapt to the various environments and cultures in the world.

Intelligence can viewed as the one trait that has allowed for massive population growth and the perceived "dominance” of humans.

Darwin (1859) used comparative psychology and biology to compare the behavior of different species to develop his theories of evolution. He concluded that animal species changed over time with later generations displaying characteristics that helped earlier generations survive (Darwin, pp. 41-63). 

Organisms can be viewed as open systems, which constantly exchange matter and energy with their surroundings. The variability in members of a population leads to variety in behavior and method of coping with certain conditions (Darwin, pp. 63-81). 

This variation due to random mutation and differing allele frequencies could be inherited from parent to offspring and shaped by the forces of natural selection. In The Descent of Man (1874), one of Darwin's later works explains that it is "highly probable that with mankind the intellectual faculties have been mainly and gradually perfected through natural selection... undoubtedly it would be interesting to trace the development of each separate faculty [intellectual skill] from the state in which it exists in lower animals to that which exists in man” (pp. 128-129). He believed it was logical to trace the development of intelligence in different species leading to the development of intelligence in humans.

However, historically, people tend to misinterpret much of Darwin's work and ideas. Many of these misinterpretations are based upon our "human-centric" views. Many believe people are the pinnacle of billions of years of evolution when in fact evolution is a continuous process with no real end goal or destination. Additionally, people tend to anthropomorphize and project human qualities upon animals. 

Certain aspects of intelligence can be traced through the development of "primitive" animals to "complex" animals; however, intelligence cannot fully be traced as it moved up the phylogenic scale by looking at the current faculties of animal's mind. All existing species are current products of millions of years of evolution and many different forms of intelligence, unique to each species, have developed. There is no reason to expect mental capacities of animals to fall into a smooth, continuous progression leading to the "superior" intelligence of humans. This linear approach is too simplistic to explain the emergence of new properties in a complex system.

We have made immense strides in science since Aristotle's Scala Naturae and History of Animals. We have to continue with open, forward thinking to properly understand the work of amazing minds such as Darwin and Aristotle. The advent of genetics and neuroscience have allowed us to theorize on human evolution in a more modern, less "human-centric" manner. As we continue to theorize on human evolution we have to properly context the great minds before us, but we cannot be blinded by some of their "ancient" observations.