Reconsidering the evolution of brain, cognition, and behavior

Reconsidering the evolution of brain, cognition, and behavior

Concluding Remarks

Beside all the methodological and conceptual problems reported here, a significant bias in evolutionary neuroscience is the particular place given to human brain and cognition. As stated by Deacon; “we are, after all, the ‘sapient’ ape, distinguished from all other species by our unusual mental powers. But this has also motivated the many preconceptions that we bring to the topic that affect both the selection of scientific evidence and our interpretations of it. The single most pervasive issue behind most of these preconceptions is the notion of human intellectual superiority” (Deacon, 1990a, original quotation marks). Under this view, it is the fact that the human brain is not at the top of a criterion that makes this criterion inadequate for determining intelligence, and conversely. The misconceptions that this approach has lead, even at the brain size level (see above), have a heuristic value and warn against considering this approach for more complex variables. This comment echoes Chittka et al. (2012) who, referring to an analysis that found human species to be the slowest in a color learning task, warned that although “there may be good reasons not to equate learning speed with intelligence […] the fact that humans do not top the chart should not be one of them.”

The importance of such fallacies can be broadened to the mammalian brain in general. For instance, spontaneous mirror self-recognition occurs with the 350 g chimpanzee’s brain (Gallup, 1970), the 2000 g dolphin brain Tursiops truncatus (Reiss and Marino, 2001) and the 4000 g elephant brain Elephas maximus (Plotnik et al., 2006) but also with the small 5 g magpie brain Pica pica (Prior et al., 2008). More generally, the complex cognitive abilities of several bird species (Emery and Clayton, 2004; Emery, 2006; Kirsch et al., 2008), suggest that the brain architecture of birds is particularly efficient. This is interesting, given the relatively recent misconception that bird intelligence was limited and their behaviors only stereotyped (Emery, 2006) and the still widely accepted postulate that the mammalian brain is the most complex and efficient structure in term of cognitive abilities. In fact, the highest ratio of cognitive abilities to neuron number could possibly be found in non-vertebrate taxa such as cephalopods (e.g., Hochner et al., 2006; Grasso and Basil, 2009; Ikeda, 2009) and insects (e.g., Menzel and Giurfa, 2001; Chittka and Skorupski, 2011).

Finally, it is particularly striking to note [as Griffin (1976) did more than twenty-five years ago] that the subjective part of behavior, that is, the way animals experience the world, has been systematically put aside in comparative studies of animal behavior. As stated byShettleworth (2001): “it is possible, indeed usual, to study the ways in which animals acquire information about the world through their senses, process, retain and respond to it without making any commitment about the nature of their subjective experience or awareness.” Yet, what makes a bird or mammal flee danger is fear or pain, to search for food is hunger, what makes it look for mates is sexual arousal and for a place to sleep is fatigue, so that the subjective dimension of animal mind; consciousness, is the fundamental link between brain, cognition, and behavior. Studying animal brain and behavior without raising the question of how animals experience the world is likely to be as incomplete as was studying biology without evolution. In fact, this is one of evolutionary neuroscience’s principal challenges.

Full Study

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