Online research in philosophy

Testosterone is related to dominance, but in a broader sense than Mazur & Booth suggest. Dominance need not be competitive. It can arise from strong personal characteristics that produce admiration and deference in others. To understand the testosterone–dominance relationship fully, we must examine behaviors that affect ordinary social encounters. Baseline testosterone levels may be more important than testosterone changes in predicting everyday dominance.

Although gestures have surface similarities with language, there are significant organisational and neurolinguistic differences that argue against the evolutionary connection proposed by Corballis. Dominance for language and handedness may be related to a basic specialisation of the left cerebral hemisphere for target-directed behaviour and sequential processing, with the right side specialised for holistic-environmental monitoring and spatial processing.

Merker's approach allows the formulation of an evolutionary view of consciousness that abandons a dependence on structural homology – in this case, the presence of a cerebral cortex – in favor of functional concordance. In contrast to Merker, though, I maintain that the emergence of complex, dynamic interactions, such as those which occur between thalamus and cortex, was central to the appearance of consciousness. (Published Online May 1 2007).

The standard behavioral index for human consciousness is the ability to report events with accuracy. While this method is routinely used for scientific and medical applications in humans, it is not easy to generalize to other species. Brain evidence may lend itself more easily to comparative testing. Human consciousness involves widespread, relatively fast low-amplitude interactions in the thalamocortical core of the brain, driven by current tasks and conditions. These features have also been found in other mammals, which suggests that consciousness is a major biological adaptation in mammals. We suggest more than a dozen additional properties of human consciousness that may be used to test comparative predictions. Such homologies are necessarily more remote in non-mammals, which do not share the thalamocortical complex. However, as we learn more we may be able to make “deeper” predictions that apply to some birds, reptiles, large-brained invertebrates, and perhaps other species.