Human Brain Hypothesis

The human brain is one of many features that make our species a unique species. It is responsible for language acquisition and logic and reasoning as well as many other cognitive functions that make us unique compared to other species. This is one of the reasons scientists aim to study the brain and its evolutionary history. Scientists believe a correlation exists between these functions and the brains large size in proportion to the rest of our bodies. Fossil evidence supports this theory. Fossil evidence has shown an increase in cranial size as higher cognitive functions, such as cave paintings and stone tools, arose. Scientists still do not understand how an increase in brain size has led to such an increase in cognitive functions. They …show more content…
They primarily focused on how the differences between the sensory and motor cortices and the association cortices of humans and other mammals could expand on the current theories explaining the evolution of the human brain and its complexity. They found many cortical pathways are arranged in a canonical and hierarchical manner and that different cortices have different functions. One hypothesis explaining the complexity of the human brain was that the regions in between the sensory and motor categories expanded allowing more complex associations between neurons to be generated. Another possibility is that this expansion allowed for the creation of functions separate from the functions of the sensory and motor cortices’ function in this region. A third hypothesis is that the association cortices work parallel to other cortices as a separate entity in the areas of information processing. Buckner and Krienen used fMRI scans to determine which of these hypotheses could be validated. They compared cortical sizes and amount of gray matter. Cortical size formation is correlated with number of cortical divisions. Signaling molecules, called patterning centers, determine what kind of neuron the neuron will be before it is sent out to its subsequent cortex to form synapses. Building off previous cortical organization theories, Dr. Buckner and Dr. Krienen came up with the tether …show more content…
By examining DNA sequences for similarities and differences within certain genes, the DNA data would be able to show if there are any genes that humans have that any other species do not have. Once these genes have been identified and their effects determined, the genes that code for proteins affecting brain development or growth could be isolated. The DNA comparisons would allow phylogenetic relationships to be established, which would help determine when traits emerged or disappeared. This would provide insight on when brain size and complexity started to increase. Once the time frame of when the traits for brain size and complexity arose has been established, what conditions and selective pressures caused them to increase could be determined by looking at the particular environments that existed in that time period. For genes that exist and are similar in both humans and mammals with smaller, less complex brains, protein levels for all the species’ could be measured and used to determine if protein concentrations affect size or