Through millions of years of evolution, primates have gained the cognitive ability to think that differentiates them from other mammals. Scientists believe that the gene that accounts for this isosteocrin (OSTN), which is expressed in the neurons of primates as well as in the bones and muscles of mammals. Scientist Bulent Ataman and colleagues cultured human neurons in vitro to simulate brain activity and learn more about the OSTN gene. They then used RNA sequencing to determine upregulated transcripts, in which they found a few transcripts specific only to human neurons, the most active one being OSTN. OSTN was also found to be expressed in the neocortex (which contains cognitive functions) and cortex of primates, and was expressed in response to brain activity, which makes this gene activity-dependent.
Ataman and colleagues also discovered the presence of the myocyte enhancer factor 2 (MEF2) family in primates, which binds to DNA sequences (MREs) in the neurons, while other mammals lack this factor. Scientists believe that the creation of MREs are due to a mutation in nucleotides millions of years ago when primates split off from other mammals. While other mammals lack the MRE site, primates contain three sites, and when bound induce transcription in other genes.
Scientists have found that this gene expression regulates the shape of dendrites, the branches of neurons that send and receive signals. The scientists conclude that this factor allows the cognitive thinkingin primates as a result of learning, as the expression can change dendrites so that the movement of signals is much more efficient. This experiment is important as it explains the reason as to why humans are able to think at a higher level than other animals, and how we can retain what we have learned to make predictions and anticipate the future rather than only live in the present.