Small but distinct differences among species mark evolution of human brain

November 23, 2017
Credit: Human Brain Project

The most dramatic divergence between humans and other primates can be found in the brain, the primary organ that gives our species its identity.

However, all regions of the human have molecular signatures very similar to those of our primate relatives, yet some regions contain distinctly human patterns of that mark the brain's evolution and may contribute to our cognitive abilities, a new Yale-led study has found.

The massive analysis of human, chimpanzee, and monkey tissue published Nov. 23 in the journal Science shows that the is not only a larger version of the ancestral primate brain but also one filled with distinct and surprising differences.

"Our brains are three times larger, have many more cells and therefore more processing power than chimpanzee or monkey," said Andre M.M. Sousa, a postdoctoral researcher in the lab of neuroscientist Nenad Sestan and co-lead author of the study. "Yet there are also distinct small differences between the species in how individual cells function and form connections."

Despite differences in brain size, the researchers found striking similarities between primate species of gene expression in 16 regions of the brain—even in the prefrontal cortex, the seat of higher order learning that most distinguishes humans from other apes. However, the study showed the one area of the brain with the most human-specific gene expression is the striatum, a region most commonly associated with movement.

Distinct differences were also found within regions of the brain, even in the cerebellum, one of the evolutionarily most ancient regions of the brain, and therefore most likely to share similarities across species. Researchers found one gene, ZP2, was active in only human cerebellum—a surprise, said the researchers, because the same gene had been linked to sperm selection by human ova.

"We have no idea what it is doing there," said Ying Zhu, a postdoctoral researcher in Sestan's lab and co-lead author of the paper.

Zhu and Sousa also focused on one gene, TH, which is involved in the production of dopamine, a neurotransmitter crucial to higher-order function and depleted in people living with Parkinson's disease. They found that TH was highly expressed in human neocortex and striatum but absent from the neocortex of chimpanzees.

"The neocortical expression of this gene was most likely lost in a common ancestor and reappeared in the human lineage," Sousa said.

Researchers also found higher levels of expression of the gene MET, which is linked to , in the human compared to the other primates tested.

Explore further: Scientists make autism advance using monkey model

More information: A.M.M. Sousa el al., "Molecular and cellular reorganization of neural circuits in the human lineage," Science (2017). science.sciencemag.org/cgi/doi … 1126/science.aan3456

Related Stories

Scientists make autism advance using monkey model

August 21, 2017
Autism is a common neurodevelopmental disorder characterized by impaired social communication and restricted and repetitive behavior or interests. The reported prevalence of autism has been rising worldwide. Due to the application ...

Human brain development is a symphony in three movements

December 27, 2013
(Medical Xpress)—The human brain develops with an exquisitely timed choreography marked by distinct patterns of gene activity at different stages from the womb to adulthood, Yale researchers report in the Dec. 26 issue ...

Changes in the path of brain development make human brains unique

December 6, 2011
How the human brain and human cognitive abilities evolved in less than six million years has long puzzled scientists. A new study conducted by scientists in China and Germany, and published December 6 in the online, open-access ...

Two heads are better than one: Gene expression reveals molecular mechanisms underlying evolution of cerebral cortex

November 9, 2012
Dramatic expansion of the human cerebral cortex, over the course of evolution, accommodated new areas for specialized cognitive function, including language. Understanding the genetic mechanisms underlying these changes, ...

Found in the developing brain: Mental health risk genes and gender differences

October 26, 2011
Most genes associated with psychiatric illnesses are expressed before birth in the developing human brain, a massive study headed by Yale University researchers discovered. In addition, hundreds of genetic differences were ...

Recommended for you

Little understood cell helps mice see color

December 14, 2017
Researchers at the University of Colorado Anschutz Medical Campus have discovered that color vision in mice is far more complex than originally thought, opening the door to experiments that could potentially lead to new treatments ...

Scientists chart how brain signals connect to neurons

December 14, 2017
Scientists at Johns Hopkins have used supercomputers to create an atomic scale map that tracks how the signaling chemical glutamate binds to a neuron in the brain. The findings, say the scientists, shed light on the dynamic ...

Journaling inspires altruism through an attitude of gratitude

December 14, 2017
Gratitude does more than help maintain good health. New research at the University of Oregon finds that regularly noting feelings of gratitude in a journal leads to increased altruism.

Gene mutation causes low sensitivity to pain

December 13, 2017
A UCL-led research team has identified a rare mutation that causes one family to have unusually low sensitivity to pain.

Activating MSc glutamatergic neurons found to cause mice to eat less

December 13, 2017
(Medical Xpress)—A trio of researchers working at the State University of New York has found that artificially stimulating neurons that exist in the medial septal complex in mouse brains caused test mice to eat less. In ...

Scientists discover blood sample detection method for multiple sclerosis

December 13, 2017
A method for quickly detecting signs of multiple sclerosis has been developed by a University of Huddersfield research team.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.