FEB 16, 2019 2:32 PM PST

Studying the Evolution of the Human Brain

WRITTEN BY: Carmen Leitch

From a genetic perspective, humans are very similar to chimpanzees and a cousin of theirs, the bonobo; the genetic difference between them and us is only about 1.2 percent. However, those small changes in genes add up to significant changes in behavior and cognition.  Researchers have been studying what it is, specifically, that makes the human brain different from the species we have so much in common with genetically. Scientists from the Salk Institute and UC San Diego have now developed a way to study the differences and similarities in the development of neurons in humans and nonhuman primates. Their work has been reported in eLife.

Human iPSC-derived neurons / Credit: eLife/Marchetto et al 2019

"This study provides insights into the developmental organization of the brain and lays the groundwork for further comparative analyses between humans and nonhuman primates," said a senior author of the study, Salk President and Professor Rusty Gage.

In development, it's essential for neurons to mature; they have to make the right connections and communicate properly with other cells. It's also imperative that they get to the right location in the brain. 

In this work, the researchers compared these processes of migration and maturation in the different species by first deriving stem cells from skin cells of each species. That Nobel-prize winning process has been used in many aspects of biological research, and now presents a way to use cell lines grown in the lab to study neurons derived from endangered primates.

"This is a novel strategy to study human evolution," said a co-first author of the work Carol Marchetto, a Salk senior staff scientist in the Laboratory of Genetics. "We are happy to share these primate cell lines with the scientific community so that researchers from around the world can examine primate brain development without the use of tissue samples. We anticipate this will lead to numerous new findings over the next few years about the brain's evolution."

The researchers identified 52 genes that were connected to neuronal migration. They also found that neurons from chimpanzees and bonobos went through periods of rapid movement, but human neurons migrate more slowly.

To further asses the differences in the migration and maturation of neurons, the team transplanted neural progenitor cells into rodent brains. They followed the transplant models for nineteen weeks and determined that neurons derived from chimpanzees move further, spanning an area that was 76 percent greater than human-derived neurons after two weeks. Neurons derived from humans developed at a slower pace but had a longer length than chimpanzee neurons in the end. 

The researchers want to create a tree with several primate species using these types of cell lines so that they can have a better understanding of the evolution of the brain. 

"We have limited knowledge about the evolution of the brain, especially when it comes to differences in cellular development between species," said Marchetto. "We're excited about the tremendous possibilities this work opens up for the field of neuroscience and brain evolution."

The video above features Gage discussing the differences between humans and great apes.


Sources: AAAS/Eurekalert! Via Salk Institute, eLife

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
JUL 01, 2020
Genetics & Genomics
How Neighborhoods Can Impact Gene Expression in Kids
JUL 01, 2020
How Neighborhoods Can Impact Gene Expression in Kids
Researchers followed 2,000 kids and determined that when young adults were raised in disadvantaged neighborhoods, their ...
JUL 06, 2020
Genetics & Genomics
Learning More About How Folds Form in the Developing Brain
JUL 06, 2020
Learning More About How Folds Form in the Developing Brain
The folds of the human brain are essential to its function, and improper folding has been linked to a variety of disorde ...
AUG 03, 2020
Genetics & Genomics
Understanding How Disease Risk Begins in Development
AUG 03, 2020
Understanding How Disease Risk Begins in Development
Many common complex diseases are thought to be caused by an interplay of genetic and environmental factors.
AUG 21, 2020
Genetics & Genomics
Genetic Variants in a Person's Genome Influence Each Other
AUG 21, 2020
Genetic Variants in a Person's Genome Influence Each Other
While it's difficult to study multiple genes at the same time, genes exist within a much larger framework that includes ...
SEP 09, 2020
Microbiology
Changing How We Think of Drug Resistance in Fungi
SEP 09, 2020
Changing How We Think of Drug Resistance in Fungi
It's been estimated that fungal infections cause more than one million deaths worldwide, and many more are affected.
SEP 16, 2020
Genetics & Genomics
Epigenetic Defects Are More Common in People Than Thought
SEP 16, 2020
Epigenetic Defects Are More Common in People Than Thought
The genome still holds many secrets, some of which probably have a direct relationship to human disease. Beyond genes th ...
Loading Comments...