‘Junk DNA’ explains the difference between humans and chimpanzees –

The chimpanzee is our evolutionary closest living relative, and the research believes our relationship is based on a common ancestor. About five to six million years ago, our evolutionary paths were divided into what are today modern chimpanzees and Homo sapiens, the twenty-first century human.

In a new study, Lund stem cell researchers investigated what is in our DNA that makes human and chimpanzee brains different and found answers.

Instead of studying living humans and chimpanzees, we used stem cells grown in a cell culture lab. Stem cells have been reprogrammed from skin cells by our partners in Germany, the United States and Japan. Next, we examined stem cells that we originated in brain cells, explains Johann Jacobson, professor of neuroscience at Lund University, who led the study in Lund.

Comparing brain stem cells between humans and chimpanzees

From the stem cells, the researchers specifically grew human and chimpanzee brain cells and compared the two types of cells. The researchers then found that humans and chimpanzees use some of their DNA in different ways, which seem to play a key role in the development of our brains.

The part of our DNA that differs was not expected, these are the so-called structural variants of DNA that were previously referred to as ‘junk DNA’, a long strand of self-replicating DNA that has long been judged to be nonfunctional. . Typically, we searching for answers have looked for answers in the part of DNA where the protein-producing genes are located – something that makes up only about 2% of all DNA – and examined the proteins themselves to find examples of differences.

The differences lie in our unwanted DNA

The new findings suggest that the differences appear outside of the protein-coding genes. In “junk DNA” that was thought to have no function and make up the majority of our DNA.

– This may explain that what underlies the evolution of the human brain may be more complex genetic mechanisms than previously thought, when the answers were thought to be in the genomic DNA of 2 percent. Our results suggest that what was important to brain development may instead be hidden in the overlooked 98 percent, which appears to be significant. This is a surprising result.

The stem cell technology used by researchers at Lund is revolutionary and won the Nobel Prize in Medicine or Physiology in 2012. It was Japanese researcher Shinya Yamanaka who discovered that specialized cells can be reprogrammed and developed into all tissues of the body. And in the case of Lund researchers, for brain cells. Without this technology, it would not have been possible to study the differences between humans and chimpanzees using ethically defensible methods.

Searching for answers to what makes a person human

Why, then, did the researchers want to investigate the difference between humans and chimpanzees?

I think the brain is the key to understanding what makes a person human. How can a person use his brain in a way that enables him to build societies, educate his children, and develop advanced technology? It’s a great!

Johann Jacobson believes that new findings in the future may also contribute to gene-based answers to questions about mental illnesses, such as schizophrenia, a disease that appears to be specific to humans.

But the road there can be a long one, so instead of doing more research on the 2 percent coding DNA, you may now have to dig deeper into each 100 percent, which is a much more complicated task to research.

Scientific material:

Structural variation effected at the ZNF558 locus in the gene regulatory network controls human brain developmentStem Cell, October 7, 2021

Call:

Johan Jacobsson, Professor of Neuroscience, Lund University, [email protected]