New research is shedding new light on the evolution of modern humans — a process that continues, millions of years after the evolutionary split from our primate ancestors.
Researchers have now added to the existing body of knowledge to create a genetic map that compares human beings to other vertebrates, finding that a host of newly identified genes are entirely unique to humans.
Additionally, scientists say these findings could help them better understand the role that genetics play in certain diseases.
Their study was published todayTrusted Source in the life sciences journal Cell Reports.
While the study of specific genes can be challenging, scientists say this new dataset helps pave the way toward a more nuanced understanding of human genetics.
Genes: Life’s instruction book
According to Katie Sagaser, MS, CGC, the director of genetic counseling at Juno Diagnostics in San Diego, it’s helpful to think of genes as a set of instructions housed within the nucleus of each cell.
“I often liken genes to the chapters of a textbook,” Sagaser told Medical News Today. “If we think of each cell nucleus as a bookcase, holding the essential instructions for a complex project, then we expect the bookcase to hold 23 pairs of textbooks — 46 total. These textbooks represent human chromosomes inherited from each genetic parent.”
While each parent contributes one set of 23 “textbooks,” the instructions can vary significantly.
When researchers delve into the coils of DNA code embedded within chromosomes, they say they can identify these differences and begin to understand how they play out in the human body.
Genetics aren’t entirely predictable
Complicating matters is the fact that mutations — essentially variations or glitches within DNA sequencing — are entirely possible.
“This is the case when a baby is born with a de novo dominant gene mutation, meaning a single letter of the DNA code was randomly changed in such a way that it resulted in the individual having a unique diagnosis not inherited from either genetic parent,” explained Sagaser.
Another variable that can make genetics difficult to predict is the fact that variations in a person’s DNA code might occur during their lifetime – for instance, as a result of certain cancers.
“Thinking back to our bookcase example, if one were tasked with transcribing and reproducing each letter, sentence, chapter, and volume of a very dense stack of textbooks – it’s absolutely possible for a transcription error to occur,” said Sagaser. “Sometimes, spelling errors have very little consequence, if any. In other instances, however, spelling and other transcription errors can change the intended message altogether.”
Human evolution continues
A pair of scientists — Nikolaos Vakirlis, the new study’s first author and a junior researcher at the Alexander Fleming Biomedical Sciences Research Center in Greece, along with Aoife McLysaght, a senior author from Trinity College Dublin in Ireland — have been studying these “orphan” de novo genes for years.
Vakirlis told MNT that they started out by looking at short sequences of DNA in the human genome.
“These are elements of the genome that are not considered to be proper genes and were until relatively recently mostly left out of ‘mainstream’ genomics studies,” he explained. “However, a recent studyTrusted Source had shown that some of them seem to have important cellular roles.”
From there, Vakirlis and McLysaght sought to pinpoint when these sequences first evolved along the human lineage, along with the mechanisms that allowed them to emerge.
They were able to find a total of 155 de novo originated microproteins. Since de novo gene emergence is now an accepted evolutionary phenomenon, these microproteins could emerge into genes.
Vakirlis said that about a third of these 155 de novo originated microproteins were already known to be functional. However, two of them were strictly specific to humans and others also overlap with known mutations that cause disease.
“What we found is significant because it adds to our understanding of the human genome, including details of human-specific genetics, albeit small,” said Vakirlis. “Our findings also suggest that many more young but important microproteins could be hiding in human cells that can only be uncovered by careful experiments.”
The challenges of studying genes
While the findings shed new light on the human genome and create new avenues for research, it’s still a challenging area to study.
“I think the small size and the recent origins are very important for these genes because they combine to make them into the most difficult cases to study,” McLysaght told MNT. “They are on the edge of detectability both in comparative genomics studies and in genome annotation. And, as Nikos said, this work suggests a greater amount of unappreciated and undetected genes might exist.”
Vakirlis says that the next steps involved gaining a better understanding of how genes can evolve from scratch.
“We can now also conduct wider studies as new datasets of human microproteins are becoming available, in the hope to discover more evolutionarily novel ones,” he said.