Gorilla DNA reveals human history, study says | Science| In-depth reporting on science and technology | DW | 08.03.2012
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Gorilla DNA reveals human history, study says

An international team of scientists has successfully sequenced the genome of the gorilla – the last great ape to have its genes decoded. Humans, it turns out, have more in common with gorillas than once thought.

Gorillas in einem Zoo in Afrika. Foto: Mark Thomson, 2012, Freigabe durch den Fotografen

Gorillas are the last great ape to be genetically sequenced

Four years after taking DNA from Kamilah, a female western lowland gorilla from the San Diego Zoo, researchers say they have now completed a basic genetic library of the four great apes.

The team's results were published Wednesday in the journal, Nature.

A worldwide team of scientists, led by Britain's Wellcome Trust Sanger Institute, sequenced 20,962 genes extracted from Kamilah's skin, comparing for the first time the genomes of all four living great apes.

"The sequencing of the gorilla genome is a major achievement," said Chris Tyler-Smith, a member of the research team at Wellcome Trust Sanger.

"That genome sequence is really the starting point for modern biology. Now we have sequences for all the great apes – humans, chimpanzees, orangutans and gorillas. We have all the information we're going to get about the big picture."

Genetic history

Scientists, for instance, will be able to compare the data to gain new insight in how humans evolved and developed key traits such as higher brain function and the ability to walk upright.

One of the significant findings between the species over millions of years of evolution turns out to be the similarities. The data show that humans and gorillas differ in only 1.75 percent of their DNA, far less than previously assumed. Humans and chimps – our closest relatives – differ only in only 1.37 percent of their genomes.

Gorillas in einem Zoo in Afrika. Foto: Mark Thomson, 2012, Freigabe durch den Fotografen

The new study hopes to unlock genetic secrets as to how humans evolved

Tyler-Smith pointed to another similarity that could well prompt the science community to reconsider how language has developed.

Previous studies suggested that genes involved in hearing evolved rapidly in humans. The new study, however, found that auditory genes evolved rapidly in gorillas, too, calling into question the belief that genetic changes were linked to the rise of language.

Humans vs. gorillas

The research on the gorilla's genetic makeup comes after the human genome sequence was declared complete in 2003, followed by the chimpanzee in 2005 and the organgutan in 2011.

By comparing the new gorilla DNA sequence with reference genes from humans, chimps and orangutans, the scientists have gained insight into the periods when the four groups diverged into separate species. Tracing exactly when these lineages diverged has been a huge challenge.

According to their new genetic research, the lineage that led to humans, chimps and gorillas evolved from a common ancestor about 10 million years ago. Humans and chimps then separated from that lineage about 6 million years ago. Previous genetic evidence pointed to a more recent split.

Minor differences, major implications

As interesting as the genetic similarities are between humans and gorillas, it could be their differences that fascinate scientists even more, according to Tyler-Smith.

"The 2 percent of differences in the sequences of humans and gorillas are really the interesting bit," he told DW. "They carry the information about what makes gorillas gorilla and humans human."

The findings could have medical implications as well, Tyler-Smith added. The research may help researchers track changes in how species with shared genetic characteristics have responded to diseases.

"There are variants in genes that in humans cause disease but in gorillas seem to be a normal sequence and don't cause disease," he said. "Two examples are dementia and heart failure."

But beyond entangling evolutionary processes and developing new medical applications, the new gorilla genome could also play a crucial role in saving four threatened gorilla subspecies in Africa, researchers say. As their numbers dwindle, so, too, does their genetic diversity and overall resilience.

Author: John Blau
Editor: Cyrus Farivar

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