Thursday, November 15, 2012

Natural selection at work: discovery of a new gene unique to humans

Hot off the press is the discovery of a new gene that is found in humans but not in other species, including other great apes.

gorillas in deep thought?

What's the big deal?

This is the first time that a new gene -- carried only by humans and not by apes -- has been shown to have a specific function within the human body.

Cartoon by Chris Madden:
check out his science cartoons
The gene, called miR-941, is especially active in parts of the brain involved in language and in tool use -- two areas that clearly distinguish humans from our nearest cousins.

The authors speculate that the emergence of miR-941 helped to maintain stem cell populations within humans, which in turn supported longer human lifespans but left human cells more prone to cancer-related transformation.

So here is an extraordinary example of superior evolutionary fitness resulting from development of a new gene millions of years ago.

What does this gene do?

With the development of this gene, early humans apparently improved their use of both tools and language, both key to our current world domination (read: uber-high level of fitness).

It also seems to have been associated with longer lives and greater vulnerability to cancer cell development.

Chimp communication not controlled by the miR-941 gene
Photo: frogbellyand Animal Photos!
Previous studies have found genetic differences between us and our ape cousins, but these were linked to changes to existing genes (i.e. in various genes shared by humans and non-human apes, we have different versions of the genes, which have resulted in different effects), rather than development of totally new genes.

The scientists estimate that this gene emerged between 1 and 6 million years ago, after humans and chimps had split from their last common ancestor. Anyone remember that far back?

The gene seems to have sprung from nowhere at a time when our species was undergoing other dramatic changes: living longer, walking upright, learning how to use tools and how to communicate.

Scientists believe this gene is connected to cognitive functioning (mental action or process of acquiring knowledge and understanding through thought, experience, and the senses) and consider it key to understanding what make us human.
golden monkey surprised at his lack of cognition

For more information, check out the Science Daily description of the findings, or, for the truly motivated, the original paper, published in the journal Nature Communications.

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