A New Take on Sex

Dec 12, 2013

Birds do it.  Bees do it.  No…we’re not talking about ‘falling in love,’ we’re talking about sex.  Biologists have long known it plays a vital role in passing new gene combinations on to the next generation, but what’s been less clear, is exactly how that works.  

Now, a Virginia Tech Biologist has a new theory that challenges long held notions about natural selection and survival of the fittest. 

Adi Livnat/Virginia Tech

You thought you knew why most organisms on earth need sex to procreate.  But Assistant Professor of Biology at Virginia Tech, Adi Livnat says scientists have actually never had a good explanation for the vital role it plays in evolution. “That’s been the question that’s been called the queen of problems in evolutionary biology.”
The biological definition of sex is rather prosaic. Two individuals exchange genes and pass on a new combination to their offspring.  That’s why it takes two.
“But the problem is, that even though it sounds like such an intuitive answer, it’s actually been an incomplete answer for 80 years.  The problem is that we live and die, and so the combination of genes that we carry, they don’t last, just as this sexual shuffling of the genes puts them together in one generation it immediately breaks them down in the next generation.”

Livnat says Charles Darwin’s model of natural selection or survival of the fittest doesn’t fully explain the ways by which traits are passed on to future generations.  But his biggest disagreement with traditional theory is that mutations, which lead to new traits in the process, happen simply by accident.
“Could mutation really be just an accident? Could it be that an accumulation of accidental genetic changes, would after a million years, lead to the evolution of a complex adaptation?”
Just last year, the Encyclopedia of DNA Elements Consortium, known as ‘ENCODE,’ announced its own discovery that there is much more going on within the human genome than previously thought. Livnat’s new theory, arrived at separately, provides a new angle from which to view the findings. "What my theory shows is that mutation is not accidental. It’s an outcome of biological process.  What this means is that mutation collects information from the complex combinations of genes that we carry and puts it together into the locus where the mutation happens.  Information is, after all, transmitted to future generations from the combinations of genes that are constantly generated by sex.”
Livnat says that for the first time, we have an explanation for the importance and ubiquity of sex across species.  He published his new theory last month in the journal “Biology Direct.” Now, people who were instrumental in the ENCODE project are looking at it with interest.

“Yeah. I think it’s incredibly novel," says Professor Michael Snyder, Stanford University Genetics Department Chairman. "What I think is really remarkable about the study is that it gives us fundamentally new understandings for how we can evolve fairly quickly. Organisms like humans go through challenges constantly with pathogens, with environmental stresses and we’ve got to be able to evolve quickly to be able to adapt to these new environments and these new challenges and it’s a new level of understanding that hasn’t been appreciated previously," said Snyder.

Some biologists question this new thinking, but none we contacted would comment for this report.  To Professor Livnat, that’s the beauty of scientific inquiry; the generation of new ideas, and the lively debates, which follow.  But there is no doubt that scientists are facing a new frontier, as they explore the complex biological machinery of how mutations work. Livnat says that’s what makes this an exciting time to be working in his field. He hopes his discovery will lead to new answers about how cancer and other diseases work  --and, about our deepest understanding of  life itself.