Carl Zimmer writes today in the New York Times in The Continuing Evolution of Genes that scientists used to believe that the some 20,000 genes we all have, came from our parents, which came from their parents, and on backwards to the very first forms of life. And that the genes all organisms have, can be traced back to these original genes.

The thinking was that at first there were just a few genes, and at times when they duplicated, making two copies of the same genes, which over time evolved into different genes, hence the increasing number and complexity of genes we now find.

With new genes evolving from earlier ones, it would be possible to compare the genes and see which genes came from which genes.

But when scientists gained the ability to read DNA sequences, they discovered that though most genes were duplicated versions of earlier ones, there were also a number of genes which were unique to a species. They called these orphan genes de novo genes. Unlike most genes which have been passed down through the generations for billions of years, de novo genes came into being much later.

Carl Zimmer’s article explains how these orphan genes came into existence, and the role they play in evolution. The article is worth a read. It also has a podcast with a segment describing the origin of genes.

One thing I am trying to find is a scientist who is researching how instinct is encoded in DNA. The first time one of my hens hatched and raised a clutch of chicks, it made me wonder how she knew how to that. She was a hatchery chick and raised without a mother. So how did she know that if she sat on an egg for 21 days that they would hatch. And all of the hens I’ve observed, use the same calls for danger, here’s good food, be quiet, etc. And all the chicks know from birth what these calls mean.

So how is all that complex behavior inscribed on DNA? I’ve come up with many scientists researching genetic behavior and trying to determine what behavior is genetic and what is learned. And scientists knocking out genes in organisms like flies to see how those genes affect fly behavior and the like. But I’ve yet to find the scientists looking at the GATC letters of specific DNA to tease out how complex behavior is carried by DNA from generation to generation. I’m sure it is extremely complicated, but hopefully there is a scientist out there who is studying this and can explain how nature does this amazing feat.