Human Genetic Variations Changing Rapidly

In the most massive study of genetic variation yet, researchers have determined that the age of more than one million variants ~ or changes to our DNA code ~ found across human populations is quite young. 

The chronologies tell a story of evolutionary dynamics in recent human history ~ the last 10,000 years ~ a period characterized by both narrow reproductive bottlenecks and enormous population growth.

According to Wired.com:

The evolutionary dynamics of these features resulted in a flood of new genetic variation, accumulating so fast that natural selection hasn’t caught up yet. As a species, we are freshly bursting with the raw material of evolution. 

“Most of the mutations that we found arose in the last 200 generations or so. There hasn’t been much time for random change or deterministic change through natural selection,” said geneticist Joshua Akey of the University of Washington. “We have a repository of all this new variation for humanity to use as a substrate. In a way, we’re more evolvable now than at any time in our history.” 

But these findings can also been seen from another angle. They teach us about human evolution, in particular the course it’s taken since modern Homo sapiens migrated out of Africa. 

“We’ve gone from several hundred million people to seven billion in a blink of evolutionary time,” said Akey. “That’s had a profound effect on structuring the variation present in our species.”

For practical reasons, rare genetic variants have only been studied for the last several years because it’s been too expensive. Genomics focused mostly on what are known as common variants.

Click here for the article.

Christian Scholars Question Adam & Eve

A growing number of conservative scholars believe the account of Adam and Eve in Genesis 2:7 has become too far-fetched in light of recent findings related to the human genome.

Asked how likely it is that we all descended from Adam and Eve, Dennis Venema, a biologist and senior fellow at BioLogos Foundation, a Christian group that tries to reconcile faith and science, told NPR: "That would be against all the genomic evidence that we've assembled over the last 20 years, so not likely at all."

With the mapping of the human genome, the evidence is clear that modern humans emerged from other primates as a large population ~ long before the Genesis timeframe of a few thousand years ago. And given the genetic variation of people today, scientists can't get that population size below 10,000 people at any time in our evolutionary history.

To get down to just two ancestors, Venema says, "You would have to postulate that there's been this absolutely astronomical mutation rate that has produced all these new variants in an incredibly short period of time. Those types of mutation rates are just not possible. It would mutate us out of existence."

Such statements are heresy to evangelicals. "From my viewpoint, a historical Adam and Eve is absolutely central to the truth claims of the Christian faith," according to Fazale Rana, vice president of Reasons To Believe, an evangelical think tank that questions evolution. "But if the parts of Scripture that you are claiming to be false, in effect, are responsible for creating the fundamental doctrines of the Christian faith, then you've got a problem."

Click here for the complete article.

Etching "Adam and Eve" by William Blake.

Schizophrenia May Reside in Our DNA

DNA double helix, potentially harboring mental illness.

New genetic studies suggest that sections of our genetic code affect a person's risk for developing the schizophrenia. In three separate studies, researchers found that code involved in brain development, memory and the immune system may contribute to this puzzling disease.

The findings are important because schizophrenia has been so hard to study, says Kari Stefansson, CEO of the Icelandic company deCODE Genetics and an author of one of the studies. One reason is that schizophrenia doesn't occur in animals.

"It's a disease of thoughts and emotions, the two functions of the brain that define us as a species and define us as individuals," Stefansson told NPR.

Scientists have tried for decades to find differences between the brains of typical people and those with schizophrenia, but without much success. So Stefansson and a consortium of researchers from around the world decided to look for subtle differences in the genes of thousands of people. Some had schizophrenia; some didn't.

One place the studies found a clue about what might be going wrong in the brains of people with schizophrenia was in a gene responsible for a protein called neurogranin, which can affect memory and thought.

Click here for the NPR “All Things Considered” article.

Does Our DNA Pass Down Environmental Traits?

The discovery of epigenetics ~ hidden influences upon the genes ~ presents huge implications for what and how we inherit traits, including those passed down from ancestors.

At the heart of this new field is the idea that genes have a 'memory'. This means the lives of your grandparents ~ the air they breathed, the food they ate, even the things they saw ~ can directly affect you despite your never experiencing these things yourself. And that what you do in your lifetime could affect your grandchildren.

Scientists believe DNA carries all our heritable information and that nothing people do in their lifetimes will be biologically passed to their children. To many scientists, epigenetics amounts to a heresy, calling into question the accepted view of the DNA sequence.

But epigenetics adds a whole new layer to genes beyond the DNA. It proposes a control system of 'switches' that turn genes on or off. It suggests that things people experience, like nutrition and stress, can control these switches and cause heritable effects in humans.

In a remote town in northern Sweden there is evidence for this radical idea. Lying in Överkalix's parish registries of births and deaths and its detailed harvest records is a secret that confounds traditional scientific thinking.

Marcus Pembrey, a Professor of Clinical Genetics at the Institute of Child Health in London, in collaboration with Swedish researcher Lars Olov Bygren, has found evidence in these records of an environmental effect being passed down the generations. They have shown that a famine at critical times in the lives of the grandparents can affect the life expectancy of the grandchildren.

This is the first evidence that an environmental effect can be inherited in humans.

In other independent groups around the world, the first hints that there is more to inheritance than just the genes are coming to light.

Click here for the complete BBC article.