Evolution Before Our Eyes

I'm astounded that nearly half the population in America does not believe in evolution.

Well, remember, it's been re-cast as a religious issue.

I know - but evolution has been and is the foundation of modern biology. Without a thorough understanding of the mechanisms that drive evolution, we couldn't understand many of our basic biological processes.

One reason why some people doubt evolution is that we haven't been able to witness the process, since major change happens over millions of years.

At least that's what we thought.

Now we know there are shorter timelines. For example, we recently did an episode on the evolution of human skin color, which actually dates back just one hundred thousand years. And now we have evidence that humans can evolve in an even shorter time frame; one within written history.

A fascinating study done in Tibet may show us natural selection at work. Tibet is in a mountainous area and the Tibetans live at very high altitudes. They're descendants of the Han Chinese, who migrated to the Himalayas four thousand years ago.

The study compared Tibetan genes with the Han Chinese, who live at sea level.

By sequencing and analyzing the genomes of people from the two groups, researchers found that ninety percent of Tibetans have what's called the EPAS1 gene mutation, while just ten percent of the Hans have it. The EPAS1 gene controls oxygen sensing in human cells.

That means Tibetans may have evolved to more efficiently regulate oxygen uptake, which allowed them to thrive in the lower oxygen environments of the Himalayas. This is evolution at work!

The study was possible thanks only to whole genome sequencing, which is becoming less expensive. With effective bioinformatics tools, we can continue to compare genes, and uncover more human evolution at work.