DNA & Evolution: Where Did We Come From? Where Did We Go?
PRODUCERS: Larry Massett
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New & Noteworthy, 2007
by Jennifer Jongsma
With the completion of the Human Genome Project researchers are able to study the entire human genome, which is approximately 99.9 percent identical among humans. In DNA and Evolution: Where Did We Come From? Where Did We Go?, The DNA Files looked into the tiny fraction that is not the same.
One of the first large-scale studies of human diversity was the Human Genome Diversity Project (HGDP). HGDP researchers wanted to sequence DNA from populations around the world to see whether genomic sequences could be associated with a specific geographical area. However, from its inception, the HGDP encountered significant ethical questions and controversy. Early opponents feared that indigenous people might be exploited by the use of their DNA for commercial purposes (also known as bio-piracy). The HGDP researchers assured detractors that they would never patent DNA or sell genomes to pharmaceutical companies, and that DNA would only be provided to non-profit laboratories. The HGDP originally hoped to collect 10,000 cell lines of 25 individuals from each of 400 populations. However, as of 2006, the HGDP has stalled at 1,051 cell cultures from 51 populations and the project seems unlikely to go any further.
A far more successful and less controversial study of human diversity was established in 2002. Completed in 2005, the International HapMap Project aimed to identify the genetic determinants of complex diseases. The project did not identify disease-related genes directly. Researchers compared the DNA of individuals who had a disease to the DNA of individuals without that condition, looking for associations. This project provided an unprecedented view of human genetic diversity by sequencing over 100 million single-nucleotide polymorphisms, or genetic variations. Many common diseases, including diabetes, cancer, heart disease, and asthma, are affected by both genes and environmental factors. That one-tenth of a percent of variation from person to person could contain genetic variants that influence who has a higher risk of disease or who will have a bad response to certain drugs. It also provided insight into many other areas of interest, including the effects of natural selection and the molecular forces that shape our genetic makeup.
Although much has been uncovered about the patterns of human gene variation, much remains to be learned. Ongoing collection of data and technological developments in DNA sequencing will continue to shed light on our health and on where and when the first humans evolved.
Original Program Description, 1998
Zuni legend tells us that humankind evolved from amphibious forms in the belly of Mother Earth, after she mated with Father Sky. Peoples all over the world have developed origin stories to explain why we're here, who we are, and where we're going. Now, genetic researchers are beginning to write their own account of our origins, through the study of DNA. This program tells us how DNA may have come into existence and how genetic studies have contributed to evolution theories so far. And it explores the controversies raised by genetic research.
Our DNA - our collection of genes - is the essential mechanism of evolution. Human DNA is 98.8 percent the same as the DNA of chimpanzees; but it's also 70 percent the same as the DNA of yeast. So what makes humans different from chimpanzees or yeast? One thing might be the way in which we created language and culture, and how we developed these things in different ways all over the earth. In other words, genetic studies can tell us how human migration occurred — when we appeared, what we were like, and where we went.
By gathering genetic information from isolated populations, the Human Genome Diversity Project (HGDP) aims to decipher those mysteries. Scientists hope that this data, in combination with traditional archaeological and linguistic research, can tell us a great deal more about our past and our relationships. But there is strong opposition from people who see the HGDP as little more than highly unethical opportunism: "colonialism at the molecular level."
Hear both sides of the debate, and find out from the researchers themselves how they think the story begins. We'll have to stay tuned for the ending.