Biophilia Project/Human genetic uniqueness

Triangulating on human genetic uniqueness. This is the first topic for the Biophilia Project.

Outline and sources

Biologists are building on the foundation of the Human Genome Project and comparing human DNA to the DNA of other living primates and DNA isolated from Neanderthal fossils. This is a review of recent results on Neanderthal DNA studies, the Chimpanzee Genome Project and Evolutionary and Biomedical Insights from the Rhesus Macaque Genome.

Script

Welcome to the first podcast of the Biophilia Project. The topic for this first Biophilia adventure is the mystery of the very nature of the human species. What accounts for unique human characteristics such as the ability of children to learn human languages? What changes occurred during human evolution that allowed our species to spread around the world and travel to the moon while our fellow apes remain jungle dwellers?

In ancient Greece, Aristotle imagined that a man's semen was an organizing force that shaped female blood into the form of a new human individual. It was not until the middle of the 20th century that biologists were able to show that it is DNA molecules inside of sperm and egg cells that carry the instructions for crafting a new human organism.

For the past 50 years it has been clear that the structure of the DNA molecules inside our cells holds the genetic program that makes us different from all other species. The Human Genome Project found that our genes specify about 20,000 proteins and a large number of non-protein coding RNAs that control the human form and establish the basic constraints of human nature. Can we compare human genes to those of other animals and learn exactly which human genes account for our features that are uniquely human?

Humans and chimpanzees are derived from a common ancestor that lived approximately 6 million years ago. In 2005, a draft DNA sequence of the chimpanzee genome became available for comparison to the already completed human genome sequence. It was found that human and chimp DNA is so similar that about 30% of human and chimp proteins have identical sequences. In terms of DNA sequences, the observed differences between individual humans and chimpanzees are only about 10 times greater than the typical genetic difference between pairs of humans. With so much similarity in the genes of humans and chimps, can we identify the subtle differences that make humans unique?

In April 2007 a genome sequence for the rhesus macaque became available thanks to the efforts of an international team of primate genome researchers. The rhesus macaque is an important laboratory animal for development of human vaccines and for experiments that allow study of many human health problems. Chimps, humans and macaques are all derived from a common ancestor that existed about 25 million years ago. Comparison of macaque, chimp and human DNA sequences allows us to see if humans or chimps have diverged more rapidly from genetic patterns common to most primates.

About 10% of all proteins have identical sequences in humans, chimp and macaque. While human and chimp DNA sequences have diverged by only 1 to 2% during the past 6 million years, human and macaque DNA sequences are about 7% different on average. By comparing the genes of humans, chimp and macaque can we identify the genetic changes that make us uniquely human?