New Scientist is carrying this summary of new DNA research related to the human genome. By studying the relative differences between human and chimp DNA, and then comparing that result with a similar comparison between mice and rats, scientists have made a very interesting discovery. It would seem that the common ancestor of chimps and humans went through an "evolutionary bottleneck", when perhaps as few as 10,000 individuals existed at one point. This has made us comparatively more susceptible to genetic-based diseases (like cancer) when compared to other species which did not go through such an event.