A few years ago, researchers in Africa had a perplexing problem. Lions were dying in record numbers on the Serengetti Plain. University of Minnesota evolutionary biologist, Craig Packer, was among the researchers who linked the problem to canine distemper. Since then, Packer and others launched "Project Life-Lion", a massive campaign to vaccinate dogs who had never been innoculated for common canine diseases. Packer just returned from the Serengetti, where he checked in on colleagues who have vaccinated about 30,000 dogs so far.