Designer viruses would not be attractive to normal terrorists, unless they thought that somehow they and their favored groups of people were immune. Biowarfare can get out of hand quite easily. On the other hand, the true nihilists who hate all humanity might find them just the thing. I could see a radical environmental group finally getting hold of, and I quote, "the right virus." One that sterilized instead of killed would be an appropriate and less messy way to eliminate the hated human race.

For instance, salmon have been created which grow 4 times as fast as normal. What would happen to the food supply if that gene jumped to other fish?



Would we wind up with a lot of big fish fast, and then no food supply? Or would we wind up with the same number, just living 1 year instead of 4?



The salmon would survive that could make the best use of the food supply, which I suspect would be the native salmon. Millions of years have selected for salmon that have just the right metabolism and growth rate for the available food supply, and I don't think anything has changed. The fast-grow salmon would likely starve quickly, while enough of the salmon with more reasonable metabolisms would get by for the next generation. Fast-grow salmon would only thrive on a farm, where someone is tossing loads of food in every day.