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Some species such as corals and trees have an extremely low breeding success rate, but compensate by producing immense numbers of offspring nearly all of which die before reaching adulthood. A fir tree produces hundreds of cones each year each of which may contain dozens of seeds, but the vast majority of those will get eaten or will sprout and die. But if over the course of its life of up to a thousand years that tree manages to produce one viable offspring then the species will survive, and if it produces two then the species will prosper. Corals have an even worse time of it, but they produce millions of offspring every year nearly all of which are eaten. Indeed, this is very common among sea creatures. Salmon lay hundreds of eggs because they have to. At the other extreme, there are a few species which rely on a very high chance of survival of offspring by investing heavily in each one. This is the "quality" approach, as opposed to the "quantity" approach used by corals. Elephants are a very good example; a female elephant probably can only produce one baby every three years and needs at least two of them to survive to adulthood. But baby elephants have a very good chance of survival. Most species shoot somewhere in the middle. Rodents are further down the "quantity" scale. There is a rodent living in Scandanavia which is so heavily predated upon that its females produce several litters per year, who mature so rapidly that females from the first litter will have had their own litters before the breeding season ends and winter sets in. So fully leveraged, one female can produce upwards of fifty young in one breeding season. This compensates for their poor survival rate. This also applies to diseases, and it turns out that the most dangerous diseases are not the ones which make us the most sick. There's a good reason why HIV is killing far more people than Ebola, even though Ebola can kill you in a few days and HIV takes 10 years. In fact, it is precisely the slow process of development of AIDS which is responsible for the spread of HIV, because HIV has a much greater chance of "reproducing" (spreading from an infected individual to an uninfected one) precisely due to the very long period in which infected people are still sexually active. Its spread is impeded somewhat by the fact that the mechanism of spread of HIV is (thankfully) rather inefficient. Most of us talk to far more people than we have sex with, and if HIV had all the characteristics it has now but also was spread approximately the same way that influenza is spread, the human race would decline 95% or more in the next fifty years. What's interesting about this is that it applies equally to study of artificial life forms such as computer viruses and worms and trojans. Successful (ahem) designers of such devious programs have to balance the rate of reproduction of their child against the chance of breeding, just as do natural critters. In this case, for a trojan such as SirCam the "chance of breeding" is the chance that any given recipient of it can be conned into clicking the attachment on an incoming letter multiplied by the chance that said sucker is running a computer with the right software on it (Windows, Outlook as primary mail client, address book in use) to permit the program to reproduce. The reproduction rate is the number of email addresses available to harvest to which to send out new copies. If the average reproduction rate is fifty harvested email addresses per successful infection, then only one out of fifty of the recipients need to be unwise for the virus to continue to spread. The reproduction rate for these kinds of beasties are pretty much a determined quantity for all members of a given class of programs, so the writers of these things tend to concentrate on improving the reproduction rate by trying to increase the chance that people will click. (This has the nice name "social engineering", based on the fact that it's an attempt to figure out how to convince people to do something they know they shouldn't.) The "Anna Kournikova" virus was particularly clever and thus successful, for obvious reasons, since the lure was sex. However, one of the problems these have is that word spreads and infection rate will plummet. There are probably still copies of the Kournikova Virus circulating now but enough people have heard about it to not be taken in any longer, and it's going to fade out. And that is what is so brilliant about the new SirCam virus: its lure is that it may be able to continue to con people even after word spreads, and indeed may even become more successful. That's because it attaches its payload to a randomly chosen file off the system, and now people know that. I myself have received two copies of it now (from someone I've never heard of) and I admit to a temptation: I wonder what is in the files which were forwarded? I didn't run them, but I can see people who might even knowing what they had. (
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