  The number of people able to end Earth's technical civilization has
heretofore been small. Emerging dual-use technologies, such as biotechnology,
may give similar power to thousands or millions of individuals. To
quantitatively investigate the ramifications of such a marked shift on the
survival of both terrestrial and extraterrestrial technical civilizations, this
paper presents a two-parameter model for civilizational lifespans, i.e. the
quantity $L$ in Drake's equation for the number of communicating
extraterrestrial civilizations. One parameter characterizes the population
lethality of a civilization's biotechnology and the other characterizes the
civilization's psychosociology. $L$ is demonstrated to be less than the inverse
of the product of these two parameters. Using empiric data from Pubmed to
inform the biotechnology parameter, the model predicts human civilization's
median survival time as decades to centuries, even with optimistic
psychosociological parameter values, thereby positioning biotechnology as a
proximate threat to human civilization. For an ensemble of civilizations having
some median calculated survival time, the model predicts that, after 80 times
that duration, only one in $10^{24}$ civilizations will survive -- a tempo and
degree of winnowing compatible with Hanson's "Great Filter." Thus, assuming
that civilizations universally develop advanced biotechnology, before they
become vigorous interstellar colonizers, the model provides a resolution to the
Fermi paradox.
