One hundred and ninety-nine years after Charles Darwin was born, and 149 years after he published On the Origin of Species, some scientists say that the theory of evolution is due for a revision.

Not a religiously inspired revision -- intelligent designers need not apply. Nobody suggests that genetic mutation and natural selection aren't responsible for the evolution of birds from reptiles or humans from tree-swingers.
But a growing number of scientists do say that neo-Darwinian evolution doesn't explain certain jumps in biological complexity: from single-celled to multicellular organisms, from single organisms to entire communities.

The jumps -- saltations, in complexity parlance -- appear to be non-linear emergent phenomena, the result of networked interactions that produce self-organization at ever higher levels. From this perspective, Darwinian evolution is a mechanism of a higher universal law, perhaps even a variant on the second law of thermodynamics.