Evolution
This article from New Scientist describes an important new model for evolution based on horizontal gene transfer between species (microbial) rather than vertical gene transfer between generations of the same species. It is in this horizontal evolution that the scientists involved in the study, microbiologist Carl Woese and physicist Nigel Goldenfled, posit that the genetic code was formed. Here is their description of the stages of evolution beginning with horizontal gene transfer:
"the simulations suggest that horizontal gene transfer allowed life in general to acquire a unified genetic machinery, thereby making the sharing of innovations easier. Hence, the researchers now suspect that early evolution may have proceeded through a series of stages before the Darwinian form emerged, with the first stage leading to the emergence of a universal genetic code. "It would have acted as an innovation-sharing protocol," says Goldenfeld, "greatly enhancing the ability of organisms to share genetic innovations that were beneficial." Following this, a second stage of evolution would have involved rampant horizontal gene transfer, made possible by the shared genetic machinery, and leading to a rapid, exponential rise in the complexity of organisms. This, in turn, would eventually have given way to a third stage of evolution in which genetic transfer became mostly vertical, perhaps because the complexity of organisms reached a threshold requiring a more circumscribed flow of genes to preserve correct function."
The article is also interesting in its focus on how scientific concepts come into being, and how one model (like Darwin's vertical model) can tend to make it difficult to see alternatives: ""Biology built up a facade of mathematics around the juxtaposition of Mendelian genetics with Darwinism," he says. "And as a result it neglected to study the most important problem in science - the nature of the evolutionary process." "
I think my addition to that part of the article would be to think of how Darwin's idea emerged at a period in history in which "progress" was a dominant cultural idea which would contribute to a vertical and generational view.
Horizontal and vertical: The evolution of evolution