DAVID: The article from Sci Am points out the minor speciation that does, by definition, occur. So far no major changes or jumps are seen as in punctuated equilibrium:

http://blogs.scientificamerican.com/science-sushi/2011/12/18/evolution-watching-speciat...

This article ties in with our discussion on how humans might have evolved. Here is a quote: “Why did the orcas split? The truth is, we don’t know. Perhaps it was a side effect of modifications for hunting different prey sources, or perhaps there was some kind of physical barrier between populations that has since disappeared. All we know is that while we were busy painting cave walls, something caused groups of orcas to split, creating multiple species.
There are many different reasons why species diverge. The easiest, and most obvious, is some kind of physical barrier – a phenomenon called Allopatric Speciation.”

You’re right – these are minor changes, and one is tempted to say they’re variations rather than new species. Darwin had difficulty distinguishing between the terms, and Matt has recently joined Tony in pondering the difference. What interests me, though, is the fact that unless we believe in a God who created each species separately, there has to be a moment at which the humanoid split from the anthropoid, and once again this article points directly towards the relationship between organisms and their environment (as opposed to random mutations). Therefore the scenario of a localized or isolated environmental change, resulting in a radical adaptation to savannah as opposed to arboreal life (new ways of thinking, brain development, body adjustments) appears perfectly feasible. Once the process has begun, the rest follows over time. Its course will still depend on the idea that environmental change can result in innovation as well as adaptation, and on new characteristics being heritable (which is why I like the idea of the “intelligent cell”). However, if we believe in common ancestry, it seems to me that given the choice between random mutation and response to a changing environment, the latter wins hands down in terms of likelihood.

Of course we shall still be left asking whether the actual mechanism for adaptation could or could not have created itself by chance, and if not, whether the creative force guided its progress or let it follow its own random course (see Matt’s latest post under Life as Evolving Software...). But at least we shall have a more coherent picture of how evolution could have led from earlier forms to ourselves: epigenetics rather than random mutations.

A careful study in fossil fish is attempting to show the effect of environment alterations on species changes.

"Evolutionary biologists have used these living species to propose at least two models of how adaptive radiations work. One model proposes a single "burst" of divergence followed by a long period of relative stability. Another, sometimes known as the "general vertebrate model," introduced the idea of staged divergences, with habitat-driven changes in body type preceding diversification of head types."

http://www.physorg.com/news/2011-12-fish-fossil-head-first-diversity-vertebrate.html