From ScienceDaily (August 3, 2011) we learn: “Six Million Years of Savanna: Grasslands, Wooded Grasslands Accompanied Human Evolution”:
Scientists have spent a century debating the significance of savanna landscape in human evolution, including the development of upright walking, increased brain size and tool use.
Part of the problem has been a fuzzy definition of “savanna,” which has been used to describe “virtually everything between completely open grasslands and anything except a dense forest,” Cerling says. He adds the most common definition is a fairly open, grassy environment with a lot of scattered trees — a grassland or wooded grassland.
Here’s the main thing you need to know: Most food plants thrive in relatively open areas. Maybe you never heard:
The green, dark forests are too silent to be real.
The very dense shade created by a giant canopy forest is not favourable to the food plants many familiar life forms like. An environment with some trees and lots of grasses is much more favourable. Obviously, early humans, however they got started, would gravitate to such an environment because it offers a chance at meat, two veg.
‘Course, if they can’t get a Darwin theory out of that, they don’t want it.