Whatever measurements you're using, you are obviously comparing the Turkana skull with an average human skull. Why not start with a pygmy skull? The average pygmy is no less intelligent than the average caucasion. What evidence do you have that a smaller brain case = less intellligence? What evidence you do you have that a pygmy skull represents the lower limit of brain size possible for a modern human. I'm looking at dog skulls from various breeds and using that as a rough guage as to how much morphologic variability can exist within a single species.<quoted text>
No way HTS. The Boy is 5+ standard deviations out of the modern range on multiple measures - and all in the direction of apes.. There is no human alive today with a forehead slope anywhere near as extreme as the flat horizontal plane from the brow ridge to the back of the skull like Turkana and all the specimens available from the Erectus/Ergaster period. And the pygmies have smaller brains proportional to their general stature but this specimen was much bigger.
Furthermore, we have fossils a bit older with even smaller skulls and more apelike features, and younger fossils with larger skulls and more human features. Goung backward, Habilis and Georgicus morph almost seamlessly into the most advanced Australopiths such as Sediba. And you could just as easily say that Georgicus is merely an outlier of the A. Sedibus type in one direction or an outlier of Erectus in the other direction.
This is, of course, exactly what we would expect from a trend of gradually more human and less apelike specimens through time. And its exactly what we found.
And you're grossly exagerrating when you describe the Turkana forehead as a "flat horizontal plane"... The photo on wiki doesn't show that... only the embellished artistic renderings.