What is brain capacity sign of, and what is it not a sign of?
Can anyone help with this? So far I understand that cranial volume increases along with ability for complex thinking but what is it NOT an indication of?
Increased cranial capacity = increased brain size = increased cognitive function and skill (e.g: problem solving).: if you have greater problem solving skills, you are more likely to survive (your at a selective advantage relative to others). Therefore more likely to reproduce and pass on favourable alleles to next generation.
Don't know what you mean by what it is
not a sign of? The general trend is over time, cranial capacity increased (hominid evolution)
Maybe what you mean by this is: increased brain capacity
does not necessarily result in an explosion of cultural and technological evolution. For example Homo. neanderthalensis had slightly larger brain capacity than modern humans. But we still outcompeted (theory for why they went extinct). If you look at the skull of a Neanderthal and a modern human, you will see that back bit of the skull is much larger in Neanderthals but the front is much larger in Homo sapiens. This indicates that the front of our brains is more developed than the Neanderthals (this part is responsible for problem solving). Hence, we have better complex thinking skills than Neanderthals, it is postulated this is why they may have gone extinct ---> competition.
Hope it helps.
EDIT: another important aspect is that its not the brain size alone, but its the brain size to body size ratio that is important. For example, elephants have a larger brain than us but that does not make them more intelligent than us, because they have a much larger body size than us!