You are of course right. You do not need to answer anything. But you are the one that one that questioned this thread. Now I agree I don't think it can be proven that the earth and universe is that young in the Quran. But saying that it's 4 billion years old leave you with a dilemma. Since Adam was the first human being and we have the Biblical account and the Tafsirs and hadith which have the genealogy traced to Mohammad. One can kind of measure how long humans have been around. It's sort of like the Bible.
Let me ask you something, what is the purpose of the brain? Why would God give us this organ?
Purpose of brain? A doctor would answer it better then me according to his/her knowledge, rest of the mysteries lies behind this brain is known to its Creator. I will still input what i know about it.
I will think of it as a command center of a body, what we do is usually decided in the brain, specially the forelock (front of head).
I think the brain is link to soul, and the soul is the Lord of the body and organs are his servants.
If we want to do something it is first executed in brain and then carried out by our organs, so it is an essential part of human body. Without a command center an army would be lost.
Rest in The Quran God told us that He will seize (probably Abu Jahl) by the forelock, a lying and sinful forelock. Examining this verse, scientist found that "the frontal lobe was found to be the part lying behind".
[96.15] Indeed, if he does not desist, We will seize him by the forelock,
[96.16] a lying, sinful forelock.
On top of that brain has links to all parts of body, specially eye , ear , hand etc.
The brain is indeed a blessing from its Creator, a submitted command center to its soul with submitted army to control.