Genesis 5:5

"Altogether, Adam lived 930 years, and then he died."  Genesis 5:5

930 years!  That's a long time to live.  Did Adam really live that long?  Why don't we live that long now?

According to Answers in Genesis with the Flood came a change to the environment and from there we see the maximum life span decrease to 120 years.  It goes on to talk about genetic reasons and mutations.  Reasons to Believe also points to our genetics and suggests that God tweaked them after the Flood to decrease our life spans.  Another website, Christianity.net.au, gives a good point that we might not have the whole picture. 

Science is always discovering new things and sometimes these appear to clash with the Bible, but sometimes a later discovery shows that there is not inconsistency or that the previous discovering was wrong.  The Bible was not written as a Science text book to explain all the workings of the universe, so it doesn't even try to explain some of the things we don't understand that it hints at.

Not only was this an incredibly long life span, but this was also centuries after the Garden of Eden when God had told the first man that he would die if he ate of the tree of knowledge.  Obviously they didn't drop dead when they ate the fruit, but instead, Adam lived 930 years.  So he did die he just took a long time getting to it.  If he hadn't of eaten from from that tree would Adam have lived forever?  If nothing else, this shows that God is patient.