[How can sin change animals? They don't even have souls?]

Sure they do but that isn't why they were affected...(they have souls but not spirits)...the weather, and natural disasters don't have souls but were affected too. Of course I realize you aren't a believer...but pretend for a minute...if you were God and created a perfect world for the first people would you honestly put them on a planet that could kill them with hurricanes, tornados, famine, disease and deadly animals and call it 'good'? Probably not. The word 'good' is listed seven times in the first chapter of Genesis. Everything God created He deemed 'good' and good in His terms usually means perfect (would have to show you other scriptures, etc, on that but its late and I need sleep)...

When they sin it wasn't just them affected by sin...everything was. Just watch the news minus man's inhumanity to man and notice just the stories on famines, droughts, natural disasters...how many died a few days ago in those tornados? How many injuried...