Football, dog fighting, and brain damage : The New Yorker
http://www.newyorker.com/reporting/2009/10/19/091019fa_fact_gladwell?currentPage=all

Offensive Play How different are dogfighting and football? by Malcolm Gladwell

The effect of football on the human brain is stomach-turning.

“I remember, every season, multiple occasions where I’d hit someone so hard that my eyes went cross-eyed, and they wouldn’t come uncrossed for a full series of plays. You are just out there, trying to hit the guy in the middle, because there are three of them. You don’t remember much. There are the cases where you hit a guy and you’d get into a collision where everything goes off. You’re dazed. And there are the others where you are involved in a big, long drive. You start on your own five-yard line, and drive all the way down the field—fifteen, eighteen plays in a row sometimes. Every play: collision, collision, collision. By the time you get to the other end of the field, you’re seeing spots. You feel like you are going to black out. Literally, these white explosions—boom, boom, boom—lights getting dimmer and brighter, dimmer and brighter.

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