看电影的时候吃爆米花已经成了很多观影人的习惯，大多数人也觉得电影和爆米花是绝配。但是是怎么样的机缘巧合，造就了这样绝妙的搭配？
Soft percussion and a toasty scent mark the violent transformation of tough seeds into cloud-like puffs.
This is the almost magical process of popcorn making.
But how did we actually end up with this whimsical food?
All the corn eaten today is derived from a tall grass called teosinte, which indigenous people in what's now southern Mexico began selectively breeding about 9,000 years ago.
An ear of teosinte originally yielded somewhere between 5 and 12 small kernels, each with a hard shell called a pericarp.
And some varieties had a fantastic feature: if they reached a certain temperature, their kernels exploded.
Popcorn kernels pop because water and starch are sealed tightly within the pericarp.
When heated, the moisture inside becomes steam.
As it expands, it increases the internal pressure, and the solid starch transforms into a gel-like substance.
The pressure finally overcomes the pericarp's resistance, and it bursts, The steam and starch expanding to form a foam that quickly cools and dries in the air.
