為什么我們喜歡吃垃圾食品?
Many people love their ice cream, pizza, french fries, candy despite knowing that these are unhealthy. What is it about those foods that give them such mass appeal?
盡管很多人都知道像冰激凌、披薩、炸薯條、糖果等食品不健康，但是人們還是喜歡吃。為什么這類食品會有如此之大的吸引力呢？
From an evolutionary perspective, it feels reasonable to be confused about why humans have strong desires for as unhealthy of a behavior as eating high-calorie and sugar-heavy foods.
從進化角度來講，關于為啥人類對高熱量高糖食物有著強烈的渴望人們表示很困惑，但似乎又情有可原。
They're bad for hearts, bad for pancreases, bad for physiques. But they taste so good.
高糖高熱量食物對心臟、胰腺、體型來說都不好，但它們味道很好。
One answer is found in a careful examination of our evolutionary history.
在仔細檢查我們的進化史后，答案找到了。
It's true that an unhealthy behavior will in general may get weeded out across time, because the members of a species drawn to that behavior will not live as long and reproduce as much as the healthier ones.
的確，隨著時間的流逝，不健康的行為一般都會被淘汰，因為喜歡這種行為的物種成員與喜歡健康行為的物種相比，他們不是活不久，就是繁殖的太少。
But at one point, a high calorie meal was crucial for human success.
但有一點，高熱量食物對人類的成功至關重要。
Early in human history, human beings had to fight for food, kill animals with rudimentary tools, give birth without anesthetic to maintain the population, and be under several high-stress situations.
在人類歷史早期，人類必須為食物而戰，比如使用最基本的工具狩獵，在沒有麻醉劑的情況下生育來繁衍后代，以及處于高壓力環境中等等。
Some scientists think that eating meat (and thus taking in the high amount of calories) helped humans have the extra energy to support their large brains and its functions.
一些科學家認為吃肉（由此可攝入大量熱量）能為人類提供源源不斷的能量，由此來支撐當時人類較大的大腦及其運作。
While there are many different ideas about why people still crave these foods, one theory is that it's an evolutionary inheritance of those days.
關于為什么現在人類對于這些食物仍有較高的熱情，很多人仍持有不同的觀點，其中一個就是從歷史進化遺傳而來。
High-calorie eating feels good to us, even though for the mass of people it's no longer necessary, and in fact, dangerous.
盡管對于多數人來說高熱量食物不再是必需品，實際上它們也是危險品，但對于它的美味，我們依舊還是不能罷休。
Many people love their ice cream, pizza, french fries, candy despite knowing that these are unhealthy. What is it about those foods that give them such mass appeal?
盡管很多人都知道像冰激凌、披薩、炸薯條、糖果等食品不健康，但是人們還是喜歡吃。為什么這類食品會有如此之大的吸引力呢？
From an evolutionary perspective, it feels reasonable to be confused about why humans have strong desires for as unhealthy of a behavior as eating high-calorie and sugar-heavy foods.
從進化角度來講，關于為啥人類對高熱量高糖食物有著強烈的渴望人們表示很困惑，但似乎又情有可原。
They're bad for hearts, bad for pancreases, bad for physiques. But they taste so good.
高糖高熱量食物對心臟、胰腺、體型來說都不好，但它們味道很好。
One answer is found in a careful examination of our evolutionary history.
在仔細檢查我們的進化史后，答案找到了。
It's true that an unhealthy behavior will in general may get weeded out across time, because the members of a species drawn to that behavior will not live as long and reproduce as much as the healthier ones.
的確，隨著時間的流逝，不健康的行為一般都會被淘汰，因為喜歡這種行為的物種成員與喜歡健康行為的物種相比，他們不是活不久，就是繁殖的太少。
But at one point, a high calorie meal was crucial for human success.
但有一點，高熱量食物對人類的成功至關重要。
Early in human history, human beings had to fight for food, kill animals with rudimentary tools, give birth without anesthetic to maintain the population, and be under several high-stress situations.
在人類歷史早期，人類必須為食物而戰，比如使用最基本的工具狩獵，在沒有麻醉劑的情況下生育來繁衍后代，以及處于高壓力環境中等等。
Some scientists think that eating meat (and thus taking in the high amount of calories) helped humans have the extra energy to support their large brains and its functions.
一些科學家認為吃肉（由此可攝入大量熱量）能為人類提供源源不斷的能量，由此來支撐當時人類較大的大腦及其運作。
While there are many different ideas about why people still crave these foods, one theory is that it's an evolutionary inheritance of those days.
關于為什么現在人類對于這些食物仍有較高的熱情，很多人仍持有不同的觀點，其中一個就是從歷史進化遺傳而來。
High-calorie eating feels good to us, even though for the mass of people it's no longer necessary, and in fact, dangerous.
盡管對于多數人來說高熱量食物不再是必需品，實際上它們也是危險品，但對于它的美味，我們依舊還是不能罷休。
