进化赋予了我们许多实用的能力
Evolution has given us some useful abilities.
在过去的上百万年 我们已经进化出双腿站立 使用工具和发明语言的能力
Over the past millions of years, we’ve evolved to stand on two legs, use tools, and develop language.
而且在近几千年前 人类还在不断进化
And as recently as a few thousand years ago, humans were still evolving.
自然选择是推动进化的驱动力之一
Part of what drives evolution is natural selection
即具有某些能够更好地适应环境特性的物种
— where those with traits that make them better adapted to their environment
趋于获得更长的寿命并使这种特性遗传给他们的后代
tend to survive long enough to pass on those traits to their offspring.
现代医学有时候会干扰这个过程
Modern medicine can sometimes interfere with that process,
因为它使一些可能会死去的人继续活下去
since it keeps people alive who maybe otherwise wouldn’t be.
但是这并不代表人类已完成进化
But that doesn’t mean humans are done evolving.
举一个最近的人类进化史上的例子来说 有35%的成年人可以消化牛奶
One recent example of human evolution is the fact that 35% of adult humans can digest milk.
但是7000年前 能消化牛奶的人却没有这么多
7,000 years ago, not nearly as many people could to do that.
反而大多数婴儿都能够摄取并消化牛奶 使他们可以从母乳中
Instead, mainly babies drank and digested milk, so they could get energy from the lactose
摄取乳糖和其能量 然而当他们一长大 允许消化牛奶的基因就会停止工作
in their mother’s breast milk. Once they grew up though, the gene that allowed them to digest milk was swiched off
但当我们圈养奶牛时 某些可以因为基因突变可以消化牛奶
But when we domesticated cattle, the mutation that allowed certain people to digest milk
的成年人变得更容易生存
as adults became something that helped them survive,
因为他们能获得更多的营养
since they had an extra source of nutrition.
几千年之后 能够消化乳糖已经变得很平常
A few thousand years later, being able to digest lactose is pretty normal.
所以 人类在近代依旧在进化
So, humans were still evolving in the not-so-distant past.
许多科学家认为我们仍在进化
And a lot of scientists think that we still are —
并且我们甚至能够预测未来人类是什么样子的
and we might even be able to predict what future humans will be like.
比如 未来的女性将会比现在更矮和稍微更胖一些
For one thing, it’s possible that in the future, women will be shorter and slightly heavier than they are now.
得出这个结论的研究采用了佛雷明汉心脏研究的数据
Researchers figured this out using the data from the Framingham Heart Study, which tracks
这份数据追踪了14000位住在马萨诸塞州的傅雷明汉的人的医疗历史
the medical histories of more than 14,000 people who live in Framingham, Massachusetts.
研究团队希望知道哪些特性使女性更容易生孩子
The team wanted to know what traits gave women higher reproductive success.
他们发现 矮的和微胖的女性有更多的孩子–这些特性也遗传给了她们的孩子
They found that shorter, slightly heavier women tended to have more children — and those traits were passed on to their children.
照这个趋势下去 10代之后女性的平均身高会减少2厘米
If this trend continues, in ten generations the average woman might be about 2 centimeters
平均体重增加1Kg
shorter and a kilogram heavier.
另一个未来和现在可能的区别是人类的大脑可能会变得更小一些
Another possible difference between us and future humans is that their brains might be a bit smaller.
听起来很怪 因为从人类历史来说 人类的大脑一直趋向于变得更大
Which is weird, because for most of human history, brain sizes tended to get bigger over time
但是在过去2万年 智人的大脑变小了
But over the past 20,000 years, the brain size of homo sapiens has decreased.
在此期间 男性的大脑容量从1500立方厘米
During that time, the average volume of the male brain has shrunk from about 1,500 cubic
缩减到1350 — 有一个网球的大小
centimeters to about 1,350 — about a tennis-ball-sized difference.
女性的大脑体积也轻微地减小了
A similar decrease in brain size happened for women, too.
但这是为什么呢？
But why the change?
一个可能性是我们的大脑变小了是因为更多复杂的社会群体的出现
One possibility is that our brains are smaller thanks to the emergence of more complex societies.
随着人口密度增加 劳动力划分更仔细
As population density increased, and there was more division of labor, humans didn’t
人类生存不需要很聪明 所以大脑不需要那么大
have to be as smart to stay alive, so their brains didn’t have to be as big.
其他的科学家认为我们的大脑变小是因为我们变得更温顺了
Other scientists think our brains have been shrinking because we’ve become more tame.
看 家养动物比起野生的同种动物大脑会更小 — 这或许是因为
See, domesticated animals have smaller brains than their wild counterparts — probably because
野生动物如果不够精明，就不容易生存下去
if a wild animal isn’t smart enough, it won’t survive too long.
所以 像家养动物一样 我们的大脑没有变得更聪明因为我们不需要一直
So, like domesticated animals, maybe our brains have gotten smaller because we aren’t constantly
担心事情比如受到捕食者的攻击
worried about things like being attacked by predators.
但是缩小的大脑并不代表了人类变得更愚蠢 — 相反
But a shrinking brain also might not mean that the human species is getting dumber — instead,
我们的大脑可能变得更有效率了
our brains might just be getting more efficient.
一个大的大脑需要更多能量 所以当它变小和高效时
Having a big brain uses up a lot of energy, so if it’s a little smaller and more efficient,
我们不需要用很多能量来维持生命
we don’t need as much energy to stay alive.
美国人最近一项关于头骨的研究表示人的头骨自19世纪初的中期开始
That said, a recent study of the skulls of Americans showed that they’ve actually been
就不断变大
getting bigger since the mid-1800s.
但是这可能是因为更好的营养并不是因为进化改变
But that’s probably because of better nutrition and not an evolutionary change.
所以如果我们排除更好的营养的因素 头骨缩小的趋势将会
So if we factor out the effect of better nutrition, it’s possible that the shrinking trend will
持续下去
continue in the future.
即使自然选择不能驱使我们在未来进化
Even if natural selection isn’t what drives the future evolution of our species, we might
我们也可以利用基因工程人工进化
artificially evolve ourselves through genetic engineering.
只要我们知道了所有的基因的能力和如何修改它们 我们就能够
As we learn more about what all of our genes do and how to modify them, we’ll be able
消除变老产生的特定的基因紊乱和疾病
to eliminate certain genetic disorders and maybe even diseases related to getting older.
最终 我们或许能够像视频游戏里创建角色一样设计人类
And eventually, we might be able to design people like we design avatars in video games
— 调整身高、智力、体能和其他特性
— altering things like height, intelligence, athleticism or any other trait.
所以 不管改变是自然的还是人工的 未来的人类会变得非常不一样
So, whether the changes are natural or artificial, humans of the future might be very different.
感谢观看这一集赞助的SciShow
Thanks for watching this episode of SciShow, which was brought to you by our patrons on
如果你想帮助资助这个节目 去patreon.com/scishow
If you want to help to support the show, just go to patreon.com/scishow
别忘了去youtube.com/scishow和订阅
And don’t forget to go to youtube.com/scishow and subscribe!