托福听力精听托福听力训练如何用好一篇音频素材( 二 ) _托福

Wittlinger noticed that sometimes desert ants carry each other.
"And here we had this unique opportunity to test traveling ants that are not walking."
If they're not walking, then they can't count their steps. So would these ants be able to find their way home?、
Bees and wasps can't count their steps, because they fly. Instead, to estimate distance they rely on what's called optic flow, which tracks how much visual information flows past them while they travel. So, do carried ants also use optic flow?
To find out, the researchers waited for an ant to emerge from its nest carrying another. After the pair walked for ten meters, the researchers separated them. And impressively, the carried ant marched straight on back to the nest—but not if their vision was blocked.
"So if they were blindfolded while being carried, they have no chance of gaining any distance information."
Which proves that they need eyesight—and therefore optic flow—to do it.
These critters live in one of the harshest environments on the planet, so it makes sense that evolution endowed them with the tools for path integration and optic flow.
"In the case of the desert ant, it's really important that they're getting navigation right...if one system fails, you still have a backup system."
Because if you're going to live in the desert you have to be very clever in finding ways to not die in the desert.
沿着这条路走，在大约一英里处的大橡树那里左拐。这种导航方向在有视觉线索的地形非常常见。但是撒哈拉沙漠是一个很难导航的地方。即使你留下脚印也会被风沙覆盖。然而，在沙漠中的蚂蚁却能够继续寻找食物，一旦它们发现食物，它们可以直接把食物搬回巢穴中。
上世纪80年代后期，研究人员发现蚂蚁可以实现这一了不起的壮举，这被称为路径整合。蚂蚁跟踪太阳在天空中的运动情况来判断回家的方向，就像过去水手们做的一样。它们通过计算步数来计算距离。
“这是一个非常恶劣的环境。它们在一天最热的时间觅食，沙漠的表面温度高达60到70摄氏度。”
德国乌尔姆大学的神经生物学家马蒂亚斯·威特林格在本周《科学》期刊的播客上发表了这项研究成果。
“它们要快速找到食物，还要快速把食物带回巢穴……它们的动作要非常快，基本上它们每秒的速度要达到身长的100倍。”
威特林格指出，有时沙漠蚂蚁会互相背着前进。
“我们有这个独特的机会来测试那些没有走路的觅食蚂蚁。”
如果它们不走路，那它们就不能计算步数。那这些蚂蚁能找到回家的路吗?
蜜蜂和黄蜂不能数步数，因为它们靠飞行移动。所以，它们依靠光流来计算距离，它们会根据飞行过程中的视觉信息流来估算距离。那被抬着的蚂蚁也用光流来计算距离吗?

托福听力精听 托福听力训练如何用好一篇音频素材( 二 )

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