This video was sponsored by 23andMe.
Hi, this is Emily from MinuteEarth.
Domestication has puppified dogs,
fluffified sheep, and spotified horses –
but there ’ s a less obvious physical change that
virtually all domesticated animals share:
Duck brains have shrunk by about 15 %,
cat brains by 30 %,
and pig brains by a whopping 35%.
We’ve even found smaller brains in farmed trout.
Which is weird, because in general,
the size of animals’ brains and the size of their bodies
is super tightly linked –
mites have smaller brains than ants,
which have smaller brains than mice,
which have smaller brains than elephants, and so on.
The same relationship exists for individuals within species.
So, for example,
small wolves have smaller brains than big wolves,
and small dogs have smaller brains than big dogs.
But when you compare wolves and dogs,
between individuals of the same size,
the wolves have bigger brains,
no matter what the body sizeis.
across different domesticated animals,
a disproportionate amount of the
shrinkage happened in parts of the brain
that monitor information from the outside world
and tell animals when and how to freak out –
sort of like the brain ’ s panic button.
We know that, in general,
animals with bigger panic buttons
have a more sensitive fight or flight response,
and animals with smaller panic buttons are naturally tamer.
So those are the ones we probably would have tried to domesticate.
And, by breeding the tamest animals with each other,
we shrunk their panic buttons –
and therefore their brains – even further.
domesticated animals have
formed long-term partnerships with humanity
by literally losing their minds.
Thanks to 23andMe for sponsoring this video.
With 23andMe ’ s simple DNA kits,
you can learn all about your own ancestral history,
as well as other parts of your DNA story,
like how your genes CAN influence everything
from your facial features to your sleep quality.
To get your kit, and show your support for MinuteEarth,
go to 23andMe.com/MinuteEarth.
There ’ s a special holiday offer now through December 26th;
click the link in the description
to get kits for you and your family.