Spend five minutes in any forest and you’ll probably hear birds chirping.
The kind of vocal communication
which are sounds animals make with their mouth or
throat parts like talking roaring or meowing
and there’re tons of papers out
there about birdsong and how it can mean anything from
“Look how cool my feathers are!” to “Run away!”
But about 150 years ago Charles Darwin had a thought
what if the non vocal sounds that birds make like by
flapping their wings mean something too.
Scientists have been looking into this question for a while
and this week a study from the Australian National University seems to
give more evidence that Darwin was right.
If you’ve spent any time on mainland Australia
you’ll have heard the crested pigeon whistle
except it isn’t a mouth sound.
They whistle when they flap their wings which got them the nickname
“Whistle Winged Pigeons” Say that five times fast.
In the 2009 paper researchers
had noticed something important:
Other pigeons seem to react to the whistle.
So a group of biologists including
one of the previous paper’s authors wanted to
do more tests to see if the noise actually communicated something.
In the 2009 research
they measured crested pigeon wing feathers and discovered a
weirdly thin one specifically the eighth primary feather.
Measurements in both studies showed that
the pigeons produced two distinct notes as their wings flap
and vibrate the feathers one is much higher than the other.
Also when the birds were flying away in a hurry
they flapped faster and the sound was louder.
So the researchers carefully removed the weird feather
from some birds all in the name of science.
But it’s okay. They grow back.
Without the narrow feather the highest note disappeared
and wind tunnel experiments confirmed that the feather makes the noise
when it’s vibrating on its own.
Most importantly the researchers compared the reaction of other crested pigeons
to recordings of birds flying away with and without the special feather
and there was a clear difference.
When the other birds heard the high-pitched sound
they were more likely to get out of there in a hurry
as if there were an alarm blaring.
But if they heard the recordings without that alarm
they were more likely to stick around or take off more leisurely.
This gives some solid evidence for Darwin’s nonverbal communication idea
showing how the sound is produced
and how other birds respond to it.
And the researchers say it makes sense evolutionarily too.
These pigeons are always going to make a sound
if there’s danger nearby
so more birds know to escape and stay alive.
Unless a scientist comes along and takes away some of their feathers.
But enough about birds. Let’s talk about humans.
Because if you’re a student a parent or really anyone
you’ve probably been sleep-deprived before.
You feel sluggish like your mind is swimming through fog
to make decisions and everything just seems harder.
And this week researchers from UCLA
took a deep look into the biology behind this feeling.
When you’re tired your neurons sort of go to sleep too.
In a paper published in the journal Nature Medicine
this team of neuroscientists monitored
the brain activity of 12 patients who had electrodes in their heads.
But before you get too weirded out by that
the patients were already in the hospital to get treatment for epilepsy.
Epilepsy is a super broad term
for abnormal brain activity that causes seizures.
There’s a lot of variation in causes and symptoms
which means treatments can vary a lot too.
Sometimes it’s hard to pinpoint the exact brain region
that’s affected so doctors can implant electrodes to keep
track of the electrical signals throughout the brain when a seizure happens.
And this can help doctors decide if brain surgery is worth
the risk to remove something
that might be causing the seizures like scar tissue.
And when doctors want to cause a seizure
in a controlled hospital setting.
Sleep deprivation is key.
Electrical activity in the brain changes when you’re asleep or awake.
So messing with that cycle can influence seizures.
This worked out well for these researchers too.
They had a group of probably bored sleep-deprived people
with their brain signals being monitored.
So they can see what happens to neurons
when we force ourselves to stay awake.
At different times the patients were given a set of
images to categorize as quickly as they could
while the researchers monitored brain activity
in a region called the temporal lobe.
Among other things the temporal lobe translates sensory information into conscious thoughts.
Basically information processing like if I see a roundish red thing
with a brown stem on top.
My temporal lobe helps me recognize that it’s an apple.
The scientists noticed that the neurons in the temporal lobe
actually fired more slowly and passed along weaker signals
事实上 神经元激动较慢 且传导信号更弱
as the patients did this task after staying awake longer.
The researchers also measured brain waves
the repeating cycles of many neurons firing
and these brain waves slowed down in certain regions too.
so they kind of looked like the ones linked with sleep.
We’ve known for a long time that
sleep deprivation can mess with how you act.
But this is the first study
in humans that might explain what’s going on biologically.
The researchers say the effects of these basically sleeping neurons
are similar to being drunk
which has huge implications for things like driving.
Like it’s going to take longer for your brain to process
an unexpected pedestrian on the road and react.
So that’s maybe something to think about next time
you’re watching Netflix until 3 a.m.
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