Thanks to Skillshare for supporting this episode of SciShow.
The first 1,000 people to click the link in the description can get
a 1 month free trial of Skillshare so you can start exploring your creativity today.
[♪ INTRO]
Let’s talk about cane toads.
Cane toads are large, hardy toads native to Central and South America
that were brought to Australia
and released into the wild in 1935 as a way to control insect pests.
They proceeded to do like invasive species do and became a pest themselves,
destroying populations of local animals like insects and amphibians.
Cane toads will eat just about anything.
In fact, scientists studying these toads in Australia recently published findings
in the journal Ecology and Evolution showing that their hunger
isn’t just a danger to other creatures, but to themselves.
While this isn’t the first time we’ve ever seen toady cannibalism,
it turns out that cane toad tadpoles in Australia go out of their way
to eat other cane toad eggs and larvae, wiping out entire clutches.
Some cane toad tadpoles feed on other cane toad tadpoles almost exclusively!
And here’s what really weird.
They seem to leave native frogs alone.
And they also don’t really do this in their native range in South America.
The behavior seems to be mostly unique to the Australian population.
To figure out what’s going on, researchers grabbed a bunch of toads,
got them to lay their long, jelly-like strings of eggs, and set up some science.
They found that the tadpoles seem to be specifically reacting to toxic chemicals
that the mother cane toad puts in the jelly around the eggs
to defend them from predators.
The toxins are released into the water when the eggs hatch.
But while these egg-protecting toxins may ward off other species, when these
chemicals got into the water, it seemed to trigger a feeding frenzy in tadpoles.
And the researchers could trigger similar behavior when they added chemicals
to water containing the eggs of other species of frog.
Which the tadpoles would otherwise ignore.
And remember that toads in their native range don’t really do this.
Which means something about being in Australia turned them into cannibals.
The researchers think the toads may be suffering from their own success.
The egg-protecting toxins likely played a role in making the toads such an effective
invasive species, since nothing native to the environment can really deal with them.
But this success may have led to competition between cane toads,
and that may have helped select for cannibalistic behavior.
The toxin that gave them a leg up also showed tadpoles where to go
to eliminate the competition.
Not that it’s any celebration for the toad’s prey species, though.
There still seem to be plenty of cane toads to go around
as far as Australian wildlife is concerned.
And now, for something completely different…
but pretty hopeful.
Amyotrophic lateral sclerosis, or ALS,
is a disease of the nervous system that causes the neurons
responsible for voluntary muscle movements to deteriorate over time.
This often starts as muscle weakness, but as the disease progresses,
it spreads and worsens to the point where the muscles don’t respond at all.
Eventually, people with ALS may lose the ability to speak as well.
So researchers are very interested in finding ways
to help these people continue to communicate.
One option that can help is brain-computer interfaces,
electronic devices that may or actually may not be surgically implanted in the brain.
In the case of ALS, these have generally worked by either reading a person’s
eye movements, or the nerves that carry signals to the eyes or facial muscles.
But these devices still depend on motor neurons in some form, as the eye and
facial muscles are also susceptible to ALS, so it’s not a permanent solution.
So far, once reliable eye movements stop,
scientists haven’t been able to get brain-computer interfaces to work.
However, researchers have now reported in Nature Communications that they’ve
been able to find a different way to let someone communicate at this stage.
But instead of controlling the interface with their visual system,
they use their sense of hearing.
To get it to work, the scientists, with the permission of the person’s family,
implanted two interface devices into their motor cortex,
the part of the brain that controls movement.
This might seem strange for a disease that takes away movement, but the neurons
here still fire in response to thinking about moving different parts of the body,
even if the message can’t get through to the muscles themselves.
And the brain implants could pick up on those activating neurons
and translate them into computer signals.
Those computer signals were then used to create an auditory tone
that was played back for the patient.
With feedback and training, the patient learned how to make this tone rise or fall
based on imagining different body parts moving,
essentially giving them a way to say “yes” or “no” to questions they were asked.
They could then use this to spell out words by having the computer read off a list
of letters signaling which one they want next.
Like, yes to W, then A, then T, E, and R spells “water”.
It’s slow, about one letter per minute, but it’s so much more than nothing.
This study serves as proof of concept that communication is still possible even
when a person loses all voluntary muscle movement due to ALS,
and doesn’t have to rely on systems based on vision.
This could open up new ways to help people.
And even more importantly, it empowers them to communicate their own needs
where they couldn’t before.
So, I hope we see a lot more research like this in the future.
Meanwhile, today’s sponsor Skillshare empowers you to grow as a creative.
Skillshare is an online learning community with 1,000’s of classes to choose from.
It’s curated specifically for learning, meaning there are no ads,
and they’re always launching new premium classes,
so you can stay focused and follow wherever your creativity takes you.
Premium Membership gives you unlimited access,
so you can join the classes and communities that are just right for you.
If you’d like somewhere to start, you might check out “Productivity for Creatives”
with Thomas Frank, which will help you build a system
to bring out your own best work.
This class also has hands-on projects that you complete
and can share with other community members.
The first 1,000 people to click the link in the description get a one month free trial
of Skillshare so you can start exploring your creativity today.
And checking them out supports us as well, so thank you for doing that.
[♪ OUTRO]