Friday, 5 September 2014
Sketchy Fact #56: Into the Freshwater Abyss
Lake Baikal in Siberia is the deepest and oldest lake in the world at 1620 meters (over a mile) deep and around 25 million years old. It holds about 20% of the world's liquid fresh water.
Wednesday, 3 September 2014
Messing with Motor Function: The Science Behind ALS
In case you missed our post last week and
in case you’ve been living under a rock for the past month, the ALS Ice Bucket
Challenge has reached a pinnacle of virility not seen since Rebecca Black gave
us a new way to usher in the weekend. However, unlike the meaningless funny
stuff that usually turns up on the internet, the Ice Bucket Challenge has done
an incredible amount of good. Apart from raising awareness of ALS (amyotrophic
lateral sclerosis), nominators and nominatees have donated over $100 million to ALS research
as of this writing. Compared to the $2.1 million raised in 2013, the past month
has been an icy flood of cash.
But what is ALS any why have we all so
enthusiastically decided that we need to drown it out? Most of us know that
baseball hall of famer Lou Gehrig suffered from the disease and eventually gave
his name to its colloquial identification. Some of us even know that
world-famous physicist Stephen Hawking lives with the disease to this day. But
what causes ALS? What does it do to a person’s body? And what can be done to
stop it?
ALS is a disease of the motor neurons.
There are two kinds of motor neurons: upper motor neurons (the ones in your
head) and lower motor neurons (the ones everywhere else in your body). ALS
starts off my damaging either the upper motor neurons, preventing them from
sending signals to the spinal cord, or the lower ones, preventing them from
taking messages from the spinal cord to the muscles. In the latter case,
muscles in one part of the body will become weak or clumsy. In the former case
a person will become more generally weak and uncoordinated.
The real problem with ALS is that it
spreads and intensifies, eventually leaving a person paralyzed and without
control of any of their voluntary muscles. Mercifully the disease tends not to
effect involuntary muscles like those in your bowel and it often spares the
muscles that control eye movement which is what allows Stephen Hawking to teach
the rest of us about black holes. He uses eye movements to type academic papers
and books in a monumental feat of patience. As ALS progresses it impacts
a person’s ability to swallow and breath normally, often leading to death by
choking.
Scientists aren’t sure what causes ALS
generally, but they are aware of a type that runs in families. Research has shown
that a mutation in the SOD1 gene is present in 20% of people with familial ALS.
SOD1 directs the body to produce an enzyme that protects motor neurons from
harmful unstable molecules called free radicals. The mutation removes this protection and causes neurons to break down. If a person has a parent with this gene
mutation, there is a 50% chance they will develop ALS. Thankfully, the sporadic (non-familial) form of the disease is far less common. On average only 2 in every 100,000 is
struck with ALS, usually between age 40 and 60.
As you have probably figured out by the
existence of the Ice Bucket Challenge, ALS has no cure… yet. While modern
treatments and technologies can help prolong patients’ lives by a few months to
a few years, most people with ALS pass away within 3 to 5 years of being
diagnosed. The notable exception is Stephen Hawking. Through a combination of
medical intervention, help from computers, and sheer force of will Dr. Hawking
has lived with ALS for over 45 years.
Modern research is focused developing gene therapies to treat mutations that can cause ALS or aims to develop chemical
therapies that increase the production of antioxidants and neurotrophic factors
in the body to help build and protect muscles cells. Stem cell treatments are
also showing some promise. In 2008 researchers were able to take stem cells
from the skin of 2 people with the harmful mutation to their SOD1 genes and raise them to produce healthy motor neurons.
One day researchers hope to be able to grow
enough motor neurons to transplant them into patients and reverse the disease's
progression. The best current treatments can do is slow down the spread of ALS through the body. In rare cases ALS can burn itself out, reaching a
certain point and just stopping. Scientists don’t understand why this happens
but research on people for whom this is the case may also help develop
treatments.
In order to do the research needed to
better understand ALS and develop treatments, scientists need money. They get
that money from organizations like the ALS Association, who rely on donations
from the general public. So next time you see a video of one of your friends
dousing themselves in water, throw them a like. And if you are nominated to do
the challenge yourself, do it and make a donation. A little discomfort for you
could mean a whole lot less for someone else.
Friday, 29 August 2014
Sketchy Fact #55: Let the Smallest Bird Bee
The bee hummingbird is the smallest bird in the world at just 5 cm long and 2 grams in weight, that's about as much as 2 paperclips.
Tuesday, 26 August 2014
The Ice Bucket Challenge: Scientific Considerations
If you’ve spent any time on the internet over the past couple weeks you’ve probably seen a bunch of viral videos of people
dumping cold water on themselves to raise money for ALS. Dubbed “The Ice Bucket
Challenge” it is a silly activity for a good cause and there is a lot of
science involved, so naturally we’ve decided to volunteer our illustrator to
take the plunge (donate at http://www.als.ca/en/donate). There are however a few things to consider before engaging in
this frozen fund-raiser, so let’s take a moment to get the facts straight.
The
Gasp Reflex
According to Beyond Cold Water Bootcamp
there are 4 stages of cold water immersion:
- Cold Shock Response
- Cold Incapacitation
- Hypothermia
- Circum-Rescue Collapse
While each of these is important when
you’re pulling unlucky fishermen from frigid arctic seas, only the first really
applies to The Ice Bucket Challenge. The cold shock response lasts for about a minute
when you’re actually submerged and it can wreak havoc with your body. It begins
with a sudden inward gasp that evolution has programmed as a reflex to help us hold our
breath. Unfortunately it can also lead to inhaling a bunch of water, so watch
out for it.
Icy
Heart
The Cold Shock Response also has serious
effects on your heart. A sudden influx of cold water makes your arteries narrow in a process
called vasoconstriction. The result is that your heart has to work harder to
pump the same volume of blood. The lesson here is, if you have a heart
condition, maybe leave the ice buckets to the rest of us and just help out with
a donation to the ALS association.
Spicing
Things Up
As a reader of this blog, you might also be
tempted to throw your own flare onto the Ice Bucket Challenge using some clever
science twists. You could try The Dry Ice Bucket Challenge. Dry ice is frozen
carbon dioxide and has a surface temperature of -78.5 degrees Celcius (-109.3
F). This makes it a pretty bad choice for our purposes. Being that cold, it has
the ability to severely damage your skin. Another reason to give it a pass is
that as dry ice warms it sublimates, meaning it turns directly from ice into
carbon dioxide gas. This has a cool effect at Halloween parties, but it isn’t
something you want to be breathing in while you try to go viral.
Another equally bad idea is using liquid
nitrogen. With a temperature of -196 C (-320 F) liquid nitrogen is probably the
coldest stuff a normal person can get their hands on. However, unless you want your
hands to shatter getting liquid nitrogen on them is a pretty bad
idea. If you don’t end up effectively turning into glass by freezing
yourself solid you might accidentally cryogenically freeze yourself. This isn’t
as cool as in the movies. Rather than waking up in the future, your cells will
all rupture as the water in them freezes and expands and you’ll just become a
very brittle corpse. You do have about a second before it contacts your skin thanks to the aptly named Leidenfrost Effect, but is it really worth the risk?
No
Pain, No Gain
Finally, The Ice Bucket Challenge has the
potential to cause you some brief pain. In studies of pain tolerance,
psychologists and the Mythbusters alike have used tubs of ice water to inflict
suffering on their volunteers. In the long-run a little momentary discomfort is
nothing compared to ALS, though; so if you don’t have a heart condition and
aren’t dumb enough to try our previously mentioned ice alternatives, we
challenge you to go for it!
Without
Further Adieu…
References:
Friday, 22 August 2014
Sketchy Fact #54: Follow the Pheromones
Male moths can detect females from up to 7 miles away. Even though they don't have noses, male moths have some of the most sensitive antennae in the business.
Wednesday, 20 August 2014
Fatally Unfair: The Science of Planet’s Most Venomous Creatures
One of the most exciting things that can happen when you head out into
the wilderness is spotting an animal that you wouldn’t see on a typical day. Such sightings, however, often carry with them a risk of bringing you
uncomfortably and unintentionally close to the food chain. Depending where you
live in the world you could risk being stalked by a tiger, mauled by a bear, or
taken down by the bite of a venomous snake.
From the perspective of someone who grew up in a country without many
venomous animals, that last option is particularly jarring. Like most Canadians
with a penchant for spending time in the woods I have a healthy understanding of what to do if I encounter a certain type of dangerous animal. Given that I am
most likely to come across a large mammal like a bear or a mountain lion the
options range from playing dead, to climbing a tree (to escape a grizzly), to
fighting back and hoping for the best. However, in the face of ambush predators that
rely on one quick bite or sting to take you down, all of the tactics I have
spent my life learning result in me twitching and dying in the dirt.
It just seems so much less sporting. With a large predator at least you
know what got you and can do something to stop it. In that sense, venom is
nature’s most unfortunate pull of the slot machine. It's that inherent unfairness
that makes venom so fascinating.
First off, it is important to know the difference between venom and
poison. Poison is nature’s passive form of toxicity. Poisonous animals will
definitely cause you some harm, but you have to bring it on yourself. By
contrast, a venomous animal actively seeks to cause trouble. Venomous animals
bite and sting and for that reason tend to be predators (ex. snakes, jellyfish,
spiders). Poisonous animals are more often prey that use there poison as
defense against predators (ex. frogs,
beetles, and plants).
One of the more fun questions a person can ask in any discussion of venom is
“Which animal has the world’s deadliest venom?” Unfortunately, like all
seemingly simple questions in the world of science, this can be a tricky one to
answer. The most common method of rating the potency of toxins is determining
their LD50 (Lethal Dose 50). This is the dose of the toxin that is lethal for 50% of animals
that receive it. Given in milligrams of toxin per kilogram of body mass, LD50
is a good starting point but is far from perfect. Animals react differently
depending on where in the world the toxin originated, how it is administered, and a host of
other variables.
It may not be foolproof, but it is the best option we have if we want to
find the world’s most venomous creature. Now that we have a method we need to
narrow down our search geographically. Fortunately this isn’t at all difficult.
There is one place that we can go with a reputation for being crawling with the
world’s deadliest versions of every poisonous animal. Pack your bags, we’re off
to Australia.
We won’t get into why Australian animals are so venomous because that is
something even scientists have a hard time answering. Let’s just take it
as a fact that Australia is about the last place in the world you want to get
bitten or stung by something. Near the top of the list of animals you don’t
want to cuddle with is the box jellyfish. Small, unassuming, and nearly
transparent but for a faint tint of pale blue these invertebrates pack a
serious punch. The venom of a box jellyfish has an LD50 of 0.04 milligrams/kg
of body mass. Keep in mind that with LD50, lower numbers equal stronger toxins. For comparison, the LD50 of coral snake venom (one of North
America’s most venomous animals) is 1.3mg/kg. Adding insult to injury, the
jelly’s venom has the ability to kill skin cells. That means if you don’t end
up dead, you can at least count on some pretty gnarly scars.
As troublesome as box jellies may be, however, there is one Australian
critter that makes even them nervous (assuming they have emotions which they
probably don’t). You may be surprised to learn that the creature most
scientists agree is the world’s deadliest is actually the cone snail. This
marine snail may look a lot like it’s cousins that kids pick of leaves in their
grandparent’s gardens but rest assured, this ain’t your gamgam’s brand of
mollusk. Not even close. With a mind-blowing LD50 of 0.012mg/kg, cone snail
venom usually kills the snails prey animals (mostly fish and other snails)
before their nervous systems can even react to being stung.
Say what you will about my pal the grizzly bear, at least it has the
decency to let you hit the ground and have a look at it before finishing you
off.
References:
Friday, 15 August 2014
Sketchy Fact #53: Fighting Fingers
Your fingers don't have any muscles in them. When you move your fingers you are actually tugging their tendons using the muscles in your forearm.
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