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Category Archives: Natural History

Scientists use Flashes of Light to Investigate Memory

If you’ve seen the Men in Black movies, you might remember the neuralyzer – the flashy thing the agents use to wipe memories? Well this might make you remember. Researchers at the University of California have just used flashes of light to find new evidence about how the brain stores memories.

What were they looking for?

Dr. Brian Wiltgen and Kazumasa Tanaka – a graduate student – were trying to investigate how the brain stores memories. It’s thought that one specific region of the brain – the hippocampus – is what triggers memory recall.

What did they find?

Their study supported their hypothesis. “Our study demonstrates that memory is retrieved when the hippocampus reinstates patterns of cortical activity that were observed during learning,” said Dr. Wiltgen in an email.

How did they do it?

To do this study, the researchers created genetically modified mice that did two specific things. First, their brain cells would light up like Christmas lights when activated by a memory. Secondly, the scientists could also temporarily de-activate cells.

The researchers then tested their hypothesis. If the mice were stimulated to remember a scary event in their past (in this case, an electric shock) they normally froze and their brain cells would light up. However, if the researchers turned off hippocampus cells, the brain cells never lit up and the mice didn’t freeze.

So?

It means that the mice didn’t recall that memory.

They forgot?

Not quite. The memory was still there – the brain cells were still there, after all – they just weren’t able to access it. Without the hippocampus to act like a key, the memory was locked away.

What does this mean?

In an email, Dr. Wiltgen said, “The hope is that once we figure out how these processes work we will be better able to understand (and treat) human disorders that affect memory.”

One caveat of this study is that the research was specifically looking at what’s known as episodic memories – memories of people, places, and events. It’s thought that other types of memory – such as skills or languages – might be controlled differently.

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Posted by on October 20, 2014 in Medicine, Natural History

 

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Moonlighting: The Effect of Moonlight on Prey Activity

Image from telegraph.co.uk

Imagine you’re stuck on the African plains at night – would you feel safer with or without the moon? Choose carefully, there are more than just lions out there.

Most people would imagine that moonless nights are safer – after all, lions need to see their prey to catch it, right? The extra light from the moon should make things more dangerous for prey. However, a new study points out a critical flaw in that logic: Wouldn’t the extra light also help the prey as well?

Turns out, each species might decide about that.

Counter to the above logic, lions tended to actually hunt less on moonlit nights, preferring the complete cover of darkness. Rodents and rabbits tended to prefer dark nights as well. Primates didn’t though – full moons correlated with more activity, not less. The researchers had originally thought that activity levels would be organized neatly into a food-chain, but what they found was that the most important factor was possibly a prey animal’s senses, not trophic level.

If you’re a sight-loving primate, for example, bright nights help you spot that creeping lion. If you’re a rabbit and depend on your ears, well, maybe that’s a good night to stay still. 

In fact, some prey species may even vary their choices based on seasonal variations and predation risk. A different study showed that snowshoe hares moved around less during bright, snowy nights than dark, snowy ones, but showed no variation during the snow-free months when, presumably, predator risks are much different.

The take-away message is that prey animals don’t just cower at any possible risk – they base their activity on measurable trade-offs and risks. The moon is bright – is my extra vision worth the risk? The moon is dark – can I depend on my ears to keep me safe?

What’s moving around out there in the night?

 
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Posted by on October 27, 2013 in Natural History

 

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Jökulhlaup

The Ice Age fascinates me. Tectonic plates take millions of years to change the earth, but a few hundred million tons of ice and water can do it in a few thousand. Or sometimes, if the conditions are just right, things happen a lot faster.

When a glacier melts, the water usually flows away as a stream or river from the base of it. However, if the water is dammed and released, or if something like a volcano causes catastrophic melting, that stream can turn into a devastating flood.

This is what is known as a jökulhlaup (pronounced yoo-kul-hloo-ee-p) or glacial outburst flood. They’re well-known in Iceland (where we get “jökulhlaup” from) because of the numerous glaciers and volcanoes, but can occur anywhere where glaciers exist and can be very dangerous. The 1755 Mýrdalsjökull jökulhlaup may have released more cubic meters of water per second than the Amazon river.

During the last ice age these kinds of massive outbursts were very common. As the planet warmed, immense lakes of meltwater formed in the middle of the retreating glaciers, eventually releasing unimaginably large floods. It’s now accepted that the bizarre geology of the channelled scablands was the result of just a handful of these outbursts.

Jökulhlaups – very dangerous, very interesting.

Source: http://en.wikipedia.org/wiki/J%C3%B6kulhlaup

 
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Posted by on October 20, 2013 in Natural History

 

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Tiny, Tiny Porpoise

Photo from whaletrackers.com courtesy of Barb Taylor

Photo from whaletrackers.com courtesy of Barb Taylor

Look at this porpoise. It is so tiny. Even its name – vaquita – means little cow. I bet you didn’t even know this guy existed.

Although, really, it’s not your fault. They’re very rare and are actually the most critically endangered of all the cetaceans (an order that includes whales and dolphins). Vaquitas are only found in the northern bay of the Gulf of California, near where the Colorado River empties out into the sea. The water there is pretty murky and these guys are hard to spot, so there’s not a lot known about them. They weren’t even officially discovered until 1958.

And when I say they’re very rare I mean they’re very rare. As few as 150 of them may be left in the wild.

Check out www.whaletrackers.com to learn more about these guys!

 
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Posted by on September 26, 2013 in Natural History

 

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Explaining the Chili’s Heat (While Eating One)

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This is a follow-up to this article I posted in June 2012.

I am not always smart.

 
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Posted by on September 13, 2013 in Natural History

 

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Do Rhinos Put Out Fires?

I actually first heard about this myth on The Simpsons. There was one episode where Marge saves Homer from a rampaging rhino by setting their car on fire. The rhino immediately abandons its attack and puts out the fire. Day is saved.

Funny joke. Thought it was just random humor.

Actually, though, it’s not just a stupid joke. I mean, it is a stupid joke, but, whatever. I found out later that it was really a spoof of two scenes from the excellent 1980 film The Gods Must Be Crazya comedy set in the Kalahari Desert of Africa. You can watch them below.

But this just creates further questions. If I got it from The Simpsons, and The Simpsons got it from The Gods Must Be Crazy, where did they get it from? It is a myth, right?

Turns out the myth dates back a ways. And it is a myth. Fire can make a rhino panic, but its first instinct is to run from the fire, not try to fight it. Also, in an interesting twist, although the myth always references African rhinos, the myth doesn’t seem to come from Africa! No native cultures in Africa ever had a story about fire-fighting rhinos.

So why is it there?

It’s actually a weird artifact of colonialism. There are myths about fiery rhinos, but they start over 7000 kilometers way in southeast Asia, near the countries of Malaysia and Myanmar. Now, Africa’s black and white rhinoceroses don’t live in Asia, but those two countries do have their own flavor of rhino, the Sumatran rhinocerous. It is smaller than its African cousins and lives in the jungle, instead of the savannah.

It’s also hairy sometimes. Which looks kind of weird.

Two Sumatran rhinos at the Cincinatti Zoo.

N. J. Van Strien notes in his study of Sumatran rhinos: “Rhinos… are said to be attracted by campfires or smoke. Whenever it sees a fire it runs up and tramples and devours it, causing a lot of damage and panic in the camp (F. Mason 1882).” The locals even have a specific name for these creatures, Badak Api, literally fire rhinos. It’s not known what they do with the fire after they eat it.

Perhaps they breathe it. That’d be scary. Fire-breathing rhinos. Or their horns could be made of fire. Maybe they’d run on propane.

Either way, the European naturalists heard these myths and brought them back to the Western world, accidentally confusing some of the details along the way. Hence fire-eating Asian rhinos became fire-hating African rhinos. Which stuck around long enough to make it to Hollywood.

And, eventually, The Simpsons.

 
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Posted by on August 24, 2013 in Natural History

 

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Hero Shrew has an Unbreakable Spine

The hero shrew – a big name for a small animal. The animal is small, nondescript. It looks like any other shrew in the world. It lives in the forests of central Africa, mostly in the Democratic Republic of Congo. It’s a relatively recent find for western science –  Europeans first heard of it in 1910 and a sister species was only discovered this year. The following account is from the field notes of one Herbert Lang, published by J. A. Allen in 1917:

“The natives of these regions, especially the Mangbetu, who are well acquainted with this shrew, first called our attention to its abnormally strengthened back-bone by their performances upon captive specimens. These people feel convinced that its charred body or even its heart, when prepared by their medicine-men, transmit truly invincible qualities, if worn as a talisman or taken like a medicine. Perhaps this mystic reputation has often contributed to make of a brave man a real hero, wherefore the Mangbetu gave it a name meaning ‘hero shrew.’ Those engaging in warfare or setting out upon an equally dangerous enterprise such as hunting elephants are anxious to carry along even a fraction of the ashes of this shrew. Though only worn somewhere about their body, they believe that neither spears nor arrows, nor any kind of attack can seriously injure them, much less bear them down. One can easily imaging that by the removal of the inhibitory influence of fear their courage, cunning and cleverness are set free for the best possible achievements.

Whenever they have a chance they take great delight in showing to the easily fascinated crowd its extraordinary resistance to weight and pressure. After the usual hubbub of various invocations, a full-grown man weighing some 160 pounds steps barefooted upon the shrew. Steadily trying to balance himself upon one leg, he continues to vociferate several minutes. The poor creature seems certainly to be doomed. But as soon as his tormentor jumps off, the shrew after a few shivering movements tries to escape, none the worse for this mad experience and apparently in no need of the wild applause and exhortations of the throng.”

An animal that only weighs 100 grams supporting a fully grown man! That’s would be like a soldier getting run over by an M1 Abrams tank!

Hero shrews can support this kind of weight because of their spines. Instead of 5 lumbar (lower-back) vertebrae which are loosely connected, like in humans, the hero shrew has 11 densely-packed inter-connected bones. These are in turn supported by enhanced muscles and chest bones.

The hero shrew is on top. A normal shrew is on the bottom.

The hero shrew is on top. A normal shrew is on the bottom.

The evolutionary benefit of this massive spine is still unclear, but a promising theory suggests that this adaptation helps the shrew hunt for invertebrates. The thinking goes that maybe the shrew can use it’s back like a hydraulic jack to lift up large rocks or logs, exposing the bugs and worms hiding underneath. This hasn’t been proven, but anecdotal evidence seems to support it.

Body of a mouse. Spine of steel.

 
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Posted by on July 27, 2013 in Natural History

 

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