We hope you’re having a wonderful, sunny day no matter what kind of sunglasses you’re wearing! Now, let Hank explain why “polarized sunglasses” is a stupid name! 

Why do certain mammals have seasonal coats, while others (such as humans), do not?
Anonymous

Humans and our nearest ancestors evolved in areas of the world that don’t have particularly pronounced seasons. Animals that have seasonal coats tend to be making a go of it in places where temperatures and weather varies tremendously between summer and winter. At the equator, the average temperature shift between solstices at the equator is pretty much 0 degrees C, while in Alaska, the daily high shifts more than 30 degrees C over the course of the year. By the time humans were headed to more variable climates, we’d developed technologies like clothing that allowed us to survive in both the summer and winter but didn’t require millions of years of evolution to develop.

-Hank

Is Earth Getting Heavier?

SciShow Space tackles a viewer question: Is the Earth getting heavier? The answers — there’s actually more than one — may surprise you!

tabletopwhale:

I made a chart of some bioluminescent species! Full image on tabletopwhale.com 

tabletopwhale:

I made a chart of some bioluminescent species! Full image on tabletopwhale.com 

edwardspoonhands:

I can barely believe this, but this is a real-life photo I took of our real-life galaxy. 120 second exposure from the top of Blue Mountian last night.

edwardspoonhands:

I can barely believe this, but this is a real-life photo I took of our real-life galaxy. 120 second exposure from the top of Blue Mountian last night.

Why do we need to clean our teeth from an evolutionary point of view? Surely our teeth haven't always been falling out as early primates
Anonymous

Well, a few things to consider. First, these days we eat a lot more foods with nutrients that bacteria REALLY LOVE, particularly simple sugars. So there is some truth to that whole “candy rots your teeth” thing. But the bigger answer is that animals get terrible tooth decay (including primates) and keepers regularly brush the teeth of animals in zoos to prevent these problems. Finally, the average human these days lives a lot longer than we’re designed to. The life expectancy of our nearest relative, the chimpanzee, is just 40 years in the wild. In captivity, that number goes up to around 60. We just live longer than we’re supposed to…so we have to keep our parts working for longer than they’re designed to work…which means brushing your teeth a couple times a day.

- Hank

Science, then, is not like the onion in the often used analogy of stripping away layer after layer to get at some core, central, fundamental truth. Rather it’s like the magic well: no matter how many buckets of water you remove, there’s always another one to be had. Or even better, it’s like the widening ripples on the surface of a pond, the ever larger circumference in touch with more and more of what’s outside the circle, the unknown. This growing forefront is where science occurs… It is a mistake to bob around in the circle of facts instead of riding the wave to the great expanse lying outside the circle.

Stuart Firestein, from Ignorance: How It Drives Science

I was reminded of this quote, which sums up the driving force of the scientific process better than just about anything I’ve ever read, today after watching the latest Vlogbrothers video, in which Hank Green channels his inner Socrates:

"I know one thing, that I know nothing."

Watch Hank admit to being a towering mountain of ignorance (something we should all admit) below…

(via jtotheizzoe)

HIV, Circumcision & The Fight Against AIDS

SciShow News reports some promising new findings about the worldwide fight against HIV, including insights about how we can make the most of one of our newest weapons against HIV: circumcision.

What does the fox say?

Lots of things! Very weird things.

artandsciencejournal:

Home Sweet Home

Usually plastic and the environment do not go hand in hand, but artist Aki Inomata uses plastic to create an environment for her little pet hermit crabs in “Why Not Hand Over a “Shelter” to Hermit Crabs?” (2009, 2010-2013).

With the help of CT scanning to render a three-dimensional model of an empty shell, Inomata creates her base and then builds houses atop these shell renderings. These architectural wonders mimic the style of popular dwellings, from Tokyo house-style to Paris apartments. 

With these plastic hermit crab habitats, Inomata wanted to explore not only the hermit crab’s adaptability to new surroundings, but how we adapt as well. Immigration, relocation, even acquiring a new identity or nationality is more or less the human version of growing out of a shell, and finding a new one to call ‘home’.

Not only is this series an amazing symbolic representation of our will to adapt, but also a fun way to learn more about the life and physiology of the hermit crab, as the dwellings are completely see-through. Have you ever wondered what a hermit crab’s body looks like inside its shell?

A video of both the hermit crabs in action and how the artist came about designing the shells can be found here.

-Anna Paluch