Welcome back to SciShow News; it's been two weeks since we saw each other in this particular format, and I have to say that I missed you all very much.
To make it up for you, I'm gonna share some news about an ancient human ancestor, own up to an error that we made about the Kelvin scale, and introduce a new segment that I like to call SciShow News Gross-Out.  It's gonna be delicious.

[Intro music]

But first, as you're watching me right now, you're probably either uncomfortably hot and sticking to your chair like I am, or you can barely hear me over the air conditioner.
Summer just started about two weeks ago and already much of the United States has seen record heat, from the Rocky Mountains to the East Coast.  According to the National Climatic Data Center, in the past month more than 4,000 record highs have been broken across the country.
And it's not just the United States that's sizzling; the NCDC's most recent global climate report found that May 2012 was the second hottest May worldwide since record keeping began in 1880, with above average temperatures in nearly all of Europe, Asia, North America, and North Africa.
Of course, all of these record breaking temperatures have led to a lot of speculation in the media about whether this extreme weather is being caused by global warming, as they say.  But let's define our terms here: weather is what's going on outside today, climate is the average of weather patterns over years and decades.
The better question is, is this weather part of a larger pattern of climate change?  In other words, is this what global warming feels like?  
For an answer, I talked to Dr. Kevin Trenberth, who holds the somewhat amazing title of Distinguished Senior Scientist at the National Center for Atmospheric Research in Colorado, and is one of the leading experts on climate change in the United States.  
His response to my question was, somewhat surprisingly, an unequivocal yes.  From heat waves in the US, to recent record rainfall in the UK and Russia, this extreme weather is, in his words, climate change in action.
Dr. Trenberth: The magnitude and the extent of the extremes that we've seen throughout the United States and also different kinds of extremes in other parts of the world certainly indicate that this is not just normal weather.  We're outside of the bounds of normal weather.  This is climate change in action, if you like to think of it that way.
Hank: He explains that, in a stable climate, the number of record high temperatures in a year is usually about the same as the number of record lows.  And that's exactly how the weather rolled until the last few decades.  Since 2000, he said, the number of record highs in the US has been twice the number of record lows, and so far this year, there have been ten times more record highs than record lows.
Dr. Trenberth: And so this is a clear indication that, you know, it's not just one or two of these things that we're picking out, but rather, it's a pattern which is occurring nationwide.
Hank: Dr. Trenberth said not every summer is going to be like this, but overall these trends will continue as long as greenhouse gas levels continue to grow and stay high.  So we should prepare ourselves for more extreme weather, and this is not why I moved to Montana, people!
Dr. Trenberth: But in the meantime, recognizing that it's happening, eh, and, and that these kinds of things are going to continue to happen, that's also something that we can begin to plan for, if we, you know, if we approach it in a reasonable fashion.  Certainly burying one's head in the sand, which is what we've tended to do, and what some politicians have done in this country is, is not the way forward.

Hank: Now, a couple of really amazing and also pretty creepy human bodies, and, no, I'm not talking about Tom Cruise in Rock of Ages.
First, anthropologists in South Africa announced yesterday that they have discovered the most complete skeleton of a human ancestor ever found, and what's more, they didn't even know that they had most of it.
For three years, a large rock sample about a meter across had been sitting in the Wits Institute for Human Evolution in Johannesburg.  But it wasn't until last month that a student noticed a human tooth sticking out of it, and took a sample for a spin at the lab's state of the art CT scanner and basically found a person in there.
The scan revealed the remains of Australopithecus sediba, a species that lived about 1.9 million years ago and is thought by some to be a possible link between Australopithecus africanus and the earliest members of the genus Homo.
The species was first identified in 2010 with the discovery of a skull in the same place where this rock was found.  So, researchers think that the new bones actually belong to the same individual.
Sediba's place in the human family tree is hotly debated at the moment, so this finding could completely change our understanding of who they were and how we're related to them.  The discovery will give anthropologists a lot to work with and argue over, including parts of a jawbone, a complete femur, ribs, vertebrae, and important arm and leg bones, some never before seen so completely in the human fossil record.
Now, what I really love about this discovery is that we'll be able to watch all of these important fossils emerge from the rock live and online.  The process of removing fossilized tissue from surrounding rock is called preparation and the Wits Institute along with our friends at National Geographic are building a super high-tech lab from which they'll live stream the preparation of the fossil for all the world to see.  That's still in the planning phases, so we don't have a link for you, but we'll keep you posted.

And now, it's time for this week's SciShow News Gross-Out!
Some of you might have heard of bog bodies, naturally mummified corpses mostly dating back to the Iron Age that have been found in peat bogs throughout northern Europe.
It's long been thought that these bodies were buried in bogs intentionally, probably as some kind of ritual.
But things just got a whole lot weirder with new research published in the Journal of Archaeological Science.
A team of British archaeologists says that two 3,000 year old bog mummies found in Scotland, one female and the other male, weren't two individuals; instead they're two complete bodies made from the parts of six different people.
[grossed out noise]
Ah, take that Human Centipede, there's something grosser than you, or close, at least.  Wow!  Crazy, Iron Age people.  Ugh!
One of the scientists figured that something was up when he noticed that the jawbone of the female didn't fit with the skull, so they extracted DNA samples from all over the body and found that the skull, the jawbone, arm, and leg all came from different people who apparently were not related.
The male mummy was composed of parts of people who lived hundreds of years apart.  Weird!
Now, why in the name of Sean Connery someone would do this is anyone's guess.  One theory is that it could have been an attempt to combine people from different clans or ancestries to create a symbol of a single shared lineage, but, like, couldn't they have just come up with a flag or a national anthem or something?
You can read the research and see more pictures in the links below.

[sad trombone]
Finally, I wanted to sign off with our first ever and so very regrettable SciShow Correction.  On June 21st, we posted a Dose about absolute zero in which I described Kelvin temperatures in terms of degrees, which is totally and embarrassingly wrong.
Degrees are only used to denote temperatures in scales that are basically arbitrary.  For instance, the Celsius scale is based on water freezing at 0 and boiling at 100 degrees, and a degree is just 1/100 of the difference between the two.
The Fahrenheit scale is just a totally useless mess.
But, because the Kelvin scale is structured around absolutes, namely absolute zero, which you can learn about here, degrees aren't needed because the scale totally makes sense on its own.
For instance, something with a temperature of 100 Kelvin has twice the heat energy of something that's 50 Kelvin, but that's not true for, say, 100 degrees Celsius compared with 50 degrees Celsius.  Celsius is arbitrary, Kelvin is absolute.
We used the wrong term because I and the people who write and edit most of our scripts are not as smart as you are.
And, of course, I have to offer my personal and most abject apology to William Thomson, 1st Baron Kelvin; mea culpa, sir.

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