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It Begins…

March 30, 2009 on 1:22 pm | In Blog info, Evolution | 316 Comments

Well, it’s happening this week, folks! I’m going to make the move over to ScienceBlogs this week, and I will have a special good-bye video post this Wednesday.

In the meantime, to help you cope with your sadness, Ian O’Neill at AstroEngine has this week’s Carnival of Space, and I have an example of artificial selection for you, duck-style:

The ones who are good at navigating metal grates survive to adulthood; the others, not so much. Yikes.

Between Bird and Mammal Lies the 6th Sense…

March 23, 2009 on 1:45 pm | In Evolution, Life | 58 Comments

This Australian “mammal” is one of the most bizarre creatures on Earth, having many of the characteristics usually reserved for either birds only or mammals only:

Ladies and gentlemen, the duck-billed platypus! Its most notable features are as follows:

1. It lays eggs. This is usually reserved exclusively for birds, reptiles, dinosaurs, etc. And these eggs are tiny! Mammals gestate with the eggs inside of them, giving birth to live young, but here’s a mammal that lays eggs!

2. It’s furry. Like mammals are — no feathers for this guy — the platypus is not only covered in fur, it’s got such a nice coat that it has historically been hunted for its fur!

3. It is venomous! This is extremely rare for mammals, and the platypus itself has three venomous compounds in it that are unique in all of nature to the platypus itself. The venom is emitted through a spur in the platypus’ foot, right around its ankle. And speaking of feet…

4. It has otter-like feet. Totally mammalian, you got it. On the other hand…

5. It has a duck-like bill. Totally bird-like, of course. On the other hand…

6. It has a beaver-like tail. Mammalian, I got it. I suppose we can go on and on, listing all the ways this animal is neither bird nor mammal, all of which I find fascinating. But this animal can do something that you and I cannot, no matter how hard we try. Your skin, your epidermal layer, is fantastic for sensing temperature, pressure, and pain. These three types of sensor suit us remarkably well, and allow us to experience all sorts of interesting sensations, like itch and ticklishness. But the platypus has us beat, because in addition to these, the platypus can detect electricity!

That’s right, the duck-billed platypus has the most sophisticated sense of “electroreception” of any mammal, allowing it to track its aquatic prey by locating where an electrical stimulus resulting from muscle contraction came from. Normally, we only see this in predatory fish, like I’ll show you in the image below:

But here it is, in a platypus! How cool of a sense is that?! So the next time someone tells you about “the sixth sense,” don’t think of ESP and don’t think of Bruce Willis, think about the platypus, an animal with a real sixth sense: the ability to detect electricity!

Because I want a sense like that…

How Quickly do Humans Evolve?

February 16, 2009 on 2:35 pm | In Evolution, Life | 30 Comments

One of the worst arguments out there against evolution is that we can see micro-evolution, in simple organisms, but not macro-evolution, or evolution in large plants and animals with long lifetimes. Therefore, the faulty argument goes, since we haven’t observed it directly, there’s no evidence for it. Let’s take a look at the obvious flaw in this argument:

Scientific studies have only been around for a few human generations. Evolution takes many generations to have visible effects. Something like a bacterium can reproduce so quickly that in just a few months you can have in excess of a hundred-thousand generations! So it’s very easy to observe evolution for microorganisms, since we have so much generational time to see change over time. This is much harder in longer-lived organisms. In humans, for instance, a typical generation is about 25 years. So while you get millions of generations for a microorganism, you only get one for humans and only a handful for even small mammals. So that logic is completely faulty.

Nevertheless, perhaps we can, if we’re clever enough, find evidence for the evolution of humans in our history. Human history goes back a long time, and if we study it properly, perhaps we can find something that shows how human characteristics change over time. As reported on MSNBC, changes in human DNA (as shown from human skeletal remains) have occurred about 100 times more quickly in the past 10,000 years than at any time in human history:

John Hawks, a professor at UW-Madison (shout-out!), rejected the assumption that human evolution ceased roughly 50,000 years ago, and working off of a sample of 35,000 years of skeletons from all around the world, uncovered the following:

In Europeans, the cheekbones slant backward, the eye sockets are shaped like aviator glasses, and the nose bridge is high. Asians have cheekbones facing more forward, very round orbits, and a very low nose bridge. Australians have thicker skulls and the biggest teeth, on average, of any population today.

“It beats me how leading biologists could look at the fossil record and conclude that human evolution came to a standstill 50,000 years ago,” Hawks says.

By his account, Hawks’ theory of accelerated human evolution owes its genesis to what he could see with his own eyes. But his radical view was also influenced by newly emerging genetic data. Thanks to stunning advances in sequencing and deciphering DNA in recent years, scientists had begun uncovering, one by one, genes that boost evolutionary fitness. These variants, which emerged after the Stone Age, seemed to help populations better combat infectious organisms, survive frigid temperatures, or otherwise adapt to local conditions. And they were popping up with surprising frequency.

The general rule here, that I love, is “adapt to local conditions“. What’s one of the simplest adaptations to local conditions in any living organism? The ability to blend in with their environment. The most stunning example is probably the chameleon, which can even adapt to change its color to match whatever it’s up against:

Does this work in humans? Could our huge variety in skin color be due to local adaptations? And if so, could we use this as evidence for human macroevolution?

Well, as reported by NPR, the answers are yes, yes, and yes! According to their research, changes in human pigmentation take only 100 to 200 generations, which is as few as 2,500 years. They specifically cite India as their example, that a few thousand years ago, when they lived farther to the North, their skin was much lighter, and has darkened dramatically over the past few millennia as they’ve migrated back to the south, to warmer climates.

Now, here’s a kicker: we already know why changing pigment is important for humans! From the NPR article:

“Humans started in Africa,” Jablonski says, the part of Africa near the equator where it is intensely sunny with lots of ultraviolet light.

Ultraviolet light, or UV, in high doses can age the skin and damage the DNA molecule, which makes it harder to build a fetus. Not to mention that ultraviolet light can sometimes cause skin cancer.

On the other hand, if a human is plopped down in, say, Norway, where the days can be short and there is precious little ultraviolet light, this creates problems, too. All vertebrate animals need ultraviolet light to help produce vitamin D. Vitamin D helps us absorb calcium from our food to build strong bones. If we don’t get enough ultraviolet light, we’re less likely to survive to reproductive age to produce strong-boned babies.

Thus the dilemma: People who live in sunny climes around the equator have too much UV. People who move away from the equator eventually have too little UV.

In fact, take a look at this map of UV radiation on Earth. How well do you think it will match the native population of that area?

Breathtaking, isn’t it? According to UV data alone, Australian Aboriginals and Africans should be the darkest, people from northern Europe, Asia and Canada should be the lightest, and Native Americans, those from the middle east (like me, ancestrally), and equatorial Asia should be in between. Sound like any world that you live in?

But science is even cooler than just this. Because we can make a computer model to simulate how the evolution of something like pigment works. We don’t need to simulate melanin or anything that complex, we can do it for a single-celled organism. If you have 10 minutes (and if you’re at work, feel free to turn the sound off; it’s just music), have a gander at how this works:

And while you’re here, I’d like to point out two things. First, I was asked a while ago where to go for educational science information on physics, astronomy, the natural world, etc. The National Geographic Channel has been putting out some good stuff recently. It seems like practically every Sunday night, starting at 8 PM ET/PT, they have a really interesting new science program on. This past Sunday, they had a 3-part program called Known Universe, where they talked about some of the biggest, smallest, fastest, and most extreme things we’ve ever discovered or created in the known Universe. This is great and rare, because it actually addresses things we know for certain, not only speculative theories or those for which there’s insufficient evidence. Yes, they have discussions about what may come next, but they’re well-done and reasonable, and it’s the things we already know that’s the (well-deserved) focus of the show. I’m really happy about it, and I regret not advertising it sooner. But look for it; it’s worth watching.

And second, the new Carnival of Space is up, just in time for… uhh… next year’s Valentine’s Day? Happy Monday, folks.

There isn’t enough punishment for this

February 9, 2009 on 3:25 pm | In Education, Life, Scientific papers | 10 Comments

I normally try to keep my nose out of areas where I’m in over my head. In other words, there are areas where I’m an expert, and there are areas where I keep myself as informed as I can, but I have to rely on experts for their information. For instance, if you wanted to know about dark matter in our own galaxy, you should definitely come to me:

I’ve got expert knowledge on this, I’m familiar with what makes my findings scientifically rigorous and valid, and I know how to draw responsible conclusions based on the data in front of me. It is completely unreasonable to expect someone who isn’t an active researcher in theoretical astrophysics and cosmology to be an expert in the same way I am.

And by the same token, there are areas where I’m not an expert, such as what the incidences, symptoms, and causes of autism in children are:

So, to be informed, it should be reasonable for me to rely on the scientific findings of experts in that particular field of medical research. Now, I’ve talked before about the importance of being a good scientist, especially when your research can affect the health and well-being of others. So without further ado, I’d like to introduce you to someone you may not have heard of (unless you’re a huge fan of Bad Astronomy), Andrew Wakefield.

To give you the extremely quick version: in 1998, Dr. Andrew Wakefield published a very controversial paper following 12 children’s conditions at a clinic. His conclusion was that eight out of the twelve developed symptoms of autism after receiving their Measles, Mumps, and Rubella (MMR) inoculation. Since that piece of research, many millions of dollars have gone into researching the possibility of a link between vaccines and autism. Thousands of children have not been inoculated out of a fear of developing autism, and a few of those children have died as a result of contracting a disease for which a simple vaccine exists. There has been a huge grassroots movement that has sprung up among parents of autistic children, blaming the vaccine for their woes:

Now, over the last 11 years, overwhelming evidence has shown up that there is no link, not even a correlation (much less a causation) between vaccines and autism. But this past Sunday, an article came out in Wakefield’s home country of the UK, declaring the following:

MMR doctor Andrew Wakefield fixed data on autism

What? We have not just a scientist, but a medical doctor dealing with one of the fastest growing epidemics in medicine, falsifying results? And publishing them in a medical journal (the Lancet)? Remember that “eight out of twelve” statistic I quoted you earlier? Here’s what we get, upon further review:

Our investigation, confirmed by evidence presented to the General Medical Council (GMC), reveals that: In most of the 12 cases, the children’s ailments as described in The Lancet were different from their hospital and GP records. Although the research paper claimed that problems came on within days of the jab, in only one case did medical records suggest this was true, and in many of the cases medical concerns had been raised before the children were vaccinated.

The details are even worse. It turns out that after Wakefield’s “suggestion” that MMR, bowel disease/inflammation and autism were linked, the children were re-examined and diagnosed with these new bowel problems. I was unable to find US data, but in the UK, the number of confirmed measles cases in 2008 was 1,346. Want to know what the number of cases was in 1998, the year Wakefield’s paper was published? 56. One scientist’s false data has led to the resurgence of a disease that should be eradicated by this point. Nice move, Andrew, seriously.

That said, autism is a serious problem. We don’t know what causes it, we don’t know why the incidence of autism is so much higher than it’s ever been in the past, and these are things that need further investigation, absolutely. But not on a foundation of lies. And not by searching for a link that doesn’t exist with vaccines. Let’s do everyone justice, and have some sort of accountability for doctors and scientists who, through their actions (whether through ethical incompetence or unethical falsification), cause unnecessary death and disease among the general populace.

If you’re going to accept being lauded as an expert, you have to accept the responsibility of being an expert. Be honest. Be ethical. Or go do something else.

How Many Intelligent Worlds Are There?

February 6, 2009 on 2:05 am | In Astronomy, Life | 9 Comments

Looking at our galaxy, and knowing there are hundreds of billions of stars in it, I can’t help but wonder how many other worlds there are out there like Earth. I wonder how many other rocky planets are close to their stars, I wonder how many of those planets have life, I wonder how many of those evolve intelligent life, and I wonder how many of those (if any) are still around today.

The problem is, if you want to estimate this, there are too many unknowns to actually make a reasonable estimate. I point you to two recent articles from the BBC. First up:

Number of alien worlds quantified

Intelligent civilisations are out there and there could be thousands of them, according to an Edinburgh scientist.

The current research estimates that there are at least 361 intelligent civilisations in our Galaxy and possibly as many as 38,000.

Sounds like groundbreaking, supremely optimistic news! Other intelligent civilizations in our own galaxy, woohoo! But wait, what was that second recent BBC article I was referring to? Oh right, this one:

Odds on finding aliens ‘too low’

Scientists have counted out the chance of finding advanced alien life during the life-time of the Earth.

Prof Watson suggests four numbers of evolutionary steps are needed to create intelligent life in the case of humans. “These probably include the emergence of single-celled bacteria, complex cells, specialized cells allowing complex life forms and intelligent life with an established language.” His model, published in the journal Astrobiology, suggests… the chances of intelligent life emerging is low - less than 0.01 per cent over four billion years.

Why is there this discrepancy? Why isn’t there any agreement? Because while everyone agrees as to the steps that humans took in order to get here, we have no reference to how likely each of those steps is to have happened. For example, we know a little bit about how many other planets are out there, and we know a little bit about how life evolves once it’s begun, but here is a short list of questions we really have no idea about:

  1. How likely is it that life spontaneously arises from non-living things? This happened pretty quickly on Earth, as there is evidence that the first living things evolved on Earth nearly 4 billion years ago. But we don’t know how likely it would be to happen again if we started with similar initial conditions.
  2. Once life exists, how likely is it that sexual reproduction evolves? This is really a necessary step to creating complex life, because asexual reproduction with random mutations is far too slow of a mechanism to evolve complex life. It took Earth nearly 3 billion years of having asexual, living organisms to evolve gender.
  3. How likely is it that intelligent life evolves? Not just intelligent life, but technologically advanced (i.e., late 20th century Earth technology or later) enough to contact another world and receive a message sent at them. Estimates of this one seem to range incredibly far and wide, from as high as about 10% to as low as about one-in-many-millions.
  4. And on all of these planets, where all this is possible, how many of them will have this happen before their star gets too hot to allow life to live anymore? The Earth was good for the first 4.5 billion years or so, but we’ve only got another 1 billion left until the Sun’s solar output boils the oceans.

My estimate is that there are about 1 million Earth-sized planets in or near a habitable zone around their stars in the Galaxy. What are the chances that all of the above steps will then happen? Is it a 20% chance for each step? A 1% chance? A one-in-a-million chance? We have no idea. None.

And anyone who tells you differently is probably trying to sell you something. Don’t buy it. Admit that we don’t know, because we haven’t done the science, and that all of this is speculation. I’m not saying it isn’t interesting, I’m just saying it isn’t science. (Not yet, anyway.) I know I’ve used this image before, but you might as well just listen to Max Cannon:

And if you want to see a few more interesting space stories from the past week or so, check out the latest Carnival of Space; this one’s pretty good! Thanks to The Space Writer for putting it together!

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