Algae and Developing Genders

An interesting question in evolution has always been how the two genders evolved. Most unicellular animals don't have district genders; they can reproduce both sexually and asexually. Two little single celled algae look pretty much the same, right down to the gametes that combine to create a new algal cell. Most multicellular animals, however, can be classified pretty easily as either male or female. The majority of these are only able to reproduce sexually (there are some species of reptile that get around this, but that's a discussion for another post). Plants, too, have a distinct male and female. Considering sexual dimorphism -the development of a distinct male and female in a species- is a trait uncommon in single cell organisms and common in multicellular ones, there must have been some evolutionary change which made different genders far more beneficial. Unfortunately, neither single cell organisms nor genetic material preserve in the fossil record, so we cannot look there for answers.

Volvox carteri

A comparison of two closely related algal species has given researchers some interesting clues on this evolutionary gap. Volvox carteri is a multicellular green algae, and its cousin, Chlamydomonas reinhardtii, is single celled. Their genomes are pretty much identical, with one giant exception. In the area of the genetic code that serves as the algal version of X and Y chromosomes, Volvox had some of the same genes and Chlamydomonas, along with a wide variety more. In fact, this section is five times larger in Volvox. This was a huge surprise. In the past, researchers had though that the "sex chromosomes," X and Y, had developed as a section of the genome deteriorated. These algae suggest that the opposite is true: that, for whatever reason, the bits of DNA involved with gender and reproduction can change and diversify very quickly.

There is a lot more study that has to be done to map out any sort of evolutionary path for this change. The team is looking more closely at the "new" genes in Volvox, as well as comparing both species to a third, Gonium, which is an intermediate between Volvox and Chlamydomonas. It's one of the first breakthroughs in determining how sexual dimorphism originally around. It will take time, but it's a very interesting first step to solving this evolutionary mystery.

Source: Science Daily- Lessons from the Pond: Clues from green algae on the origin of males and females

A Life Without Air

When you think of an organism, you probably think of some type of animal. These creatures need one particular element to gain energy and survive: oxygen. Most of the sugars and fats that are burned within our bodies, and those materials are made with oxygen. There are some bacteria which can survive anaerobically - without air - but certainly no animals that can, right?

An anaerobic animal,
of the group Loricifera
Image Source: Science Daily

Well... not quite. Deep in the Mediterranean Sea live little multicellular creatures that have never come across oxygen. More than that, they are submersed in sulphides, which are usually toxic to animals. Researchers had previously found some multicellular organisms in this and other deep hypersaline anoxic basics, but had assumed that they had died and floated down into this harsh environment. Not the case with these little Loricifera, however. Tests showed that not only where the animals alive, they were thriving and reproducing.

So, how do they do it? Most animals, including humans, need to metabolize oxygen using mitochondria. This process produces energy. For a short period of time, individual cells can produce enough energy to survive without oxygen, but not for any extended length of time. These creatures live in a complete absence of oxygen. The researches used an electron microscope to see what the Loricifera used to produce energy. Instead of the aerobic mitochondria common in pretty much every other animal, they have hydrogenosomes, similar to those found in bacteria that also inhabit anaerobic environments. In other words, instead of using oxygen dissolved in the water to survive, they use the hydrogen dissolved in the water.

This finding is really exciting. Before this, scientists had guessed that there must have been some form of animal that lived without oxygen, way back in the early history of life (550 to 600 million years ago). This gives us more clues about the nature of these creatures. It also opens the door to more research in other anoxic part of the ocean. It seems unlikely that the Loricifera species is the only animal that thrives in this environment, now that we've discovered it is possible.

Source: Science Daily- First Animals to Live without Oxygen Discovered

Venus May Still have Active Volcanoes

A Volcano on the Surface
Image Credit: NASA/JPL

I find Venus one of the most interesting places in our solar system because it is so hard to study. Venus is shrouded in an atmosphere 90 times thicker then ours, making the surface incredibly difficult to image. What images we do have are mainly from the early days of the space age. The European Space Agency launched the Venus Express Mission in 2005, and it has given us new insights into this mysterious planet. Still Venus is a place where we have lots of big questions with few answers. One of these questions for a long time has been if Venus is volcanically active. We have seen volcanoes on Venus's surface, but could they all be dormant?

Venus and Earth are about the same size. The heat in the Earths core that allows it to stay molten comes from when the planet originally formed, as well as the radioactive decay of elements. Since Venus should be made up of about the same stuff as the Earth, it is reasonable to assume that it also has a molten core. If there is a molten core that heat will want to escape, and it does so on the Earth via volcanoes. So what about Venus?

New data from Venus Express suggests that there may still be active volcanoes on the surface of Venus. Peeking through the clouds in infrared light, researchers looked for variations in the ground temperature. "The solidified lava flows, which radiate heat from the surface, seem hardly weathered. So we can conclude that they are younger than 2.5 million years old – and the majority are probably younger than 250,000 years," Jörn Helbert from the DLR Institute of Planetary Research. "In geological terms, this means that they are practically from the present day." This is not a slam dunk of Cytherean* volcanism though. There could be hot spots on the surface, without active volcanoes. So while this debate is certainly not over, this is an exciting new piece of the puzzle for scientists to look at.

*Cytherean, not Venusian, is the proper term for things related to the planet Venus. It also sounds cooler.

It's The End of The World!!! Again?

There are many popular issues that you really need to look at their history to understand. The best example of this might be the end of the world theorists. By now the idea that world ending in 2012 is part of mainstream culture: I even get asked about it by 12 year olds. So is there any truth is it? Are we really all doomed as the Mayans predicted? What does history have to with the apocalypse?

2012 is not the first time people predicted the end of the world. One of the more famous end of the world predictions is the Tolendo letter from 1184. This letter was sent to the Pope of the time and said the world would end in 1186. The Archbishop of Canterbury in England fasted in order to try and prevent this catastrophe. Low and behold, the world went on, and so did the letter with different dates, for years afterwards.

Even in my own lifetime the end of the world has come and gone. There was the turn of the century, where people thought that the new millennium would hail in the apocalypse. Then large groups were worried that the Large Hadron Collider (LHC) would create a black hole that would destroy the world. Well, last week the LHC started up with out a problem. So far I don't think the world has ended.

So now the end of the world marches on to 2012. There are all kinds of unsupported ideas on how the world will end, and why. The reality is that 2012 is not special. People who claim it to be the end of the Mayan calendar, just don't understand the Mayan calendar. A really good through description can be found at Universe Today, but the basic idea is that the calendar doesn't end, it just turns over.* So I cannot see how this prophecy differs much in any way for the Tolendo letter.

Someday, the Earth will no longer be inhabitable to humans. Lucky for us we still have a few billion years before the sun makes the Earth into a fairly miserable place. It is possible that an asteroid will come and wipe us out, but we are getting better at finding and tracking potentially dangerous asteroids. Maybe we will develop the technology to prevent such an impact, and then travel to the stars to preserve our species. When I look at the end of the world claims, I see a pattern. The end of the world always seems to be just around the corner, and you know what, eventually they will be right (just be very very patient).

*I'm not entirely sure why the ending of an ancient calendar would signify the end of the world even if it were true.

Untangling the Truth about Autism

There are a lot of claims made about autism. What causes it? How common is it? What are the common symptoms? Is there a cure? I can't go through every single claim ever made about autism here, but I'd like to take some of the common ones and sort out myth from fact, and explain why.

• One out of every 110 children is affected by autism in the United States, including one out of every 70 boys. (source)
  This is fact, but a bit misleading. The data that the Autism Speaks report uses is from the CDC's autism report, found here. The study compares the autism rates of 15 different communities, and includes every instance of an autism spectrum disorder. This means that both a very mild case of Asperger's syndrome will be counted as a hit equally to a debilitating case of severe autism, so long as they are diagnosed. Thus, while the numbers are accurate, the statement would be more correct stated as: "One out of every 110 children is diagnosed with an ASD in the United States, including one out of every 70 boys."
• Studies have shown that environmental toxins like mercury and pesticides can trigger autism. (source)
  This one is plausible. There is some evidence that autism prevalence rates are higher where there are higher concentrations of heavy metals and pesticides before birth. However, the results of these studies are still fairly preliminary, as far as I could find from my research, and more studies will have to be done before there is a true consensus on this.
• Sources:
  DeSoto, M. Catherine, 2009. Ockham's Razor and autism: The case for developmental neurotoxins contributing to a disease of neurodevelopment. NeuroToxicology, 30(3):331-337
  Abstract at PubMed
• There has been no study that has directly linked a pure genetics basis for autism. (source)
  False. Plain and simple. There are quite a few studies that link genetics to autism. For instance, this study provides a quite strong correlations between autism and a genetic mutation. This one provides a relatively complete summary of the genetic basis for autism. Even the DeSoto article I linked to above discusses how there is a genetic predisposition to autism, depending on how sensitive an individual is to the toxins. The genetic basis for autism is well-established scientifically.
• Vaccines cause autism (source- note that this is implied throughout the whole "Vaccines" section of the website, but is never stated directly)
  False. This is by far the biggest autism controversy. Because of this, there has been a lot of scientific research. After all, if there was something to the claim, there would be major reason to change the vaccines given. But the consensus has come back with a definitive result: autism is not caused by vaccines. A really good summary of the current evidence can be found in this article. The one study that did show a link between the MMR vaccine and autism was retracted earlier this year, as it was shown to be a fraud. There is no cause for concern that vaccinating children will give them autism. Not vaccinating them is likely to cause them polio, measles, and other potentially deadly diseases, as well as spread those illnesses to other children (source). The risks of not vaccinating far outweigh those of getting the vaccinations.
• Autism is reversible (source)
  While there are treatments available that can help lessen the symptoms of autism, this claim that autism is completely reversible is, as of this point in type, false. As I mentioned here, autism is a disorder, not a disease. A kid doesn't "get sick" and start acting autistic; instead, something is wired differently in their minds, whether due to a genetic mutation or to exposure to toxins during development. As stated on the Autism Speaks website:
  
  

  Most parents would welcome a cure for their child, or a therapy that would alleviate all of the symptoms and challenges that make life difficult for them. Just as your child's challenges can't be summed up in one word, they can't be remedied with one therapy. Each challenge must be addressed with an appropriate therapy. No single therapy works for every child. What works for one child may not work for another. What works for one child for a period of time may stop working. Some therapies are supported by research showing their efficacy, while others are not. The skill, experience and style of the therapist are critical to the effectiveness of the intervention.

This list of claims is far from comprehensive, but these are the five I hear most often, and that cause the most controversy. If you have other questions, feel free to send me an email using the link to your right. Or, better yet, do some research of your own. Talk to a medical doctor, preferably one who specializes in neuroscience; search for relevant studies on PubMed; gather knowledge to be able to sort out fact from fiction. Be aware that not everyone uses science-based medicine, and that even the most well-meaning people can give bad, and potentially dangerous, information. With a bit of skepticism and a little work, though, it is always possible to find good information to make the best choices you can, especially concerning things like autism.

If you want more general information on what autism is, take a look at What is Autism?