Monday 28 March 2011

A picture is worth a 1000 words



While at a conference in Italy in 2009, I attended a talk on new observations of a nearby spiral galaxy. The speaker presented several interesting results but had to confess she did not have an image of the galaxy, since they were still waiting for data from the Hubble Space Telescope. From across the room of eminent astronomers came a collective sigh of disappointment.

It was hard not to laugh. In fact, I don't think I succeeded. The idea that professionals in the field would bemoan the lack of a pretty picture was deeply amusing; surely we should all be above requiring such frivolities? 

The truth, however, is that visualisation is an intricate part of successful science. Presenting your data in such a way that the main results stand out makes for better communication, without which scientific ideas cannot be shared, tested or accepted. This was the concept behind the "Science Illustrated" conference in Toronto that Masters student, Mikhail Klassen, attended last month and was badgered into talking about at the department's weekly journal club.

Mikhail explained that the conference discussed how the way you present your results can both help and hinder the viewer. Consider, for instance, the block of letters in the image at the top of the page. If you were asked to count the number of occurrences of the letter 'v', it would take you at least a few minutes to carefully examine each line. If instead each 'v' was coloured red, the task becomes a matter of seconds. A more extreme example is that of Anscombe's Quartet which is shown in the bottom half of the image. These four data sets have statistically identical properties, including exactly the same average and spread. If these were actual scientific measurements, a glance down the columns might cause you to think that they were showing the same result. However, if you plot them on a graph, you can see at once that they show completely different trends.

On the other hand, you can also choose to visualise data in a way that confuses the viewer. A famous example of this was a power point slide showing the current situation in Afghanistan. So crowded with interlinked lines was this plot, that General Stanley McChrystal, the US and NATO force commander, remarked dryly:

"When we understand that slide, we’ll have won the war."

A common error, if slightly less extreme than the above example, is to pick a bad colour scheme. Using colours that are similar to one another can obscure the trends you are trying to illustrate. Our brains also have a 'perception priority' when dealing with visual input, placing relative position above colour. This means that if an important result is, for example, the maximum density in your galaxy, it could be that plotting this on a line graph is more effective that colouring an image of the galaxy by density.

Mikhail went on to point out that there is also an ethical side to data presentation. By plotting two quantities against one another to demonstrate a relationship, you are excluding any information about other, possibly important, factors. A non-astrophysical example of this is a reconstruction of the Air France flight 358 that crashed in Toronto in 2005. From a reconstruction of the plane landing, it appears to be a pilot mistake; the plane drifts, touches down too late on the runway and over-shoots to crash into the creek (no fatalities). However, there is no weather information in the movie and eye witnesses report strong rain and winds with terrible visibility. As scientists, it is our duty to state clearly what is and isn't shown in our plots to ensure we do not mislead our audience.

Mikhail's final point from the conference was to remind us that communication of results depends on our audience. If we are presenting our findings to the public, we will be competing with Lady Gaga for their attention! This might lead us to choose difference visualisation techniques than if we were presenting to other astrophysicists. Although, if my experiences in Italy were anything to go by, that isn't necessarily the case.

--
[Thanks to Mikhail for sharing his (very clear!) slides from his presentation. The bottom right image showing plots from Anscombe's Quartet was taken from wikipedia.]

Monday 21 March 2011

Sneaky little hobbitses

Despite what you may have claimed over coffee this morning, 18 million years of evolution separates your landlord from a gibbon. If it's any consolation, he's only about 5 million years from a chimpanzee. After that time, our own branch of the tree-of-life evolves through a series of distinct 'hominids' before producing grad students.

But who were our ancestors and what did they look like? Is it possible to distinguish them from other branches of the ape family tree?

This was the topic of today's Origins Seminar, given by Dr Dean Falk from the School for Advanced Research in Sante Fe, New Mexico. Dr Falk is what is referred to as a 'paleoneurologist', a peculiar sounding term for someone who studies fossilized brains. Ancient remains of mammals can have a cast of their brain (known as an 'endocast') preserved via sand and other debris filling the cavity between skull and tissue. This hard coating is protected from weathering by the fossilised skull which slowly wears away, leaving the natural endocast in its wake.

The process of analysing an endocast is not an easy one since it is only an imprint of the brain's surface, so no internal information regarding the neurons or chemical structure is preserved. However, by comparing endocasts from humans and apes with those from ancient remains, much can be learnt about our own evolution.

Of course, it does help if the ancient remains you are studying are not fake. A famous example of this situation is the "Piltdown Man". Discovered in the UK in 1912 in Piltdown, East Sussex, these fossilised remains were exposed as a forgery in 1953. Rather than being the missing link between humans and chimpanzees, this skeleton was created from a human skull attached to an orangutan's jaw. The teeth had been filed down and the bones stained to look like a single specimen. In part, its success as a hoax was due to it fitting in with the preconceived idea that a measure of evolution was the brain-case size; the prevailing belief was that brains became bigger first and the rest of the body, including the jaw, changed afterwards. The discovery was also pleasing to local scientists who embraced the idea that the first human was an Englishman!

In reality, however, the first hominids were found in Africa. Ten years after the 'discovery' of Piltdown Man, Raymond Arthur Dart discovered the remains of the 'Taung Child' in South Africa; a fossil dating back 2-3 million years. With its small ape-sized brain and location far from England, the Taung Child contradicted everything seen in the Piltdown Man, making it a controversial discovery. Dart examined the brain endocast and concluded that, while the brain was relatively small, it was advanced due to its structure. In particular, he identified two groves whose positions matched those found in humans but not in apes.

Ultimately, Dart's analysis was proved to only be partially right, but the technique of examining the position of the brain's major groves (sulcal patterns) is the main way of differentiating hominid brains from our ape cousins. These differences come about as regions of the brain that were previously separated become more interconnected in humans.

Interestingly, our own ancestors were not the only bipedal species walking around Africa 300 million years ago. Paranthropus are thought to be an extinct hominid species, unrelated to us. Their brains were characterised by a prominent central ridge from which strong jaw muscles would have been attached. Our relatives were the Australopithecus africanus, of which the Taung Child is an example. The migration and spread of A. africanus is thought to be north out of Africa and then into Europe and Asia. This has been called into question recently, however, by the discovery of a hobbit.

The announcement of the three feet tall hominid remains found in Indonesia came in 2004. The attractively named, "Lb1" was female with very short legs and therefore seemingly disproportionate long arms. Her feet were genuinely long, stretching a length equal to the distance between her knee and ankle. The remains were found with primative tools, similar to those found in Africa, and she would have lived alongside giant Komodo dragons, which is a slightly unnerving prospect for someone only three foot high.

At 417 cubic centimetres, Lb1's brain was chimp sized but the endocast revealed advanced features reminiscent of a human over an ape. Her discovery opens many questions, with schools of thought differing over whether Lb1 can be a new human species from our ancestry when her brain is small and she was found so far from the picture of migration out of Africa.

One thing that appears to be clear from the endocast discoveries is that brain evolution can occur in many different ways. It is possible to rewire and reorganise our grey matter without it becoming larger. This leads to different combinations throughout the fossil history; a difficult challenge to place in logical order. So in short, size does matter, but it's not just about how much you've got. It's what you're doing with it that counts.

Wednesday 9 March 2011

Can you build a transmitter?

"You claim that there are many Earth-like planets while finding none!"

"But we have found many Jupiter-sized planets and they should be rarer than Earth-sized so the trend is pointing towards a large number!"

I was sitting in the audience of "The Great Extraterrestrial Debate", an event hosted by the Centre for Inquiry in Toronto. It was part of the organisation's "Extraordinary Claims" campaign which is designed to put some of today's most controversial allegations through a critical examination. This evening's topic surrounded the likelihood of alien life interacting with us on Earth.

The debate comprised of a panel of three individuals whose profession gave them a stake in this field. The first was Astrophysics Professor, Ray Jayawardhana, from the University of Toronto, whose research focusses on planetary formation outside our Solar System. The second was science fiction author, Robert J. Sawyer, and the third was Seth Shostak, a senior astronomer at S.E.T.I. (Search for Extraterrestrial Intelligence) Institute.

Despite being labelled a 'debate', it was stated upfront that all three panellists were in agreement; to this date, there has been no strong evidence for life outside of Earth. That said, the three unique view points being brought to the table did lead to passionate discussion. The above snippet was between Ray Jayawardhana and Robert J. Sawyer and was wrapped-up by Seth Shostak who pointed out:

"Ray and Rob arguing shows how hard it is to find stupid life. If they can built a basic radio transmitter (and you should all ask yourself now if you can do that) then their biology doesn't matter!"

Apart from the thinly veiled implication that S.E.T.I. would not count most of the audience as 'intelligent life', Dr Shostak's point highlighted a fundamental difference between his work and that of many astrobiologists; S.E.T.I. is only interested in life-forms that can talk to us. This bypasses all the problems with defining what life is and how we should go about detecting it when it is likely to be nothing like our own (a problem previously touched on in this post).

But is it really likely that we will make contact with aliens who can communicate with us?

Seth Shostak and Ray Jayawardhana both discussed the recently launched Kepler mission which is uncovering a flood of planets, with 1235 possible candidates identified in the first year of operation alone. This is in comparison to the 500 planets that have previously been discovered in the last 15 years. This huge influx of data in such a short time indicates the vast number of planets there must be in our galaxy which suggests that it would be a miracle if we were the only life to have been created on any of them. Dr Shostak also added that S.E.T.I.'s current failure to find life should not be interpreted as an absence of extraterrestrial intelligence. Currently, S.E.T.I. has only searched a tiny patch of the sky and declaring the Universe baron of life based on such a survey would be the equivalent of searching a square kilometre of Africa and concluding there were no elephants on the continent.

On the other hand, even if life did evolve on another world, we might have a problem with timing. Robert J. Sawyer made the argument that while the human race has existed for a few thousand years, there is a much narrower window between the invention of radio (needed for communication with S.E.T.I.) and the creation of the atomic bomb. It could be that almost as soon as a life-form can communicate, it self-destructs. Dr Shostak counted this by stating that the invention of rockets would take place in the same time-frame to launch the bombs, which gave the possibility of members of the species leaving the destroyed planet behind them to colonise somewhere else. He suggested that, like cockroaches, a life-form such as humans would be impossible to fully wipe out.


So ... if you're not able to build a transmitter, S.E.T.I. consider you too stupid to be interesting. If you ARE able to build a transmitter, you are analogous to a cockroach. Everyone feeling good? Then I'll continue...


Then there is the problem that if aliens were to appear, how would we react? Contrary to popular movies, it was deemed unlikely that such a discovery would cause rioting in the streets. For one, the signal would be coming from so far away that it isn't going to affect your ability to buy your morning coffee from Tim Hortons any time soon. Secondly, 1/3 - 1/5 of the population believe aliens are here already doing (and I quote Seth Shostak) "experiments your mother would not approve of", so a significant fraction of the world would not even be surprised.

Robert J. Sawyer suggested that it might be unhealthy for our own future to discover a more advanced life-form. If it could be shown that most life did survive their 'technological adolescence', then the human race might not strive as hard to solve its own problems, being content to let time take its course. Dr Shostak took this idea to a more personal level by saying that tenured professors might find it depressing to know all their scientific research had been solved a million years ago by this advanced alien race. Professor Jayawardhana, however, seemed to think this would save on having to publish more papers!

Finally, Robert J. Sawyer pointed out that S.E.T.I. did make one very big assumption:

That life, if it's out there, would be remotely interested in us.