Faith vs Trust

August 24, 2011

Creationists – the loud ones, like Ken Ham, Kirk Cameron, and Kent Hovind – often repeat that evolution, like religion, is a matter of faith, and therefore evolution and religion-based beliefs on creation stand on equal ground. But this is a rhetorical ruse. In order to uncover the man behind this curtain, we need to look at “faith” vs “Faith”.

Faith with a capital F refers to religious faith – complete, unwavering acceptance of the tenets of a religion. But faith with a small f means something different. We can say we have faith in a pilot, and in the aircraft he is flying. What this means is not a complete, unwavering acceptance of the miracle of flight, but that we trust the pilot’s training, and the engineers’ skill. But that trust is not unwavering – evidence to the contrary (missteps by the pilot, or mechanical issues with the aircraft) will shake that trust. In the case of religious Faith, many are taught and believe that evidence contradictory to their religious beliefs is there to test their Faith, and so they entrench themselves further rather than changing their worldview.

In a sense, science is a matter of faith – but it is most definitely not a matter of Faith. I would rather say that science is a matter of trust. We trust that the laws of nature will not suddenly change. We trust that the tools we have at our disposal will give us reliable information. We trust that a preponderance of converging data is on the right track to representing how a phenomenon actually works.

But wait, there’s more…

Creationists will say that you have to have faith in Science just as you have to have Faith in religion – but you don’t. The reason Science is so reliable is that it works whether you believe in it or not! You can disbelieve in gravity, rocket propulsion (aka Newton’s 3rd Law), fluid dynamics, and evolution all you like. But that doesn’t make them not happen. So while most people do put some faith (trust) in Science, it is not required that they do so. And, in fact, a critical eye and healthy dose of skepticism (by which I mean real skepticism, not denialism) are necessary for Science to move forward – so scientists who trust the preponderance of existing knowledge do not automatically trust new discoveries.

So the next time you hear the argument that Science is just like religion, because it relies on faith, call that argument what it is: Bullshit.


Economic argument against the woo

October 20, 2010

XKCD for the WIN:


Quality, not quantity, leads to speciation

October 7, 2010

In 1859, Charles Darwin published a book that changed how biologists understand the living world. Although his book was titled “On the Origin of Species by Means of Natural Selection”, it never actually explained the process of speciation. Although an elegant and thorough explanation of the mechanisms underlying evolution, he extrapolates this to say “species have changed, and are still slowly changing by the preservation and accumulation of successive slight favorable variations”. In other words, natural selection produces change, and the accumulation of enough changes produces a new species. A century and a half later, this is still accepted wisdom.

For most Biologists (and scientists in general), accepted wisdom is not enough. Ernst Mayr put forth the notion of allopatric speciation – that physical isolation can allow genetic change to occur separately in two populations, eventually leading to reproductive isolation and thus to speciation. Steven Gould and Niles Eldridge produced the idea of punctuated equilibrium – that the history of life consists of long periods of stasis (ie species remain relatively unchanged) punctuated by rapid bursts of species diversification.

Although many viewed speciation and macroevolution as the rapid accumulation of many individual variations, effectively speeding up the process, others (Goldschmidt, Gould) proposed that these events occurred through single (or a small number of) events that produced significant morphological or physiological change. The technical term for this is saltation (meaning a jump), though Goldschmidt’s term “hopeful monster” is also used – not always kindly.

In the early 80’s, Homeobox genes were discovered. These are genes that regulate body pattern, and it was discovered that the duplication, relocation, and modification of these genes is responsible for significant changes in body plan. Suddenly there were genes that could produce “hopeful monsters” without significant genetic change. And yet, the gradualistic model of speciation through accumulation of many small changes has persisted, primarily because there has been no evidence that a single or small number of changes can produce enough change to create a new species.

Recently, Dr. Mark Pagel at the University of Reading decided to put to the test. He reasoned that if speciation is dependent on the accumulation of a number of genetic changes, that would show up statistically as a normal distribution in a survey of the number of genetic differences between species in the family trees of different groups.

What he found was that the distribution did not follow a normal curve, but an exponential (poisson) distribution instead. This is the distribution one finds with truly random distributions, such as the frequency of lightning strikes. The differences between these two random distributions are subtle but significant. The most important difference is that a normal distribution has a mode – a peak value around which the values are distributed. A poisson (exponential) distribution does not – any value is equally likely.

The implication for evolution is that there is no typical, usual, or expected number of mutations required for a population to become a separate species from its parent population. In other words, We can’t say that a new species arises after about 20 (or 60 or 2000) mutations. It may take any number of mutations to form a new species – 50, 100, 1000. Or just one.

At first this seems to fly in the face of the “accepted wisdom” that there is some sort of threshold for speciation. But given that mutation is random, any number of mutations could occur that produce little or no effect, or that do produce an effect but in genes that are unimportant. For speciation to occur, a change must arise that leads to a reproductive barrier. What this study tells us is that a sufficiently significant change is as likely to occur from a single mutation as from 10, 30, or 100.

So while the accepted wisdom – or at least the default assumption – is that speciation arises as the result of an accumulation of minor changes, it now looks more like a single significant change is responsible for a speciation event. The implication being that the quality of mutation, not quantity, is the deciding factor for speciation.

Although in retrospect this makes perfect sense, it does provide additional context for models of evolutionary change – such as punctuated equilibrium and Goldschmidt’s “hopeful monsters” – that were ridiculed when first proposed. Which just goes to show that Hamlet was right: There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy.

http://www.nature.com/nature/journal/v463/n7279/full/nature08630.html

http://www.newscientist.com/article/mg20527511.400-accidental-origins-where-species-come-from.html?full=true


Gliese 581g – Define “Habitable”

October 1, 2010

Much has been made of the announcement about the recently announced discovery of a potentially habitable planet around a nearby sun. The planet, dubbed Gliese 581g is estimated to be around 3 times the Earth’s mass, and about 1.5 x it’s diameter (depending on composition).

The excitment over this particular exoplanet – the 492nd discovered – is that it lies in the “goldilocks zone” where th etemperature is not too hot, not too cold. That is, its distance from the star is such that the surface temperature is likely to be such that liquid water could exist on the surface, something that is key to life as we know it.

However, the announcements touting “Scientists discover habitable planet” and “Earthlike planet discovered around nearby star” are grossly misleading.

It is true that Gliese 581g lies in the goldilocks zone. However, we know nothing of its composition, its amosphere, or its rotation. This latter is important, as the planet lies only 0.15 AU’s from its parent star. In contrast, Mercury 0.39 AU’s from our sun. 581g’s proximity to the star means the planet is likely tidally locked – in other words, one side always faces the star, the other away. One side would be a permanent, hot day, the other a permanent, frozen night. Even with an atmosphere to carry heat back and forth between the two sides, much of the water and other atmospheric gases could freeze out on the night side, leaving a thinner atmosphere, and permanent desert on the day side. The temperature along the terminator (the “twilight zone”) should be intermediate, allowing for liquid water, but not if all the water is frozen on the night side.

On the other hand, the star Gliese 581 is a red dwarf star (which is why the goldilocks zone i sso close), which is very stable and long lived, so if there were conditions suitable to life, it would have a good ling time to evolve.

Until we have the tools available to analyze the spectrum of the atmosphere, we really can’t know any more, as much as we want to speculate.

This doesn’t mean we shouldn’t get excited – far from it. The discovery of Gliese 581g tells us something very important. It tells us that there are two earth(ish) size planets orbiting in the goldilocks zone in a tiny volume of space (relatively speaking) – Gliese 581g and our own. the statistical implication is that goldilocks planets are likely common in the galaxy. And that means that even if 581g is a lifeless, half-frozen wasteland, there are more earthlike planets out there.


The Triceratops that Never Wasn’t

August 11, 2010

 

I recently returned from a holiday abroad to find headlines proclaiming that Triceratops Never Existed! My first thought was of course, WTF? And my second thought was, just how stupid are they? And then the little pessimistic third thought was that the way this story is being waved about, it will be used as “ammunition” by antievolutionists, one more little item with which to further wrap themselves in ignorance.

So here is the story.

Ceratopsian dinosaurs were (mostly) large, quadrupedal herbivoves with a frill behind the skull, and many bore horns from the nose and/or the top of the skull over the eyes. There is substantial diversity in the group in the shape and size of the frill and horns, leading to the definition of many different genera and species. But there is also variation within each species, blurring the boundaries between the different classifications. Because of this, the group as a whole has undergone taxonomic revision several times. The recent work by John Scanella and Jack Horner continues this trend by further clarifying the taxonomy of this intriguing group.

Scanella and Horner surveyed known specimens of the ceratopsian classified as Torosaurus, and concluded that the developmental and morphological evidence suggests they are not members of a separate genus, but in fact “fully grown” members of Triceratops. This is bolstered by the fact that there are no known juvenile Torosaurus remains – though the discovery of such remains would, of course, reverse this change in classification. Since the name Triceratops was coined first, it remains while Torosaurus becomes obsolete (pending further study and corroboration by other researchers). This sort of thing happens all the time, partly because defining “species” for organisms that have been dead for 70 million years with only a limited dataset is tricky business, and partly because we learn more. Science progresses.

So, in fact, the story headlines should have read “Torosaurus reclassified as adult Triceratops“. But a) that requires understanding what is being written, and b) wouldn’t sell papers. It really ticks me off just how wrong the statement “Triceratops never existed” really is. Animals classified as Triceratops and Torosaurus did exist, which is why we have their fossils. The classification of one of these groups may be in error, but it would be Torosaurus that ceases to be as a genus.


On the Verge

March 30, 2010

We are now only hours away from the first attempted collisions in the LHC at an energy level of 7 TeV. This is the single largest scientific experiment in human history. The status can be followed online in real time:

http://op-webtools.web.cern.ch/op-webtools/vistar/vistars.php?usr=LHC1


UFOs and the Argument from Ignorance

March 29, 2010

This is a great video clip of Neil DeGrasse Tyson explaining the principle of argument from ignorance in the context of UFO sightings.