Showing posts with label evolution. Show all posts
Showing posts with label evolution. Show all posts

Monday, 17 October 2011

Evolution: 'nuff said!

This picture was posted on Facebook and made so many points which I end up making repeatedly, and it did so succinctly. I may just use this over and over:


My only slight quibble would be the claim that life does not improve, though to be precise on that matter would have required a lot more text on the poster. Improvement is often subjective, and the way this poster means it is that things don't become "better" over time in the sense most of us would think. Evolution does, however, involve improvement in another way, because populations adapt to their environment and can be said to become "better fit" or "adaptively improved". This is, of course, dependent on the environment, so what is "better" or an "improvement" in one environment is not automatically so in another. Sadly all of the words we could use seem to be loaded in such a way which gives the wrong impression. A lot of what I just typed felt wrong because I know those words give the wrong idea about evolution.

Thursday, 13 October 2011

Christians and Fossils: an overview

I posted this to Facebook as an overview which I do intend to do as a blog series here. Naturally it will be in much more detail, looking at each individual view and providing a critique. Some will be more detailed than others, as there are views which require more debunking and there are some where I know little about them. I also intend to do this as a possible book some day, though I intended to start it last year. 



This will simply be a brief look at modern Christian explanations for the fossil record. If any of these fit your view, then feel free to expand on what I write and explain why you believe it. If I have missed any, then please present the views I have missed.

Dismissive views:

1. Fossils can only tell us that something died. This sort of statement is often used in order not to address the fossil record or to dismiss any succession perceived in it.
2. Fossils are a test of faith. A view which allows for dismissal of the evidence.
3. Fossils were planted by Satan. This is similar to 2.
4. Fossils are fake. A rare view which invokes global conspiracy as the explanation.
None of the above views are serious attempts to engage with the evidence and so will not be addressed in any more detail.

Young Earth Creationist views:

The following four views are not necessarily mutually exclusive and all invoke a global flood.

1. Hydrological sorting. This is the view that the fossil record can be explained by organisms being sorted by density and other factors rather than evolution.http://creationwiki.org/Hydrological_sorting

2. Differential escape. This explanation is used to account for the increase in complexity seen in the fossil record. It posits that smarter, faster animals were able to escape the flood for longer, while all the slower, dumber animals died first, giving the illusion of evolving complexity. It also tries to explain the abundance of marine fossils.

3. Habitat sorting/ecological zonation. In this explanation, differing environments are used to explain fossils found in different strata and locations. The reason we do not find trilobites and man together is because trilobites are marine and humans are terrestrial, for example.

4. The European flood model. This is more complex than the other YEC models, as it does not propose the flood as an explanation for the whole fossil record. Instead, the pre-flood/post-flood boundary is in Carboniferous strata. The fossil record shows a succession of pre-flood organisms which died (all were marine because the land was destroyed), through organisms which proliferated during the flood, followed by the progressive filling of the Earth after the flood receded. A proponent of this view is Paul Garner.

Favourite evidences used by the YEC groups include polystrate fossils and fossil lagerstatte (areas of exceptional preservation). Proponents include Duane Gish, Henry Morris, Kent Hovind and the palaeontologist Kurt Wise.
http://www.bryancore.org/anniversary/04.pdf

Devolution:

I have included this one for a laugh. I once met a guy on a different discussion board who is trying to raise funds to start a museum which will explain the fossil record his way:

The greater ancestor explanation: The fossil record shows devolution, where ancestors were bigger and better in the past and have been progressively getting worse. Favoured evidence includes large mammal fossils from throughout the Cenozoic and large insect fossils from the Carboniferous.

Old Earth Creationist views:

1. Gap theory: This explains the fossil record by considering it as almost a separate creation, before God wiped the slate clean and started afresh with man and other animals. The fossil record is therefore the remnants of a failed creation.

2. Concordism and day-age: This view accepts the age of the Earth and instead suggests that there were many stages of creation and that Genesis matches what the fossils show. No large scale evolution was involved, just God stepping in to make created kinds.

Proponents of these views try to take the fossil record as a whole, though tend not to engage with it much. A prominent proponent is Hugh Ross.

Intelligent Design:

1. The patterns in the fossil record are real, but not explained by evolution. This is simply a rejection of evolution as an explanation for the whole fossil record. ID theorists differ in the degree to which God has stepped in during geological history.

Evidence given often includes the Cambrian explosion as a rapid source of new "information", and also examples such as whale evolution are used to claim that evolution would be too slow. Proponents include Michael Behe and Stephen Meyer.
http://www.discovery.org/a/2177

Theistic evolution views:

1. Evolution as cosmic warfare/modified gap theory: The fossil record is explained by cosmic warfare between Satan and good, corrupting the creation and causing mass mortality. It accepts a literal Genesis with a gap in Genesis 1.http://www.gregboyd.org/blog/evolution-as-cosmic-warfare/

2. Teleological evolution: Evolution is the explanation for the fossil record, but it also shows that there is an inevitable progression in complexity, which points to God. Proponents of this view, such as palaeontologist Simon Conway Morris, use palaeontological evidence of convergence in evolution as support, combined with constraints in nature. http://www.mapoflife.org/

3. Generic theistic evolution: Simply accepts evolution as the explanation for the fossil record, based on the evidence for an increase in the spread of complexity and faunal succession, along with transitional forms and other lines of fossil data.

Proponents of theistic evolution include Kenneth Miller, John Polkinghorne, and palaeontologists Bob Bakker and Mary Schweitzer.

Saturday, 24 September 2011

A Creationist Misconception About Transitional Forms

Palaeontology is just the study of old bones and all we can know about them is that something died. It is surprising how many people have that view of the fossil record, with no idea that we can study the lives of many fossil organisms in a lot of detail, even able to determine their behaviour. When it comes to studying evolution using the fossil record we can learn quite a lot about what happened. The creationist misconception I intend to clear up is not the impoverished understanding I just mentioned, but the idea that in order to claim a fossil as a transitional form we must demonstrate that this particular organism reproduced and passed on its genes. This is an unreasonable request based on a misunderstanding of palaeontology.

What is a transitional form?


The public often use the term "missing link" when talking about fossils which plug a gap in our knowledge. This term is a useless tautology because a missing link is always missing by definition. Not to mention, whenever a "link" is found, that just creates two more smaller gaps which need filling. The correct term is transitional form which is used to refer to fossils which possess traits which fit them between two taxonomical groups (intermediate form is roughly synonymous with transitional form). Technically all fossils are transitional forms, but that assumes evolution and so will not pacify creationist attacks. What creationists seem to request is those transitions between major groups which grab the headlines and fortunately we have many.

One thing to keep in mind is that transitional forms should not be put in a chain of ancestor-descendent relationships. This cannot be done with the fossil record because it creates untestable hypotheses and becomes nothing more than story telling. Transitional forms should instead be thought of in terms of the traits they possess, as they indicate the latest possible time that trait could have evolved (the traits in question are shared, derived characteristics, which can get confusing when taken in isolation and with convergence taken into account). The traits should also not be expected to evolve at the same rates or in a sequential order; there can be overlapping.

So, did transitional forms reproduce?


It is safe to assume that they did and here is why.

  1. Fossilisation is rare. Small populations are unlikely to be preserved in the fossil record, even just an individual. The larger the population, the more likely it is that an individual will become part of the fossil record and will be discovered by a palaeontologist. It is therefore safe to assume that a transitional form was not some atypical individual, but part of a large population.
  2. Evolution functions by the spreading of genes in the gene pool of a population. Populations reproduce, so even if the individual which was preserved did not reproduce, it was part of a population which did reproduce. 
  3. If, somehow it was a "freak of nature", then it is unlikely that it was physically very different to the population average as survival to adulthood would also be unlikely. 
Some transitional fossils are clearly part of a population, as numerous fossils have been found. Archaeopteryx is a key example considering its fame, as there are several fossil examples. Clearly these Archaeopteryx individuals were part of a large population and even if they did not reproduce themselves, the population contained many reproducing members. They are transitional forms which bridge the gap between non-avian dinosaurs and birds.
8 of the 9 Archaeopteryx specimens
A more recent example is Darwinopterus, a transitional pterosaur which fills the gap between the two major groups. It is known from numerous specimens which have yielded a wealth of information, providing evidence for sexual dimorphism in pterosaurs. One of the specimens has an egg preserved, showing unequivocally that they were capable of reproduction and the numbers demonstrate that it was part of a population.
The famous female Darwinopterus with egg.
Some transitional forms are, of course, represented by a single individual which is also often fragmented. A good example is the now well known Tiktaalik, which has been labelled as a "fishibian" due to its mixture of fish and amphibian traits. It is so clearly transitional that when its discoverer, Neil Shubin, took a model of it into an infant school class and asked them what they thought it was, some said it was a fish, some said a crocodile, whereas others recognised that it could be both. Only an unthinking pedant would claim that they are wrong. Only one specimen is known, but it is not the only organism which is part of the fish to amphibian transition. Whenever Tiktaalik is brought up, it makes sense to think of the other forms it fits with too, showing the evolution of key traits: 
This applies to all transitions. They should not be taken in isolation, but viewed as part of the whole evolutionary narrative, alongside the other transitional forms. Check out the evolution of whales or the early evolution of mammals, as there are numerous species known for each transition and all should be seen as part of a population in the deep past. 

Probabilities mean that it is extremely likely that transitional forms found were part of a population which involved reproduction. The individuals themselves need not have reproduced because evolution functions in populations, not a string of individuals. If a creationist demands evidence that the individual reproduced they are making a claim based on ignorance of palaeontology. 


Tuesday, 22 February 2011

The 'babbler's top 10!

Those who know my palaeontological interests tend to know that I have a major passion within palaeontology and there is a particular fossil group which I adore more than any other. They are of course the Ediacaran fossils and I have written about them at length many a time. Just click on the search labels and see, or click here and here  for the same effect. And if you want to know how I got interested in them, see here.  This list, believe it or not, is not going to include Ediacarans. They are my number one, so the list would be too predictable if I included them. This list will not be static, instead it reflects what gets my attention at the moment. I am hoping that those who know me well will find at least one or two surprises.

Before I count down I want to mention those groups which narrowly missed out on making the list. The fauna of the Zechstein sea, particularly fossils found in South Yorkshire, interest me a lot as they are my local fossils. I have blogged about them a few times and hope to do something more academic with them too. I also briefly considered adding crocodiles to the list, as their past threw up many interesting variations which look nothing like our modern crocs, but I know little about them (I would say that if you want to be a vertebrate palaeontologist then crocodiles may be a great area to study). I also considered adding jawless, armoured fish from the Silurian, as I had a lecture on them today and found them very interesting, but they just missed out to some groups which I have liked for longer. So, onto the list...

10: Crinoids 
A crinoid fossil from Doncaster Museum.
This one might surprise a few people, as many find crinoids to be quite dull. I also often mock crinoids and call them flowers, but that doesn't mean that I don't like them, I genuinely do. I've even written about them a few times, see here (though I should add that I have written more than just those, but sometimes I get lazy with the labels). Crinoids are often beautifully preserved, are very impressive fossils (when articulated) and are thankfully rather common. They are also still alive, with a fossil record going back all the way to the Ordovician. This makes them a good group to study, yet they have not gotten much attention. They should be used as textbook examples of things like evolutionary responses to predation, so one can hope for that in the future. I got interested in them during my first year of my uni course as I had to make a poster with a course-mate. I paired up with James, whose main interest is crinoids, which we combined with my main interest (at the time) of evolution, producing a poster about crinoid adaptive strategies. I thoroughly enjoyed the research and recognised them as a group with a lot of beauty and potential. Certainly worthy of my top ten and I would not be opposed to dabbling in them some more in future if opportunity knocks.

9: The Dinosaur to Bird Transition
It is well established now that birds evolved from dinosaurs, which is testament to the hard work of many palaeontologists. Laboriously comparing traits on fragmented fossils, they had to rely completely on a few rare transitional fossils to come to their conclusions. No genetic testing was available, only comparison of fossils. If we had no Archaeopteryx then our understanding might have been rather different. We are fortunate now to have quite a range of fossils spanning this transition, with feathered dinosaurs on one side, primitive birds on the other, and a spectrum in between, where individual traits can be seen to gradually change. It also allows me to include a group I like but have not included in this list - dromaeosaurs. Those swift, vicious hunters were closely related to the ancestor of birds, possessing many key skeletal precursors and covered in many feathers. This group of fossils speaks of my childhood love of dinosaurs (which still exists in a non-academic sense, enough to get a tattoo of one) and of my love of evolution. I do not intend to study them academically, though I would not turn down a good look at Archaeopteryx and will undoubtedly write about them in future.

8: Thyreophora
These are the armoured dinosaurs. This group includes the stegosaurs of the Jurassic and the ankylosaurs of the Cretaceous, along with the nodosaurs which tend to get less attention (though thyreophorans as a whole tend to get overlooked, except perhaps Stegosaurus itself). The stegosaurs were a favourite of mine as a child, with Tuojiangosaurus being an obscure preference. These have leapt into my list because I attended a lecture about the thyreophora just last week, by a friend of mine, and was reminded how fascinating they can be. I also have an ankylosaur-obsessed friend, so I hear about them a lot. They might have been slow and stupid, but it worked! They were incredible beasts and deserve more attention. I think if I were fortunate enough to have the skeleton of just one dinosaur  on display, it would have to be some sort of stegosaur.

7: Fossils of the Hunsrück-Schiefer
A beautiful pyrite-preserved brittle star Ophinurina lymani. 
This is a  lagerstätte from the Devonian, found in Germany, also known as the Hunsrück slate. This diverse array of fossils has soft tissue preservation, with many fossils being exceptionally beautiful as they are preserved in pyrite. Various echinoderms are found, including crinoids (more than 60 species), alongside trilobites, brachiopods, jawless fish, even jellyfish. The fossils found at this site are some of the most beautiful in the world in my opinion. I am thoroughly jealous of the person who owns the fossil pictured. I may write about them at length soon, as I intend to do an essay about them as an assignment.



6: The Fish to Amphibian Transition
Another fascinating evolutionary transition which is documented well by the fossils, yet manages to keep astonishing us. The "fishibian" Tiktaalik is becoming one of the main transitional forms mentioned, though it would need a lot more publicity to surpass Archaeopteryx in fame. One of the reasons this group of fossils makes my list is because Neil Shubin's book Your Inner Fish had a big impact on me, informing my understanding of evolution and helping reignite my passion for palaeontology. A good portion of the book is dedicated to Tiktaalik, which the author was instrumental in finding.

5: Eurypterids
These are the mighty sea scorpions, scourges of the Silurian seas. Some of them grew enormous, up to around eight feet long, yet recent studies sadly suggest that they were not the vicious sea monsters we would love them to be. They most likely spent a lot of time lurking, waiting for prey to come into close proximity, before they attacked. They did not have incredible strength, so likely went for weak and small prey in the sea. Even so, they are still impressive and their fossil remains are often beautiful and not too difficult to recognise. I managed to get a good look at quite a few eurypterid fossils last summer at the museum, Pterygotus and Slimonia, which gave me an interest in them. I enjoyed having to closely inspect them and try to work out how many segments each had, while attempting to learn the names of each part. I would love to see the giant sea scorpion up close some day. And for the record, they are not ancestors of terrestrial scorpions.

4: The Transition from Reptiles to Mammals
This is arguably the most beautiful transition in the fossil record. We are exceptionally lucky to have numerous well-preserved fossils documenting this pivotal change in our history. It is most famous for the fact that we can see the changes from the reptilian jaw, which contains around seven bones, to the mammalian condition where there is one main jaw bone. What is incredible about this is that the fossils show the other jaw bones becoming reduced and migrating to the ear, where they have become the inner ear bones of all mammals. There are even some fossils with double hinges on their jaws, caught in the act in a way. The changes in the jaw and ear are alongside changes from reptilian motion (side to side) to the up-down undulation of mammalian movement; changes in dentition and the development of a secondary palate, allowing them to chew; the development of fur and warm blood, and a whole host of other changes which are intimately linked (usually metabolism and consumption) and documented by the fossils. Astonishing!

3: The Cambrian "Explosion" Fauna
The fossils of the Cambrian are undoubtedly some of the most important, as we find the earliest examples of most of the modern phyla during a time of exceptional evolutionary creativity. Not only are there the familiar groups, such as trilobites and even members of our own phylum, but there are a host of oddballs which defy classification, such as Opabinia. My favourites during this period are the unusual arthropods, such as Anomalocaris, and lobopod worms such as Hallucigenia (pictured). There are a few famous sites of exceptional preservation during the Cambrian diversification event, giving us amazing windows to peer into the ancient world. Stephen Jay Gould made the Cambrian fossils of the Burgess Shale the stars of the show in his book Wonderful Life which I thoroughly recommend. This is likely a very predictable group for my list, as our understanding of Ediacara impacts on our interpretations of what was going on during the Cambrian. There are always new ideas popping up trying to explain the Cambrian explosion and it has been a constant source of fascination for palaeontologists for a while now.

2: Trilobites
I would be very surprised if trilobites did not make the list of the vast majority of palaeontologists, if they were asked to make such lists. Anyone interested in palaeontology should read Richard Fortey's Trilobite and marvel at the myriad forms and uses of this important fossil group. Trilobites are iconic, fascinating and are often beautifully preserved fossils. They exploited pretty much every marine niche possible and had stunning diversity, before their demise at the end of the Permian. They are justifiably one of the most studied groups, better known than some extant groups! They are not just wonders to gaze at, but are also heavily used in biostratigraphy, biogeography, palaeoecology and more. I have done a few blogs on trilobites, so this should have come as no surprise. I have sadly not been anywhere to find any yet, but that will be remedied soon. I'd love to work on them too.

1: Small Shelly Fauna
Often referred to as SSFs these may seem like an odd group to have at number one. The informed or observant reader might have predicted this though. The blog icon is Microdictyon, a lobopod worm and SSF which is related to the aforementioned Hallucigenia. SSFs are microscopic mineralised parts which are largely enigmatic, though some are recognisable. They are found during the earliest stages of the Cambrian, right before the Cambrian explosion and right after the Ediacaran fossils. They herald the arrival of mineralised parts (not quite true, as there are a couple of genera at the end of the Ediacaran with hard parts) but we do not know what many of them are. Some fortunate soft tissue preservation has shown some of them to be parts of bigger organisms; the tiny, net-like sclerites of Microdictyon for example. There are cap-like shells which are micromolluscs, but many of them remain incredibly mysterious, though they are useful in biostratigraphy and overlap with trilobite zones which occur a bit later. I liked this group before I started getting really into Ediacarans, though I don't know too much about them. They are currently my favourite topic of research as I am considering doing a major project on them, which I am really looking forward to.

So there you go, my top ten. While I was writing it I felt like swapping around the order, but this list is meant to be transient, so I thought I would stick to it how I originally order it rather than constantly shuffling them around. I can possibly guess what you are currently thinking and I bet the words "nerd" or "geek" pop up at least once.

Friday, 13 August 2010

A Critique of a Critique of a Creationist Critique

In my previous Critiquing Creationist Blogs post, I took a look at the creationism posts of the A Sure Word apologetics blog of RK Bentley (he blogs about a lot more than just creationism). Since then, Bentley has responded to the criticisms of one of his posts. Myself and another had been highly responsive to his Five Lies Evolutionists Tell post so he has responded to us both in a new post, titled Answering the Critics About the Five Lies of Evolution. With this post, I want to ask one simple question. Has RK Bentley succeeded in establishing that these are indeed lies?

Lie #1: “Evolution is a FACT”

In his first post on this topic, Bentley's problem was that evolutionists would demonstrate the fact of a change in allele frequencies in a population, then claim that this makes evolution as a whole a fact. His issue was the equivocation of observable evolution with long term evolution leading to common descent. But Bentley missed my point, when we say evolution is fact we are not just talking about a change in allele frequencies; we are saying that the theory of evolution explains the fact of common descent. Within the scientific community common descent is a fact. Bentley's exact statement was, that "[the Palaeobabbler] goes on to say that I am,“completely unaware that most scientists consider common descent to be the fact of evolution.” I assure you that I am well aware of that. I said as much in my post. To quote, “A person who says, “Evolution is a FACT” is merely stating his conviction that “evolution” is true; that doesn't make it true regardless of his use of all capital letters!” I did indeed say this, but if you carry on reading my original response, I then added, "It is beyond reasonable doubt with scientists, so if Bentley wants to claim that this is a lie he must demonstrate why evolution does not occur. He cannot do so. "

So, I maintain from my original response that the equivocation is not there and as such this cannot be a lie of evolution. If Bentley wants to claim that common descent is the lie of evolution, well, then he has to demonstrate that evolution is false. So far none have succeeded. 



Lie #2: “Evolution and the Bible are compatible.”

In his response to the second "lie" of evolution, Bentley does not say too much, but does raise a glaring misconception of his own:

"TP [the Palaeobabbler] and I had a protracted discussion on Face Book about the genre of Genesis. Anyway, he asserts overtly that the creation account in Genesis is a “powerful creation myth and is not meant to be literal.” In other words, the Bible doesn't mean what it clearly says."

To maintain such a statement requires the Bible to be taken out of its cultural and historical context. The plain meaning of words constantly change. Not only do the meanings of words change and languages evolve, but we also find that ways of teaching and ways of thinking change too. We live in a society which favours dry, "scientific" prose when making truth claims; poetic language is for artistic expression. If we want to know how something works we ask the scientist, not the local painter. Our society tells us to ask certain questions, not least how we got here. But Genesis was written thousands of years ago, by a culture which had a very different appreciation for how to express truth and different ways of thinking. To claim one has the clear meaning of Scripture is borderline arrogant and is ignorant of context. What the Bible "clearly" says to a modern reader is not likely to be the same as it was to the ancient Hebrews.

On this point Bentley has only established that this is a lie of evolution if his view is correct. I still maintain that this is not a view promoted by evolutionists, they are divided on the issue. It is a claim of compatibilists, but Bentley has not demonstrated that this is a lie. 

Lie #3: "There is no evidence for Creation"

Helpfully, Bentley restates his claim quite succinctly, saying, "My point is that theories are attempts to explain the evidence while the evidence itself is neutral". This is a common creationist argument and tends to be the view of those who have managed to get a PhD in sciences involving evolution. Under one paradigm the evidence suggests evolution, under another it suggests that there is a designer. If this were true then paradigm shifts would be difficult, if not impossible. Using the language of theory, a good theory must be flexible, but must also be able to make predictions and be falsified. This means that there can be evidence in favour of it and also evidence against it. It also means that new evidence with surprise value can completely change our views. Under the static paradigm view of many creationists, this just would not be possible. Thankfully the creationists during the early 1800s who began to explore the rock record in detail did not cling to their views. Perhaps a list of lies of creationists would include "we all have the same evidence, we just interpret it differently". Creationism requires the ignorance or rejection of evidence in order to be maintained.

During the first discussion of the third lie, Bentley also put forward the Bible as evidence. He has now stated that "their explanations as to why they don't accept the Bible don't make the Bible disappear. It is still on the table for people to consider as evidence." I have no desire to make the Bible go away, but I also have no desire to abuse and misuse it by claiming it as a scientific treatise. I do wonder if creationists would be comfortable if we turned to every Holy Book whilst conducting science and not just the Bible. 

Lie #4: “Evolution has been tested and proven even more than gravity.”

The fourth lie is an interesting one as Bentley believes I have contradicted myself, so I need to be more clear. He said:

Now it's TP's turn to contradict himself. He claims I'm making a straw man then immediately says, “I have certainly seen the claim that gravity has been tested more, but this needs some qualification.”Indeed it does need some qualification but not from me.

In my response I was stating that lie four is a strawman, the statement that "evolution has been tested and proven even more than gravity". However, the statement that "evolution has been tested more than gravity" is not the same claim, it lacks the proven aspect and is a worthwhile distinction. I'm not sure why Bentley quite indignantly states that it does not need qualification from him, I would not expect it, which should be obvious by the fact that I went on to qualify the statement myself. 

As I have never seen anyone claim the proven aspect of the "lie", Bentley's argument is a strawman. No contradictions here. 

Lie #5: "Microevolution over time leads to Macroevolution"


In an interesting twist, Bentley starts by saying that we did not get his point, which oddly enough I agree with. His claim is that time is not a mechanism in evolution. The reason we did not get his point is that it is one of the biggest straw men I have ever seen, rivalling the one in The Wicker Man with consummate ease. Time is not a mechanism of evolution, it is simply what occurs when there is change, when things go from one state to another. Populations constantly change state and this happens in the dimension of time. What Bentley does not realise is that I agree with him and did so in my original response. Natural selection plus time does not result in new species, if that is all that is happens then we will simply end up with a depleted stock. 

What we need is a mechanism for the addition of variation.  Interestingly enough I said this in my first post: "With more variation entering the gene pool, natural selection can become more versatile, often being directive. " If we did not have new variation then we would only see stabilising selection, just as my first post mentioned. Bentley seems to think that time is what we think adds variation to a population and I can't fathom where he got this idea. 

He even has the audacity to put words into my mouth: "Natural selection is a process by which traits not suitable to an environment are removed from a population. Contrary to TP's claims, it indeed does remove variation from a population." In my original response, whilst discussing an analogy Bentley used, I had this to say: "If Bentley is selecting against new colours then the population will remain static, much like stabilising selection does." How much more clearer do I have to make it that stabilising selection is what Bentley is describing? I even gave a link for more information on natural selection, in which I also said:

In stabilising selection the existing mean of the distribution of inherited variability is favoured. In other words, variance is reduced as extreme variants are selected out. For example, in a population both the largest and smallest individuals may be selected against, maintaining a mean between the two. This is often seen with birth rates in populations.

In the same post I linked to I discussed the other forms of selection and how they are not the same as stabilising selection. Bentley's next audacious statement is as follows:

"TP makes the unsubstantiated claim that, “variation does not run out.... With more variation entering the gene pool, natural selection can become more versatile.” So what is the mechanism that adds variation to the gene pool? I know what the mechanism supposedly is and it isn't time."

Of course it isn't time, nobody thinks it is. Time is indeed required, for going from A to B is not possible without time. If Bentley wants to know how variation is added to the gene pool, well, he could have kept reading my response to him, where I clearly said that "[mutation] is the major source of variation and it happens every time a sperm or egg is made, followed by the recombination of DNA in sexual reproduction which gives a completely unique offspring with new variation. Natural selection works on this variation and so microevolution can add up to macroevolution." 

Bizarrely he then goes on to mention that "Time doesn't add traits to a population – mutations do." This has been the point all along, nobody claims that time adds traits, it doesn't, it merely allows traits to be added by mutations and acted on by selection. Bentley's "lie" has nothing to do with micro and macroevolution, it is to do with time and is nothing but a straw man. 

What's That Swimming Toward Me?

With the vast size of the Earth's oceans, it is not unlikely that many of us will swim in them from time to time. Whether you are going for an innocent paddle, catching waves on your surfboard, or sailing the seas on a fishing trawler or pirate ship, you will be sharing the waters with myriad different animals, some of which are dangerous. If you were to find yourself swimming under water with a big, moving animal coming ever closer, how do you know whether you have a friendly dolphin swimming towards you or whether it might be a hungry shark? Well, the easiest way can be done at a distance and is a simple observation with an interesting explanation - evolution.

So, with that large, looming shadow swimming towards you, what do you look out for? If you can see its tail, simply look at the orientation of the tail fluke, is it horizontal or vertical? Failing that, look at how it moves, does it undulate its body up and down, or does it move its body from side to side? Dolphins and whales have a horizontal tail fluke, which means they have to undulate their body up and down in order to propel themselves through water, so if you see either the horizontal tail fluke or the undulating movement, you have a dolphin or whale coming towards you. 
Sharks, on the other hand, have a vertical tail fluke and so must flex their body from side to side for propulsion. If you see the vertical tail fluke or side to side motion, then what is coming towards you is a fish and so might be a shark. 
Posture changes in dinosaurs.
As our fishy ancestors used a side by side motion to propel themselves through water, so did our earliest terrestrial ancestors and so do reptiles today. Snakes are an extreme example of this sort of movement, but the side to side motion is still there. During the Mesozoic era things began to change, as our ancestors (and convergently in dinosaurs too) developed a more upright posture, instead of the sprawling gait of reptiles. With an erect posture the more effective way to rapidly move is to flex the spine up and down whilst running, rather than side by side (see image below).

Many vertebrates have some of their vertebrae fused to facilitate particular movements, so future evolution can often be restricted to working within the confines of that movement. As dolphins evolved from terrestrial mammals, their semi-aquatic ancestors also used this up and down movement and so adapted this to movement in the water. Side to side motion, like that of a shark, would require a larger number of changes when there was the simpler solution of up and down movement (though note that evolution does not have the foresight, it simply uses what is available - quick fix solutions often work in evolution). The motion of whales and dolphins is testament to their ancestry, having descended from active land mammals. 

During the Mesozoic another group secondarily took to the waters and adopted the torpedo shape of dolphins and sharks. These were the ichthyosaurs, descending directly from terrestrial reptiles. As their ancestors used the side to side motion, so did the ichthyosaurs when they swam, also possessing a vertical tail fluke. They had some unusual traits for reptiles, giving live birth and being warm blooded, but their swimming motion gives away their reptilian status. This also quite ably demonstrates that they are not dinosaurs as many laymen mistakenly think, for dinosaurs did not have a sprawling posture which uses the side to side motion. So, if you are somehow in Mesozoic waters with a shape swimming towards you, it may be too late before you can discern whether or not it is an ichthyosaur or a shark.

Sunday, 8 August 2010

Critiquing Creationist Blogs - Part 2

In part 1 of Critiquing Creationist Blogs I looked at the blog of Daniel Mann and mentioned that I would be looking at a single post by RK Bentley in part 2. Instead I will be looking at two posts on his blog, as the latest post is about evolution. Bentley is more of a challenge than Mann was and has quite a persuasive writing style, masking the fact that his posts are littered with misconceptions.

Bentley - Is Young Earth Creationism a Modern Invention?


In the first of Bentley's blogs which I want to look at, I was pleased to see that he had been exposed to this view as it is one I hold (see here). In Bentley's words the argument is that "never before in Church history has there been such an emphasis or hyper-literal interpretation of the creation account in Genesis." Something which he brands as "clever spin". I wouldn't disagree with his words here, except of course that it is clever spin. What it does is show that the literalistic reading of Genesis is not the default position for Christians.

Naturally Bentley's first port of call is to look at the Church Fathers, stating unequivocally that the majority took Genesis literally. Yet when we look at the Church Fathers we actually find it to be a bit of a mix, some took it literally some did not. The minority that Bentley sees appear to be those who were perhaps overzealous in their allegorical readings of Genesis. When we look at early Christians we find non-literal interpretations from such luminaries as Origen, Augustine, Clement, Cyprian, Justin Martyr and Irenaeus, not to mention some prominent Jewish commentators of the time who would have undoubtedly influenced interpretations. Here can be seen an example of the differing views which were prevalent, though I think this quote from Archbishop Rowan Williams sums it up well:

"[For] most of the history of the Christianity there's been an awareness that a belief that everything depends on the creative act of God, is quite compatible with a degree of uncertainty or latitude about how precisely that unfolds in creative time."

It is interesting that the response to Darwin's theories was much the same, with mixed reactions but largely an uncertainty about how the creative act unfolds. The earliest fundamentalists, the authors of The Fundamentals, at the start of the 20th century had mixed reactions to evolution, with some accepting it and some rejecting it outright. Most notable in acceptance is James Orr, who stated that “evolution is coming to be recognized as but a new name for ‘creation’, only that the creative power now works from within, instead of, as in the old conception, in an external, plastic fashion.”

According to Bentley, whenever we mention that a literal Genesis was not strictly accepted in early Christianity, we fail to mention that Augustine believed in an instantaneous creation, not one which is billions of years old. I'd like to know who he has been reading as I personally do add that fact and have read many more prominent theistic evolutionists doing the same. It is also a red herring. The point of bringing up early Christian views is to argue against a strict literal interpretation, not in favour of an old Earth. The early Christians believed in a young Earth, but not necessarily for Scriptural reasons. They were making the bold claim that creation had a distinct begin, whereas many non-Christians believed that the Earth was either eternal or going through cycles. They needed to date creation, so they did it the only way they knew how - genealogies. To claim that they were strict young Earth believers is to ignore the context of the time they were living in. 

Bentley's next point is that according to us non-YECs, they are cult like because they put too much emphasis on a young Earth. I find this to be curious as I have never heard this accusation before and it is not one I would use. I do think that YEC views can be very distracting, but YEC is not a phenomenon which can be pinned down to a single church denomination. Christians of many denominations are YECs and many, if not most, share congregations with OECs and theistic evolutionists. If anyone is claiming this then I am with Bentley, they are wrong. However, Bentley's reasons are different to mine.

Bentley states that there was no reason, until 100 years ago, for ministries like AiG (Answers in Genesis) or ICR (the Institute of Creation Research). He says that a "literal 6-day, recent creation had been the default position of the Church for nearly 2,000 years." I hope that it is clear that this is not true as the literalist reading did not have the monopoly where interpretation was concerned. It is also notable that older ages for the Earth were first proposed by Christian geologists and quite readily accepted by the majority of Christians. Old Earth creationism, before Darwin, seemed to be the majority position. Young Earth creationism reared its head during the 20th century as an old Earth is necessary for evolution - disproving an old Earth would pull the rug out from evolution. Such desires are not truth seeking, but one-upmanship. In Bentley's eyes, the response to Darwin (see here for my view) was poor:

Rather than trust the word of God over the flawed opinions of flawed men, many Christian leaders of that day capitulated without a struggle. Some began to invent new interpretations of Genesis that were “compatible” with the new theories of science. These new interpretations included absurd notions like theistic evolution, the gap theory, the day-age theory, the framework hypothesis, and the simple “Genesis-is-allegory” interpretation.

The idea that new interpretations were "invented" due to evolution is clearly false. Allegorical interpretations were prevalent in early Christianity, along with day-age hermeneutics, though let us not forget that there were indeed many literalists too. One could say that evolution swung the pendulum in favour of less-literal interpretations. The gap theory was in response to geological discoveries pre-Darwin. The reality is that Genesis was flexible in interpretation, allowing for many possible readings for which the majority view often changed. The Reformation took things back towards the literal in reaction to overzealous allegorising, but then science took things back towards symbolic readings. With this in mind we can embrace creation and allow it to help us better understand Scripture. We are trusting the word of God, but all interpretations are human, not least YEC readings, so the flawed opinions of flawed men are embraced no matter what! I feel it is worth mentioning the words of the historian of religion J. Estlin Carpenter:

“Theories [about the Bible] once ardently cherished have been overthrown. Conceptions that had exerted immense influence for centuries, can no longer be maintained. On the other hand, the true value of the Bible has been enhanced. We have ceased to ask of it what it cannot give us; we cherish all the more highly what it can.”

Bentley finishes by criticising compartmentalising, something theistic evolutionists generally do not do and mentions Jesus' statement where he said that if we do not trust his words about Earthly things, how can we trust him about Heavenly things? (John 3.12) I agree with this as Jesus did not write Genesis (nor is it clear how he read it, considering many contemporary Jews held a non-literal interpretation). The last paragraph of Bentley's well structured post mentions the "ground-breaking" work of "Dr." Henry Morris, author of The Genesis Flood. He is indeed qualified for the title of "doctor", but a curious thing about creationists is that they put a lot of emphasis on when a creationist has a PhD, despite the fact that professional scientists do not use the title except in official circumstances such as forms (though "professor" is a much used title).  Morris' work was a rehash of the work of MacCready Price, a Seventh Day Adventist whose literalist views were influenced by a vision by the "prophetess" of the church. To any trained geologist the views of Morris are untenable, misguided and extremely naive. It is not surprising that many "flood geologists" who finally decide to do fieldwork find it difficult to hold their young Earth views.

Folds like this, with subsequent deposition, are indicators of deep time and not explained by "flood geology". 


Bentley - Five Lies Evolutionists Tell

For the second blog of Bentley's which I would like to look at the theme is evolution. He has chosen several common statements by evolutionists which he intends to demonstrate are false. Instead we find many strawmen as you will see. 

Lie 1 - Evolution is a Fact

To Bentley this is a case of equivocation on the behalf of evolutionists. Apparently we claim that the fact of observable evolution makes common descent itself a fact. He is not completely wrong as I have seen some debaters online make this claim. The proper claim, or rather that which is put forward by actual scientists, is that evolution is both theory and fact. Theories explain facts, they tell us how and why things occur, whereas the facts are things we observe. The facts of evolution are that allele frequencies change in a population over time, and that all life shares a common ancestor. The theory of evolution explains how these facts occur. Bentley's mistake is to think we are doing a bait and switch, where we present evidence for the fact of microevolution and claim that it proves macroevolution. He is completely unaware that most scientists consider common descent to be the fact of evolution. It is beyond reasonable doubt with scientists, so if Bentley wants to claim that this is a lie he must demonstrate why evolution does not occur. He cannot do so. 

During his criticism of lie 1, Bentley gives a little run-through of a typical conversation using caricatures. The evolutionist character is incredibly rude, branding his creationist opposition an idiot at every given opportunity. In reality there are a very small minority which do this, the majority are willing to discuss. 

Lie 2 - Evolution and the Bible are Compatible

Unsurprisingly the criticism here is that compromise is the only way to reconcile the two, with the Bible usually being compromised the most. It is interesting that he accuses "evolutionists" of this lie, when many creationists use the term to mean mostly atheists, many of which share his belief that the two are incompatible. His first point against reconciliation is the difference in order, which I also agree with. Many theistic evolutionists do try to keep Genesis literal, but this is a mistake. Genesis is a powerful creation myth and is not meant to be literal, the reconciliation here is relatively simple. He then adds at the end that the Bible states sin before death whereas evolution would put death before sin; this is the biggest issue with theistic evolution, one which has many solutions. Is the death in question really spiritual and not biological? Did death become mortality (or recognition of mortality) with sin? Did none in God's image die before sin? Did the Fall affect the past just as many see Salvation as doing? Did God use death as a tool with ultimate redemption waiting in the future? I'm not going to provide an answer here simply because it is a deep topic, but clearly there is not a lack of solutions to his problem.

Lie 3 - There is no evidence for Creation

According to Bentley evidence is neutral. The point he misses is that theories must have predictive power in order to become a theory, they therefore must be able to predict evidence which would favour the theory and evidence which would falsify it. If creation were a theory it would make predictions, so evidence could go against it. The disparate lines of evidence show that the Earth is 4.54 billion years old and that evolution has been taking place for around 3.8 billion years. If this is not evidence against young Earth creationism I don't know what is. Bentley has gone for the old creationist lie, that we both use the same evidence. He gives an interesting example of how the logic works:

As we watch the sun move across the sky, one might say that is “evidence” for the sun revolving around the earth. Indeed, people had believed in a geocentric model of the universe for centuries but, of course, no one believes this anymore. Over time, we gathered more information and now we have a better theory – the heliocentric model. Even though the model has changed, some “evidence” hasn't changed: the sun still appears to move across the sky. The difference is now we have a better explanation about why it appears to do so. The sun itself never told us which theory is correct.

As we see here, there is no evidence that the Sun moves around the Earth as mere observation is invalidated by more evidence which contradicts it and the newer explanation explains things better. This is what happened to creationism, it seemed obvious to unscientific minds, but then as more evidence accumulated it was invalidated and more parsimonious explanations were sought and given. This new evidence is evidence to the contrary and causes us to discard what we thought of as evidence for creationism as it is now evidence which evolution explains. Bentley's next statement is worth quoting as it is on my favourite subject:  

Similarly, when we find a fossil, the fossil doesn't “tell” us anything. The fossil isn't evidence “for” evolution any more than it's evidence “for” creation. It's just a dumb rock (dumb as in not speaking). We just have different theories about how the fossil came to be.

Actually fossils can yield a wealth of information, even more so if we have them in their stratigraphic context. Fossils can tell us a lot about the organism depending on how well they are preserved. We can often see last meals (plus coprolites teach us about diet) and even behaviour if they were rapidly fossilised. Some behavioural indicators are actually very common, as trace fossils of sea floor trails are often found and can even be seen on many paving slabs. Some fossils are excellent indicators of environments, for example, aquatic photosynthesisers must be in the photic zone. Reading the rocks we can learn a lot, a single fossil can yield a wealth of information, just think what thousands upon thousands of fossils can tell us!



Bentley then states that he cannot fathom why evolutionists ignore the Bible as evidence. As this post has shown, it is open for interpretation, so why should we favour his? Why would creation tell us any different? As for what evidence we do use, there is evidence from ecology, zoology, palaeontology, embryology, genetics, genomics, biogeography and more. All the evidence we find is explained by evolution, but creation cannot manage this. The claims of Genesis 1 are untestable and based on relatively subjective interpretation, it is not fit for governing science. If it were meant as a scientific treatise it would be the ultimate evidence, but alas, it was not.

To summarise, Bentley's mistake is that he does not recognise that there is evidence against creationism and in favour of other explanations. This leaves us with the conclusion that there is no evidence FOR creationism because there is so much against it. In Bentley's world it seems all views can claim evidence supporting them, no matter how much contradicts it or whether there are superior explanations. 

Lie 4 - Evolution has been tested and proven even more than gravity

Bentley's claim here is a strawman, but an understandable one. I have certainly seen the claim that gravity has been tested more, but this needs some qualification. Anyone can test gravity, we can drop things and watch them fall, we can drop things of different weight and see what happens. The thing is, this is the same experiment being repeated over and over. If we counted the experiments done on gravity and compared them to evolutionary experiments (and other disparate, non-experimental lines of evidence) we would find that evolution has been tested in many more ways. It is not that there has been more tests, for we test gravity every time we walk, but there is more of a variety of tests which have been performed. 

I have not seen anyone claim that evolution is more proven than gravity. Bentley is unwittingly muddling this up with the claim that evolution is better understood than gravity, which is interesting as he even mentions that we do not understand how gravity works. We understand how evolution works for the most part, far better than we understand how gravity works. Perhaps he genuinely has come across people claiming this, but I haven't. I have, however, seen the claim that I just made, stating that we better understand evolution than we do gravity. So we aren't lying, he just misunderstood us it seems. 

Lie 5 - Microevolution over time leads to Macroevolution

I almost missed this one as it was mistakenly labelled as lie 4. Bentley's problem with this claim is that he sees natural selection as a negative process, eliminating the weak and leaving only the strong. In such a scenario there is no way that macroevolution could be sustained over time as it results in a reduction in variation. This is a clever but common move by Bentley, as it can cause the reader to forget that variation does not run out, something Darwin was certainly aware of. With more variation entering the gene pool, natural selection can become more versatile, often being directive. For more on natural selection see here. Bentley criticises the peppered moth example, something which is only ever claimed to show natural selection acting in an obvious observable way. Bentley puts it this way:

If I continuously removed one colored moth from the population, how long would it take until new colors began appearing? The answer is obvious: you cannot add new colors to a population by continuously removing colors.

In his analogy he is playing the role of natural selection, mucht like breeders do with dogs, cattle and birds etc. The problem with analogies is that they can be incomplete and Bentley forgets to mention that new colours will inevitably emerge. If Bentley is selecting against new colours then the population will remain static, much like stabilising selection does. However, there are three forms of selection: stabilising, disruptive and directed. If Bentley did not remove the new variations but instead removed only the original coloured ones (bit by bit, not all at once) he would eventually have a population of a very different colour. Natural selection can act like this on a whole suite of traits. Bentley almost acknowledges this:

“Change” plus time isn't a magic formula; it must be a certain kind of change. It must be a change that adds new traits to the population.

Indeed, new traits must be added. But Bentley is attacking an experiment solely on natural selection and criticising it for not giving an example of new traits emerging. Oddly enough, though the experiment is on natural selection, the different colour which evolved was a new variant which went on to become dominant. Mutation is the major source of variation and it happens every time a sperm or egg is made, followed by the recombination of DNA in sexual reproduction which gives a completely unique offspring with new variation. Natural selection works on this variation and so microevolution can add up to macroevolution. He finishes by adding:

The peppered moth example occurred more than a century ago. In the last 100 years, what macroevolution has occurred? Some will argue that 100 years isn't long enough. OK, but let me ask you this: what microevolution has occurred? Over time, the population returned to normal. The microevolution over time led to a net change of ZERO!

This is what we often term "wobbles around the mean" in which a population fluctuates. It is much like if you measure the weight of somebody who is growing. If you measure them over long periods of time you will notice a gradual trend, an increase in weight. However, if you weigh them at a really fine scale, with very accurate measurements and do so several times per day, then you will find that their weight fluctuates throughout the day (especially after meals and trips to the toilet), often returning to the mean. The net change on the small scale will be roughly zero, but over the larger scale of weeks, months and years, you will notice a large trend. It is like this with micro and macroevolution. Time really is on the side of evolution. 

Conclusion

When it comes to the more Christian oriented issues, Bentley is a bit of a challenge. He is excellent at pulling the wool over your eyes and making it sound as though his point is valid. It might be useful to ask what he isn't telling us in his posts, though I don't think he deliberately misses things out. His misconceptions are likely to be genuine, the problem is that he is articulate in expressing them and desires to influence others. He is not as transparent as Mann was, so is quite the tricky customer. When he addresses science he drops into the typical creationist techniques and is not a challenge at all; one can only hope that this weakness of his causes others to see through his misconceptions. 


Saturday, 31 July 2010

End of the Month - Time for some news.

It's that time where I feel I have not been educational enough, or haven't written enough, so I force myself to seek out interesting news, usually resulting in me raiding ScienceDaily and giving snippets of insight into what's going on in the science world. This time I have gone a little bit further and have found a wider range of stories, from other sites too. Some are up to date (ish) whereas the odd one might be a few weeks old. Ah well, here goes:

Segmentation Solved?
One of the most important innovations in evolutionary history was the evolution of segmentation, allowing for evolution to become more creative. Many segmented organisms have repeating segments which are identical (think of a centipede or millipede for example) and this allows evolution to co-opt these segments for other purposes, allowing differentiation whilst not disrupting the original function, as one segment continues its job whilst the other alters (this occurs at genetic levels with the duplication of genes and gene complexes too). Increases in differentiation lead to specialisation and the result is often a highly complex structure. Dawkins termed the evolution of segmentation a watershed event in evolution, opening up the door for incredible diversification (see The Ancestor's Tale for details). Organisms such as arthropods and annelid worms are obviously segmented, but so are we and the rest of the chordates. Our segmentation is slightly more obvious when we look at the vertebral column, though keep in mind that segments can fuse and merge together.

A question that has been looming in the minds of scientists is whether or not segmentation evolved once, in a common ancestor of the three aforementioned groups, or whether it is a convergent feature. The three groups are not closely related, so a segmented common ancestor would be back in the Precambrian, around 600 million years ago. If it evolved multiple times, then it may have appeared close to the Cambrian explosion, but then an explanation is needed in order to explain why it evolved in three separate lineages at the same time. A recent study looking at the genes involved in segmentation has found that they are remarkably similar in the separate segmented phyla, suggesting that we all did evolve from a segmented common ancestor and that segmentation evolved only once. See here for more details.

Necks: An Important Evolutionary Innovation
Interestingly the last item of news segues into this one quite nicely. Scientists have found that the evolution of necks, during the transition of our ancestors from sea to land, was a very important step in our evolution. The neurons controlling limbs were moved from the brain into the spinal column (fish still have them in their brains) separating the limbs from the head. This allowed for improved dexterity and coordination in our "fishibian" ancestors which eventually led to diverse limb forms such as those in birds, apes and whales. See here for more.

Stress and Lampreys
The lamprey is a jawless fish which attaches itself to its prey and sucks out their innards, causing havoc in some lakes. Trace our history back, past the fishibian (Tiktaalik roseae) in the last segment but not as far as the common ancestor in the segment before that and you will find that we descend from jawless fish and so share a common ancestor with lampreys. Evolutionary biologists look at relationships like this in order to work out how certain traits evolved as the differences can give great insight, especially when the other organisms have a "primitive" form of the trait being analysed. In this case the system being studied was the endocrine system, especially the production of stress hormones. Humans have more than 30 stress hormones and this study has shown that lampreys appear to have only one, giving insight into how our own, more complex system evolved. See here for more.

Belly Flopping Frogs
This story seems to be on every science site, but it is quite a good one so I thought I would mention it. A study in "primitive" frogs has shown that they evolved the ability to launch themselves through the air before they were able to land properly. The evolution of a proper landing, which came later, made them more efficient and less vulnerable, as anyone who has tried to catch them will know when they continuously hop away. This is a great story which also conjures up amusing images, so read here. It saddens me that frog diversity is really struggling right now, especially in a time when we are discovering some very interesting adaptations among them (who can forget the frog which walks on water; the Pinocchio-nosed  frog; the frogs which breathe through their skin; or the elaborate behavioural patterns of some frogs?) who knows what we will never discover?

Sex-y News
A bold new theory for the evolution of sex has been put forwards which looks deep into our prokaryotic past. How meiosis evolved has been baffling scientists for a long time. Meiosis is the process in which the genome is divided and recombined with that of another individual in order to produce offspring. It is generally believed to have evolved from mitosis, the process by which eukaryotes divide; their DNA is divided into two and goes off into two daughter cells. Researchers have now been looking into the reproductive processes in prokaryotes, binary fission and transformation. Binary fission has similarities with mitosis and is where a prokaryote splits its DNA strands to act as templates for two new strands which inhabit the daughter cells. Transformation on the other hand is where bacteria take a segment of DNA and insert it onto the genome of another cell where it recombines. The researchers have suggested that the process of transformation is the precursor to meiosis, not mitosis as most think.

The "basic machinery" for sex appears to have been present in eukaryotes from very early on, whereas the evolution of meiosis from mitosis would suggest a long period where there was no meiosis. The key to the problem appears to be stress; prokaryotes tend to favour transformation in conditions where stress is common and damage to DNA occurs. Similarly, in eukaryotes which reproduce by both mitosis and meiosis, such as yeast, stressful conditions tend to favour meiosis over mitosis. Both transformation and meiosis are utilised during stressful conditions as they combat DNA damage. The researchers have suggested that this gives great insight into how meiosis evolved from transformation. See here for more on this fascinating story.

Red Blood and More Lampreys
Studies have shown that red blood has evolved independently in both jawless fish (lampreys again, for example) and jawed vertebrates. Similar situations, in this case the need to get oxygen around bigger bodies, has resulted in the parallel (or is it convergent?) evolution of haemoglobin in these two lineages. The two groups co-opted completely different proteins for the same role. See here for more.

Smelling Whales
It has long been thought that all cetaceans, the order containing whales and dolphins, were devoid of a sense of smell. After all, toothed whales and dolphins lack many of the necessary features to achieve olfaction (sperm whales, killer whales and dolphins have been studied). The dissection of a bowhead whale brain found that they have enlarged olfactory systems, suggesting that they could possibly smell. Bowhead whales are baleen whales, so they may have kept their sense of smell in order to detect krill, they also have two blowholes, meaning they may have a directional sense of smell. Whale olfaction gives good insight into evolution as toothed whales cannot smell at all, yet descended from mammals which could. A look into their genomes shows that their olfactory receptor genes are there but not able to be used due to mutation. See here for more on the whale olfaction discovery and see here for my own previous discussion of whales and evolution.

Underwater Palaeontology?
Yes it's true, this segment is not going to mention evolution (except in mentioning that I am not mentioning evolution). It also looks at a recent underwater fossil find. Scuba divers searching an underwater cave found the bones of an extinct monkey in the Dominican Republic. The monkey fossil is relatively recent, but comparisons with older fossils is giving insight into, errrm, evolution (oops, sorry). This unusual find may give a lot of information on the divergence of monkeys and apes. See here for more on this story. Although it would likely be very difficult, the idea of underwater palaeontology is quite appealing as we normally look for fossils on land, even though most of the planet is underwater. It is almost as appealing as extra-terrestrial palaeontology, which is the subject of another post maybe...

New Species and Novel Fundraising
David Penney from the University of Manchester has discovered a new species of spider (the world's oldest) and a new species of lacewing encased in amber among others. He is offering people the opportunity to give these species scientific names, at a cost. He is accepting donations of £5,000 or more in order to name the species and raise money to fund his research. It is an excellent idea for fund raising and ordinarily I would hope that the names given would be good ones, but scientists are not always known for giving species insightful names and some get silly or playful (see Richard Fortey's book Dry Storeroom No. 1 for example, or look at the dinosaur Irritator). See here for some beautiful pictures of the fossils and here for the university's public article.

Ducks: More Obsessed With Penis Size Than We Are
Some species of duck compete with penis size in order to win mates. Instead of bulking up like many organisms do, experiments showed the ducks varying their penis size depending on how much competition there was. See here for the article. Also, with the mention of birds, check out this article about sex chromosomes in mammals and birds, it turns out we took opposite paths.

That's all for now, but not quite all I have to talk about. Some of the news I found was worthy of its own post, due later (or tomorrow). That's not to say that these others aren't as interesting, they simply caused less tangents.

Thursday, 15 July 2010

Falling Behind - Mega News Round-up

Whenever I stop posting often I start feeling guilty. I have had enough time to update the blog regularly but just haven't. I have planned a fair few lengthy posts which just don't seem to want to write themselves. So, in order to feel like I am making effort, I am going to do what I usually do when I fall behind. I am going to round up the best stories from ScienceDaily and say a little about them.

Triceratops and Torosaurus Were the Same Animal
Torosaurus  was a beast of a ceratopsian, stomping around in the late Cretaceous, showing off its three horns and enormous, impressive neck frill. In popular depictions of dinosaurs it is Triceratops  which reigns supreme amongst the ceratopsians, yet it turns out that these two dinosaurs may actually have been the same species, only at different stages of development.

A recent extensive study has shown that Triceratops  may be a younger version of Torosaurus  and that the adults are not simply scaled up juveniles. This is an important lesson for palaeontologists faced with the possibility of naming new species. As we cannot go out and watch our subjects growing and maturing, we cannot know exactly how they grow. If fossils are rare we are left largely in the dark. A young form and an old form can often appear like two different species, though closely related (imagine how wrong we could be with species which metamorphose!).

Another insight from this study is that it means diversity may have been a lot lower than previously thought towards the end of the Mesozoic. This will enable us to better understand what was going on to result in the demise of the non-avian dinosaurs and will also give insight into current extinction. For more, here is the obligatory SD link.

Sabre-Toothed Cats Were Strong Gits
I'm not normally very interested in what was going on in the Cenozoic, it is all too familiar looking. I mostly mention this story about Smilodon fatalis  because I just wish I could find a huge fossilised cat and call it Brontofelis or "thunder cat". It turns out that the Smilodon had very strong arms and used its formidable fangs after subduing its prey manually. See here for more.




Baby Brains and Evolution
A recent study, intended to shed light on abnormal brain development, has inadvertently given insight into human evolution. The study found that the regions which grow the most during infancy are the ones which seem to set us apart from our closest relatives such as language and reasoning. This is a testament both to the fact that changes in developmental timing can have massive effects, and to the fact that our evolutionary past has left its indelible stamp on our bodies. See here.

 More Insights into Multicellularity
Multicellularity has evolved several times. It has evolved in plants, animals, fungi and in green and red algae (and more times if you accept some of the hypotheses concerning the Ediacaran forms). It has also been observed evolving in some unicellular protists in response to predation. That said, it is still not fully understood. A recent study comparing the genomes of Volvox carteri  a multicellular algae, and Chlamydomonas reinhardtii a protist which is its closest unicellular relative, has shown that very few changes are needed for multicellularity to evolve.

Like many other aspects of evolution, the transition simply required using the same proteins for new jobs. The article uses the helpful analogy of a lego set in order to explain this, which I may steal (or perhaps I could say K'nex...). The organisms in question were used because Volvox  evolved multicellularity only 200 million years ago, whereas the other groups achieved it over 500 million years ago, so it is difficult to trace their genetic changes. Personally this is one of the more exciting bit of news, for more see here.

Borrowing Genes
Good old Drosophila, the fruit fly, has given yet more insight into evolution. A species of fruit fly has been observed being infected by a bacteria which conveyed an advantage. The flies then passed this bacteria on to their offspring and it spread through the population, much like genes do. Symbiosis as a source of new defence is a very intriguing strategy. It fits well for those who believe symbiosis and cooperation are major driving forces in evolution, though how prevalent it is remains to be seen. It is also a very rapid and efficient way of improving defences, as it happens a lot quicker than making a new gene, you just borrow the genes of another species. This if fascinating stuff, see here, perhaps more so than the previous mention of multicellularity. Dawkins will probably be drooling over this, as it lends credence to his selfish gene and extended phenotype views. Normally I don't like when scientists, or rather science journalists, claim that a new find will revolutionise our views of evolution, but this one should certainly not be ignored.

Island Evolution Challenged


It is commonly believed that evolution acts differently on islands. Big animals often evolve to be smaller, such as elephants, and smaller animals evolve unusually large sizes. A recent study challenges this view, suggesting that it is merely our perception that sees a pattern, when really none exists. See here.

Ostrich Movement Gives Insight into Dinosaur Movement


I must apologise, I am attempting to speed up here as I intended to go to bed an hour ago. This article is worth reading though.

Two-billion Year Old Multicellular Life
I unwittingly saved the best for last. Current wisdom holds that complex multicellular life appeared around 600 million years ago. Not any more. The earliest origin of multicellular life has now been set back a whopping 1.5 billion years to 2.1 billion years. More than 250 fossils have been found in Gabon and investigated through non-invasive methods. They have been carefully analysed and the conclusion is that they are indeed biological in origin. The image on the left shows both the internal and external morphology.

They vary in shape and size, reaching up to around 12cm, making them too big and complex to be single celled organisms. They have clearly defined, regular shapes and appear to have lived in colonies in often calm, shallow marine environments (20 to 30 centimetres). They potentially correlate with a rise in oxygen levels between 2.45 and 2 billion years ago. There was then a drop in oxygen levels around 1.9 billion years ago. This has some interesting implications. It is possible that these were another multicellular 'experiment' by life, much like how many see the Ediacaran forms. All of these Gabon forms may have gone extinct 1.9 billion years ago, leaving the Earth back in the....errrm....hands of the single celled organisms until mutlicellularity evolved again around 600 million years ago (though potential evidence for porifera is a lot older than the Ediacaran fossils).

This is one I am going to have to look more into, but for now I have to go to bed as I need to be up early to go fossil collecting in Runswick Bay, which I will talk about when I get back. Here is the article, hopefully the site where the fossils were found will be protected for years to come.