Sunday 16 March 2014

Chapter 14: Kakapos (and how recent is recent?)

On pages 344-5 of The Greatest Show on Earth, Dawkins makes a passing reference to New Zealand's flightless birds.
Moas lost their wings entirely. Their home country of New Zealand, by the way, has more than its fair share of flightless birds, probably because the absence of mammals left wide open niches to be filled by any creature that could get there by flying. But those flying pioneers, having arrived on wings, later lost them as they filled the vacant mammal roles on the ground. This probably doesn't apply to the moas themselves, whose ancestors, as it happened, were already flightless before the great southern continent of Gondwana broke up into fragments, New Zealand among them, each bearing its own cargo of Gondwanan animals.
It surely does apply to kakapos, New Zealand's flightless parrots, whose flying ancestors apparently lived so recently that kakapos still try to fly although they lack the equipment to succeed. In the words of the immortal Douglas Adams, in Last Chance to See, "It is an extremely fat bird. A good-sized adult will weigh about six or seven pounds, and its wings are just about good for wiggling about a bit if it thinks it's about to trip over something - but flying is completely out of the question. Sadly, however, it seems that not only has the kakapo forgotten how to fly, but it has also forgotten that it has forgotten how to fly. Apparently a seriously worried kakapo will sometimes run up a tree and jump out of it, whereupon it flies like a brick and lands in a graceless heap on the ground." [footnote 1]
It's worth noting that Dawkins' comment about the moa's ancestor is now considered out-of-date (though not unanimously), as molecular analysis in 2010 concluded moa evolved from birds that flew to New Zealand.[2]

Dawkins appears to have mentioned the kakapo simply so he could quote the amusing description of the bird made by his late friend Douglas Adams.  Adams' description favours a good story over factual accuracy – kakapo don't run up trees and then jump from them in an attempt to fly, but they do use their wings to help them leap or parachute short distances when descending from trees.[3]  

Unfortunately, rather than pointing this out, Dawkins makes the throw-away comment that the kakapo's "flying ancestors apparently lived so recently that kakapos still try to fly".  If read without an evolutionary time-scale in mind, this comment gives the impression that the kakapo lost the ability to fly only a few generations ago.

Unsurprisingly, Sarfati seizes on Dawkins' flippant comment, particularly his loose use of the word 'recently'.  Sarfati argues the kakapo's flightlessness "is a problem for long-age ideas", because New Zealand was "supposedly" isolated for millions of years but "this flightlessness is clearly recent" (page 256).

The best response to Sarfati (and to Dawkins' poor choice of words) is to clarify what 'recent' might mean in this context.

Broadcaster and natural history writer Alison Ballance outlines the biology, natural history and evolutionary history of the kakapo in her book, Kakapo: Rescued from the Brink of Extinction.  She notes that traditionally parrots have been viewed as "relative latecomers in the bird world, appearing between 12 and 25 million years ago, and reaching here by flying across the Tasman Sea".  In this case, 12 million years ago is considered to be relatively recent.  Where the kakapo fits in the traditional theory is unclear as the fossil record for kakapo is poor.  Ballance suggests the kakapo's flightlessness could even have happened in "the blink of an evolutionary eye", but it's important to note that she characterises this 'blink' as a span of a million years.[4]

For further context: a 2009 paper argued that the moa radiated into new species "just" 5-8.5 million years ago – "much more recently" than previous estimates of 15 million years ago.[5]  Here, 5 million years ago is considered recent on an evolutionary time-scale.

Therefore, while the evolution of the kakapo's flightlessness may be recent in evolutionary time, 'recent' means at least hundreds of thousands of years and, more likely, millions of years.[6]  This is far beyond the maximum 4,500 years allowed by the young-Earth creationist model.[7] 


References: 

[1] Richard Dawkins, The Greatest Show on Earth: the Evidence for Evolution, London: Bantam Press (2009), pp 344-5. 

[2] See my previous post: http://greatesthoaxonearth.blogspot.com/2013/11/geographical-distribution-lost.html and also: David Winter, 'Did the Moa's ancestor fly to New Zealand?' (4 February 2010) http://sciblogs.co.nz/the-atavism/2010/02/04/did-the-moas-ancestor-fly-to-new-zealand/

[3] "This behaviour is most often seen when birds are descending from trees to avoid recapture by conservation managers".  R G Powlesland, D V Merton and J F Cockrem, 'A parrot apart: the natural history of the kakapo (Strigops habroptilus), and the context of its conservation mangement', Notornis, Vol 53, No 1 (2006), p 4; online at http://notornis.osnz.org.nz/system/files/Notornis_53_1_3.pdf 

[4] Alison Ballance, Kakapo: rescued from the brink of extinction, Nelson: Craig Potton Publishing (2010), p 54. 

[5] M Bunce, T Worthy, et al, 'The evolutionary history of the extinct ratite moa and New Zealand Neogene paleogeography', Proceedings of the National Academy of Sciences, Vol 106, Issue 49 (24 September 2009), pp 20646-20651; online at: http://www.pnas.org/content/early/2009/11/17/0906660106.full.pdf 

[6] The Department of Conservation's Kakapo Recovery website says that kakapo may have flown "many hundreds of thousands of years ago": 'How Kakapo Get Around' (2008) http://www.kakaporecovery.org.nz/index.php?option=com_content&view=article&id=84&Itemid=182 

[7] See, for example: Adrian Bates, 'Parrot of the night - NZ's kakapo', Creation, Vol 30, No 4 (2008), pp 28-30; online at: http://creation.com/kakapo

Saturday 8 March 2014

Chapter 13: 'Simplest Possible Life?'

The following elaborates on a post made by the Amazon user 'stickler', which you can see here.

Chapter 13 of The Greatest Hoax on Earth addresses the origins of life on Earth.  On pages 224-8 Sarfati discusses the complexity of cells and contends that cells have always been too complex to have evolved from any non-cellular structure.  At the end of page 227 he quotes from a New Scientist article (which discusses research into the origins of life) to support his argument:
There is no doubt that the common ancestor possessed DNA, RNA and proteins, a universal genetic code, ribosomes (the protein-building factories), ATP and a proton-powered enzyme for making ATP. The detailed mechanisms for reading off DNA and converting genes into proteins were also in place. In short, then, the last common ancestor of all life looks pretty much like a modern cell.[footnote 1]
Anyone reading the quote in isolation would conclude it supports Sarfati's argument.  But what they would not realise is that Sarfati has quoted the New Scientist article rather selectively.  The article's next sentence, omitted by Sarfati, changes the meaning:
Yet the differences are startling. In particular, the detailed mechanics of DNA replication would have been quite different. It looks as if DNA replication evolved independently in bacteria and archaea, according to Eugene Koonin at the National Center for Biotechnology Information in Bethesda, Maryland.
The article goes on to point out:
"At face value, the defining boundaries of cells evolved independently in bacteria and archaea"...If Martin is right, the last common ancestor of life on Earth was a sophisticated entity in terms of its genes and proteins, and was powered by proton currents rather than fermentation. Yet at the same time, its bounding membranes were apparently different to anything found today. It was life, but not as we know it.
The article then describes 'white smokers' – alkaline hydrothermal vents, an important area of origins of life research (mentioned only in passing by Dawkins in The Greatest Show on Earth, and not addressed by Sarfati).[2]  After outlining how these vents make an ideal setting for the "RNA world hypothesis (which is discussed by Sarfati on pages 234-46), the article concludes:
The last common ancestor of all life was not a free-living cell at all, but a porous rock riddled with bubbly iron-sulphur membranes that catalysed primordial biochemical reactions. Powered by hydrogen and proton gradients, this natural flow reactor filled up with organic chemicals, giving rise to proto-life that eventually broke out as the first living cells - not once but twice, giving rise to the bacteria and the archaea.
The way Sarfati has quoted the New Scientist article gives the impression the last common ancestor was basically as complex as a modern cell, whereas the article actually states the last common ancestor was not even a free-living cell.  Given Sarfati's creative use of non-creationist sources elsewhere in The Greatest Hoax on Earth (see for example pages 57, 106, and 156-7), it is likely he has deliberately used the New Scientist quote out of context.

Part of the problem is that Sarfati seems to have conflated the ideas of a 'simple cell' and of 'simple life'.  But the simplest possible life does not necessarily have to be a cell.  Another complicating factor is that the last common ancestor does not necessarily have to be the simplest possible life, as it may not have been the first living thing.  This is best explained by physicist Paul Davies (whom Sarfati quotes in support of a different point on page 226):
It is important to realise that the last common ancestor of life on Earth is not necessarily the same as the first living thing.  To understand this, it is helpful to use Darwin's metaphor of the tree of life, in which, from a simple originating "trunk," new species have arisen by branching and re-branching over time.  Extant life is represented by the twiglets at the top of the tree.  By tracing back from two extant organisms, their last common ancestor will be encountered at the point where the branches meet.  Taking all life on Earth today, we can imagine following the myriad branches right back to a deep common branching point – the universal ancestor organism.  But this branching point may not lie on the central trunk of the tree.  There may have existed earlier branches of the tree of life that became dead ends, i.e. have no surviving descendants today.
Indeed, from the foregoing it will be clear that the universal ancestor must have already been an immensely complicated and sophisticated organism.  There was surely a long period of prior evolution leading up to it.  Pushing the tree analogy to the extreme, we can identify the origin of life with the single stem (or trunk, or root) from which all the subsequent branches sprang.  Taking this literally implies that all life would have descended from a single microbial Adam.  However, this interpretation is over-simplistic.  Microbiologists know that genes can be transferred laterally between organisms, and this can blur the unique association of species with tree branches.  In the ancient, primitive microbial realm, about which almost nothing is known, the tidy compartmentalisation into different competing species may have broken down.  All we can really say with confidence is that all life on Earth has descended from a community of genetically promiscuous closely inter-related microbes.


References: 

[1] Nick Lane, 'Was our oldest ancestor a proton-powered rock?', New Scientist, Issue 2730 (19 October 2009) http://www.newscientist.com/article/mg20427306.200-was-our-oldest-ancestor-a-protonpowered-rock.html; available in full online at: http://www.sott.net/articles/show/195226-Was-our-oldest-ancestor-a-proton-powered-rock

[2] A summary of the hydrothermal vent theory accompanied the New Scientist article cited above.  It is available in full online.  See: Nick Lane and Michael Le Page, 'How life evolved: 10 steps to the first cells', New Scientist, Issue 2730 (2009) http://www.newscientist.com/article/dn17987-how-life-evolved-10-steps-to-the-first-cells.html

[3] Paul Davies, 'The origin of life I: When and where did it begin?', Science Progress, Vol 8, No 1 (2001) http://cosmos.asu.edu/publications/papers/OriginsOfLife_I.pdf

Sunday 2 March 2014

Chapter 12: Ocean Salinity

On pages 215-18 of The Greatest Hoax on Earth, Sarfati gives a relatively lengthy discussion of the salt in the Earth's oceans as something that proves the Earth must be thousands, not billions, of years old.

Here's a link to a paper titled 'Ocean Salinity as a Failed Scientific Clock'.  The paper is written by a graduate student and explains simply and clearly why young-Earth creationist are being disingenuous when they use ocean salinity to claim the Earth can't be billions of years old.  

Here's an excerpt from the paper that serves as a good summary:

For a process to be considered a good natural clock, it must contain the following: a known initial condition, an irreversible process, a uniform rate, and a final condition. With the salt clock, the initial condition is not known. The process of salt accumulation has been proven to be reversible and in constant change. There is also no uniform rate of accumulation of salt. The only criterion met is the known final condition. Because of these factors, the salt clock can obviously not be used as a natural clock to calculate any type of age.
Despite the known scientific reasons for which this method cannot be used as an accurate natural clock, measuring the salinity of the ocean has recently been used by young earth creationists as supposed proof that the earth is not, in fact, billions of years old. The website Answers in Genesis, a young earth proponent, actually explains the salt clock as a valid measuring device. According to the site, "Many processes bring salts into the sea, while they don't leave the sea easily. So the saltiness is increasing steadily. Since we can work out how much salt there is in the sea, as well as the rates that salts go into and out of the sea, we should be able to calculate a maximum age for the sea (Sarfati)."
What is even more curious about this selected article is that the author even cites the works of John Joly and Edmund Haley in his references. The works of Joly and Haley, while vital in tracing the progression of scientific thought on the age of the earth, are in no way current or up to date. The article fails to comment on the shortcomings of the salt clock, and concludes by reiterating that the amount of salt present in today's oceans coincides with the age of the earth according to biblical accounts.