On pages 196-8 Sarfati discusses tree-ring dating (dendrochronology). As noted in my overall review of The Greatest Hoax on Earth, Sarfati bases his discussion on an article published by his colleague, Don Batten, on the Creation Ministries International website.[footnote 1]
Batten's article is quite misleading. For example, he compares the Bristlecone Pine (which is slow-growing, lives at high altitude, and is not known to produce multiple rings per growing season) with the markedly different Monterey Pine (which is fast-growing, has a natural environment that is coastal, and is known to produce multiple rings per growing season) to suggest the Bristlecone Pine could produce up to five growth rings per year. Even other young-Earth creationist organisations disagree with this approach. An article on the Answers in Genesis website admits that at present there is no good evidence that Bristlecone Pines can produce multiple rings per growing season.[2]
In my wanderings on the internet I came across a thorough critique of Batten's article:
Paul Smith, 'Dendrochronolgy Fact and Creationist Fraud' (14 Jan 2007) http://razd.evcforum.net/dendrochronology.html
I have no idea who Paul Smith is (not that I'm in a position to pass judgement, given that I'm publishing anonymously as Washington Irving!) and I've had trouble accessing any kind of home page for the razd.evcforum.net website. Nevertheless, Smith's article is well worth a read as it clearly sets out the many problems with Batten's approach.
Here's a good non-technical summary from the end of Smith's article:
False rings, missing rings and other sources of error are relatively rare and random in the growth patterns of trees, even though some species have higher susceptibility than others. Dendrochronologists use the tree species with the fewest known sources of errors, and they work to eliminate all sources of errors. They cross-check the data with other species and other locations. If dendrochronology depended on one lone species, Dr. Batten might have an argument: it doesn't.
That all the different dendrochronologies correlate with each other also refutes Dr. Batten's implication of this being a problem that science somehow has not dealt with already. If Dr. Batten really is a scientist in this field ("As a tree physiologist"), then he is aware of - and used - the techniques used by scientists for identifying false rings. That he doesn't say anything about this speaks to his "honesty" again - his willingness to misrepresent the truth is evident.
It is curious that Dr. Batten wants to be seen as a scientist on this topic, but he doesn't include any information on his methodology or his results in the paper discussed.
References:
[1] Don Batten, 'Tree ring dating (dendrochronology)' (undated) http://creation.com/tree-ring-dating-dendrochronology
[2] John Woodmorappe, 'Biblical Chronology and the 8,000-Year-Long Bristlecone Pine Tree-Ring Chronology' (2009) http://www.answersingenesis.org/articles/aid/v4/n1/biblical-chronology-bristlecone-pine
From 1997-2005, the Institute of Creation Research and the Creation Research Society ran a research project named RATE (Radioisotopes and the Age of The Earth). RATE's work underpins many of the recent young-Earth creationist arguments against accepted dating methods for the age of the Earth. RATE is cited is cited in several places by Sarfati (see his discussions of accelerated decay and carbon-14 on pages 189-192 and of helium in zircons on pages 214-5).
The key points of RATE's final report[footnote 1] can be summarised as:
- There is overwhelming evidence of more than 500 million years worth of radioactive decay.
- RATE's interpretation of the Bible and some scientific studies indicate a young Earth.
- Therefore, to reconcile the above points, radioactive decay must have been accelerated by approximately a factor of one billion during the first three days of creation and during the Flood.
- The concept of accelerated decay leads to two unresolved scientific problems, the heat problem and the radiation problem, though there is confidence that these will be solved in the future.
RATE's report identifies four separate pieces of scientific evidence for the acceleration of radioisotope decay: helium in zircon crystals, polonium halos in granites, isotope discordance, and the presence of Carbon-14 (C-14) in diamonds.
Helium diffusion in zircons
Zircon crystals contain high quantities of uranium, which produces helium during its decay process. This helium should normally be able to escape the crystal more quickly than it would be produced by uranium decay. RATE found high concentration of helium in zircons and argued these can only be explained by a young Earth and accelerated decay (if the Earth has existed for billions of years, the helium would have escaped).
RATE has been criticised over the purity of the zircon samples it used, for the method in which it took diffusion measurements and for problems in its calculations. More importantly, geochronologists do not consider diffusion rates of helium in minerals a reliable dating measure when used in isolation, because the rates are known to be highly variable.[2]
Radiohalos in granites
Radiohalos are darkened spherical patterns in rocks, caused by alpha particles released during radioactive decay. Looking at polonium halos, RATE argued that because polonium has a short half-life and granite is thought to be formed by a long period of cooling, the halos should have disappeared by the time the granite hardened. Therefore the granite must be much younger and have cooled rapidly. As uranium and polonium halos are relatively abundant, RATE concluded the granites must have formed during the Flood and there must have been highly accelerated decay rates.
As RATE's report highlights, there is not an agreed and proven scientific model of explanation for all aspects of polonium halos. However, there are several likely theories, to do with the presence of uranium in the granite.[3] RATE also acknowledges the dilemma they face by proposing accelerated decay, which produces extraordinary heat, and also proposing a rapid cooling rate to form the granite.
Isotope discordances
RATE's report states that radioisotope dates for all the isotopes in a rock should always agree, and then provides a number of examples where this is not the case. RATE then argues that all radiometric dates are untrustworthy and accelerated decay explains the discordance in dates. However, RATE fails to explain why there are so many cases beyond their examples where there is good date concordance for different isotopes.[4] While discordances occur and their cause is not always understood, these instances fail to invalidate the vast amount of concordance.
Trace amounts of C-14 in diamonds
RATE argues that the detection of trace amounts of C-14 in diamonds (dated as hundreds of millions of years old) supports their claim of a young Earth. After 100,000 years there should be no C-14 left in a sample which has not been exposed to external sources of carbon. Therefore the presence of approximately 0.1 percent of C-14 as a percentage of the total carbon indicates an age for these rocks of approximately 50,000 years.
The difficulty, however, is in assuring there is not, and never has been, another source of C-14 for that sample since it was originally formed from organic material. There are many subtle sources of C-14 such as contamination, microbial action, and some nuclear interactions. RATE's report states extraordinary care was taken in handling the samples but it is virtually impossible to eliminate such sources, which is why chronologists discount the reliability of C-14 dating if the concentration is below approximately 0.5 percent. Coal and diamond samples that the RATE team collected and analysed show significant variation from sample to sample, suggesting contamination.
Additionally, were the C-14 dating on these samples valid, this is still a date ten times older than RATE's desired age of 5-6,000 years. Thus RATE has to argue for a different concentration of C-14 to total carbon in the atmosphere before the Flood (500 times lower than it is today), which changed rapidly during the Flood due to accelerated radioactive decay.[4]
The problem of accelerated radioactive decay
RATE's report provides no direct evidence for accelerated decay but rather explores theoretically how such an increase in the decay rates might have occurred. RATE theorises that if God had slightly weakened the coupling force that holds protons and neutrons of an atom together in the nucleus, it would have lead to a change in decay constants of many orders of magnitude. RATE speculates that this coupling force took a different value in at least two time periods in the past: the first three days of the creation week and the year of the Flood. At other times, it was the same as today. Critics of such a theory point out that the coupling force is a fundamental constant of particle physics.
RATE's report acknowledges the two most serious problems with the theory of accelerated decay: heat and radiation. Over the 4.5 billion year history of the Earth, radioactive decay has produced tremendous amounts of both. RATE theorises that around 4 billion years of the decay occurred within the first three days of the creation week and the remaining 500 million years occurred during the year of the Flood. The Flood acceleration alone would have released enough energy to heat the Earth to a temperature of more than 22,000° C (roughly four times the temperature of the surface of the Sun). That amount of energy would have vaporised the Earth, including the geologic evidence RATE cites in support of acceleration (such as radiohalos and zircons).
To remove the heat and preserve the Earth, RATE proposes volumetric cooling: when God accelerated radioisotope decay he also expanded the size of the universe twenty-fold to dissipate the heat. However, volumetric cooling only works for gases, not solids such as the Earth. Furthermore, even if volumetric cooling were valid, it is uniform rather than selective (so in order to sufficiently cool radioactive material it would also freeze the Flood waters, and all life aboard the Ark would have died).
The other major problem with accelerated decay is radiation damage. Noah and his passengers would have to survive a year in which radioactivity was one million times greater than it is today. RATE's report admits no known solution exists. The lethal effect of radiation appears to be the primary reason RATE concluded that most accelerated decay occurred during the first two days of creation, before life existed, and not during the Fall and Judgment.[5]
References:
[1] Larry Vardiman, Andrew Snelling, and Eugene Chaffin (eds.), Radioisotopes and the Age of the Earth, Volume II, Waco: Institute for Creation Research (2005).
[2] See: Gary Loechelt, 'A response to the RATE team regarding helium diffusion in zircon' (2009) http://www.asa3.org/ASA/education/origins/helium-gl4.htm; Kevin Henke, 'Dr Humphreys' young-Earth helium diffusion "dates": numerous fallacies based on bad assumptions and questionable data' (2005-2010) http://www.talkorigins.org/faqs/helium/HenkeZircon2010.pdf
[3] See: Glen Kuban, 'Unfounded creationist claims about polonium radiohalos' (2006-2012) http://paleo.cc/ce/halos.htm; Lorence Collins, 'Polonium halos and myrmekite in pegmatite and granite' (1997) http://www.csun.edu/~vcgeo005/revised8.htm
[4] See: Randy Isaac's review and reply in 'A dialogue about RATE', Perspectives on Science & Christian Faith, Vol 60, No 1 (2008), pp 35-39 http://www.asa3.org/ASA/education/origins/rate-pscf.htm
[5] See: Isaac in footnote 4 and Matthew Rognstad, 'Creationism and accelerated decay' (2005) http://orgs.usd.edu/esci/age/content/creationism_and_young_earth/accelerated_decay.html; Greg Neyman, 'Creation science book review: Thousands...Not Billions' (2006) http://www.oldearth.org/bookreview/tnb/thousands_not_billions_9.htm
A strong scientific theory is supported by the convergence of multiple, independent lines of evidence. When numerous lines of evidence from different scientific disciplines are in agreement, then their agreed conclusion is strong. As historians Michael Shermer and Alex Grobman put it:
We know about the past through a convergence of evidence. Cosmologists use evidence from astronomy, astrophysics, planetary geology, and physics to tell the history of the universe. Geologists reconstruct the history of the earth through a convergence of evidence from geology and the related earth sciences. Archaeologists piece together the history of civilization using artwork, written sources, tools and weapons, and other site-specific artifacts.
The historical theory of evolution gains confirmation by many independent lines of evidence converging on a single conclusion. Independent sets of data from geology, paleontology, botany, zoology, herpetology, entomology, biogeography, comparative anatomy, physiology, and many other sciences each point to the conclusion that life has evolved. Creationists demand "just one fossil transitional form" that shows evolution. But a single fossil cannot prove evolution. Evolution involves a convergence of fossils and many other lines of evidence, such as DNA sequence comparisons across species. For creationists to disprove evolution they would need to unravel all these independent lines of evidence and find a rival theory that can explain them better than evolution.[footnote 1]
A conclusion based on multiple sources of evidence can still be very strong even if none of those individual sources of evidence are as strong on their own. As psychologist Keith Stanovich puts it:
[S]uppose the findings from a number of different experiments were largely consistent in supporting a particular conclusion. Given the imperfect nature of experiments, we would go on to evaluate the extent and nature of the flaws in these studies. If all the experiments were flawed in a similar way, this circumstance would undermine confidence in the conclusions....On the other hand, if all the experiments were flawed in different ways, our confidence in the conclusions would be increased because it is less likely that the consistency in the results was due to a contaminating factor that confounded all the experiments....When evidence from a wide range of experiments, each flawed in a somewhat different way or carried out with techniques of differing strengths and weaknesses, points in a similar direction, then the evidence has converged. A reasonably strong conclusion is justified even though no one experiment was perfectly designed.[2]
Convergent evidence is an important principle to remember when assessing young-Earth creationist criticisms of evolution. A good case study is the age of the Hawaiian island chain.[3] Scientists think the chain, which stretches about 3,000 miles (5,000 kilometres) across the Pacific Ocean, was formed by a volcanic 'hotspot': an area where magma periodically breaks the Earth's surface. As the magma (lava) cools and hardens it forms islands. The Hawaiian islands are on the Pacific Plate, which is moving to the northwest. So the islands closest to the hotspot should be the youngest and those that have moved furthest from the hotspot should be much older.
The islands have been dated by potassium-argon dating, which shows the islands have a linear age range that reflects the distance of each island from the hotspot. The oldest island remnants, at the northern end of the chain, are over 80 million years old. The youngest island, closest to the hotspot, is less than one million years old. If you take an island's potassium-argon age and divide it by the island's distance from the hotspot, you can work out that island's movement per year. Using this method, scientists find the islands are moving at a rate of 2.6-3.6 inches (6.6-9.1 centremetres) per year.
Of course most young-Earth creationists argue radiometric dating such as potassium-argon dating is flawed (see pages 192-3 of The Greatest Hoax on Earth). Fortunately, there's another way to determine the age of the Hawaiian island chain. Scientists can use Global Positioning Systems to measure the rate the islands are moving. These measurements give a movement of approximately 3.1 inches (7.9 centimetres) per year, which happens to be exactly in the middle of the rate of movement calculated by potassium-argon dating. Assuming the islands have always moved at this rate, scientists can work out how old the islands are based on how far they are from the hotspot.
Of course young-Earth creationists would question the assumption that the islands have moved at the same rate in the past. Fortunately, there's another source of evidence supporting the age of the Hawaiian islands. Volcanic islands gradually subside and erode as they age: height and activity are both thought to peak when the volcano is around 500,000 years old, then they decline as the volcano (which becomes dormant and eventually extinct) is slowly eroded over millions of years. Thus, in Hawaii, the newest islands should be the tallest ones and they should be closest to the hotspot. And that is the case: as you move northwest along the island chain, away from the hotspot, you find the islands decrease in elevation and show an increase in weathering and erosion.
Of course young-Earth creationists would dispute a timeframe of millions of years for the erosion of the islands. Fortunately, there's yet another means of dating the islands. Ancient coral reefs form terraces off the shore of many of the Hawaiian islands. Scientists can use radiometric dating (such as uranium-thorium dating) to determine the age of the coral. Of course, as noted already, young-Earth creationists reject radiometric dating. Fortunately, the coral is useful in other ways. First, the coral reefs reinforce the evidence based on the elevation and erosion of the islands. If the islands formed over millions of years, then the oldest islands should not only be more eroded, they should also have much larger and thicker coral reefs – which is the case. Second:
Both modern corals and fossil corals deposit daily and annual growth bands. By careful analysis of these bands, we can tell how many days there were in a year when the coral was growing. For modern corals, this technique yields 365 day-bands per year, more or less, just as it should. For corals that grew in formations identified as Early Devonian [around 400 million years ago], the technique shows a little over 400 day-bands per year. Astronomers can measure the rate at which Earth's rotation is slowing. Assuming the rate of slowing has remained constant, a day-count of 400 days per year indicates an age of roughly 400 million years. And when Early Devonian rocks are dated radiometrically, we get dates of roughly 400 million years.[4]
Thus the radiometric evidence and the biological and astronomical evidence provide similar dates. Of course young-Earth creationists also dispute the reliability of these types of evidence (though they appear to rely on literature from over 30 years ago to do so).[5]
The example of the Hawaiian island chain shows that young-Earth creationists have to reject an awful lot of evidence from multiple, independent sources. The problem for young-Earth creationists is that all of these lines of evidence support the same conclusion: the Hawaiian islands were formed over millions of years. Further lines of evidence (such as those from evolutionary biology and biogeography[6]) not summarised here also support this conclusion. Additionally, other island chains on the Pacific Plate thought to have been formed by hotspots have the same patterns of movement and of radiometric ages as the Hawaiian islands.[7]
The counter-argument from young-Earth creationists is that much of the explanation for the how the Hawaiian island chain was formed is hypothesis, rather than confirmed fact. For example, even the 'secular' literature disputes the precise location and form of the Hawaiian hotspot and there is evidence it has moved at certain points in the past.[8] The few young-Earth creationist articles addressing the Hawaiian island chain seize upon such examples in an attempt to discredit the millions-of-years timeframe.[9] However, these young-Earth articles fail to address the principle of converging evidence: scientists may disagree over specific aspects of how the Hawaiian island chain was formed, but all the evidence still points to the chain having been formed over millions of years. Young-Earth theories (like catastrophic plate tectonics) fail to account for all the independent lines of evidence, which conclude the Hawaiian island chain was formed over millions of years and not in a matter of days during Noah’s flood.
References:
[1] Michael Shermer and Alex Grobman, Denying History: Who Says the Holocaust Never Happened and Why Do They Say It?, Berkeley: University of California Press (2000), p 32.
[2] Keith Stanovich, How To Think Straight About Psychology, Boston: Allyn & Bacon (2004, seventh edition), p 128.
[3] In this discussion I use the term ‘island chain’ loosely – it also includes seamounts: underwater mountains that rise above the ocean floor but don’t break the surface of the water (effectively underwater islands). My description of the Hawaiian island chain draws on the following sources: Robert Tilling, Christina Heliker, and Donald Swanson, ‘Plate Tectonics and the Hawaiian Hot Spot’ (2010) http://geology.com/usgs/hawaiian-hot-spot/; Hawaiian Volcano Obervatory, 'Evolution of Hawaiian Volcanoes' (1995) http://hvo.wr.usgs.gov/volcanowatch/archive/1995/95_09_08.html; Ken Rubin, 'The Formation of the Hawaiian Islands' (2005) http://www.soest.hawaii.edu/GG/HCV/haw_formation.html; Steve Olson, Evolution in Hawaii: A Supplement to Teaching About Evolution and the Nature of Science, Washington, DC: The National Academies Press (2004), pp 5-9; Monterey Bay Aquarium Research Institute, 'Hawaiian Coral Reefs' (2012) http://www.mbari.org/volcanism/Hawaii/HR-CoralReefs.htm
[4] Jonathon Woolf, 'An Introduction to Radiometric Dating' http://www.jwoolfden.com/rad_dat.html; see also: Normal Newell, Creation and Evolution: Myth or Reality, Westport: Greenwood Press 1984, pp 119-24.
[5] See, for example: Shaun Doyle and Tas Walker, 'BioLogos and the age of the earth: Pushing an anti-biblical doctrine' (4 October 2012) http://creation.com/biologos-age-earth
[6] See, for example: C Barry Cox and Peter Moore, Biogeography: An Ecological and Evolutionary Approach, Hoboken: John Wiley & Sons (2010, eighth edition), pp 231-238; Warren Wagner and Vicki Funk (eds), Hawaiian Biogeography: Evolution on a Hot Spot Archipelago, Washington, DC: Smithsonian Institution Press (1995).
[7] Patrick Nunn, Pacific Island Landscapes, Suva: The University of the South Pacific (1998), pp 161-3; Daniele Buigues, 'Geology and Hydrogeology of Mururoa and Fangataufa, French Polynesia', in H L Vacher and T Quinn (eds), Geology and Hydrogeology of Carbonate Islands, Oxford: Elsevier Ltd (1997), pp 433-5.
[8] On location and form, see: Qin Cao, et al, ‘Seismic Imaging of Transition Zone Discontinuities Suggests Hot Mantle West of Hawaii’, Science, Vol 332, No 6033 (2011), pp 1068–1071, online: http://www.sciencemag.org/content/332/6033/1068.full; on past movement, see: Caroline Uhlik, 'The 'fixed' hotspot that formed Hawaii may not be stationary, scientists conclude', Stanford Report (8 January 2003) http://news.stanford.edu/news/2003/january8/aguhotspots-18.html
[9] Tas Walker, 'The Hawaiian hot spot and the Bible' (28 May 2011) http://creation.com/hawaii-hot-spot; Tas Walker, 'The elusive Hawaiian hot spot spoils a nice geological story' (4 June 2011) http://biblicalgeology.net/blog/elusive-hawaiian-hot-spot/
Sarfati devotes several pages (177-180) of The Greatest Hoax on Earth to the theories of catastrophic plate tectonics and runaway subduction, proposed by geophysicist John Baumgardner as a young-Earth alternative to mainstream theories of plate tectonics.
In 1983 Baumgardner developed a computer programme called TERRA, which uses supercomputers to create three-dimensional models of processes in the Earth's mantle. As Sarfati notes, at one time TERRA was one of the best programmes of its kind. Indeed, a 1997 US News and World Report feature on Baumgardner by Chandler Burr reported that "there is universal agreement that Terra...is one of the most useful and powerful geological tools in existence" and "Baumgardner is seen as one of the world leaders in numerical models of mantle convection".[footnote 1]
What Sarfati doesn't mention is that the models produced by TERRA depend entirely on the data entered into the programme. As Burr's article puts it:
Run Terra one way, and you can watch Noah's flood take place before your eyes, mathematically calculated by a supercomputer. Run Terra another way, and you get the standard geological story of 4.6 billion years. The results obtained from the code are – as Baumgardner readily points out – dependent on the numbers fed into it in the first place.
The reason geologists use TERRA is because it can produce models consistent with accepted, mainstream geological data (as opposed to Baumgardner's young-Earth data). That's why Sarfati is able to make vague statements such as "Aspects of Baumgardner's mantle modelling have been independently duplicated and thus verified by others" (page 179). Burr's article points out the reality of how geologists regard Baumgardner's young-Earth theories:
Among geologists, there is universal agreement that Baumgardner's [young-Earth] views are simply wrong. The fact that the sedimentary record contains anomalies is unremarkable, they say. There are always anomalies. The real debate is about physics and belief. Runaway subduction, these scientists add, requires the suspension of the most basic laws of physics. The theory requires a Through the Looking Glass world where nothing is as it seems and no scientific principle – from gravity and electromagnetism on down – exists as it exists today.
Baumgardner himself says, "The only way to square the radiometric data with a flood that caused all these changes is to conclude that one aspect of the catastrophe was rapid radioactive decay." But what this means is that for a few years the universe behaved completely differently, compressing processes which now take millions of years into merely days. This is not impossible. It just contradicts almost every existing piece of evidence.
Catastrophic plate tectonics is not supported by anyone outside young-Earth creationist circles. And Sarfati concedes (footnote 44 on page 177) the theory isn't even supported by all young-Earth creationists.
The following list outlines some of the key problems with the theory of catastrophic plate tectonics (see the references for further detail).
- The amount of energy released by Baumgardner's model would completely boil off the Earth's oceans.[2]
- Many aspects of the theory (such as the sudden cooling of the ocean floor, the greatly reduced viscosity of the mantle, the rapid magnetic reversals) cannot be explained by conventional physics.[3]
- The model requires both frictional heating (as the heat source to accelerate the subduction) and a reduced viscosity of the mantle. But the reduced viscosity of the mantle would likely also reduce frictional heating.[4]
- Baumgardner's own modelling shows that during the Flood, currents would be faster over continents than over ocean basins, so sediments should, overall, be removed from continents and deposited in ocean basins. Yet this is not the case (sediments on ocean basins have an average thickness of 600 metres, while those on continents have an average thickness of 2.6 kilometres).[5]
The main problem for catastrophic plate tectonics is that it is incompatible with so much geological evidence.[6] A good example is the Hawaiian island chain, which I will discuss in my next post. Multiple lines of evidence point to the conclusion that the island chain formed over millions of years. Young-Earth creationists claim such evidence "could easily be incorporated into a creationist scenario such as Catastrophic Plate Tectonics",[7] but I've yet to find any young-Earth literature actually explaining how this would work. Geologists reject catastrophic plate tectonics not because there is a conspiracy among geologists (many of whom are Christian) blinded by a 'secular world view', but because catastrophic plate tectonics fails to adequately account for the geological evidence.
References:
[1] Chandler Burr, 'The Geophysics of God: A Scientist Embraces Plate Tectonics – and Noah’s Flood', US News and World Report (8 June 1997) http://www.usnews.com/usnews/culture/articles/970616/archive_007221.htm
[2] Donald Wise, 'Creationism's Geologic Time Scale', American Scientist, Vol 86, No 2 (1998), pp 160-173
[3] Mark Isaak (ed), 'Claim CD750: Catastrophic plate tectonics' (2004) http://www.talkorigins.org/indexcc/CD/CD750.html
[4] Molleen Matsumura, 'Miracles In, Creationism Out', Reports of the National Center for Science Education, Vol 17, Issue 3 (1997) http://ncse.com/rncse/17/3/miracles-creationism-out
[5] Mark Isaak (ed), 'Claim CH430: Runaway subduction' (2003) http://www.talkorigins.org/indexcc/CH/CH430.html
[6] See, for example: William Powell, Philosophy of Scientific Creationism, New Delhi: Global Vision Publishing (2009) pp 259-60; see also: Mark Isaak (ed), 'Claim CD750: Catastrophic plate tectonics' (2004) http://www.talkorigins.org/indexcc/CD/CD750.html
[7] Tas Walker, 'The Hawaiian hot spot and the Bible' (28 May 2011) http://creation.com/hawaii-hot-spot
This post is the third in my series on biogeography from pages 173-5 of The Greatest Hoax on Earth. See here for the first, and here for the second.
Sarfati tags the following comment on to the end of his paragraph on the floras of Eastern Asia and Eastern North America, I think to make the point that all plant species around the world can only have been there for a maximum of 4,500 years (following Noah's flood):
Indeed, many of our crop plants can be traced back to the 'Fertile Crescent' – the plain of Shinar – consistent with the biblical account of human dispersion from Babel, bringing along their plants (and domestic cats). [Page 174]
Crop plant domestication is thought to have occurred independently and almost simultaneously in several places around the world.[footnote 1] A Fertile Crescent origin is true for wheat, barley, lentil, chickpea, pea, vetch and flax.[2] But many crop plants did not originate in the Fertile Crescent. Maize[3], potato[4], sweet potato[5] and cassava[6] come from Central and South America; rice[7], soy bean[8], and foxtail millet from China; pearl millet and probably sorghum from sub-Saharan Africa; and broomcorn millet from Central Asia.[9] Other crops that didn't originate in the Fertile Crescent include yam, taro, squash, plantain, quinoa, squash, and the common bean.[10] These multiple centres of crop origin don't discount the Babel story outright (whether the story should be interpreted as historical narrative is a whole other discussion), but neither do they match a strict young-Earth timeframe.
Sarfati wraps up his discussion on biogeographical anomalies with some sweeping statements that aren't supported by the references he cites. He starts off reasonably well, pointing out that explanations for the disjunct species shared by Africa and South America tend to invoke either a crossing of the Atlantic Ocean or a long migration via joined-up land to the north. His reference here is a 2002 paper by Charles Davis, et al, that argues the Malpighiaceae family of plants (found in Africa and South America) migrated from northern South America to North America and Europe (which were joined), and then on to Africa. This "Laurasian migration route" occurred "during episodes starting in the Eocene [56 to 34 million years ago], when climates supported tropical forests".[11] So far, so good. But then Sarfati says:
Indeed, to 'explain' whether faunas are shared or not between Africa and South America, evolutionists resort to ad hoc openings and closings of the Laurasian route, which show how plastic evolutionary theory can be.[Page 174]
Sarfati again references Davis' 2002 paper – this time a specific citation in Davis' paper of a 2001 paper by S Renner, G Clausing and K Meyer. The 2001 paper is about the distribution of the Melastomataceae family of plants.[12] Davis cites this paper as an example of other plants appearing to have spread from South America to Africa through the Laurasian route during the Eocene.
Neither the Davis nor the Renner paper makes any reference to faunas. Perhaps Sarfati simply made a mistake and he meant to say 'floras', not 'faunas'. But I also can't see anything in either paper to support his claim they rely on "ad hoc" openings and closings of the Laurasian route. Both papers refer to specific instances when the Laurasian route would have supported the migration of floras (such as the "Eocene climate optimum", when the warmer climate meant tropical forests were present in higher latitudes and land bridges joined the northern land masses). These are not ad hoc claims – they are supported by genetic analysis of plants, and studies of the fossil record, geology and the ancient climate. Naturally young-Earth creationists reject this kind of evidence when it doesn't suit their arguments. Indeed, looking at some of the young-Earth creationist literature on migration routes and land bridges, you could make a case that young-Earth creationists are the ones resorting to "ad hoc" claims to fit their "plastic" theories.[13]
The fossil record also presents problems for evolutionary explanations of biogeography. For example, there are many similar plant fossils in western North America and eastern Asia, yet the evolutionary timescale 'dates' them to a time when Alaska and Russia still had thousands of miles of ocean between them. [Page 175]
Here Sarfati gives a reference to a paper by geologist Charles Smiley from a book published in 1976.[14] Smiley's paper documented distribution patterns of plant fossils in the Beringian region (areas of modern-day Alaska and eastern Siberia around the Bering Strait) from the later Paleozoic (around 350-250 million years ago) and Mesozoic (around 250-66 million years ago) and showed they did not match the latest models for continental drift, which drew on the new theory of plate tectonics. He concluded:
The geometry of recognized floral provinces does not always coincide with the global geometry that is postulated in current models of continental drift...The evidence of floral interchange between Eurasia and western North America implies the presence of a land dispersal route across the Beringian region at least from later Paleozoic time. But plate tectonics theory requires an oceanic separation perhaps thousands of kilometers wide through this region prior to the Cenozoic [66 million years ago].
So Smiley believed the fossil record suggested there was a land bridge between Alaska and Siberia that existed as far back as the later Paleozoic, but some models of plate tectonics said these regions were separated by an ocean at that time. It's important to remember the theory of plate tectonics was still in its infant stage in the early 1970s (it had only emerged as a unified theory in the late 1960s) and there wasn't yet agreement on all aspects of the models criticised by Smiley. For instance, a 1975 paper by zoologist David Gaskin saw things quite differently, noting "There is good geological evidence [the] Bering Strait closed periodically during the Cretaceous [145-66 million years ago] and Tertiary [65-2.6 million years ago]".[15]
More recent papers suggest there is now greater agreement that Beringian land bridges existed much further in the past (perhaps that's why Sarfati is referencing such an old paper, rather than anything published in the last 35 years). For example, a 2012 paper focusing on the Eocene notes the Beringian land bridge was already in place at the beginning of this period.[16] And a 2011 paper describes how the dinosaur fossil record in Asia and western North America supports the mounting evidence that a Beringian land bridge existed at least 108 million years ago, to the Early Cretaceous.[17] This is still not as far as Smiley would have liked. There may well be other papers demonstrating land bridges at even earlier periods, but I haven’t been able to find them.
References:
[1] I Usha Rao and B K Pandey, 'Origin and Introduction of Crop Plants, Cereals, and Pulses' (2007) http://nsdl.niscair.res.in/bitstream/123456789/125/1/corrected+Origin_of_crop_plants_cereals_and_pulses.pdf
[2] Daniel Zohary, Maria Hopf and Ehud Weiss, Domestication of Plants in the Old World: The Origin and Spread of Domesticated Plants in Southwest Asia, Europe, and the Mediterranean Basin, Oxford University Press (2012: fourth edition).
[3] Dolores Piperno, et al, 'Starch grain and phytolith evidence for early ninth millennium B.P. maize from the Central Balsas River Valley, Mexico', Proceedings of the National Academy of Sciences, Vol 106, No 13 (2009), pp 5019-24; online at: http://www.pnas.org/content/106/13/5019.full.pdf
[4] D Spooner, et al, 'A single domestication for potato based on multilocus amplified fragment length polymorphism genotyping', Proceedings of the National Academy of Sciences, Vol 102, No 41 (2005), pp 14694-9; online at: http://www.pnas.org/content/102/41/14694.full
[5] 'Sweet Potato (Ipomoea batatas)' (2012) http://libweb.hawaii.edu/libdept/scitech/agnic/sweetpotato.html
[6] K Olsen and B Schaal, 'Evidence on the origin of cassava: phylogeography of Manihot esculenta', Proceedings of the National Academy of Sciences, Vol 96, No 10 (1999), pp 5586-91; online at: http://www.pnas.org/content/96/10/5586.full
[7] Jeanmaire Molinaa, et al, 'Molecular evidence for a single evolutionary origin of domesticated rice', Proceedings of the National Academy of Sciences, Vol 108, No 20 (2011), p 8351; online at: http://www.pnas.org/content/early/2011/04/27/1104686108.full.pdf+html
[8] Li-Juan Qiu and Ru-Zhen Chang, 'The Origin and History of Soybean', Guriqbal Singh (ed), The Soybean: Botany, Production and Uses, Wallingford: CAB International (2010), pp 1-23.
[9] Zohary, Hopf and Weiss, pp 8, 20, 69, 71, 72-3.
[10] Rao and Pandey.
[11] Charles Davis, et al, 'Laurasian migration explains Gondwanan disjunctions: evidence from Malpighiaceae', Proceedings of the National Academy of Sciences, Vol 99, No 10 (2002), pp 6833-7; online at: http://www.pnas.org/content/99/10/6833.full.pdf
[12] S Renner, G Clausing and K Meyer, 'Historical biogeography of Melastomataceae: the roles of Tertiary migration and long-distance dispersal', American Journal of Botany, Vol 88, No 7 (2001), pp 1290-1300; online at: http://www.amjbot.org/content/88/7/1290.full
[13] See, for example: Dominic Statham, 'Migration after the Flood' (12 March 2013) http://creation.com/Flood-biogeography; Ken Ham, Jonathan Sarfati and Carl Wieland, 'How did animals get from the Ark to isolated places, such as Australia?' (2000) http://www.christiananswers.net/q-aig/aig-c006.html; and Michael Oard, Frozen in Time: The Woolly Mammoth, the Ice Age, and the Bible, Green Forest: Master Books (2004) pp 18, 145.
[14] Charles Smiley, 'Pre-Tertiary Phytogeography and Continental Drift – Some Apparent Discrepancies', in J Gray and A J Boucot (eds), Historical Biogeography, Plate Tectonics and the Changing Environment, Corvallis: Oregon State University Press, pp 311-319.
[15] David E Gaskin, 'Revision of New Zealand Crambini (Lepidoptera: Pyralidae: Crambinae)', New Zealand Journal of Zoology, Vol 2, No 3 (1975), p 273.
[16] Jaelyn Eberle and David Greenwood, 'Life at the top of the greenhouse Eocene world - A review of the Eocene flora and vertebrate fauna from Canada's High Arctic', GSA Bulletin, Vol 124, No 1/2 (2012), p 7; online at: http://geode.colorado.edu/~eberlej/Eberle%20and%20Greenwood%20Arctic%20Eocene.pdf
[17] Lindsay Zanno and Peter Makovicky, 'On the earliest record of Cretaceous tyrannosauroids in western North America: implications for an Early Cretaceous Laurasian interchange event', Historical Biology, (24 February 2011), p 1-9
This post is a continuation of my last one, looking at pages 173-175 of The Greatest Hoax on Earth.
Crowberries (Empetrum) are found only in the northern latitudes of the northern hemisphere and in the very southern regions of the southern hemisphere (page 174).
The crowberry is another fascinating case. As Sarfati states, the crowberry is found only across the north of the northern hemisphere and in southern South America (and some offshore islands). Sarfati (and Statham, whom Sarfati is summarising) provides no references on crowberries.
I could only find one paper examining the crowberry's distribution, published in the Proceedings of the National Academy of Sciences in 2011 (The Greatest Hoax on Earth was published in 2010).[footnote 1] The paper finds the evidence (molecular analysis and pollen records) doesn't support a gradual migration explanation for the crowberry's presence in South America, and concludes instead "a single dispersal by a bird from northwestern North America to southernmost South America, taking place in the Mid-Pleistocene, is sufficient to explain the disjunction in crowberries." While that explanation has an aspect of deus ex machina to it, the paper points out modern-day arctic birds are known to feed on crowberries before migrating to breeding grounds in South America.
At this point it's worth commenting on Sarfati's use of evidence. Sarfati is focusing on the few exceptions (some of which can be easily explained anyway) to generally cohesive explanations of biogeography. There are plant species, such as the crowberry, that have a puzzling geographical distribution; there are also hundreds of thousands of other plant species that don't present such a puzzle. Likewise, Sarfati mentions Rhipsalis baccifera but not the 1,500 other cactus species that don't have an anomalous distribution. On to Sarfati's next example:
About 150 seed plant genera are common to eastern Asia and eastern North America but are not found in the intervening western North America. Many of these are even of the same species, showing they must have diverged recently, not millions of years ago. Significantly, some of the plants (and animals) found in eastern Asia and eastern North America are identical at the species level, indicating that the disjunctions occurred very recently (that is, within the last few thousand years).
This is a rather selective and misleading presentation of evidence. Sarfati supports his statements with a reference to a paper by botanist Hong Qian.[2] Sarfati is correct in his comment that about 150 seed plant genera are common to Eastern Asia and Eastern North America but are not found in Western North America. However, some context (so often missing from Sarfati's summaries) is useful.
First, Qian found:
- Eastern Asia shares 627 genera with Eastern North America (151 of which aren't found in Western North America)
- Eastern Asia shares 520 genera with Western North America (44 of which aren't found in Eastern North America)
- Eastern North America shares 765 genera with Western North America (289 of which aren't found in East Asia)
So yes, at the genus level (the level above species) Eastern Asia's flora has significantly more in common with the flora of Eastern North America than it does with the flora of Western North America. On the face of it that is remarkable. But we should also note that Eastern North America shares far more genera with Western North America than it does with Eastern Asia, and Eastern Asia also shares some genera with Western North America that aren't found in Eastern North America.
Second, Sarfati gives no reference to back up his claims about similarities at the species level: that some of the plants from Qian's study "are even of the same species" and therefore "must have diverged recently, not millions of years ago"; and, in the next sentence, that "some of the plants (and animals) found in eastern Asia and eastern North America are identical at the species level" so the disjunctions must have occurred "within the last few thousand years". There is no support for these assertions in Qian's paper. Qian compared the relationships between the floras of Eastern Asia, Eastern North America and Western North America at the genus level. He was comparing genera, not species. This is stated clearly in the abstract ("floristic relationships based on genera shared among EAS, ENA, and WNA were examined") and the body ("this study focuses on the genus level") of his paper.
The wider literature further undermines Sarfati's statements. A 1999 paper by botanist Jun Wen also examined the similarities between the floras of Eastern Asia and Eastern North America.[3] Wen notes that botanists originally thought East Asia and Eastern North America shared many identical species of plant. For example, in the mid-1800s botanist Asa Gray listed 134 identical species. (It may be from such early work that Sarfati got his mistaken idea that many of the disjunct flora of Eastern Asia and Eastern North America are of the same species.) But now they are understood to be largely congeneric (belonging to the same genus) and not conspecific (belonging to the same species). Botanists had narrowed the conspecific list to eight examples by 1992, and to only one example by 1999.
Third, Qian found the similarities between Eastern Asia's and Eastern North America's genera are greater among basal (earlier or more 'primitive') lineages and they decrease among more modern lineages. This isn't the case for the similarities between Eastern North America and Western North America – the similarities between these two tend to increase as you get more modern. This suggests the connection between Eastern Asia and Eastern North America that resulted in their similar floras occurred some time ago (that is, at least several million years ago).
Fourth, Qian describes how Eastern Asia and Eastern North America were connected some time ago, which (partly) explains the similarities in their disjunct floras:
The observed similarities between the floras of EAS, ENA, and WNA resulted, to a large extent, from largescale historical processes such as species movements in the geological past when Eurasia and North America were geographically connected to each other. According to geological and paleobotanical evidence, two major land bridges have connected Eurasia and North America: the Bering land bridge across the north end of the Pacific Ocean connected Siberia and Alaska throughout most of the Tertiary, and the North Atlantic land bridge across the north end of the Atlantic Ocean linked northern Canada to Europe via Greenland in the early Tertiary. It is widely accepted that the intercontinental connections via these two land bridges significantly contributed to the floristic similarities between EAS and North America....
During the Eocene, climates were warm enough to support tropical vegetation at high latitudes in the Northern Hemisphere from which many fossils of tropical taxa have been recovered. The existence of the Bering and North Atlantic land bridges and warm climates at high latitudes during the early Tertiary facilitated the interchange of both temperate and tropical floristic elements between Eurasia and North America.
Wen's paper reaches a similar conclusion:
Phylogenetic, molecular, geologic, and fossil data all support the hypothesis that the eastern Asian and eastern North American disjunct distributions are relicts of the maximum development of temperate forests in the northern hemisphere during the Tertiary. Fossil and geologic evidence supports multiple origins of this pattern in the Tertiary, with both the North Atlantic and the Bering land bridges involved.
The prevailing explanation for the similar floras of Eastern Asia and Eastern North America is that they are remnants of genera once widely distributed across a temperate zone in the northern hemisphere during the Tertiary Period (which began around 65 million years ago). A wide distribution (including Asia and North America) was possible because of land bridges: at certain times the Bering land bridge connected Asia to North America and the North Atlantic land bridge connected North America to Europe via Greenland. After the establishment of a flora across the northern temperate zone, the continued formation of the Rocky Mountains changed the climate and rainfall patterns, causing the genera to disappear from Western North America. And changes in the last two million years also caused the genera to disappear from Western Europe.[4]
[Discussion on biogeography will continue in the next post]
References:
[1] Magnus Popp, Virginia Mirré, and Christian Brochmann, 'A single Mid-Pleistocene long-distance dispersal by a bird can explain the extreme bipolar disjunction in crowberries (Empetrum)', Proceedings of the National Academy of Sciences, Vol 108, No 16 (2011), pp 6520-6525; available online at: http://www.pnas.org/content/108/16/6520.full
[2] Hong Qian, 'Floristic relationships between eastern Asia and North America: test of Gray's hypothesis', The American Naturalist, Vol 160, No 3 (2002), pp 317-332; available in part online at: http://business.highbeam.com/437070/article-1G1-91659969/floristic-relationships-between-eastern-asia-and-north
[3] Jun Wen, 'Evolution of Eastern Asian and Eastern North American Disjunct Distributions in Flowering Plants', Annual Review of Ecology and Systematics, Vol 30 (1999), p 421-55.
[4] David Yih, 'Land Bridge Travelers of the Tertiary: The Eastern Asian-Eastern North American Floristic Disjunction', Arnoldia, Vol 69, No 3 (2012), pp 14-23; available online at: http://arnoldia.arboretum.harvard.edu/pdf/issues/2012-69-3-Arnoldia.pdf
On pages 173-175 of The Greatest Hoax on Earth, Sarfati focuses on apparent anomalies in the biogeographical evidence for evolution. Apart from references 31, 32, 33, 34 and 35 (on page 174), all of Sarfati's examples are borrowed from a chapter on biogeography in a young-Earth creationist book written by Dominic Statham.[footnote 1] Statham is an engineer. At first glance Sarfati's examples appear to weaken the evolutionary explanations of biogeography. However, such an impression quickly vanishes if the reader checks the references for Sarfati's examples (where they can be checked) and reads the literature around the arguments he raises.
In several instances, Sarfati's use of references is difficult to check for accuracy. He cites a reference that no longer exists (reference 27 gives an undated webpage that is no longer available). And he cites references to out-of-print texts not readily available online or in public libraries. Because biogeography is a rapidly changing and growing field, such references are likely to be based on out-of-date information (for example, he cites a paper from 1972 and books from 1976, 1991 and 1993).
What follows (in this blog post and a couple more) is an examination of Sarfati's arguments and references where they can be easily checked.
For example, species of cactus, which supposedly evolved in South America 30 million years ago, are also found in Africa, yet these continents are said to have separated 70 million years before. [Page 173]
Another example is the cactus, a specialized desert-adapted plant. One genus, Rhipsalis, is native to Africa, Madagascar and Sri Lanka. So did they predate the breakup of the southern supercontinent Gondwana, or were its seeds secondarily introduced by ocean-crossing birds? [Page 174]
Firstly, apart from one species, all cacti are native exclusively to the Americas. The one exception is Rhipsalis baccifera, which originates in the Americas but also has a distinct subspecies found in Africa and Sri Lanka. Any species other than Rhipsalis baccifera (including other species of the genus Rhipsalis) found in Africa or Asia have been introduced there by humans. Thus, both of Sarfati's statements are misleading.
There are several theories for how Rhipsalis baccifera found its way to Africa and Sri Lanka. The leading theory seems to be distribution by migratory birds.[2] Another theory is that the seeds floated across the Atlantic.[3] And a more recent theory questions Rhipsalis baccifera’s 'native' status in Africa, arguing the plant was first carried between continents by people and then spread widely by birds.[4]
The same applies to rodents and a number of other creatures, also found on both continents [South America and Africa], yet are meant to have emerged long after the separation. [Page 173]
Sarfati's reference for this statement is to a book chapter by zoologist Wilma George titled 'The strange rodents of Africa and South America', from George and René Lavocat's 1993 book The Africa-South America Connection. While I couldn’t find a copy of the book, I found another far more recent book chapter on the same topic by de Oliveira, E Molina and G Marroig.[5] The chapter references George and Lavocat's work and seeks to answer the question: "how did monkeys and rodents manage to travel across the Atlantic Ocean?"
Primates and rodents are thought to have arrived in South America between 50-20 million years ago (though young-Earth creationist don't accept this timeframe). De Oliveira, Molina and Marroig note at this time Africa and South America were not linked by land bridges, but were closer together than they are now (around 1,000 kilometres apart 50 million years ago). The authors provide evidence of islands along latitude 20◦S, which, 50 million years ago, could have stretched at least 500 kilometres into the Atlantic from the South American coast. They also note the absence of mammals from South America in the African fossil record – suggesting a one-way migration from Africa to South America. And studies of ancient ocean currents and winds suggest they strongly favoured a westward crossing of the Atlantic. This leads the authors to argue that "small or medium-sized mammals" could plausibly have traveled from Africa to South America by floating on islands of vegetation (a theory discussed by Sarfati on pages 169 and 171 of The Greatest Hoax on Earth) and then island-hopping.
Furthermore, continental drift doesn't explain disjunct species that are often found on continents that never bordered one another. For example, many plants and insects display range fragmentation across the Pacific Ocean. [Page 173]
Sarfati doesn't elaborate on what the "many plants and insects" are. His references here are the defunct webpage mentioned earlier and a 1972 paper on seed plants by Robert Thorne (which I haven't been able to access). Statham's chapter gives one example from Thorne's paper – it reproduces a diagram showing the distribution of the plant genus Clethra. However, Statham provides no analysis beyond the comment: "The distribution of the plant genus Clethra, for example, is shown in figure 2." Nevertheless, further on in his chapter, Statham goes some way to answering his own (and Sarfati's) anomaly of species' fragmented distribution around the Pacific Ocean:
The potential for dispersal of plants and animals across large stretches of water by natural rafts has been accepted by evolutionists and creationists for many years....Significantly, biogeographers sometimes refer to oceans rather than continents as the main biogeographic regions. This is because, very often, patterns of disjunction are seen where many terrestrial organisms are distributed around the land bordering an ocean. So clear was this to the twentieth-century biogeographer Léon Croizat that he spent much time drawing "tracks" to chart repetitious occurrences of these patterns....From these generalized tracks, Croizat identified five biogeographic "nodes" or "gates" of plant and animal dispersal across the world.[6]
Back to Sarfati:
There are many other examples where the similarities of disjunct species don't match the pattern expected by evolution and slow continental drift. For example, animals in central and southern Africa are closer to those of southern Asia than those of northern Africa. [Page 174]
Actually this example matches the pattern expected by evolution and slow continental drift. Around 125 million years ago, India broke off from what is now southeast Africa and drifted north for around 75 million years until it collided with what is now Asia (creating the Himalayas). Thus at one point India and southern Africa shared the same species, which then evolved separately after the continents separated. Climatic changes 20 million years ago caused the extinction of many of the species in India. And after that mammals entered India from the rest of Asia, through passes on either side of the emerging Himalayas. However, the remnants of species of African descent were still there and the similarities between African and Indian wildlife have remained until today.[7]
Plants in Madagascar are remarkably similar to the flora of Indonesia rather than mainland Africa. [Page 174]
Here Sarfati cites a paper by George Schatz.[8] The paper provides explanations, within an evolutionary framework (stretching back 120 million years), for the similarities between the flora of Madagascar and the Malay Archipelago (modern-day Indonesia). The easiest explanation to grasp is that is that there has been continuous long-distance dispersal of plants across the Indian Ocean from Indonesia to Madagascar. This is greatly assisted by prevailing winds and the Indian Ocean currents. Hence it is the flora on the east coast of Madagascar that is most similar to Indonesia's flora. The currents and winds also help to explain the interesting fact that Madagascar's first settlers came not from the African mainland, but from Indonesia.[9]
[Discussion on biogeography continued in the next post]
References:
[1] Sarfati references Statham's chapter in footnote 22 on page 173. The chapter is also reproduced in full on the Creation Ministries International website: Dominic Statham, 'Biogeography' (2010) http://creation.com/biogeography
[2] Outlined, with references to the wider literature, by Charles Davis, et al, 'High-latitude tertiary migrations of an exclusively tropical clade: Evidence from Malpighiaceae', International Journal of Plant Sciences, Vol 165, No 4 (2004), p 107; available online at: http://dash.harvard.edu/bitstream/handle/1/2710470/Davis_High-LatitudeTertiaryMigrations.pdf?sequence=2
[3] Susanne Renner, 'Plant dispersal across the tropical Atlantic by wind and sea currents', International Jounral of Plant Science, Vol 165, Supp 4 (2004), pp 23-22; available online at: http://www.umsl.edu/~renners/Renner.Dispersal.IJPS2004.pdf
[4] J Cota-Sánchez and M Bomfim-Patrício, 'Seed morphology, polyploidy and the evolutionary history of R. baccifera', Polibotánica, Vol 29 (2010), pp 107-129; available online at: http://www.herbarium.usask.ca/research/articles/Cota-Sanchez_Bomfim-Patricio_Polibotanica_2010.pdf
[5] F de Oliveira, E Molina and G Marroig, 'Paleogeography of the South Atlantic: a Route for Primates and Rodents into the New World?', in Paul Garber, et al (eds), South American Primates: Comparative Perspectives in the Study of Behavior, Ecology, and Conservation, New York: Springer (2009), pp 55-68; available online at: http://www.academia.edu/182638/Paleogeography_of_the_South_Atlantic_a_route_for_primates_and_rodents_into_the_New_World
[6] Dominic Statham, 'Biogeography' (2010) http://creation.com/biogeography
[7] 'India, the Other Africa' (13 October 2011) http://www.krugerpark.com/blog/index.php/india-the-other-africa/; see also: 'South Asia: Physical Geography' http://www.harpercollege.edu/mhealy/g101ilec/sasia/ssd/ssphys/ssphysfr.htm
[8] George Schatz, 'Malagasy/Indo-Australo-Malesian Phytogeographic Connections' (1996) http://www.mobot.org/MOBOT/research/phytogeographic/welcome.shtml
[9] 'Thirty lost souls: How Africa's largest island was colonised by Asians', The Economist, (24 March 2012) http://www.economist.com/node/21550759
