DNA Study Offers New Take on Marsupial Migrations | The Institute for Creation Research
DNA Study Offers New Take on Marsupial Migrations

Marsupials are mammals that nurture their young in a special pouch. Their fossils are rare. Few have been discovered in Australia, for example, which is home to several unique marsupials, including kangaroos. So, determining their origins has been a longstanding challenge for evolutionists.

In trying to trace animal origins, evolutionary researchers have compared various traits or features (morphological data) from among different animals to try and fit them into an evolutionary "tree" showing roughly when one form evolved into another. But this data is subjective and constantly being reinterpreted.

M. J. Phillips and D. Penny wrote in 2003, "Morphological and molecular data are currently contradictory over the position of monotremes with respect to marsupial and placental mammals,"1 a statement that shows the confusion that characterizes origins studies of marsupials and other mammals.

Neither fossils nor morphological or certain DNA comparisons have provided enough data to answer the big questions of marsupial origins. Now, researchers claim to have followed a different set of genetic clues found in the DNA of modern marsupials, finally "solving" the riddle of the differences between marsupials found in Australia and those in South America.

Publishing in PLoS Biology, Maria Nilsson and her colleagues analyzed the distribution patterns of unique DNA sequences called retroposons.2 For their analysis, they had to rely on certain starting assumptions. A key premise was that some ancestral marsupial evolved from non-marsupials, and that this ancestor later "gave rise" to all other marsupials. Also, they assumed that comparable retroposons were caused by an ancient viral infection that left its DNA inside a marsupial. Similar-looking sequences among its supposed descendants are now interpreted as marks of that ancient infection.

But if the retroposons are useless viral leftovers, then why, after all the millions of supposed years since, have they not become riddled with mutations to the point that they are no longer recognizable?

Also, some retroposons and similar repetitive DNA sequences are known to have key functions in cells,3 and new functions are continually being discovered.4 Since this is the case, it stands to reason that retroposons, although they are passed down from one generation to the next, were originally put in place by the animal's own well-designed cellular mechanisms or possibly by the Designer Himself, but not by a virus. And since the retroposons are still "clean" enough to read clearly and compare to one another, they look very young.

The researchers in the PLoS study concluded that some marsupials from South America migrated to Australia across Antarctica during the time when those continents were connected. But given the poor track record of marsupial and so many other evolutionary origins models, it would be a safe bet that a different evolutionary story will be derived from a different data set sooner or later.

Is there any source of information that can provide enough quality data to definitively answer questions of marsupial origins? Evolutionary conjectures ignore the highest quality evidence: In forensic analyses, eyewitness testimony is the best, and such testimony is found in the Bible.

According to the Genesis account, a barge carrying the only living representatives of all land-dwelling, air-breathing creatures landed on the mountains of Ararat. Thus, Australian marsupials like the kangaroo began their post-Flood journey toward Australia from the Middle East. South American marsupials did likewise, such as the unique nocturnal Monito del Monte.

Also according to Genesis, there was a tremendous upheaval and restructuring of the earth during and immediately following the Flood. The aftermath of this cataclysmic event is the most fitting explanation for oceans that were hot enough to generate the precipitation required for an Ice Age.5

By following these scriptural clues, one can reconstruct the past with more reliability than what can be gleaned from scant and subjectively understood fossils or gene sequences. Each marsupial kind travelled from Ararat, perhaps on land bridges that existed during the post-Flood Ice Age when ocean levels were much lower. When the ice melted, sea levels rose and isolated some formerly connected land masses. This could have stranded certain marsupials on Australia and different ones on South America.

Origins stories cobbled from DNA or fossil fragments--and mixed with plenty of imagination--will always fall short of the very best evidence about earth's most distant past…the written record of the Bible.

References

  1. Phillips, M. J and D. Penny. 2003. The root of the mammalian tree inferred from whole mitochondrial genomes. Molecular Phylogenetics and Evolution. 28 (2): 171-185. Quoted in Morris, J. and F. Sherwin. 2010. The Fossil Record. Dallas, TX: Institute for Creation Research, 158.
  2. Nilsson, M. A. 2010. Tracking Marsupial Evolution Using Archaiec Genomic Retroposon Insertions. PLoS Biology. 8 (7): e1000436.
  3. Thomas, B. 2010. Evolution's Best Argument Has Become Its Worst Nightmare. Acts & Facts. 39(3): 16-17.
  4. Thomas, B. Gene 'Jumps' Serve a Purpose, Study Shows. ICR News. Posted on icr.org July 26, 2010, accessed August 10, 2010.
  5. See, for example, Vardiman, L. 2010. An Ice Age in Yosemite National Park. Acts & Facts. 39 (3): 12-13. 

* Mr. Thomas is Science Writer at the Institute for Creation Research.

Article posted on August 12, 2010.

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