Sunday, 12 July 2015

Creationism - Ignoring the Elephant

First comprehensive analysis of the woolly mammoth genome completed -- ScienceDaily

Creationism is largely about ignoring evidence. In fact, it depends almost entirely on pretending the evidence either isn't there or means something else, whilst simultaneously pretending there is a lot of evidence supporting creationism - if only it could be found and didn't need to be misrepresented.

Take, for example the known evolution of the elephant family, including the geologically very recently extinct mammoths of Euro-Asia and North America, the two species of African elephant and the Asian or Indian elephant. We know from genetic analysis how they are related and how the woolly mammoth adapted to the cold Ice-Age environment of Asia and Europe. We know too from recent studies that the two distinct North American species actually interbred on occasion, just as the two African species do when their ranges overlap.

Schematic representation of elephantid mtDNA phylogenies under introgression scenarios. (a,b) Hypothetical mammoth (b) (this study) and observed African elephant (a) cladograms, with male body size comparisons and predominant geographic ranges of the species indicated. Solid lines represent observed data; dashed lines represent predicted but presently unobserved lineages under an M. primigenius-M. columbi introgression hypothesis.*

Late Pleistocene North America hosted at least two divergent and ecologically distinct species of mammoth: the periglacial woolly mammoth (Mammuthus primigenius) and the subglacial Columbian mammoth (Mammuthus columbi). To date, mammoth genetic research has been entirely restricted to woolly mammoths, rendering their genetic evolution difficult to contextualize within broader Pleistocene paleoecology and biogeography. Here, we take an interspecific approach to clarifying mammoth phylogeny by targeting Columbian mammoth remains for mitogenomic sequencing.

We sequenced the first complete mitochondrial genome of a classic Columbian mammoth, as well as the first complete mitochondrial genome of a North American woolly mammoth. Somewhat contrary to conventional paleontological models, which posit that the two species were highly divergent, the M. columbi mitogenome we obtained falls securely within a subclade of endemic North American M. primigenius.

Though limited, our data suggest that the two species interbred at some point in their evolutionary histories. One potential explanation is that woolly mammoth haplotypes entered Columbian mammoth populations via introgression at subglacial ecotones, a scenario with compelling parallels in extant elephants and consistent with certain regional paleontological observations. This highlights the need for multi-genomic data to sufficiently characterize mammoth evolutionary history. Our results demonstrate that the use of next-generation sequencing technologies holds promise in obtaining such data, even from non-cave, non-permafrost Pleistocene depositional contexts.*

*© 2011 Enk et al.; licensee BioMed Central Ltd. Published under the terms of Creative Commons Attribution License CC BY 2.0

So, putting these together we can show clear evolutionary relationships between the Euro-Asian and North American elephants, including the Indian elephant as derived from a common ancestor after it diverged from the common ancestor of the African species.

We know that the African species diverged between 2.6 and 5.6 million years ago into forest and savanna species. Incidentally, this was about the same time that the common ancestor of humans and the other African aped diverged into the forest-dwelling ancestor of the gorilla and chimpanzees and the savanna-dwelling proto-hominids, the Australopithecines, suggesting there was a climate change and change in distribution of forests and savanna in Africa, leaving several forest species with no forest.

We also know from their mitogenomes that these two African species interbreed occasionally, showing only partial evolution, or evolution in progress with limited gene flow between the still diverging species.

We know that before that divergence, the common ancestor to the Euro-Asian and North American elephants had split off from the African elephants. We also know that the southern North American species (M. columbi or Columban elephant) evolved from an early migration of Asian elephants from Siberia into Alaska about 1.5 million years ago, before the woolly mammoth evolved as a Ice-Age adaptation. We know also that woolly mammoths (M. primigenius) migrated into North America about 1 million years later and were very probably pushed further south as the Ice-Age ice-sheets advanced, so their range came to overlap that of M. columbi.

We also know that, despite 1 million years of evolutionary separation, and considerable morphological divergence, even this divergence wasn't complete and, as their mitogenomes also show, just as with the African species, these different North American species could still interbreed and did so on occasion, demonstrating evolution in progress.

Meanwhile, the southern Asian elephants were evolving into the Indian elephant we see today.

In fact, what we seem to have, spread over a vast range, is something resembling an elephant ring species. Ring species, to the constant annoyance of creationists, are examples of evolution in progress, proceeding at different rates in different parts of the range, according to local environmental selection pressures, just as the Theory of Evolution by Natural Selection predicts.

The problems here for creationists are of course multiple and insurmountable unless they abandon most of their cherished dogmas - which is impossible if one wishes to remain a creationist, of course:
  1. Time. This genetic diversity takes time, as, for example, with the time needed for two distinct species to diverge then meet up again in North America where they could interbreed. Without the evidence of considerable divergence there would be no evidence of interbreeding and without evolution acting over this long period there would be no divergence. How does this fit with a narrative which requires belief that Earth is just a few thousand years old?
  2. Species. There is no doubt that these populations were distinct species in all scientific definitions of that term. This means, for those creationists childish enough to also believe the Noah's Ark fairy tale, they either have to explain how all these different species of elephant came together in the Middle East to board this boat and then dispersed again leaving no descendants in the 'wrong' place, or they have to explain how all these distinct species evolved in just a few thousand years from a single elephant 'kind', especially when they claim 'macroevolution', i.e. the evolution of new species, is impossible.
  3. Distribution. How did the different elephants come to be distributed on two different continents with no connecting land bridge (if the Earth was created as we see it today with no plate tectonics and no time for land-bridges for form and disappear) and no record of them having done so in recorded human history and no record of people seeing these new elephant species diverge and evolve?
  4. Faked Evidence? If the different elephant species were created all at the same time, and just a few thousand years ago, why did creationism's creator god rig the genetic and geological evidence to make it look like they had evolved slowly over time from a common ancestor by an evolutionary process, then placed them geographically so it just looked like they had dispersed at a time when other geological evidence suggests there were connections between Asia and North America. Why did creationism's god, as with all the other similar evidence for evolution, rig it so that it just looked like all these different strands of science supported one another and made it look like species evolve slowly over a long time, that Earth is very old and that the account of creation given in the Bible is a primitive creation myth bearing no resemblance to reality?

And yet again we see that the observable evidence fits entirely within the scientific understanding of evolution, how it happens and what causes it, and that it meshes neatly with other strands of science such as geology, chemistry and physics. As always, the observable evidence simply fails to support any of the current notions of creationism no matter how flexible the pseudo-science creationist frauds have to make them, and nowhere does any of it require magic.

This is, of course, how we know that creationism is wrong and that science is right.

'via Blog this'

submit to reddit
Income from ads will be donated to charities such as moderate centre-left groups, humanist, humanitarian and wildlife protection and welfare organisations.

No comments :

Post a Comment

Obscene, threatening or obnoxious messages, preaching, abuse and spam will be removed, as will anything by known Internet trolls and stalkers or by known sock-puppet accounts.

A claim made without evidence can be dismissed without evidence. Remember: your opinion is not an established fact unless corroborated.


Related Posts Plugin for WordPress, Blogger...
Web Analytics