Tuesday, 12 May 2015

Another Of Those 'Non-Existent' Missing Links Found


Hydrothermal vent field along the Arctic Mid-Ocean Ridge
Credit: Centre for Geobiology (University of Bergen, Norway) by R.B. Pedersen.
Missing link in the evolution of complex cells discovered

It must be puzzling and disconcerting for creationists the way a new scientific discovery never seems to support creationism and always seems to support science. Not that this will affect creationist superstition, of course, but there is a very simple explanation for this: science is based on evidence and so is demonstrably true; creationism is a superstition with no supporting evidence and so is not demonstrably true.

It's entirely predictable therefore that evidence will always support science and never supports creationism. In fact, this is how we know that creationism is false and why creationists need to ignore evidence and try to discredit science.

Take for instance this latest discovery of yet another of those missing links that creationists insist aren't there. This one fills a gap between the simple, prokaryote cells and the more complex eukaryote cells. It was found in Arctic Ocean sediment around a hydrothermal vent by a team from Uppsala University, Sweden.

It has long been recognised that eukaryote cells evolved from prokaryote cells, at least partially by inclusion of other prokaryote cells such as those that became mitochondria (which still retain some of their own DNA) but until now there were no known intermediates between one or other of the two groups of prokaryotes, bacteria and archaea, so no clear indication of which gave rise to the eukaryotes and so ultimately to all the multicellular organisms.

As explained in this paper published a few days ago in Nature, DNA from this archaea, dubbed 'Lokiarchaeota', contains about 100 genes normally associated with complex cells, coding for such things as membrane folding, so it seems very likely that our prokaryote ancestors had already evolved some complexity before eukaryotes proper split from them. It also shows that the ancestors of eukaryotes were archaea rather than bacteria, although this becomes mere semantics when true eukaryotes contain bacterial DNA in the form of mitochondrial DNA.

Abstract

The origin of the eukaryotic cell remains one of the most contentious puzzles in modern biology. Recent studies have provided support for the emergence of the eukaryotic host cell from within the archaeal domain of life, but the identity and nature of the putative archaeal ancestor remain a subject of debate. Here we describe the discovery of ‘Lokiarchaeota’, a novel candidate archaeal phylum, which forms a monophyletic group with eukaryotes in phylogenomic analyses, and whose genomes encode an expanded repertoire of eukaryotic signature proteins that are suggestive of sophisticated membrane remodelling capabilities. Our results provide strong support for hypotheses in which the eukaryotic host evolved from a bona fide archaeon, and demonstrate that many components that underpin eukaryote-specific features were already present in that ancestor. This provided the host with a rich genomic ‘starter-kit’ to support the increase in the cellular and genomic complexity that is characteristic of eukaryotes.


It should be obvious to anyone with even a passing interest in science that it is firmly rooted in reality and that reality is coherent. It doesn't matter what the starting point is, whether it's chemistry, archaeology, genetics, evolutionary biology, physics or whatever, they all reinforce and support one another and contribute a different view of the same coherent picture. Along comes a surprising piece of evidence like the beginnings of complexity in archaea, and it dovetails neatly into what we know already.

This, quite simply, is why all sciences and in particular all biological sciences alway provide evidence which often directly supports a fundamental science like evolution or at least never contradict it. This is why there is no evidence against evolution and museums and science libraries overflowing with evidence for it.

By contrast, creationism has no foundation in reality. It is wholly imaginary with not a single shred of definitive supporting evidence, so not surprisingly, no piece of scientific evidence ever supports creationism or its poorly disguised version for people who want to pretend to be scientific - 'Intelligent Design'.

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