Tuesday, 5 June 2018

Human Brains Refute Creationism Without Effort

Human-Specific NOTCH2NL Genes Affect Notch Signaling and Cortical Neurogenesis | Cell.

Here's another of those regular occurrences where science casually and without effort or intent, refutes creationism with a few facts. It's the news that a team have identified a trio of genes that account for the increase in the human brain from a volume of about 0.5 litres in our earlier ancestors to the 1.4 litres we have today.

Although embarrassing, that's not the most embarrassing finding for creationism; that comes from the discovery that these genes have evolved from ancient genes that once served an unrelated purpose, by gene multiplication and mutation. Creationists of course insist that all mutations are harmful and that no new information can arise by mutation. Here we have beneficial mutations that now contain the necessary information to make the large human brain that gives us our almost unique intelligence and ability to learn and reason - although creationists seem determined to prove by example that the later has never evolved in humans.

The four genes, one of which is inactive, were previously regarded as the same gene, NOTCH2NL which was itself a modification of the NOTCH gene family of genes, an ancient family of genes that control development in species as diverse as fruit flies and whales. Now a team led by David Haussler and Frank M. J. Jacobs of the University of California, Santa Cruz, has shown that the three active NOTCH2NL genes are slightly different and arose by a series of accidents during human evolution, the last of which occurred immediately before the fossil record shows our ancestor's brains began to expand.

The first accident occurred in a common ancestor we share with the other African Great Apes about fourteen million years ago when part of a NOTCH2 gene got copied and inserted in chromosome 1 and, being incomplete, was inactive - just part of the junk DNA that gets copied and passed down the generations. Then about eleven million years ago, the NOTCH2 copy was repaired when another part was inserted to give rise to a functional NOTCH2NL gene.

Later on, NOTCH2NL got copied twice more to give the three active genes at one end of chromosome 1 and a inactive copy at the other end of the same chromosome.

Basically, the way these genes work is to produce proteins which delay the specialisation of stem cells into neurons, giving them more time to produce more stem cells. This confirms an earlier finding by Wieland Huttner, a neurobiologist at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany who showed that when human NOTCH2NL is introduced into developing mouse brain tissues in cell cultures, they produce more stem cells.

The teams findings were published a few days ago in Cell. The full paper can be read here. Unfortunately the publishers, Elsevier, want money for the right to reprint the abstract here.

Any creationists prepared to explain why we have this example of beneficial mutations giving rise to new information, given that creationists claim both to be impossible, or is this just another example of reality having to be discounted when it doesn't comply with creationist dogma?

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