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Wednesday, 11 October 2017

Peter Harrison - Why religion is not going away and science will not destroy it

In 1966, just over 50 years ago, the distinguished Canadian-born anthropologist Anthony Wallace confidently predicted the global demise of religion at the hands of an advancing science: ‘belief in supernatural powers is doomed to die out, all over the world, as a result of the increasing adequacy and diffusion of scientific knowledge’. Wallace’s vision was not exceptional. On the contrary, the modern social sciences, which took shape in 19th-century western Europe, took their own recent historical experience of secularisation as a universal model. An assumption lay at the core of the social sciences, either presuming or sometimes predicting that all cultures would eventually converge on something roughly approximating secular, Western, liberal democracy. Then something closer to the opposite happened.

Not only has secularism failed to continue its steady global march but countries as varied as Iran, India, Israel, Algeria and Turkey have either had their secular governments replaced by religious ones, or have seen the rise of influential religious nationalist movements. Secularisation, as predicted by the social sciences, has failed.

Sunday, 24 September 2017

What's new at Christadelphian - Origins Discussion

It's heartening to see other Christadelphian Internet sites discussing both evolution, and how to understand our faith tradition in the light of the fact of common descent and large-scale evolutionary change. One of these, Christadelphian Origins Discussion has recently added a webpage, which includes a number of posts on subjects ranging from common descent to refuting and correcting common Christadelphian misunderstandings on evolution to ancient Hebrew cosmogeography. Definitely a website to add to your bookmarks.

Friday, 22 September 2017

Where's the Evolution? Why, here!

One of the more common tactics evolution denialists employ is to juxtapose photographs of fossils and contemporary organisms, and claim that the apparent absence of change means evolution never occurred. There are many fundamental problems with this problem, such as the fact that poor quality photographs of fossils fail to pick up the subtle morphological details that are apparent when the actual fossils are examined, morphological stability in environments where there are no strong selective pressures, not to mention the fact that even in the absence of marked morphological change, there will nonetheless be strong evidence of change at the genomic level which is of course not apparent in a grainy photograph.

Arguably the most notorious proponent of this deceptive tactic is the Turkish evolution denialist Adnan Oktar, otherwise known as Harun Yahya. Oktar is hardly alone, with many special creationists using this approach to attack evolution. One example is the Facebook page Where is the evolution? which has in turn triggered the creation of another page Here is the evolution, which exposes the intellectually vacuous approach of their approach by focusing on the fundamental concept of evolution - descent with modification produces an evolutionary tree.

Friday, 25 August 2017

How Molecular Clocks Are Refining Human Evolution's Timeline

How Molecular Clocks Are Refining Human Evolution's Timeline


By Bridget Alex and Priya Moorjani

This article was originally published at The Conversation and has been republished under Creative Commons.

DNA holds the story of our ancestry—how we’re related to the familiar faces at family reunions as well as more ancient affairs: how we’re related to our closest nonhuman relatives, chimpanzees; how Homo sapiens mated with Neanderthals; and how people migrated out of Africa, adapting to new environments and lifestyles along the way. And our DNA also holds clues about the timing of these key events in human evolution.

When scientists say that modern humans emerged in Africa about 200,000 years ago and began their global spread about 60,000 years ago, how do they come up with those dates? Traditionally researchers built timelines of human prehistory based on fossils and artifacts, which can be directly dated with methods such as radiocarbon dating and Potassium-argon dating. However, these methods require ancient remains to have certain elements or preservation conditions, and that is not always the case. Moreover, relevant fossils or artifacts have not been discovered for all milestones in human evolution.

Analyzing DNA from present-day and ancient genomes provides a complementary approach for dating evolutionary events. Because certain genetic changes occur at a steady rate per generation, they provide an estimate of the time elapsed. These changes accrue like the ticks on a stopwatch, providing a “molecular clock.” By comparing DNA sequences, geneticists can not only reconstruct relationships between different populations or species but also infer evolutionary history over deep timescales.

Molecular clocks are becoming more sophisticated, thanks to improved DNA sequencing, analytical tools, and a better understanding of the biological processes behind genetic changes. By applying these methods to the ever-growing database of DNA from diverse populations (both present-day and ancient), geneticists are helping to build a more refined timeline of human evolution.

Sunday, 23 July 2017

Nothing in Medicine Makes Sense Except in the Light of Evolution

The title of this post is a direct allusion to Theodosius Dobzhansky's famous 1973 article Nothing in Biology Makes Sense Except in the Light of Evolution [1] in which he outlined facts from areas such as ecology and molecular biology, and stated that "all these remarkable findings make sense in the light of evolution: they are nonsense otherwise." In a similar manner, aspects of human anatomy, developmental biology, physiology, and genetics which look bizarre, poorly designed, and otherwise defy rational description (not to mention difficult to memorise and store for quick recall) become perfectly understandable when understood in the light of an evolutionary origin for the human species. Examples include extra nipples along the milk line [2], the inverted retina [3], the multiple  pseudogenes, retrotransposons, and endogenous retroviral elements we share with primates [4], not to mention the presence of non-coding intronic DNA, which leads to mutations at intron-exon borders that "often disrupt premRNA splicing in ways that alter gene products and lead to countless genetic disabilities, including various cancers and other metabolic defects." [5]

I am not the first to allude to Dobzhansky in reflecting on the increasing importance evolution has for both understanding the basic clinical sciences on which medicine is based, and for the practice of medicine itself. Ajit Varki, Distinguished Professor of Medicine and Cellular & Molecular Medicine at the University of California,  San Diego wrote in 2012 a paper with the same title as this post where he states that the 'scientific aspects of medicine are rooted in understanding the biology of our species and those of other organisms that interact with us in health and disease. Thus, it is reasonable to paraphrase Dobzhansky, stating that, 'nothing in the biological aspects of medicine makes sense except in the light of evolution'" and proceeds to outline his experience in teaching evolution to medical students. [6] Given that there are more than 4.7 million hits in Google Scholar when searching for evolution and medicine, Varki's desire (and that of many other physician and scientists) to integrate evolutionary biology in the teaching of medicine is eminently sensible.

Monday, 17 July 2017

Endogenous Retroviruses and the Evidence for Common Descent

Overview

Common descent has not been an issue in the mainstream scientific community for over one hundred years. The case for common descent, which was considered solid in the early 20th century, has now become overwhelming based in no small part on the evidence from molecular genetics. The evidence is overwhelming when it comes to endogenous retroviral inclusions. ERVs are remnants of prior retroviral infections that have become integrated into the DNA of organisms. If they pass into the germline of an organism, its descendants can inherit them. Their presence is clear evidence of past infection in an ancestral organism.
Common descent would predict that the descendants of a species infected by a retrovirus, which subsequently became integrated into the germline, would inherit that retroviral inclusion at the same point in the DNA of the descendant organisms. We find evidence of this in organisms ranging from primates to sheep to crocodiles. It is difficult to imagine a more comprehensive demonstration of common descent, particularly when closely related species such as humans and chimpanzees share significant numbers of ERVs at the same point in their genome.
One analogy that should drive home this point is that of a mathematics teacher who receives ten exam papers that not only get the same questions wrong, but show the same errors in the working of the problem, and even share the same spelling errors at the same questions. Copying is the only reasonable conclusion, as it stretches credibility to assume that the ten students independently got the same questions wrong, made exactly the same mistakes in derivation and made the same spelling error. This is similar to what we see with closely related species with shared ERVs at exactly the same point in their genomes.
The following article should serve not only as an introduction to retrovirology for the layperson, but point out in detail the evidence for common descent from ERVs, examples where evolution has co-opted ERV components to perform new functions, and refutations of common evolution denialist arguments against the evidence for common descent from ERVs.
This review is large, but no apology is made for this. Shared ERV elements in related species is overwhelming evidence for common descent, which is why creationists, who are unable to refute this evidence raise objections which while superficially appealing to the layperson do not pass the critical scrutiny of the scientists whose professional life involves working with them. Dismissing the molecular evidence as “circumstantial evidence” is a merely an attempt to evade the burden of proof expected of anyone who opposes a consensus view. If one challenges a long-established position, one needs to understand what one us challenging intimately, and produce hard evidence for critical review by the scientific community. Otherwise, if that is not done, no one will take such attempted rebuttals seriously - and rightly so. No creationist refutation of this evidence from shared ERV elements exists - the consensus view that they support common descent remains unchallenged.

Thursday, 29 June 2017

Cancer, pain, and suffering before The Fall

Two things that YECs claim to be true, namely recent human creation and the absence of disease and suffering before Adam's sin are of course impossible to honestly defend given the overwhelming evidence against these assumptions. Further demonstration of this fact would not unreasonably be seen as redundant. However, given my medical background, a recent fossil discovery in South Africa of bone cancer in a 1.7 million year old hominin fossil caught my attention as a particularly powerful demonstration of facts of human antiquity and human suffering well before the earliest possible date for Adam in one powerful image.