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Saturday, December 22, 2018

Most popular Sandwalk posts of 2017

I was looking at some of my posts from the past few years and wondered which ones were the most popular. I had previously identified the most popular post of 2016 but not the most popular ones from 2017 so here they are.

The one with the most views (7481) is a link to a video by Michio Kaku who tells us that humans have stopped evolving [Another physicist teaches us about evolution].

The one with the most comments (259) is a post about my attempts to teach a creationist about glycolysis and evolution [Trying to educate a creationist (Otangelo Grasso)].

The post that I'm most proud of is: Historical evolution is determined by chance events


Unknown said...

I missed that third post first time around. Thanks for reposting it.

Tom Mueller said...

I would like to take this opportunity to express my gratitude for insights gained by hovering about this site.

The theme of "Historical evolution is determined by chance events", in particular, can be misconstrued by some high school teachers.

For example: the HHMI activity

Here is a quick excerpt:

[DR. NACHMAN:] In effect, each of these lava flows is like rewinding the tape of life and allowing evolution to occur again and again. And in each case, we find the dark mice have evolved."

Oh wow! Talk about propagating misconception!

Students often fall into the trap of imagining that these "adaptive" mutations are inevitable, that there may even be teleological and ultimatatly non-Darwinian aspects to evolution that can even impinge into Theology or Metaphysics.

Quick reminder to students in my classroom - different mutations were responsible for the same phenotype in different Rock Pocket Mice populations when adapting to the new habitat.

Second Quick Reminder to students in my classroom - by definition, we were unable to observe the most frequent outcome, namely the extinction of those populations that failed to adapt.

That all said - the post which had the most profound effect to reevaluating my understanding of Biology (such as it is) was the eureka revelation elicited when Larry enjoyed a battle of wits with an unarmed opponent

Trying to educate a creationist (Otangelo Grasso)

Larry elicited a complete rethink on my part - which I translated into two worksheets which I post below together with explanatory overviews.

It should be obvious that Larry's fingerprints are all over my efforts and that I remain in his debt (see first link). Ironically, I also remain in debt to Otangelo Grasso, very much so (see last link)!

Best and grateful regards, hoping everyone enjoys a joyous celebration of the pagan saturnalia.

Piotr Gąsiorowski said...

I'm also enormously indebted to Larry and to many of the Sandwalk regulars. I've learnt a lot about modern evolutionary theory from these post, from the discussions stimulated by them, and from the stuff I had to read in my attempts to catch up intellectually with more knowlegeable commenters. Season's greetings to our good host and all felllow Sandwalkers!

Tomi Aalto said...

I found this from 2009 written by Larry Moran:

"Because a large percentage of gene mutations are neutral, and because most of our genome is junk, we can easily tolerate 130 mutations per individual per generation without going extinct. "

Modern scientists have revealed that there's no junk in genomes. At least 90% of the genome is transcribed to different types of RNA molecules and the rest is still usable because DNA is just passive for of information.

"In addition, there has been an explosion of research addressing possible functional roles for the other 98% of the human genome that does not encode proteins. In fact, >90% of the human genome is likely to be transcribed yielding a complex network of overlapping transcripts that include tens of thousands of long RNAs with little or no protein forming capacity; they are collectively called non-coding RNA."

"Don’t call it junk

Repeated DNA sequences have had a bad nickname, “junk DNA,” for about 20 years. Scientists decoding the genome called it junk because they were initially focused on understanding the functions of individual genes.

Since then, studies have shown that repeated DNA sequences are in fact essential for many nuclear activities, but their defective repair is also linked to aging and disease.

“Heterochromatin is mostly composed of repeated DNA sequences,” Chiolo said. “The low gene content is part of the reason why these sequences are less characterized.”

In fact, mutations that compromise heterochromatin repair result in massive chromosome rearrangements affecting the entire genome."

Genetic degradation is easily observed in the wild and in the human genome. There are 561,119 gene-disease-associations in the human genome at population level but the number of random beneficial mutations is close to zero. There's no mechanism for evolution.

Unknown said...