BioLogos Basics Video #8: Genetics | The BioLogos Forum


(system) #1

Today we release the 8th episode of our BioLogos Basics Videos. It is the third video in the series which gives a snapshot of some of the scientific evidence that points clearly to the common ancestry of all life forms on earth. This one is particularly focused on a topic that has been near and dear to the heart of BioLogos: genetics. Our founder, Francis Collins, is one of the world's leading geneticists, and this field of science has exploded in the last two decades with remarkable discoveries that put common ancestry beyond a reasonable doubt (in our humble opinion!). Of course these videos are not long enough to do much besides point toward this evidence, so be sure to explore the links to further information on the topic. We're particularly pleased in this video to feature the lovely Scottish accent of our friend from the Faraday Institute in Cambridge, Ruth M. Bancewicz, who runs her own very interesting blog. Enjoy!

Script: Jim Stump Video Production: Andrew DeSelm Narrator: Ruth M. Bancewicz

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Script for “Genetics":

Some of the strongest evidence for the common ancestry of all life forms comes from genetics. Genetics is the study of how changes are passed down from generation to generation through DNA.

The basic units of heredity, called genes, are spread out along strands of DNA called chromosomes. Chimpanzees and other great apes have 24 pairs of chromosomes, while humans have just 23. If humans share a common ancestor with other great apes, as evolutionary theory proposes, we would predict that, at some point in the distant past, two chromosomes fused together in an ancestor of modern humans.

To test this prediction, we need to know something about the structure of chromosomes. While each chromosome contains different genes, all of them have two common features. The first are telomeres. Telomeres are repetitive sequences at each end of the chromosome, which act kind of like the plastic bits on the end of your shoelace that prevent it from fraying. The second feature in common is the centromere, a region in the middle of the chromosome that is used during cell division.

It turns out that the DNA sequence of human Chromosome 2 is nearly identical to that of two chimp chromosomes laid end to end. Furthermore, the human chromosome has leftover telomere sequences in the middle, as well as an extra centromeric sequence. This is like finding a shoelace with two of the plastic bits laid down end to end right in the middle that no longer serve a purpose. These non-functioning sequences are exactly what you would expect if two chromosomes fused in the past, confirming the prediction of common ancestry.

There are many other features of the human genome that point to common ancestry. Humans still have a remnant of the gene required for producing the protein found in the yolk of bird and reptile eggs. Mutations accumulating since the distant past have disabled this gene such that it no longer functions to produce yolk protein. This gene remnant was precisely located by scientists who predicted where it would be based on the location known from the chicken genome. This only makes sense if humans and chickens shared a common ancestor long ago. We have thousands of other such non-functional genes and each one tells part of our story as a species.

It is very hard to explain these and many other genetic features apart from common ancestry. Of course this evidence raises some theological questions. In our next video we’ll see how some scholars understand the evidence from God’s world in light of God’s Word.


This is a companion discussion topic for the original entry at https://biologos.org/blog/biologos-basics-video-8-genetics

(James Stump) #3

I’d be happy to respond to questions and comments about our video.


(Dcscccc) #4

chromosomal fusion isnt evidence for commondescent at all. because the fusion event happaned in the human population, not apes (apes doesnt have fusion in their genome). so in the creation event human have 24 pairs and after some time 2 of them fused together.

the yolk protein have the same problem. vitellogenin have different function then making yolk. so it cant be evidence for making yolk in the past. by this logic- alligators have genes for feathers development. does it mean that alligators evolve feathers in the past? not at all.

another problem is that those “predictions” are not predictions at all. we first find those evidences and after the finding we make interpretation for them. its called ad hoc.


(Nate) #6

A few follow-up questions out of curiosity. Do Neanderthals and Denisovans have 23 or 24 chromosomes? If 23, I would assume they possess the same marker showing that this is a very ancient fusing. Does the number of chromosomes affect the ability for inter-species breeding or does it depend on which chromosomes specifically are different? What do the genes in the fused chromosome 2 relate to?


(Nate) #7

I confirmed my suspicions and found that both Neanderthals and Denisovans have the same fused chromosome 2 so the fusion event could not have possibly occurred among modern humans. I thought I had seen something on this before.
http://www.motherjones.com/politics/2014/02/evolution-creationism-bonobos-neanderthals-denisovans-chromosome-two


(James Stump) #8

This just isn’t true in any accepted sense of the word “evidence.” You might claim that it is not conclusive proof, but it certainly is evidence.

That is like saying if someone uses an old automobile as a rabbit cage now, there is no evidence that it ever functioned as an automobile. Vitellogenin clearly has the “shape” of making yolk protein. The fact that it is used for something else now does not hide the fact of what it once did.


(Dcscccc) #9

jstump. how chromosomal fusion is evidence for commondescent if apes doesnt have fusion in their genome?

about the vitellogenin- if it have another function then making yolk, then you cant say that this gene is evidence for making yolk. simple logic. again- by this logic alligators have genes for feathers development. does it mean that alligators evolved feathers in the past?


(Dennis Venema) #10

The Vitellogenin pseudogenes found in the human genome are hugely degraded - they cannot, in any way, be transcribed and translated into a protein product. The suggestion that they have some other, as-of-yet undiscovered function, is pure speculation. Even if they did have some function (as far-fetched as that suggestion is) it does not remove the evidence that they were once functional vitellogenin genes.


(Dennis Venema) #11

The chromosomal fusion seen in human chromosome 2 is predicted based on common ancestry. If humans and other great apes share common ancestors, then one needs to make sense of the difference in chromosome structure we see between humans (23 pairs) and all other great apes (24 pairs). The simplest hypothesis to resolve the difference is that human chromosome 2 is a fused chromosome - and we see internal telomeres and a second, defective centromere just as this hypothesis predicts.


(Dcscccc) #12

dr venema. the vitellogenin may be a real pseudogene because of mutations. but it doesnt show any evidence for commondescent because it have other function then making yolk. so even if its a real broken gene, its not evidence for commondescent.

second- the chromosomal fusion is actually predict by a commondesigner. because we know that a loss of a full chromosome will be fatal. so if we know that chimp is about 98% similar to humans, then we can predict that those chromosomes fused together. again- we dont need to involve the evolution theory.

by the way dr venema. i find this paper very interesting:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1135526/


(system) #13

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