Evolution: A Basic Understanding

There is a lot of misconception of what evolution is or means thanks to a lot of Creationist pseudoscience cropping up all over the internet. It seems to me that the lack of education of evolutionary theory is in dire need of being addressed, and I so hope to help marginalize the damage Creationists are causing by writing a few articles covering some of the basics. Here in my first article I shall go over the common definitions and provide a basic argument for evolution. I may however get deeper into the science and the complexity of the subject matter as I write more about evolution here on my blog. But for now, lets start simple and provide some basic definitions, and a basic argument for evolution. Thus first thing I think we need to address is the definition of evolution, Micro evolution, and Macro Evolution:

  • EVOLUTION:

Evolution is the change in the inherited characteristics of biological populations over successive generations. Evolutionary processes give rise to diversity at every level of biological organisation, including speciesindividual organisms and molecules such as DNA and proteins.[1]

^ Hall, B. K.; Hallgrímsson, B., eds. (2008). Strickberger’s Evolution (4th ed.). Jones & Bartlett. ISBN 0-7637-0066-5.

  • MICROEVOLUTION:

Microevolution is a change in gene frequency within a population over time. This change is due to four different processes: mutation, selection (natural and artificial), gene flow and genetic drift.

Population genetics is the branch of biology that provides the mathematical structure for the study of the process of microevolution. Ecological genetics concerns itself with observing microevolution in the wild. Typically, observable instances of evolution are examples of microevolution; for example, bacterial strains that have antibiotic resistance.

  • MACROEVOLUTION: 

Macroevolution is evolution on a scale of separated gene pools.[1] Macroevolutionary studies focus on change that occurs at or above the level of species, in contrast with microevolution,[2] which refers to smaller evolutionary changes (typically described as changes in allele frequencies) within a species or population.

Within the Modern Synthesis school of thought, macroevolution is thought of as the compounded effects of microevolution.[9] Thus, the distinction between micro- and macroevolution is not a fundamental one – the only difference between them is of time and scale. As Ernst W. Mayrobserves, “transspecific evolution is nothing but an extrapolation and magnification of the events that take place within populations and species…it is misleading to make a distinction between the causes of micro- and macroevolution”.[9] However, time is not a necessary distinguishing factor – macroevolution can happen without gradual compounding of small changes; whole-genome duplication can result in speciation occurring over a single generation – this is especially common in plants.[10]

Changes in the genes regulating development have also been proposed as being important in producing speciation through large and relatively sudden changes in animals’ morphology.[11][12]

  • SPECIATION:

Speciation is the <href=”http://en.wikipedia.org/wiki/Evolution”>evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term ‘speciation’ for the splitting of lineages or ‘cladogenesis,’ as opposed to ‘anagenesis‘ or ‘phyletic evolution’ occurring within lineages. Whether genetic drift is a minor or major contributor to speciation is the subject matter of much ongoing discussion.

There are four geographic modes of speciation in nature, based on the extent to which speciating populations are geographically isolated from one another: allopatricperipatricparapatric, and sympatric. Speciation may also be induced artificially, through animal husbandry or laboratory experiments. Observed examples of each kind of speciation are provided throughout.

Now as we know, some Creationists believe only in “Microevolution”, and this usually stems from woeful ignorance of what Macroevolution and Microevolution actually mean, and what impact they have on any given species.  Thus to help clear up some of the misconceptions, here is a video demonstrating by example of the difference between micro and macro evolution:

Further citations notable in regards to primates such as ourselves show macro evolutionary changes:

http://www.nature.com/scitable/knowledge/library/macroevolution-examples-from-the-primate-world-96679683

This is in contrast to the Creation Institute’s claim that you somehow need gradual transitional forms to confirm macroevolution. Their entire argument rests on needing to convince you of this, and they are so intellectually lazy and dishonest that it’s blatant to the casual observer that they are desperately trying to save their religious beliefs while knowing they are academically fictitious.  Thus when we ask these Creationsists to give us the number of transitional forms between a poodle and and a Wolf in their morphology,  they quickly can’t handle that since their common argument rests on needing thousands of transitional forms and some sort of half wolf and half poodle looking creature. However, Macroevolution doesn’t always have much to do with needing slow and gradual morphology of an organism when microevolutionary changes can and do often result in the macromorphology of a species since you are dealing with gene expression. Likewise as an analogy, a missing comma or a change of a single word in a sentence can entirely change the intended context and expression of what is written on a macro scale even though the actual change change noted is small, or in this case a micro change in the sentence structure.. Thus when presented with this problem we get goal post shifting in their definition to say “a dog can’t give birth to a cat”, or something like “It’s still a dog” as if dogs are a specific species (Kind). They can’t even coherently define “Kind” to which I could even expand to being all Carbon based life forms to simply claim all life on Earth is the same “Kind”  And this is Just to show how intellectually disconnected they are here, and this just gets much worse when the subject of ring species is brought up as noted in the following video on the subject:

You know their argument is bad when they start to backpedal, and worst part is that ring species directly demonstrate common descent and macroevolution. There is no argument about this, it’s a fact. They are clever when they try to save face by renaming evolution as “Variation” , “Development  with modification”. They will literally avoid using the “E” word at all costs.. I dare say the backpedaling is embarrassingly obvious! Despite this embarrassment, let us pretend for a moment they hadn’t, and let us assume they still insist evolution in the sense we know it in science isn’t possible. Here we can ask ourselves what kind of evidence can we show evolution is a credible scientific theory?

Well to answer that question here is something we call empirical evidence to where a human embryo has a full tail in development, and with possibly developing vertebra at 4 weeks:

That’s pretty impressive, and it’s through human embryology in which we can find many clues to our ancestral past. You might ask why do we have a tail in our embryonic development if we were supposedly designed not to have them. If it were not for gene regulation in which deactivates the continued expression of these genes, you would most assuredly be born with some sort of tail, and possibly a functional tail vs a vestigial true tail. Though it would probably still be vestigial giving the evidence that we may lack the ancient instructions to fully complete the process. However, If you are curious where the original photo I posted on the human embryo comes from to which shows it’s tail and developing vertebra, it comes from “The Developing Human:Clinically Oriented Embryology, Moore and Persaud, 5th ed”.. Unfortunately you have to own the PDF to access that image. In light of this I can offer you an alternative:

http://www.ehd.org/developmental-stages/stage16.php
http://www.ehd.org/classics/gasser_ch6.php

Supported by Carnegie Stages of Human Development:

These genes are the WNT-3a(1) and CDx1(2):

1 – WNT-3a) http://en.wikipedia.org/wiki/WNT3A

2 – CDx1) http://en.wikipedia.org/wiki/CDX1

As also noted at Talk Origins:

Tails in mice and other vertebrates have been identified (the Wnt-3a and Cdx1 genes; Greco et al. 1996Prinos et al. 2001Schubert et al. 2001Shum et al. 1999Takada et al. 1994). As predicted by common descent from the atavistic evidence, these tail genes have also been discovered in the human genome (Katoh 2002Roelink et al. 1993). As discussed below in detail, the development of the normal human tail in the early embryo has been investigated extensively, and apoptosis (programmed cell death) plays a significant role in removing the tail of a human embryo after it has formed. It is now known that down-regulation of the Wnt-3a gene induces apoptosis of tail cells during mouse development (Greco et al. 1996Shum et al. 1999;Takada et al. 1994), and similar effects are observed in humans (Chan et al. 2002). Additionally, researchers have identified a mutant mouse that does not develop a tail, and this phenotype is due to a regulatory mutation that decreases the Wnt-3a gene dosage (Greco et al. 1996Gruneberg and Wickramaratne 1974Heston 1951). Thus, current evidence indicates that the genetic cause of tail loss in the evolution of apes was likely a simple regulatory mutation(s) that slightly decreased Wnt-3a gene dosage. Conversely, a mutation or environmental factor that increased dosage of the Wnt-3a gene would reduce apoptosis of the human tail during development and would result in its retention, as an atavism, in a newborn.

Humans contain both the gene to develop tails along with apoptosis (programmed cell death) that plays a significant role in removing the tail while humans are still in the embryo form. The tail genes are retained from distance ancestors to humans and apoptosis was adapted later during the course of our ancestors’ evolution.””

And very rarely you see tail Atavism in humans such as this:


http://www.talkorigins.org/faqs/comdesc/section2.html#Bar-Maor_etal1980
http://www.bjj.boneandjoint.org.uk/content/62-B/4/508.long

This is incredibly strong evidence for evolution as all human embryo’s have tails, and all of us had gone through this embryonic stage.., just like how all chickens have ancestral tails in their embryonic development as well:

Furthermore, Talk Ted has a great video about the hox gene in regards to Chickens and how we can possibly create a dino chicken by preventing the regulation of various ancestral genes.:

http://www.ted.com/talks/jack_horner_building_a_dinosaur_from_a_chicken.html

From here you can learn about the hox code / hox gene and how these tails get reabsorbed.. And when this fails to completely happen, you have rare cases of Atavisms. Atavisms deal with active ancestral genes to where you have whales, or even snakes with their ancestral limbs.. Kinda like these lovely snakes:



To which of course is supported by paleontology in which show how snakes lost their legs:

http://www.examiner.com/paelenotology-science-news-in-national/x-rays-show-how-fossil-snakes-lost-their-legs

Or maybe chickens growing teeth is something to chew on:

http://www.scientificamerican.com/article.cfm?id=mutant-chicken-grows-alli
http://www.nature.com/scitable/topicpage/atavism-embryology-development-and-evolution-843

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