This I believe: we need to understand evolution, adaptation, and phenotype

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I believe that there are three genetics-related concepts that, if taught properly, would greatly improve the biological literacy of our fellow citizens.

The first is evolution, the big idea of biology, that living things have common ancestors. Misunderstandings about the concept of evolution could produce an entire new column, but suffice to say that this basic biological principle, explaining why phenomena in biology are the way they are, rather than some other way, somehow hasn’t filtered into American scientific literacy.


It is genes that make evolution possible. All eukaryotic organisms are related in a massive tree of life that includes organisms familiar and unfamiliar, linked through the transmission of genes from generation to generation over the last 2 billion years. The differential transmission of genes over time produces evolutionary change, and ultimately, with speciation, the branching of the tree of life. In addition to being fundamental to biology, this realization of our linkage through genes to every other living thing on the planet, past and present, has profound religious and philosophical implications.

Genes produce traits that either do or do not suit an organism for the environment in which it finds itself. This brings us to the second basic concept, adaptation. Natural selection is adaptive differential reproduction. Some genes produce traits that enable an organism to survive better and reproduce more in a particular environment. Those traits and the genes that affect them will become more prevalent over time, as long as the environment favors them. Those same genes, in a different environment, might not be adaptive, and because environments change, “perfect” adaptation neither occurs nor is expected—but nobody said the concept of natural selection was simple. Natural selection is best understood as survival of the fit enough.

 

Written By: Eugenie C. Scott
continue to source article at frontiersin.org

22 COMMENTS

  1. “Survival of the fit enough” – I love that phrase. The concept accounts for so many things that don’t at first sight make sense: why cheetahs can’t run at 90 mph, why tree kangaroos are rotten climbers, why sickle-cell anaemia persists in black populations, and so on.

  2. @OP – All eukaryotic organisms are related in a massive tree of life that includes organisms familiar and unfamiliar, linked through the transmission of genes from generation to generation over the last 2 billion years.

    wikipedia.org/wiki/Eukaryote

    There is a vast complexity in the evolutionary tree of life on its various branches! Here are a few diagrams.

    wikipedia.org/wiki/File:Collapsed_tree_labels_simplified -

    wikipedia/commons/5/5d/Eukaryote_tree

    There is an interesting selection of historical attempts at the various “trees of life” on this link, – including Darwin’s classics :-
    wikipedia.org/wiki/Tree_of_life

    Alt Text

  3. In reply to #1 by CEVA34:

    “Survival of the fit enough” – I love that phrase. The concept accounts for so many things that don’t at first sight make sense: why cheetahs can’t run at 90 mph, why tree kangaroos are rotten climbers, why sickle-cell anaemia persists in black populations, and so on.

    I also like ‘survival of the most adequate’.

  4. Survival of the fit enough is really semantics. I like the phrase and think it is more descriptive and a better phrase than survival of the fittest. However, we are really splitting hairs here. The survivors survive is the actual real truth of the matter but that phrase is circular and not rewarding at all.

    I often ask my students “who is the fittest” in the room? The answer has always been “me”. They then cite how fast this one can run and how high this one can jump…. I let the discussion go and then insert “yes, but so far I have left the most babies”.

    It is surviving long enough to leave offspring that we are talking about here. And then those offspring having genotypes and phenotypes that allow them to survive long enough to leave offspring …etc…

    As far as Dr. Scott’s observations, she is dead on, in my opinion!!!

  5. I completely agree: this should be the centerpiece of the education system, and the world would be a very different place. So good to hear Ms Scott on this.

    My friends are getting tired of hearing me say this, so I’ll forward this article to all of them!

  6. Slightly off-topic perhaps…

    I wonder sometimes just how human evolution, in the biological sense, can take place when recent advancement in medicine and surgery allow our children to live long enough to mature and have their own, when otherwise they might have perished.

    Do we include the ‘increasing scientific knowledge’ in our survival-of-the-fittest-tool-kit in a Darwinian context?

    Are those human groups, where little or no modern medical treatment is availble, evolving ahead of the developed groups?

  7. Excellent piece! Considering the time-scales involved, natural selection really is quite apathetic.

    In reply to #5 by Jack M.:

    But we are 100% determined, Eugenie, though not by genes alone, as you note.

    There may be some indeterminacy, but that still doesn’t give us anything like “free will”.

  8. RollingSausage,
    I think, perhaps, that these groups with little or no medical help have a higher mortality rate as children. This can be seen as a stressor or a pressure. Populations with stresses on the are apt to change differently and maybe at a different rate than populations with different stressors and pressures.

    The important thing to keep in mind is that populations evolve, not individuals. Therefore your questions are awesome and we will have to watch and see if this stress (lack of medicine availability) is stress enough to cause change.

    And, there is no “evolving ahead”… They would be diverging. And whether that is occurring or not would be an awesome research topic.

  9. I have a technical question, if someone in the know doesn’t mind answering it that would be great.

    What is an allele and how does it fit in with genes and phenotypes? I had a notion that an allele was a bundle of genes and in turn genotypes were bundles of alleles and that a phenotype was was a genotype shaped by the environment. Is this way off? I just read the Wikipedia page on alleles and I’m not to sure that describing alleles as ‘bundles of genes’ is quite right.

  10. In reply to #12 by The Jersey Devil:

    I have a technical question, if someone in the know doesn’t mind answering it that would be great.

    What is an allele and how does it fit in with genes and phenotypes? I had a notion that an allele was a bundle of genes and in turn genotypes were bundles of alleles and that a phenotype was was a genotype shaped by the environment. Is this way off? I just read the Wikipedia page on alleles and I’m not to sure that describing alleles as ‘bundles of genes’ is quite right.

    An allele is a version of a gene. Without going too deeply into specifics, lets use the old favorite of eye color. We all have a gene (or genes) that determine eye color, but the version, or ‘allele’, for brown vs green vs blue vs pink is different. A phenotype is the physical attribute corresponding to a genotype. A genotype is the genetic ‘code’ pertaining to a feature, whereas the phenotype is the physical manifestation of that section of coding.

  11. In reply to #9 by RollingSausage:

    Slightly off-topic perhaps…

    I wonder sometimes just how human evolution, in the biological sense, can take place when recent advancement in medicine and surgery allow our children to live long enough to mature and have their own, when otherwise they might have perished.

    Do we include the ‘increasing scientific knowledge’ in our survival-of-the-fittest-tool-kit in a Darwinian context?

    Are those human groups, where little or no modern medical treatment is availble, evolving ahead of the developed groups?

    I have the same concern. A “watering down” of the gene pool by keeping people alive who wouldn’t have survived a hundred years ago, artificially inseminating otherwise barren parents, etc… It seems to be making the gene pool less ‘fit’ and may cause serious repercussions in the future from a super-plague or the like. Although, without modern technology, the true genius of Stephen Hawking would have never been realized. But perhaps that’s the exception that proves the rule…

  12. Hey Jersey!!!
    Alleles are different forms of a gene. It is subtle and I’ll try my best to convey this idea.

    Adam and Eve had brown eyes. Their children had brown eyes. Their children’s children had brown eyes. However, a mutation in the eye color gene allowed for a baby to be born with blue eyes (it is way way more complicated than this — so I am really oversimplifying…. I am doing it this way to poke fun at the creation story while also answering your question).

    Now, chances are that this first blue eyed baby would be murdered to please god. But, suppose this child had survived. On the chromosome (at a spot called a locus) where “eye color” genes reside, there has always been a gene that causes the protein in the iris to be brown. But now, due to mutation, there is a new possibility — blue.

    If we take a blue eyed and a brown eyed person and they mate, brown shows up and blue “hides”. This makes the brown version of the gene “dominant” while the blue version is “recessive”.

    Each baby gets a copy of the brown or blue allele from each parent. This combo is called the genotype. The color that the genotype produces is called the phenotype.

    Now, there is environmental interaction between genotype and phenotype and many other complicating factors. But, here is the kicker, even if creation is true and we had an Adam and Eve, evolution is STILL the process by which we have developed traits that vary from generation to generation.

    So, in a nutshell:
    alleles are different versions of the same gene.
    Phenotype is traditionally known as the outward appearance of a given trait.
    Genotype is the underlying gene combo’s that cause the phenotype (along with environmental interactions).
    Adam and Eve is bullshit.
    Evolution is the concept that galvanizes all we know.

    In reply to #12 by The Jersey Devil:

    I have a technical question, if someone in the know doesn’t mind answering it that would be great.

    What is an allele and how does it fit in with genes and phenotypes? I had a notion that an allele was a bundle of genes and in turn genotypes were bundles of alleles and that a phenotype was was a genotype shaped by the environment. Is this way off? I just read the Wikipedia page on alleles and I’m not to sure that describing alleles as ‘bundles of genes’ is quite right.

  13. In reply to #15 by crookedshoes:

    Thanks Crookedshoes and Prime8. Wikipedia uses blood type as an example so I will too, just to see if I’m getting this.

    There are 3 pieces of genetic code that an individual gets from their parents. A, B or O. So then there are 6 possible combinations (AA, BB, OO, AB, AO, BO). Because O is recessive, AO is the same as AA and BO is the same as BB. (AB is apparently some kind of special case). So of the six possible combinations there are 4 outcomes.

    The six combinations are the genotype. The four outcomes are the phenotype (the actual blood). The part I’m pretty sure of.

    The gene is the part of the crhomosome that says, “Make blood”. The allele is the part of the chromosome that says, “And make the blood this variety.” Am I close?

    Anyway, crooked shoes, you were right to throw the Adam and Eve story out there. It was because something I read over on Creation Ministries International that got me to ask about alleles. Not that I was being taken in by their arguments. I just didn’t understand the point they were making well enough to refute the point they were making. It had to do with the fact that they acknowledged that changes in allele frequency over time existed but denied that this change in allele frequency lead to ‘goo to you evolution’ (their words).

  14. Hey Jersey,

    Your succinct explanation concerning blood typing leads me to believe that “you got it!!!!”. I mean, awesome choice of words and very clear definitions. Hats off to your brin, your communication skills, and wikipedia!!!!

    Funny coincidence about the Adam and Eve slant to the story!!! Intuition???
    In reply to #19 by The Jersey Devil:

    In reply to #15 by crookedshoes:

    Thanks Crookedshoes and Prime8. Wikipedia uses blood type as an example so I will too, just to see if I’m getting this.

    There are 3 pieces of genetic code that an individual gets from their parents. A, B or O. So then there are 6 possible combinations (AA, BB, OO, AB, AO, BO). Because O is recessive, AO is the same as AA and BO is the same as BB. (AB is apparently some kind of special case). So of the six possible combinations there are 4 outcomes.

    The six combinations are the genotype. The four outcomes are the phenotype (the actual blood). The part I’m pretty sure of.

    The gene is the part of the crhomosome that says, “Make blood”. The allele is the part of the chromosome that says, “And make the blood this variety.” Am I close?

    Anyway, crooked shoes, you were right to throw the Adam and Eve story out there. It was because something I read over on Creation Ministries International that got me to ask about alleles. Not that I was being taken in by their arguments. I just didn’t understand the point they were making well enough to refute the point they were making. It had to do with the fact that they acknowledged that changes in allele frequency over time existed but denied that this change in allele frequency lead to ‘goo to you evolution’ (their words).

  15. Singing about it might help to get the message to the wider population:

    So here are Brian Cox and Eric Idle with a new video & audio version of THE classic from Monty Python’s “The meaning of Life”! – in the trailer for Brian Cox’s new BBC Wonders of Life Series!
    Eric Idle & Brian Cox’s new DNA Galaxy Song –
    facepunch.

    (As I already finger pick the beautiful harmonies on guitar & sing the older version, —- – I have some new lyrics to learn!)

  16. Any living organism is adaptive to its eviroment. Can you think anyone not adaptive to their own environment?
    Population may change, of course, but they are still same species. Human emigrated from Africa to other parts of the world, are they same species, aren’t they?

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