This post was inspired by my Anth 102
students and should be quite helpful to them particularly but will hopefully be
an invaluable resource to all physical anthropology students.
Any student who has taken a Physical Anthropology course, particularly an introductory course, has faced the infamous topics on evolution, heredity, and population genetics. As an educator, I have watched annually as my students have struggled to grasp and understand these topics, while others catch on quickly and without any issue. If you are the latter and not the former, this post is not for you. If you are the former, then keep reading because this post will provide you with a lot of resources that will hopefully assist you in understanding this material.
One needs only to look at the great diversity within the human species to know that there are a lot of biological characteristics that make us up as a species. These differences, along with differences noted in other species, drove scholars Charles Darwin and Alfred Wallace to come up with the idea of natural selection based on their observations of biological variation. They understood that biological variation existed within different populations of species, but they did not understand how it originated or was created. Darwin thought the species were the result of blended characteristics from their parents, and that a mechanism identified as natural selection enabled certain members of a species to survive and reproduce.
Unfortunately, some of Darwin's ideas were incorrect, but that is because he did not have the information available to scholars today that enables us to more fully understand the mechanism of inheritance that Darwin was trying to comprehend and understand. It was not until Gregor Mendel conducted his now famous pea plant experiments that the foundations of the field of genetics, the study of the mechanism of inheritance (Feder & Park, 2012), were set. From here, all sorts of mechanism of evolution and heredity could be and were understood. And instead of explaining these, I will allow this informative video (NSFW) to do that for me.
Any student who has taken a Physical Anthropology course, particularly an introductory course, has faced the infamous topics on evolution, heredity, and population genetics. As an educator, I have watched annually as my students have struggled to grasp and understand these topics, while others catch on quickly and without any issue. If you are the latter and not the former, this post is not for you. If you are the former, then keep reading because this post will provide you with a lot of resources that will hopefully assist you in understanding this material.
One needs only to look at the great diversity within the human species to know that there are a lot of biological characteristics that make us up as a species. These differences, along with differences noted in other species, drove scholars Charles Darwin and Alfred Wallace to come up with the idea of natural selection based on their observations of biological variation. They understood that biological variation existed within different populations of species, but they did not understand how it originated or was created. Darwin thought the species were the result of blended characteristics from their parents, and that a mechanism identified as natural selection enabled certain members of a species to survive and reproduce.
Unfortunately, some of Darwin's ideas were incorrect, but that is because he did not have the information available to scholars today that enables us to more fully understand the mechanism of inheritance that Darwin was trying to comprehend and understand. It was not until Gregor Mendel conducted his now famous pea plant experiments that the foundations of the field of genetics, the study of the mechanism of inheritance (Feder & Park, 2012), were set. From here, all sorts of mechanism of evolution and heredity could be and were understood. And instead of explaining these, I will allow this informative video (NSFW) to do that for me.
Now this leads physical anthropology students to have to
complete two exercises in order to fully understand this material: Punnett squares
and Hardy Weinberg Equilibrium. Punnett
squares are diagrams for predicting the genotypes (genetic composition of
alleles) of potential offspring based on known genotypes of the parents. I find that students often struggle with
Punnett squares, in understanding and constructing them, so I found this handy video that really helped
many of my students.
The Hardy-Weinberg Equilibrium is a formula that
demonstrates genotype percentages under hypothetical conditions of no
evolutionary change within a population (Feder & Park, 2012). Several conditions must be met for a
population to be potentially at genetic equilibrium:
- The population must be considered a large breeding population
- There must be random mating present
- There must be no mutations present that would change the allelic frequency in the population
- No gene flow or genetic drift
- No natural selection
In order to determine if genetic equilibrium has been met,
students are expected to complete the following equation:
P2 + 2PQ + Q2 =
1
Students often see that this requires math and they panic,
and the first thing that I tell all of them is to relax! Breathe.
You can get through this. And you
are not alone in your panic. In order to
assist panicked students, I provide them with several resources, including this
video and several practice problem websites:
Hopefully these resources are as helpful to you as they have
been to my students. If you are a
student or an educator who has found a trick that is helpful, I encourage you
to share in the comments section in order to assist others like you who are
struggling with this material. Thank you
in advance and best of luck!
7 comments:
Once it was described to me in your class how P2 and Q2 related to the Dominate and Recessive genes it was easy to determine the rest of the equation. Therefore it was a matter of simple addition and subtraction from that point on ;)
This is way over my head.
This is a great way to break it down. There was a little confusion on the math part for me but after this post, I am reassured on how to correctly calculate genotype percentages. I just always second guess myself!
The Hardy-Weinberg Equilibrium confused me until you described how it was all a game of plugging things in. I then labeled all of the components on the top of the paper, and it became much easier that way.
Math and science has always been a weakness of mine but its neat when they lay out the correct way to calculate the percentages of genotype. Now if you were to ask me to do this without a calculator it prob be a little difficult.
😨😩😨😩 This is probably the most difficult mathematical, biological, anthropological equation I done ever had to witness, good read, but golly this was difficult just to understand, but it's def worth reading though.
Math and science has dependably been a shortcoming of mine yet its flawless when they lay out the right approach to figure the rates of genotype. Presently if you somehow happened to request that I do this without an adding machine it prob be somewhat troublesome.
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