The following is a list of my responses to the questions presented in the PBS Human Diversity quiz.

Approximately how old are modern humans?

I should know this, but I’ve forgotten the answer.  I want to say my first choice is 170,000 years because that’s the number that looks right; I know modern humans have been around for a long time, so (B) and (C) seem like too short.  My next guess is 1.2 million years, as 5 million seems too long.

Turns out my gut was right — hopefully next time I’ll be more confident in following it!

Which group has the most genetic variation?

Again, another question in which I’m not sure.  My gut says it’s not humans, as the group with the most genetic variation would be the one with subspecies.  Penguins and fruit flies I think are both subspecies themselves, same with chimpanzees — which leaves elephants as my guess.

As it turns out, fruit flies were the right answer: the text says that due to their short life span there’s more chances for genetic mutations — beyond that, they are a very old species.  This makes my guess very, very off!

What causes genetic variation in humans?

One of the things I’ve had difficulty with even since I took physical anthropology is fully remembering how each type of evolutionary pressure plays into changes.  In this case, I believe mutation is the only one that really changes genes — the rest have more to do with which genes survive from one generation to the next.

I was right for more or less the reasons I believed (remembering vocabulary is not my strong suit).

Which two present-day populations are most likely to be genetically similar?

This question I believe has most to do with locations: groups living next to each other and occasionally intermingling are more likely to have developed similarly than those who have been separated by distance and time.  As such, I believe the Saudi Arabians and Ethiopians to be the closest to each other, and therefore the most genetically similar.

So far, this was the question I have been most confident on, and most correct with the explanatory text in the answer.

What caused differences in skin color to evolve?

Considering the last module, this one should be easy, but I am caught between the environment and natural selection.  The environment causes the natural selection to happen (location causing more or less UVR). However, ultimately, the natural selection is what causes the evolution, so that’s my answer.

PBS puts the correct answer as (E) we don’t know, but I feel like the research that we were presented in the last module painted a very, very strong case for UVR being the cause, and natural selection — using the tribes in far north North America as the exception that proves the rule.

If you know a person’s skin color, what can you predict about them?

I feel like (C), the likelihood they will get certain inherited diseases is somewhat likely, considering the previous module pointed out that light-skinned people are more likely to have their folate destroyed in high-UVR areas, and dark-skinned people are likely to have vitamin D deficiencies leading to disease in low-UVR areas, as well as the lead-in to sickle cell — but the earlier paper talking about heart disease in African-American populations and how that’s more a case of socio-economic status than skin color, as well as all of the discussion about skin color not being bundled with many genetic traits (a population might have certain genetic traits, but that’s not really skin color) points me to pick (E) None of the above.

I was right, though the answer makes me feel like I might have misunderstood or read too far into diseases associated with eumelanin.

An individual from which of the following countries is most likely to carry the sickle cell trait?

Africa (and malaria) is what I associate sickle cell traits with, but I feel like this might be a trick question.  Even so, I’m going with gut and choosing South Africa.

It was wrong.  In my head, Mexico was my next choice (when I think of malaria carrying mosquitoes, I think of South America, and Mexico was the closest choice).  I was not expecting Greece, but I think that was the point of the question.  The fact that I associate sickle cell with Africa so strongly means that I need to pay more attention to the information we’re being presented with.

Which of the following is likely to be your ancestor?

This question confuses me, as it feels like all of these people are too recent for me to count as an ancestor — except Qin Shi Huang, since I have a little bit of Chinese ancestry in me.  Going by population percentages (Asia being the most populated continent), C is probably the right answer, with my second guess being none of the above, followed by all of the above.

I wasn’t completely wrong, just mostly wrong.  In any case, it’s an interesting concept to think about being related to all three of those individuals.

Which continent has the greatest human genetic diversity?

Given the answer to the fruit fly question, I feel like Africa is the best answer given it has the oldest modern human remains, and therefore is where we believe modern humans came from.

My reasoning was right, and I have a feeling I’m going to have a stronger recollection about genetic mutation after this quiz.

If a catastrophe wiped out everyone except people in Asia, how much of the genetic variation in our species would be left?

Due to the fact that there is not a lot of variaton between humans (which is a main argument for races not being a thing — we don’t have enough diversity to qualify for subspecies), I’m going to pick C) 94%.  I think I remember reading that total variation is something like 2-6% (or 4-6%).

I was partially wrong: the answer notes that “any local population contains 85% of all human genetic variation” which shows I was wrong on how much the human population varies — but the correct answer was indeed 94%.  My reasoning was wrong, but I arrived at the right answer.


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