Name________________________________________
HUMAN EVOLUTION LAB
Write all answers in complete sentences, please.
Part 1. Comparative Mitochondria DNA Analysis.
We will view some good resources at DNAi (http://www.dnalc.org/view/15165-Mitochondrial-Eve-MarkStoneking.html)
Mitochondrial DNA is usually passed on by the mother and cannot change except by mutations. These mutations
occur randomly as a natural process of living on this planet. By comparing DNA pattern, biochemists can detect
any new mutations that have been added to the small piece of original mtDNA that was passed on from mother
to child through thousands of human generations.
If a group of humans splits off from a common ancestral group, then both groups will begin to accumulate
different mutations from each other. Each group is genetically separated from the other group. This starts at the
point where they no longer interbreed. The easiest way to show that two groups have separated in the past is to
count the number of new mutations found in the mtDNA of one group and not found in the mtDNA of the other
group. The greater the number of different mutations, the longer the amount of time the two groups have been
separated from each other. If the mtDNA of groups is quite similar, they have not been separated for very long.
Provided below is a “pretend” sample of mtDNA of four geographically separate groups. Each bar represents a
mutation. As you can see, I have a DNA fingerprinting image here. The process for mapping mtDNA is similar, so
I have taken the liberty of swapping (in your mind, replace “suspects” with “anthropological samples”). For
mtDNA the sample is from a group. For DNA fingerprinting, the sample is from individuals. Let’s call the groups
CS, S1, S2, and S3.
National Institutes of Health. GeneEd. http://geneed.nlm.nih.gov/topic_subtopic.php?tid=37&sid=38. 16 Nov 2014. Web.
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Answer these questions.
1. Which two groups are the most similar?
2. Which one is the most different from the other groups?
3. Which group has been geographically or reproductively separated from the others the longest?
4. Which two groups have not been separated from each other as long?
Biologists have determined that it takes about 500,000 years for 1% of the mtDNA to be changed by mutation.
This mutation rate can be used as a molecular clock.
Researchers have gone around the world and collected mtDNA samples and have counted the small number of
differences between humans today. Each one of the differences represents a mutation equal to an amount of
time on the mitochondrial clock.
A representative sample of different human geographical location/ethnic origin DNA has been collected and
analyzed. When all the different mutations were counted, scientists found that only 0.4% of the DNA of modern
humans had been mutated.
5. Calculate how many years modern humans have been on this planet. It takes 500,000 years for 1% to be
mutated. (Hint: use multiplication for this type of question.)
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If you want to know how long it has been since two groups have been separated, you must
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Use the figure, as determined by genetic researchers, for the percent of genetic difference
between the two groups.
Multiply the percent of genetic difference by 500,000 years.
6. Using this information, calculate approximately how long the two groups described below have had the
opportunity to interbreed. Show your work.
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Group A, the Altitudinals, have lived in the high mountain ranges of Nepal for as long as anyone
can remember.
Group B, the Basinals, have lived in the flat delta country for hundreds of centuries.
A genetic researcher has recorded a 0.5% difference in their mtDNA between the Altitudinals
and the Basinals.
How long have the groups been interbreeding? Show your work.
7. When genetic researchers compare the DNA of northern Asian populations with Native American
populations, they find a 0.7% difference. According to the mitochondrial clock formula, how many years
has it been since separation of these two groups? Show your work.
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Part 2. Hominid Skull Comparison
1. Pick three skulls one at a time from the counter, make the observations indicated on this table, and
enter the data. Measure in centimeters using the calipers.
* protruding maxilla or mandible, such as one might see in a dog
** a space between a canine and an incisor of the upper jaw into which a lower canine occludes (goes into)
*** compression and slanting forward of lower canines and lower incisors
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2. Use your data from the skull comparisons to answer the following. Write in detail after close
observation.
A. Which traits distinguish Specimen A from Specimen B?
B. How is Specimen C different from Specimen A?
C. How is Specimen C different from Specimen B?
D. Is Specimen C more closely related to A or B? Give evidence.
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University of Connecticut. Primate Evolution. http://cognition.clas.uconn.edu/~jboster/courses/anth1006_f13/lectures/primate_evolution/index.htm. 16
November 2013. Web.
Part 3. Thinking About Humans
1. List five obstacles to migration of early hominids/humans and how natural selection could have acted to
mold separate populations.
To answer this, you would think about early humans and how they spread across the world and what they could
have encountered. The answer comes from different concepts in the text being put together. If we begin with the
earliest hominids, they separated into groups and dispersed across Africa. As each group encountered different
environments, some individuals would have genes that adapted them to that environment and live and those
unadapted would die or not produce offspring. The ones that survived would likely reproduce; and the genes
associated with the adaptation is carried to the next generation. This is called natural selection and is the one of
the ways that hominids evolved into to different species, eventually Homo sapiens.
So with that think about what physical obstacles would have been the environmental force for this live or die
scenario. Would the food be different in different places and certain individuals could not metabolize it? Would
the trek across hostile environements be too much for some, and only the extremely hardy would make it?
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2. List five obstacles to survival once the hominids/humans were relatively settled.
Again this is an opportunity to think about natural selection. Picture yourself in a group of pre-humans; what sort
of pressures would be on you? Disease, predation, etc.?
3. Name five natural selection pressures on modern humans and hypothesize about how they could shape
human evolution.
Now that you get the idea, think about what in our modern world causes humans to die or to not reproduce.
These are natural selection pressures.
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4. Define mutation, natural selection, genetic drift, and gene flow. In terms of these processes, discuss the
differences in the groups represented by the hominid skulls you chose to observe above. In other words,
how could these processes have shaped the evolution of these populations?
The first part is on page 513. Think about the skulls you chose to examine. How were they different from each
other? What can you learn from your text about them (p. 518-520)? If they started as one group, what could
have happened through natural selection to make them different?
5. Make a list of the skulls you measured today and explain the fate of each of these hominid ancestors of
modern humans.
In your text p. 518-520, that they became extinct may be stated. That is obvious! Please tell me why you think
this happened.
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More on back 
6. What traits do humans possess that might have given them an advantage in evolution and affecting
other species?
7. List the taxonomic classification of humans starting with the domain designation and ending with our
proper species name in proper format.
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