Engage: How did humans come to dominate the planet?
Post Darwin’s “On the Origin of Species,” scientists worked to put organisms into classes. First attempts to organize humans sought continental similarities between people.
Step 1: Go to the ArcGIS Online map, The Human Journey, and explore the map.
Step 2: With the Details pane visible, click the button, Show Contents of Map.
Step 3: Click the map notes near each of the continents.
- What traits could be used to differentiate people from different continents?
- Over the past 200 years, global migrations are increasing the variety of features seen in local populations, but blurring regional patterns in traits. (T/F)
Step 4: Turn off the layer, Continental People Groups.
Explore: What do blood-type distributions tell us?
Blood types, discovered in 1901, predict who can share blood without clotting and killing the recipient. Within 20 years, A, B, and O patterns were determined globally.
Step 5: Turn three layers on and off as needed for the following questions: Type O Blood Distribution, Type A Blood Distribution, and Type B Blood Distribution.
- What blood type is the most prevalent?
Explain: How did the blood type get us closer to the heart of the matter?
- What patterns occur in blood types?
- Where is Type A blood likely to be found?
This does not provide enough evidence, but it suggests to support the theory of Type O being the original blood type.
Elaborate: Why do those living in the Americas have such similar blood types?
Mitochondrial DNA mutates at rates higher than DNA from the cell nucleus. This leaves recognizable patterns in how long populations have been separated.
Step 6: Turn on the layers, Human Migration from Africa and Austronesian Expansion.
Many of the blood types in these regions can be explained by recent historic migrations. Australia and the eastern/central U.S. could be a legacy of European blood types due to recent immigration. Northern Canada could have possibly been influenced by arctic nomadic populations that also settle near Scandinavia.
- What might explain why Native Americans have such an overwhelming prevalence of O blood types?
Evaluate: What other blood type variations could be added to the map?
- What other old-world disease information can you find to look for spatial relationships to these blood types?