Under the environmental conditions of the savanna, the behavior of upright walking was advantageous to survival and reproduction. Those who didn’t engage in this behavior couldn’t survive so welland/or had less offspring. So there was natural selection of this behavior and the behavior became more frequent in the population.
We can represent this with a red arrow from environment to the trait “upright walking”, that means “requires, favors the natural selection of”.
Remember what natural selection means: it’s a mechanism that influences the frequencies of traits in the population. (draw icon of population change, as a reminder of the natural selection worksheet)
Check for understanding: Ask a student to explain in their own words what the causal map shows.
requires/ favors the natural selection of...
Upright walking
Environmental conditions of the savanna
If the behavior of upright walking was advantageous to survival and reproduction, those whose body features enabled that behavior or made it more efficient, had again higher chances of survival and reproduction than others. So there was natural selection of these body features and they became more frequent in the population.
We can represent this again with a red arrow from the behavioral trait “upright walking” to the body features enabling that behavior.
Remember what natural selection means: it’s a mechanism that influences the frequencies of traits in the population. (draw icon of population change under the second red arrow)
Check for understanding: Ask a student to explain in their own words what the causal map shows.
requires/ favors the natural selection of...
Body features enabling upright walking
Upright walking
Environmental conditions of the savanna
We can also add a different kind of arrow to the causal map that represents the way that these two traits influence each other.
A green arrow means “enables” or “facilitates” or “favors the development of”.
So these body features enable or facilitate or favor the development of this behavior of upright walking - those who have these body features are more likely to walk upright more often.
Check for understanding:
Ask the class - so now can I also draw a green arrow from the behavior of upright walking to the environment?
No - it does not make sense that the behavior of upright walking enables or in some other way influences the environmental conditions.
Check for understanding: Ask students to explain in their own words what the causal map shows.
enables, facilitates, favors the development of...
requires/ favors the natural selection of...
Body features enabling upright walking
Upright walking
Environmental conditions of the savanna
So those who engaged in the behavior of upright walking and had body features that enabled upright walking, had higher chances of reproduction. But only those whose body features were influenced by their genes, would inherit these traits to their offspring.
So there was natural selection of these genes and they became more frequent in the population.
We can represent this again with a red arrow from the body features enabling that upright walking, to the genes that are involved in the development of these body features.
Remember what natural selection means: it’s a mechanism that influences the frequencies of traits in the population. (draw icon of population change under the third red arrow)
Check for understanding: Ask a student to explain in their own words what the causal map shows.
enables, facilitates, favors the development of...
requires/ favors the natural selection of...
Body features enabling upright walking
Upright walking
Environmental conditions of the savanna
Genes involved in the development of body features enabling upright walking
enables, facilitates, favors the development of...
requires/ favors the natural selection of...
Check for understanding:
Ask the class - so now can I also draw a green arrow from the genes to the body features?
yes, genes were selected that enable or favor the development of these body features
So these genes favor the development of body features - those who have these genes are likely to develop these body features.
Body features enabling upright walking
Upright walking
Environmental conditions of the savanna
Genes involved in the development of body features enabling upright walking
Other people walking upright, giving support, cheering on
Causal map expansion with the possible role of social environment in the development of the behavioral trait of upright walking
What might be the role of the social environment in the development of our ability to walk upright?
Would we humans learn to walk upright, if there weren’t other humans around who also walked upright, who gave us support in our attempts to walk upright, who cheered us on?
How could we expand our causal map to include the possible role of the social environment in the development of upright walking?
let students discuss and then ask students to add the piece “other people walking upright…” to the causal map on the board
enables, facilitates, favors the development of...
requires/ favors the natural selection of...
Body features enabling upright walking
Upright walking
Environmental conditions of the savanna
Genes involved in the development of body features enabling upright walking
Environmental conditions�of the savanna
Upright Walking
Body features that facilitate/ enable�upright walking
Genes that influence �the development of these body features
Other people walking upright, giving support, cheering on
Human body features enabling upright walking and quadrupedalism
Other people walking on all fours, lack of doctors or other supports for upright walking
Genes that hinder the development of the cerebellum
Function of the cerebellum (motor control and balance)
enables, facilitates, favors the development of...
constrains, decreases, limits
Quadru-
pedalism
Causal map for reflecting on possible causation in Uner Tan Syndrome - humans who habitually walk on all fours.
Note that this is one way to depict the presumed complex interactions between enabling and constraining factors during development.
Upright walking
Author: Susan Hanisch
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This work is licenced under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) Licence.
This material was developed in collaboration with the department of Comparative Cultural Psychology at the Max Planck Institute for Evolutionary Anthropology and the biology education working group of Friedrich Schiller University Jena.
https://www.eva.mpg.de/comparative-cultural-psychology/research-areas/education-innovation/ https://www.biodidaktik.uni-jena.de/