Control - Abundance of resources in Prehistoric Nile Valley - 1 group scenario

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WHAT IS IT?

(a general understanding of what the model is trying to show or explain)

This is a control model where only one group of people are living in a land with equal resource distribution. This model shows that in the absence of any sort of competition, in the shape of other group of humans or changes in environment etc., a population continues to thrive until an external or internal factor acts on it. In this case, the factor can be time. This model stops after 500 ticks.

The code for this model was taken from the Netlogo practice tutorials on the Net Logo website. It is slightly adapted.

HOW IT WORKS

(what rules the agents use to create the overall behavior of the model)

The turtles eat, die and reproduce in this model. They consume energy from the 'grass' which in this case represents food. The turtles keep on eating, reproducing and dying until the model run reaches 500 ticks.

HOW TO USE IT

(how to use the model, including a description of each of the items in the Interface tab)

To use this model, the user has to press the ‘set up’ button followed by the ‘go’ button. The model goes on up till 500 ticks. There are a range of factors that can be altered as is demonstrated by a range of slider buttons. The description of the buttons is given below:

Set-up button: This button is used to reset the model. Go button: This is used to start and stop the model. This is a forever button. Count turtles button: This shows the number of turtles throughout the model run. This will increase as the model run progresses. Green patches button: This shows the number of green patches as the model runs. This fluctuates as the model run progresses. Show energy switch: This switch, when turned on, shows the individual energies of the turtles as the model runs. Initial-number slider: This button allows the user to set the number of initial turtles before running the model. Energy-from-grass slider: This slider lets the user set the amount of energy the turtles gain from consuming food which in this case is grass. Grass-regrowth-time slider: This slider button lets the user alter the amount of time it takes for the grass to grow back. The units are arbitrary however they are depicted as 'day' for a time reference. Birth-energy slider: This is an extra feature that lets the user set the birth energy of the turtles before a model run. The graph/plot: This shows the change in number of turtles and patches against time. Here, the user can observe graphically what is happening in the model in real time.

THINGS TO NOTICE

(suggested things for the user to notice while running the model)

Notice how the populations of turtle and grass fluctuate with time when different conditions are applied using the slider buttons.

THINGS TO TRY

(suggested things for the user to try to do (move sliders, switches, etc.) with the model)

Try altering the values on different sliders and see what type of behaviour emerges. For example, try running the model with the value of grass regrowth time really low like 1 day and then try it with 100 days and compare the results. Try altering the birth energy of the turtles. Try running it as zero for example and then at 100 and see what happens. Are turtles still able to reproduce with zero birth energy? How quickly do they reproduce at 100?

Note: Make sure only one or at most two factors are altered in one experiment and the rest are kept constant otherwise the results might become too confusing to interpret.

EXTENDING THE MODEL

(suggested things to add or change in the Code tab to make the model more complicated, detailed, accurate, etc.)

This is a fairly simple model and a range of features can be added to it to make it more complicated.

For example, another breed of turtles can be added.

Energies of different patches can be altered so 'food' is not distributed equally across the land. So in this case turtles would only be able to eat food if they land on the patch with energy. If the patch energy is zero, they do not consume any energy from that patch.

The dimensions of the Netlogo world can be made bigger.

NETLOGO FEATURES

(interesting or unusual features of NetLogo that the model uses, particularly in the Code tab; or where workarounds were needed for missing features)

This is a fairly simple model that lets the user observe how turtles interact with the patches and what type of emergent behaviour they exhibit when different factors such as birth energy or grass regrowth time are altered.

RELATED MODELS

(models in the NetLogo Models Library and elsewhere which are of related interest)

The links to related models are given below. They are found on NetLogo Modeling Commons:

Jebel Sahaba Model 1 - equal resource distribution: http://modelingcommons.org/browse/one_model/6783#model_tabs_browse_info

Jebel Sahaba Model 1 - equal resource distribution + cows: http://modelingcommons.org/browse/one_model/6786#model_tabs_browse_info

Jebel Sahaba Model 2 - unequal distribution of resources in the Nile Valley: http://modelingcommons.org/browse/one_model/6779#model_tabs_browse_info

Jebel Sahaba Model 2 - unequal distribution of resources in the Nile Valley - bigger world: http://modelingcommons.org/browse/one_model/6782#model_tabs_browse_info

Jebel Sahaba Model 3 - equal resource distribution 3 group scenario: http://modelingcommons.org/browse/one_model/6788#model_tabs_browse_info

CREDITS AND REFERENCES

(a reference to the model's URL on the web if it has one, as well as any other necessary credits, citations, and links)

These sources of information were directly used to construct the model or their content directly influenced the model. Individual citations and a range of other references related to warfare, violence and conflict amongst hunter gatherers and early societies are available in the main paper.

Crevecoeur, I. et al. (2021) ‘New insights on interpersonal violence in the Late Pleistocene based on the Nile valley cemetery of Jebel Sahaba’, Nature Scientific Reports. Nature Publishing Group UK, 11(1991), pp. 1–13.

Peterson, D. and Wrangham, R. (1997) Apes and the Origins of Human Violence: Demonic Males. 2nd edn. London: Bloomsbury Publishing Plc.

Railsback, S. F. and Volker, G. (2019) Agent-Based and Indivudual-Based Modelling: A Practical Introduction. 2nd edn. Princeton and Oxford: Princeton University Press.

Wilensky, U. (1999). NetLogo. http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.

Wrangham, R. (2020) Goodness Paradox: How evolution made us both more and less violent. 2nd edn. London: Profile Books.

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