Milly Gaines
Diet breadth is a classic optimal foraging theory (OFT) model from human behavioural ecology (HBE). It is used by anthropologists to model the decisions made by hunters and gatherers about how to get enough food. Diet breadth models are built on the presumption that, in ideal circumstances, a hunter will only exploit the most profitable prey. The model takes into account the time it takes to encounter prey ('search time') and the time it takes to capture and process the animal ('handling time').
| Characteristics | Values |
|---|---|
| Definition | Diet breadth is a classic optimal foraging theory (OFT) model from human behavioral ecology (HBE) |
| Basis | Diet breadth models are built on the presumption that, in ideal circumstances, a hunter will only exploit the most profitable prey |
| Factors | Overall foraging time depends on "search time" and "handling time" |
| Decision-making | A forager will preferentially take the highest-ranked resources (providing the highest net return). Within increasing dietary stress, a forager will be willing to take a wider variety of resources at different ranks |
| Dietary niche width | Taxonomic diet breadth is an incomplete index of host range or dietary niche width |
| Dietary niche width calculation | Phylogenetic family-level diet breadth, as measured by phylogenetic distance (PD) among hosts, changes globally: mean PD declines toward lower latitudes |
| Specialization | Higher values of the shape parameter (α) indicate more specialized diets |
Explore related products
What You'll Learn
- Diet breadth is a classic model from human behavioural ecology
- Diet breadth is used to model decisions made by hunters and gatherers
- Diet breadth is based on the presumption that hunters will only exploit the most profitable prey
- Diet breadth is influenced by the time it takes to encounter and capture prey
- Diet breadth is related to the diversity of available resources
Diet breadth is a classic model from human behavioural ecology
The model assumes that a forager will preferentially take the highest-ranked resources, providing the highest net return. The ranking is based on the food value and processing costs of different resources, which are distributed in the environment in different densities. For example, a hunter might encounter many squirrels but will still not bother to hunt them unless their desired resources become more costly. This is because the use of a resource is decided not by its own value but by the value of the resources ranked above it. As such, top-ranked resources are often overhunted until they become too costly to find, leading foragers to turn to lower-ranked resources.
The diet breadth model also considers the costs of searching for a resource and the costs associated with processing it once captured. The key assumption is that the forager is attempting to maximize their energy returns. As such, the model predicts that within increasing dietary stress, a forager will be willing to take a wider variety of resources at different ranks. For instance, hunters may expand their diet late in the hunt because there are few remaining encounter opportunities.
Archaeologists have used the diet breadth model to explain various human behaviours, such as why the first people in the Americas focused on hunting mammoths and why people eventually expanded their diet to include labour-intensive gathering of small seeds and grains, eventually leading to permanent agriculture.
Mountain Dew's Zero-Calorie Claim: Fact or Fiction?
You may want to see also
Explore related products
Diet breadth is used to model decisions made by hunters and gatherers
Diet breadth is a classic model from optimal foraging theory (OFT) in human behavioural ecology (HBE). It is used to model decisions made by hunters and gatherers about how to get enough food. The model simplifies a complex problem to just a few variables, such as the time and energy spent searching for and processing food.
The model assumes that a hunter-gatherer will spend a certain amount of time searching for food. When they encounter a resource, they will consider the additional time spent chasing it and the energy return in the form of kilocalories. The resource's rank, which is determined by its post-encounter return rate, will influence whether the hunter-gatherer decides to take it. The post-encounter return rate is calculated by dividing the time to catch and process a resource by the kilocalorie return.
According to the diet breadth model, a hunter-gatherer will preferentially take the highest-ranked resources, which provide the highest net return in terms of energy. However, under increasing dietary stress, they may be willing to take a wider variety of lower-ranked resources. This can lead to overhunting of top resources until they become scarce, at which point lower-ranked resources become more attractive.
The model has been used to explain various dietary patterns, such as the focus on hunting mammoths by early Americans and the eventual expansion to include labour-intensive gathering of small seeds and grains, leading to permanent agriculture. It also helps understand the variation in diets among tropical hunter-gatherer groups, with some studies indicating higher consumption of animal foods in certain contexts.
Calorie Counting: Should Exercise Calories Be Added Back?
You may want to see also
Explore related products
Diet breadth is based on the presumption that hunters will only exploit the most profitable prey
Diet breadth is a classic optimal foraging theory (OFT) model from human behavioural ecology (HBE). It is a popular model used by anthropologists to make predictions about hunter-gatherer decisions regarding food acquisition. Diet breadth assumes that hunters will only exploit the most profitable prey, with profitability determined by several ecological variables.
The model predicts that hunters will ignore low-profitability prey when more profitable options are present and abundant. The profitability of prey is influenced by the amount of energy (calories) it provides, the handling time required to process it, and the search time needed to locate it. For example, an animal will choose to eat prey1 over prey2 if the energy gained from prey1 outweighs the combined handling and search time for prey1.
The diet breadth model simplifies a complex problem by focusing on a few key variables. It assumes that hunters have basic knowledge of their environment, such as their chances of catching different types of prey and the time and effort required to process them into edible products. This knowledge guides their decisions on which prey to pursue.
The model has been applied to understand dietary choices in both ancient and modern contexts. For instance, it has been used to explain why early humans in the Americas focused on hunting mammoths and why they eventually expanded their diet to include labour-intensive gathering of small seeds and grains, leading to the development of permanent agriculture.
Additionally, diet breadth is interconnected with land use, technology, and economy. Changes in diet breadth can indicate shifts in social organisation and subsistence strategies. For example, in the Gobi Desert, hunter-gatherer groups took advantage of a diverse range of plant and animal species, increasing their caloric intake and the potential for storable food commodities. This expansion of diet breadth may have contributed to the reorganisation of technology and settlement patterns during the early to middle Holocene.
The BRAT Diet: What Does It Mean?
You may want to see also
Explore related products
Diet breadth is influenced by the time it takes to encounter and capture prey
Diet breadth is a classic optimal foraging theory (OFT) model from human behavioural ecology (HBE). It is a measure of the range of food types eaten by an animal within a habitat. The diet breadth model is used by anthropologists to understand the decisions made by hunters and gatherers about how to obtain enough food.
The optimal diet model, also known as the prey choice model, predicts that a forager will ignore low-profitability prey items when more profitable items are present and abundant. The profitability of a prey item is dependent on several ecological variables, including the amount of energy (calories) that a prey item provides the predator, and the handling time, which is the amount of time it takes the predator to handle the food, beginning from the time the prey is found to the time it is eaten. The search time is also a factor, which is the amount of time it takes to find a prey item and is dependent on the abundance of the food and the ease of locating it.
The time it takes to encounter and capture prey is a key factor in influencing diet breadth. The rate of prey capture is dependent on the density of the prey. At low prey densities, the search time is long, and the predator eats every prey item it finds. As prey density increases, the rate of prey capture also increases, and the predator can afford to be more selective, choosing only the prey items with the highest profitability (E/h).
In practice, the optimal foraging theory can be limited by the difficulty in defining basic concepts such as prey type, encounter rates, and the patch as perceived by the forager. The theory also does not always accurately predict the diets of foragers that hunt mobile prey, as the variability in encounter rates and capture success may be more important in determining predator diets than the active choices of predators.
Overall, the time it takes to encounter and capture prey is a critical factor in influencing diet breadth, as it determines the profitability of different prey items and the selective behaviour of predators.
Calorie Counting on the Mediterranean Diet: How Many?
You may want to see also
Explore related products
Diet breadth is related to the diversity of available resources
Diet breadth is a classic optimal foraging theory (OFT) model from human behavioural ecology (HBE). It is used to model the decisions made by hunters and gatherers about how to get enough food. Diet breadth is related to the diversity of available resources, as well as the time and energy costs of foraging.
The model assumes that a forager will preferentially take the highest-ranked resources, providing the highest net return in terms of food value and processing costs. The ranking of resources is based on their food value and processing costs, which can include the time it takes to encounter, capture, and process the food. For example, a hunter might know their chances of catching a deer, how long it will take to catch it, how much edible food it will provide, and how long it will take to process.
Within increasing dietary stress, a forager will be willing to take a wider variety of resources at different ranks. This can lead to overhunting of top resources until they become too costly to find, at which point lower-ranked resources enter the diet. The use of technology can also make lower-ranked resources more attractive by reducing handling time, such as using nets to catch a lot of squirrels or rabbits at once.
The global distribution of diet breadth in insect herbivores provides additional insights into the relationship between diet breadth and resource diversity. Phylogenetic family-level diet breadth, as measured by phylogenetic distance (PD) among hosts, changes globally, with mean PD declining toward lower latitudes. This is driven by the increase in the number of specialists (species with low PD) at lower latitudes, indicating a negative relationship between the diversity of available resources and the diet breadth of consumers.
Calorie-Controlled Diets: Counting Every Calorie Counts
You may want to see also
