Being fat is unhealthy because it does leave you more susceptible to disease.
That level of fat is not what I’m trying to address here. Many people are termed “fat” who are not so overweight as to actually correlate significantly with these diseases. I believe the data shows that exercise and genetic disposition, not weight, is more strongly correlated (sorry, no reference handy; feel free to prove me right or wrong on that). Many “fat” people are actually not at much of a health risk because they are in good shape, as you get at.
I would argue that the fat people would be killed off first
It depends on what kind of starvation scenario we’re talking about here. In the ancestral environment, starvation would typically be the result of changes in weather patterns. From what I understand, much of Africa during human evolution was temperate or subtropical forest with increasing amounts of savannah (the appearance of which it is often argued motivated the move to bipedalism). In a savannah seasonal changes drastically change the environment, such that in dry months there would be far fewer food resources than during wet months. Dry months don’t mean total starvation, but with fewer animals and fewer plants producing fruit or edible vegetative parts, the average daily caloric intake would have dropped. This is when fat reserves become important: fatten up in the wet months to help you make it through the dry months.
Total starvation scenarios don’t typically appear until the development of agriculture, because crop failure in an agricultural society often spells doom, especially if a monoculture provides the bulk of the sustenance. Such scenarios are a relatively recent occurrence, evolutionarily speaking, so we should expect to see only a slight selection effect as a result. In those cases, depending on the society, I can see how physical fitness may lead to survival (you out-compete your neighbors for the local food supplies, cf. post-apocalyptic survival scenarios), although the existence of a class of elites or strong cultural taboos might give greater advantage to those with other qualities.
What good are obese/severely obese people in the hunter/gatherer world?
None, but it’s a moot question because they don’t exist except perhaps in a hunter-gatherer society that is sufficiently large to require the emergence of strong hierarchical governance, thus allowing a few elites who no longer have to work to become fat. Just as with most animals, hunter-gatherers simply don’t have the opportunity to get fat.
That level of fat is not what I’m trying to address here. Many people are termed “fat” who are not so overweight as to actually correlate significantly with these diseases. I believe the data shows that exercise and genetic disposition, not weight, is more strongly correlated (sorry, no reference handy; feel free to prove me right or wrong on that). Many “fat” people are actually not at much of a health risk because they are in good shape, as you get at.
It depends on what kind of starvation scenario we’re talking about here. In the ancestral environment, starvation would typically be the result of changes in weather patterns. From what I understand, much of Africa during human evolution was temperate or subtropical forest with increasing amounts of savannah (the appearance of which it is often argued motivated the move to bipedalism). In a savannah seasonal changes drastically change the environment, such that in dry months there would be far fewer food resources than during wet months. Dry months don’t mean total starvation, but with fewer animals and fewer plants producing fruit or edible vegetative parts, the average daily caloric intake would have dropped. This is when fat reserves become important: fatten up in the wet months to help you make it through the dry months.
Total starvation scenarios don’t typically appear until the development of agriculture, because crop failure in an agricultural society often spells doom, especially if a monoculture provides the bulk of the sustenance. Such scenarios are a relatively recent occurrence, evolutionarily speaking, so we should expect to see only a slight selection effect as a result. In those cases, depending on the society, I can see how physical fitness may lead to survival (you out-compete your neighbors for the local food supplies, cf. post-apocalyptic survival scenarios), although the existence of a class of elites or strong cultural taboos might give greater advantage to those with other qualities.
None, but it’s a moot question because they don’t exist except perhaps in a hunter-gatherer society that is sufficiently large to require the emergence of strong hierarchical governance, thus allowing a few elites who no longer have to work to become fat. Just as with most animals, hunter-gatherers simply don’t have the opportunity to get fat.