Fitness is scalable for the rich

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When fecundity does not equal fitness: evidence of an offspring quantity versus quality trade-off in pre-industrial humans:

Maternal fitness should be maximized by the optimal division of reproductive investment between offspring number and offspring quality…We used a dataset of humans spanning three generations from pre-industrial Finland to test how increases in maternal fecundity affect offspring quality and maternal fitness in contrasting socio-economic conditions. For ‘resource-poor’ landless families, but not ‘resource-rich’ landowning families, maternal fitness returns diminished with increased maternal fecundity. This was because the average offspring contribution to maternal fitness declined with increased maternal fecundity for landless but not landowning families. This decline was due to reduced offspring recruitment with increased maternal fecundity. However, in landowning families, recruited offspring fecundity increased with increased maternal fecundity. This suggests that despite decreased offspring recruitment, maternal fitness is not reduced in favourable socio-economic conditions due to an increase in subsequent offspring fecundity. These results provide evidence consistent with an offspring quantity-quality trade-off in the lifetime reproduction of humans from poor socio-economic conditions. The results also highlight the importance of measuring offspring quality across their whole lifespan to estimate reliably the fitness consequences of increased maternal fecundity.

Remember the fecund upper classes in Farewell to Alms? In any case, one thing that I have assumed is that this sort of model might explain the success of the Neolithic lifestyle despite its decreases of average quality of life. When populations first take up farming, or migrate to a new area, they are well below the Malthusian limit. In contrast resident hunter-gatherers, who aren’t as efficient at extracting productivity per unit area, would already be at their Malthusian limit. One can imagine that a Neolithic deme would rapidly expand and demographically surpass the hunter-gatherers around them. During the initial phases of expansion there would be enough land so that all farmers might be prosperous on a absolute scale. Consider the fitness, both reproductively and physiologically, of Americans on the frontier in comparison to their European ancestors. Of course, within a few generations the land would be “filled up” and a stagnant stationary state would be reached…at which point health decreases and the social pathologies characteristic of down-trodden peasantry would manifest themselves.

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12 Comments

  1. Razib, 
     
    Often, hunter-gatherer societies are far healthier than their settled cousins. (Farewell to Alms mentions the heights of the American Indians encountered by the western explorers, for instance.) This is because hunter-gatherer societies can also be well below the Malthusian limit: if you kill enough people off through feuds, violence, and war, starvation never becomes an issue.

  2. What does “recruitment” mean here? 
     
    Henry Harpending

  3. This is because hunter-gatherer societies can also be well below the Malthusian limit: if you kill enough people off through feuds, violence, and war, starvation never becomes an issue. 
     
    right. though i think lower population density & lack of mutualism with domesticate animals are independent parameters not related to malthusianism as such which one needs to take into account (the diverse diet is related to the malthusian limit obviously). i say population density is independent because even ag societies not at the malthusian limit, like farmers on the american western frontier, probably are subject to more epidemics because of their relative density.

  4. What does “recruitment” mean here? 
     
    i was puzzled by this wording too. i looked it up and the best i can tell is that it means the offspring stays alive long enough to make it into the breeding population. i’m still not positive this is the true meaning however.

  5. It is quite probable, as well, that the hunter-gathering band is likely to approach such straits as the Malthusian far more slowly through some voluntary limitation of fecundity, recognizing the interference such offspring pose to their food-gathering requirement of frequent site-change. Munchkin manageability differs appreciably from that of the settled planters.

  6. Dan: 
     
    If feuds, violence, and war are all that separate you from starvation, you’ve reached the Malthusian limit.

  7. Henry and Wongba: 
     
    I’m also somewhat puzzled but interpreted it as signifying a period of change upon completion of which the individual becomes a net contributor to the fortunes of the group.

  8. It is quite probable, as well, that the hunter-gathering band is likely to approach such straits as the Malthusian far more slowly through some voluntary limitation of fecundity, recognizing the interference such offspring pose to their food-gathering requirement of frequent site-change. 
     
    by ‘voluntary limitation’ = infanticide & extended weening. but you’re right, many HG groups are notably anti-natalist because they can’t drag a gaggle of toddlers around. mobility serves as a constraint. the number of gestations that a farmer’s wife is expected to go through is freakish.

  9. i think wongba is right. that is what i assumed it was, and casual googling seems to confirm assessment. it would be nice if life history biologists would use english when possible ;-) but since this is out of a finn lab one can’t expect too much intelligibility….

  10. Razib, 
     
    “even ag societies not at the malthusian limit, like farmers on the american western frontier, probably are subject to more epidemics because of their relative density.” 
     
    Right. In “Farewell to Alms,” Clark emphasizes that East Asian societies managed much higher population densities than Europe, because the European lifestyle was filthier (hence more disease, less people, higher living standards). 
     
    Gene, 
     
    “If feuds, violence, and war are all that separate you from starvation, you’ve reached the Malthusian limit.” 
     
    Could you rephrase? I don’t understand this.

  11. Dan: 
     
    Just reference to the remark that they didn’t reach the Malthusian limit–starvation–because those other activities kept them “well under.” 
     
    You pays yer money and picks yer Malthusian limit. 
     
    Or maybe God does it. (Yer gets to pick yer explanation, too.) And yer description: nasty, brutish, and short or nasty, brutish, and shorter. More than one way to skin whatever yer a mind to. Or, whatever floats yer ark. And, since I brought it up: Did Noah get weather reports from NOAA? 
     
    Sorry–I sometimes get under the influence (of stuff like “though he might have been more humble, there’s no police like Holmes.” and I just have to get it out of my system.

  12. Dan: 
     
    I was thinking of writing A Farewell to Arums but realized I don’t know anything about ‘em.

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