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Dairying, diseases and the evolution of lactase persistence in Europe, Evershed et al, 2022

Discussion in 'Other health news and research' started by cassava7, Jul 28, 2022.

  1. cassava7

    cassava7 Senior Member (Voting Rights)

    Messages:
    985
    In European and many African, Middle Eastern and southern Asian populations, lactase persistence (LP) is the most strongly selected monogenic trait to have evolved over the past 10,000 years1. Although the selection of LP and the consumption of prehistoric milk must be linked, considerable uncertainty remains concerning their spatiotemporal configuration and specific interactions2,3.

    Here we provide detailed distributions of milk exploitation across Europe over the past 9,000 years using around 7,000 pottery fat residues from more than 550 archaeological sites.

    European milk use was widespread from the Neolithic period onwards but varied spatially and temporally in intensity. Notably, LP selection varying with levels of prehistoric milk exploitation is no better at explaining LP allele frequency trajectories than uniform selection since the Neolithic period.

    In the UK Biobank4,5 cohort of 500,000 contemporary Europeans, LP genotype was only weakly associated with milk consumption and did not show consistent associations with improved fitness or health indicators. This suggests that other reasons for the beneficial effects of LP should be considered for its rapid frequency increase.

    We propose that lactase non-persistent individuals consumed milk when it became available but, under conditions of famine and/or increased pathogen exposure, this was disadvantageous, driving LP selection in prehistoric Europe.

    Comparison of model likelihoods indicates that population fluctuations, settlement density and wild animal exploitation—proxies for these drivers—provide better explanations of LP selection than the extent of milk exploitation. These findings offer new perspectives on prehistoric milk exploitation and LP evolution.

    https://www.nature.com/articles/s41586-022-05010-7

    Author-provided access to the PDF: https://go.nature.com/3vHVEn5

    Twitter summary thread by Adam Rutherford:
    https://twitter.com/user/status/1552317438829760515
     
  2. shak8

    shak8 Senior Member (Voting Rights)

    Messages:
    2,203
    Location:
    California
    why would famine be a deterrent to consuming milk?
     
    Peter Trewhitt and MeSci like this.
  3. cassava7

    cassava7 Senior Member (Voting Rights)

    Messages:
    985
    Per the article:

    “First, as postulated in ref. 24, the detrimental health consequences of high-lactose food consumption by LNP individuals would be acutely manifested during famines, leading to high but episodic selection favouring LP. This is because lactose-induced diarrhoea can shift from an inconvenient to a fatal condition in severely malnourished individuals [69] and high-lactose (unfermented) milk products are more likely to be consumed when other food sources have been exhauster. This we name the 'crisis mechanism', which predicts that LP selection pressures would have been greater during times of subsistence instability.”

    (L(N)P = lactase (non) persistence)

    Ref 24: Direct estimates of natural selection in Iberia indicate calcium absorption was not the only driver of lactase persistence in Europe, Sverrisdóttir et al, 2014

    Ref 69: Malnutrition as an underlying cause of childhood deaths associated with infectious diseases in developing countries, Rice et al, 2000
     
    Last edited: Jul 28, 2022

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