Table 1.
Variable definitions.
Fig 1.
Summary statistics for vital rates and elasticities.
95% Confidence Intervals (Mean ± 2 SEM) are calculated across the age-specific vital rates estimated for five hunter-gatherer societies (dark blue fill, solid lines), five non-exclusive forager societies (light blue fill, dotted lines), and five wild chimpanzee populations (red fill, dashed lines). (A), Mortality (μx). (B), Age-specific fertility rate (ASFR). (C), Survival elasticities (Ex+1,x). (D), Fertility elasticities (E1x).
Fig 2.
Summary of demographic measures for chimpanzee and human populations.
(A) Stacked bars indicate survivorship (%) to maturity (lα), to mean age of reproduction (lM) and to maximum age of reproduction (lω); life expectancy (e0) is indicated by a large asterisk. (B) Stacked bars indicate rough ages at each parity from zero (nulliparous) to the total fertility rate (TFR) estimated for each population. Parity is indicated by inset text in each stacked bar, TFR is indicated above each bar and the mean interbirth interval (IBI) is in bold text inset in the lowest (nulliparous) bar. Vertical dashed lines separate Hunter-gatherers (HG), Non-Foragers (NF) and Wild Chimpanzees (WC). Hunter-gatherers are labeled: Ac (Ache), Ag (Agta), Ha (Hadza), Hi (Hiwi), Ku (Ju/’hoansi! Kung), hunter-gatherer mean life history (HG). Non-foragers are labeled: Ab (Aborigines), G (Gainj), Ts (Tsimane), Y(Yanomamo), He (Herero), non-forager mean life history (NF). Chimpanzee populations are labeled: Go (Gombe), Ka (Kanyawara), N (Ngogo), Ti (Taï), wild chimpanzee mean life history (WC), Ga (Gambia), Tr (Taronga).
Fig 3.
Ternary diagrams of elasticities and contributions.
(A) Populations are arranged using the summed fitness elasticities for vital rates underlying child survival (Ec, left axis), adult survival (Ea, right axis) and fertility (Ef, bottom axis). (B) Populations are arranged using the summed fitness effects (contribution magnitudes) made by differences in child survival (Cc, left axis), adult survival (Ca, right axis) and fertility (Cf, bottom axis).
Fig 4.
Net contributions of fertility (x-axis) and survival (y-axis) from a Life Table Response Experiment (LTRE) comparing humans and chimpanzees to the mean life history estimated across five hunter-gatherer societies.
Hunter-gatherer societies are indicated by filled circles, non-foragers by filled squares and chimpanzees by open circles; the non-forager mean life history (labeled NF) and the mean life histories for declining (WC-) and increasing (WC+) chimpanzees are each indicated with a black-and-white dot, and the mean hunter-gatherer (HG) reference by a bullseye at the origin. Contours show population growth rate (r) isoclines with a bold line at r = 0. Compared to the HG reference, populations have positive net survival contributions if they fall above the horizontal dashed line and positive fertility contributions if they fall to the right of the vertical dashed line. Humans are labeled: Ab (Aborigines), Ac (Ache), Ag (Agta), G (Gainj), Ha (Hadza), He (Herero), Hi (Hiwi), Ku (Ju/’hoansi! Kung), Ts (Tsimane), Y(Yanomamo); chimpanzee populations are labeled: Ga (Gambia), Go (Gombe), Ka (Kanyawara), N (Ngogo), Ti (Taï), Tr (Taronga).
Fig 5.
Summed contributions for each composite life history.
(A), stacked bars show summed contributions of infant, child and adult survival and of early, prime and late fertility to the net difference (Δr) in population growth rate (inset white bars) between the composite mean hunter-gatherer reference (HG) and each focal population, with the black-and-white line crossing the bars indicating the focal population growth rate (r = log(λ)). Note that positive and negative contributions are summed separately above and below the horizontal line at zero, and thus may reflect opposing contributions from the same life cycle component (e.g., negative and positive contributions of early vs. late infant mortality, respectively, if Δp0 < 0 and Δp1 >0). Results are shown for four composite life histories with vital rates averaged over: declining chimpanzees (WC-), all wild chimpanzees (WC), increasing chimpanzees (WC+), hunter-gatherers (HG), or non-foragers (NF). HG (indicated by a bullseye) has zero contributions by definition because it is the common reference. (B), total effects (Σ Cij*) reflecting the combined magnitude of contributions, are averaged across the populations within each of the groupings in (A) plus averaged across all human groups (HS), in contrast to the results for the pre-averaged mean life histories shown in (A). Stacked bars decompose the mean total effect (the proportion of the combined magnitude of all contributions) made by infant, child and adult survival and by early, prime and late fertility (inset text shows the percent of total effects, with late fertility effects labeled above the bars).
Table 2.
Fitness effect: Potential ratios.
Table 3.
Life history correlations.