This assessment is based on a time trend analysis of census data from relatively well-studied Lion subpopulations (Packer et al . 2013, plus additional unpublished data provided by contributors). Census estimates were obtained by scientific research methods including total count, individual identifications, total or sample inventory using calling stations, radio telemetry, photo databases, spoor counts and density estimates based on direct observations corrected for patrol effort. These methods are rated as producing the most reliable type of Lion population estimates by background papers for the 2006 IUCN regional Lion workshops (Table 5 in Bauer et al. 2005a, b). We did not include population estimates for sites which were based on extrapolation of Lion densities obtained by research in other areas, or informed guesstimates by researchers. The minimum number of census surveys per site over the assessment time period is two, but some sites have been more regularly monitored (Table 3 - Data Points column, in Supplementary Material). In some cases census methodology varied between years, and for some surveys accuracy may have been low, but the complete data set shows an obvious trend that is unlikely to be an artefact of methodological insufficiencies.
IUCN Red List Criteria define three generations as the relevant time span for trend assessment. Lion Generation Length (GL) is based on the formulation of Pacifici et al . (2013):
Ionizing radiation has deterministic and stochastic effects on human health. Deterministic (acute tissue effect) events happen with certainty, with the resulting health conditions occurring in every individual who received the same high dose. Stochastic (cancer induction and genetic) events are inherently random , with most individuals in a group failing to ever exhibit any causal negative health effects after exposure, while an indeterministic random minority do, often with the resulting subtle negative health effects being observable only after large detailed epidemiology studies.
On average and after the end of puberty , males have darker hair than females and according to most studies they also have darker skin (male skin is also redder, but this is due to greater blood volume rather than melanin).   Male eyes are also more likely to be one of the darker eye colors. Conversely, women are lighter-skinned than men in all human populations.   The differences in color are mainly caused by higher levels of melanin in the skin, hair and eyes in males.   In one study, almost twice as many females as males had red or auburn hair. A higher proportion of females were also found to have blond hair, whereas males were more likely to have black or dark brown hair.  Another study found green eyes , which are a result of lower melanin levels, to be much more common in women than in men, at least by a factor of two.   However, one more recent study found that while women indeed tend to have a lower frequency of black hair, men on the other hand had a higher frequency of platinum blond hair, blue eyes and lighter skin. According to this one theory the cause for this is a higher frequency of genetic recombination in women than in men, possibly due to sex-linked genes, and as a result women tend to show less phenotypical variation in any given population.