Human Evolution Simulation

Hominid Population

Population size 80

Selection pressure 0.6

Mutation rate 0.05

Seconds per generation 1.5

Generation

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Avg. trait

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Diversity (σ)

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Population

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How it works

Every hominid in the population carries one adaptive trait value x between 0 (small-brained, hunched ape-like ancestor) and 1 (large-brained, upright modern human) — a stand-in for real composite traits such as encephalization or bipedalism discussed in the article. Each generation, an individual's chance of becoming a parent is weighted by its fitness, so a higher trait value under strong selection pressure means more offspring — exactly the mechanism that pushed brain size and upright posture upward across the hominin lineage.

fitness(x) = 1 + pressure · (x − 0.5) · 2
offspring.x = clamp(parent.x + N(0, mutationRate), 0, 1)
parent ∝ fitness  (roulette-wheel selection)

Population size — smaller populations drift more: chance alone can shift the average trait even without selection, echoing genetic drift in small, isolated hominin bands.
Selection pressure — how strongly a higher trait value improves reproductive success; near zero the population just drifts, high values drive fast, steady increase.
Mutation rate — the spread added to each offspring's trait; too low and the population stalls once it runs out of variation to select on, too high and it never settles.
Seconds per generation — how fast time advances; slow it down to watch individual generations reshuffle, speed it up to see long-run evolutionary trends.

Watch the figures themselves change: as the average trait rises, bodies straighten toward an upright stance and heads enlarge — a visual echo of the transition from early hominids like Australopithecus to encephalized Homo species and eventually Homo sapiens.

Low trait (ape-like) Mid trait High trait (modern)

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