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Ageing is mostly explained as a by-product of evolution, since selection weakens after reproduction. Biologists still debate whether it is a side effect or an optimised trade-off.
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Evolutionary mismatch is the idea that a trait shaped by one environment can become harmful when the environment changes faster than evolution can respond.
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The Prisoner's Dilemma shows that one-shot interactions favor defection. Cooperation can evolve when interactions repeat, as with reciprocity strategies like tit-for-tat.
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The handicap principle holds that signals are honest because they are costly. It became widely accepted, but a 2019 review argues the idea is erroneous and that honesty can evolve without costs.
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Richard Dawkins's 1982 idea holds that a gene's phenotype includes all its effects on the world, inside or outside the organism's body, such as dams, manipulated hosts and mimicry.
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Both theories explain how altruism evolves and can often be translated into each other mathematically. The dispute is over whether that equivalence means they describe the same causes.
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No. Humans and chimpanzees both descend from a shared, now extinct ancestor that lived roughly 8 to 6 million years ago, and each lineage has evolved separately since.
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It depends on what counts as a shark. Shark-like fishes date to about 400 million years ago, before the first trees, but modern sharks emerged about 195 million years ago, after them.
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Yes. Stegosaurus lived roughly 80 million years before T. rex, while T. rex lived about 66 to 70 million years before the present, so we are nearer to T. rex.
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DNA comparisons, protein tests and shared anatomy all point the same way: humans sit inside the great apes, and chimpanzees and bonobos are our closest living relatives.
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No one knows for certain. The leading idea is that losing fur helped early humans shed heat by sweating, while a parasite-based explanation is the main alternative.
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Researchers think long childhoods evolved mainly as time to learn complex skills and explore, supported by costly family care. Several explanations overlap, and none is settled as the only one.
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It proposes that women who stopped reproducing and helped feed grandchildren left more descendants, favoring long post-fertile lives. Specialists debate whether menopause itself was selected.
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No one knows for certain. Several overlapping hypotheses involve climate, food carrying, energy use, cooling and terrain, and the old savanna story has been revised.
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Richard Wrangham proposes that cooking made food easier to digest and richer in energy, freeing resources for bigger brains. The timing and the role of cooking remain debated.
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Human babies fit tightly through a rigid birth canal shaped by competing evolutionary pressures. Researchers still debate how much the old 'obstetrical dilemma' explains it.
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Sexual selection is evolution driven by success in winning mates rather than surviving. Darwin found the peacock's costly tail hard to explain by natural selection alone.
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Several mutations keep the lactase gene active in adulthood. They spread after animal domestication, though why they spread so strongly in Europe is still debated.
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