30-Second Evolution

Evolution by natural selection made humanity; evolution by culture will complete it.

Around 1.8 million years ago Homo erectus adopted a hunter-gatherer lifestyle and spread out of Africa and into Asia. The next few hundred millennia witnessed the evolution of the Neanderthals in Europe, the Denisovans in Asia and in Africa, about 200,000 years ago, Homo sapiens. This last species spread out of Africa and by 60,000 years ago reached Australia; 40,000 years ago they reached Europe and 15,000 years ago arrived in South America.

Hominins Hominids that are genetically closer to human beings than chimpanzees – Homo sapiens is the only extant (living) species of hominin.

Hominids The family of primates that in living species comprises the great apes: humans, chimpanzees, gorillas and orangutans. It also includes the extinct species that are closer to us than the chimpanzee.

Other key concepts on which Hamilton worked were Hamiltonian spite and extraordinary sex ratios. Spite is, biologically, the antithesis to altruism, the idea that there is a genetic survival benefit to harming those who are less similar to yourself than the average population. Such ‘spiteful’ behaviour does exist – for example, when animals kill the infants of their rivals – but the concept has never had the same level of support as altruism in evolutionary psychology.

sexual, rather than asexual, reproduction allows for swifter response to evolutionary demands because it boosts genetic variation.

‘Red Queen’ hypothesis The idea that – like Lewis Carroll’s character the Red Queen in Through the Looking-Glass who had to keep running simply to stay in the same place – organisms need to evolve in order to survive when the environment, competitors and predators are themselves evolving.

The peppered moth’s colouring enabled it to blend well with lichen-covered trees. However, during the Industrial Revolution, pollutants killed the lichen, exposing darker bark in trees that were also blackened directly by soot. Dark moths in the population were better camouflaged when resting on a blackened tree, so had a better chance of surviving the attacks of predators and hence reproducing. As a result, natural selection over generations produced more dark moths.

Species that look similar are not always close relatives – physical adaptation to a shared environment has given them similar features despite a very different inheritance.

Convergence is characterized by species overtly sharing very similar characteristics, when those characteristics are not similar by descent. The ancestors of dolphins were land-dwelling deer-like animals that were well adapted for a terrestrial lifestyle and lived around 60 million years ago. In contrast, the ancestors of fish lived in the sea well over 500 million years ago.