Two main ideas I think people may get wrong. One is that there needs to be survival of an individual (not dying), while it rather refers to survival of a speci

Two main ideas I think people may get wrong. One is that there needs to be survival of an individual (not dying), while it rather refers to survival of a species (not going extinct). This survival thus has little to do with actual life or death, rather it has to do with reproduction. For example a one-day-fly is, generally spoken, in a terrible situation when it comes to survival, it's life/death perspective is awful, just one day. But it survives as a species because its able to reproduce so rapidly that even a short life doesn't make the species go extinct. Evolution doesn't care for survival of an individual as long as that individual manages to reproduce before it does. The second is that there is somehow some 'fitness' variable, the better the more you survive. So a lion would be more fit than say a fly because it's stronger. But this too refers to a different concept, which is that 'fit' is in relation to the environment. A fly is quite fit to live in many environments over long periods of time, whereas a lion isn't fit for many environments and will have trouble surviving say changes in climate and habitat. Fitness is thus purely in relation to its environment. So really 'survival of the fittest' is more like 'species fit for the environment will survive long enough to reproduce', or something to that effect. From this then originates the argument that random mutations of a species will create different offspring that is more or less fit for the environment, and those more fit will survive, those less fit will not. That is survival of the fittest. And again, when I refer to survive, I mean the species, on the basis that when individuals of a species are fit for their environment, they have a good chance of reproducing enough offspring before death preventing the species from going extinct.