This is very wrong. Evolution is selecting for the total reproductive fitness of genes, and to a slightly lesser extent, individuals. There’s no mechanism that helps the process of evolution select for the survival or reproduction of the species. See any recent textbook on evolutionary biology, or read Dawkins, or even Darwin. I don’t know where you got this idea but it’s exactly wrong.
The "mechanism" is just the process of evolution itself, and how it plays out in practice, e.g. via punctuated equilibrium.
Over shorter timespans the gene pool of a breeding population incrementally drifts according to the success of individual genetics, but then once in a while, over multiple generations, something in the environment (disease, food, competition, etc) may change quickly and the gene pool as a whole, not just that of individuals, is thereby tested, with accumulations of previously benign changes sometimes suddenly becoming critical. In this way evolution is acting on the entire gene pool - of the species or more correctly of that interbreeding sub-population.
Success in evolution, the ability of the species as a whole to adapt and compete, also requires genetic diversity, not only to avoid inbreeding, but also to provide species level resilience, and species level ability to quickly adapt. e.g. It seems that the success of sexual reproduction is because it is a way to "game the game" by increasing genetic diversity and therefore improve along these axis of resilience and fast adaptation.
There are also social species, such as ourselves, where the social group becomes port of the individuals environment, and genetics best-fitted-to-the-environment becomes a group dynamic.
and one group ate their dead relatives’ brains at funerals so consistently that they gave themselves a mad cow type disease called kuru, which killed a large percentage of their population and then, within a few generations, evolved a genetic mutation[1] that protects against it, one of the fastest cases of natural selection ever documented in humans
The suggested evolution is:
* there is one ancestor with a gene that protects against kuru.
* children and mothers without that ancestor often die from kuru
* children of that ancestor have a much higher chance of survival
* eventually everyone is a child of that ancestor
* any children of that ancestor that didn't get the protective gene also eventually die out
The gene is selected for. There are no population effects.
The key part in the paper is where they mention adult men with the gene, because they are measuring the counterfactual of the many males that died because they didn't have that gene (males that ate brains as young kids but then died because they didn't have the gene from that ancestor).
The paper is hard to understand in part because of the confounding effects of males not eating the brains. Plus the confounder of stopping cannibalism in 1960.
The idea of "Group selection" is fundamentally wrong - regardless of how sensible the belief feels. Anybody using the words "group selection" is indicating their belief system, and they usually then have biased narratives to 'support' their belief.
[0] horrifically incorrect sciencedaily link in Wikipedia.
[1] We don't fucking evolve genetic mutations
Let's say that everyone has a skin color gene that makes them either red or blue. And a new predator turns up that only eats blue things. To you this is a tale about individuals, while it seems that an equally valid, and frankly preferable, view is this this isn't about individuals - it's about being red or blue and is a species level effect.
Your pink and blue example is actually a great model to work from. Think about the genes and the expression of those genes, and then think about what is being selected if all the blue animals are eaten.
Or think about what would happen if there was a mountain range, and pink animals were eaten on one side and blue ones were eaten on the other side.
Or think about what if one of the blue fathers has pink polka dots that gave it a 10% better chance of survival.
Always concentrate on watching that genes are passed on by reproduction - getting eaten doesn't have to be a problem if reproduction has already occurred (unless parental investment is needed or you get complicated like kin selection).
I am not a biologist. But 'The Selfish Gene' is one of my favourite books because of the concepts within. Unfortunately I think Dawkins went off the deep end later (with what I thought was religious zeal). The Extended Phenotype is even harder to read, but also worthwhile.
It is a fun topic because many phrases about evolution seem misleadingly about death rather than reproduction. And the meaning of the word evolution is absolutely twisted in everyday conversation. Ignoring the troubles with bible bashers. https://en.wikipedia.org/wiki/Survival_of_the_fittest - "fittest" has an unobvious meaning.
Words matter. Talking about "species level" is misleading because talking about an effect (blue phenotype) distracts us from the cause (a gene for blue).
And evolution is confusingly another step removed: the red survives because the blue did not.
Most of us struggle to see the counterfactual absence of a something.
The blue "species" never exists - our brains want to find groups and patterns. Our words mislead us.
The same thing is alluded to in the paper: the deaths of people without the gene is what is driving the gene to spread (through reproductive success of those that didn't die).
Reproduction is what matters (which death or sickness may interfere with).
Even the paper is confusing because it talks about 50 year old women (measuring survival bias; not whether they are expected to pass on genes at 50).
(reedits for clarity).