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Does increased longevity positively affect the success of a population? Evolution is about the population, and pretty much disregards the individual unless that
by ksaj 6y ago
Does increased longevity positively affect the success of a population? Evolution is about the population, and pretty much disregards the individual unless that "beneficial" individual makes sweeping positive changes in the next generation. I don't think 80 year olds are reproducing all that often these days, so at least my understanding of how evolution works doesn't apply to this. Aging out of individuals is a way of keeping that balance.
More technically:
In evolutionary computation, there is a specific area focused on scaling. The quick gist is that the warmer and larger an organism is, the more energy is required to keep its population alive. Populations of different organisms tend to use the same amount of energy. This is why you have dense populations of bacteria and ants, but not of elephants and hippos. When that goes awry, parts of one or the other population dies off to keep that balance.
So the more predators there are, the more prey is needed to support the predator population. The models present that the sum of all biological activities in any given population scales with the individual's mass by a power of 3/4. This rule shows up everywhere in nature, except for one.
Humans are the only life form known that violates this principle, and our population is already hyper-dense by a factor of 58,000 times over all other life forms. Domestication of plants and animals (farming) and industrial advances have propelled us beyond that limit.
Living so far beyond reproduction and family-building age is an exercise in the law of diminishing returns.
- JoshuaDavid 6y agoOh yeah when I'm talking about evolutionary pressure in that direction I'm referring to the time before agriculture, and probably before language. Definitely not modern civilization -- as a general rule, if you don't see massive differences between human populations in varying regions on a particular metric, you can assume that there hasn't been any strong evolutionary pressure on that attribute in the last few hundred generations (e.g. height varies quite a bit, as does melanin concentration, implying fairly recent selection for those traits, while lifespan is pretty constant given similar access to healthcare, implying that there hasn't been a significant difference in evolutionary pressure from region to region on lifespan). Additionally, humans have a much longer lifespan than other mammals of similar size, implying that at there was strong evolutionary pressure for increased lifespan around the time humans diverged from other primates, and even a bit before that as other primates also live longer than most mammals their size.
- ksaj 6y agoFor the most part, yes, then. Humans have the skill of extrapolation and invention that other animals completely lack, or only barely approach to our level. Our ability to communicate instantly to other humans on the other side of the world (or even not on this world) is testament to the ways we have overcome certain barriers in natural selection. We literally chirp louder than any bird ever could. Lots of diseases simply wouldn't exist today if we didn't learn how to medicate and operate, because those diseases would have killed off those humans prone to them, and only "immune" humans would survive. Etc. So in the early days when Homo Sapiens were not the only beings headed towards our modern (evolved) form, there probably were vastly different mortality rates depending almost solely on that scaling equation. There probably still is today, but more or less nature forcibly trying to maintain that 3/4 ratio. I'm only speaking in re evolution since you mentioned that, because otherwise you're spot on.