So humanity is also breeding aversion to birth control?
Could be. However, more progeny is not always best. if limiting reproduction gives the ones you have a better shot at surviving, then birth control could be selected for.
Birth control might be more in the realm of the spread of memes, not genes though.
Of course humanity is evolving. Everything alive evolves. The environment is constantly changing, even if we don’t perceive it. If the earth is getting progressively warmer, we will evolve to develop more heat tolerance.
An interesting point is about genetic homogeneity in the human population. Humans are a very young species, and there is not a lot of genetic variation between different populations. In fact, the most ancient branches of humanity only were separated around 80,000 years ago IIRC. Before that (and IIRC even after that) there have been major population bottlenecks which have drastically reduced the pool of alleles around. Add these together, and you get a pretty homogenous species.
This may cause us to have a slower rate of evolution per generation time right now than other species. Natural selection generally works on already present genetic variation, not on newly arising alleles. Imagine a bunch of neutral mutations which are present in a population. The environment changes and the one allele becomes advantageous. It usually doesn’t happen the other way, the way of X-Men and science fiction, where new mutations which have big advantages crop up.
This reminds me of the fruitflies.
Some university was fooling with the lifespan of fruitflies, which is like a lunch hour (I jest). What they did was remove all but the last couple of eggs from the female fruitflies. What they found was that nature naturally extended the fruitflies lifespans until an egg was actually fertilized, then they all died off.
At last count they had tripled the life span.
Unless that boinking is used to make little boinkers none of those would be selected for by the evolutionary process which, as Voyager said, is only concerned with reproduction. As few people who are old enough for the usual causes of heart disease to affect their lives are also older than the age at which people usually reproduce (Susan Sarandon being an exception) there is no connection between heart disease and reduced fertility. This does not mean that a genetic treatment for preventing heart disease won’t be found. It’s just that we will have to find it ourselves. It may even already exist as a mutation that has survived and spread, either because it provides some other protection for the organism or else because it doesn’t cause any harm.
If the chance of a fruitfly reproducing is dependant on a) how many eggs it’s got and b) how long it’s around to reproduce (longer life, more chances to get laid) then if you reduce the number of eggs, the lifespan will become more of a factor in reproduction. So the ones with a longer life would reproduce more; any mutations resulting in a longer life span would spread very quickly; hey presto! Fruit flies that live til 3pm.
Anyway, human evolution. I’ve heard theories that modern society could encourage evolution in certain respects:
Because our career-centred society favours having children later in life, those whose reproductive systems fail at an early age will be weeded out.
Similarly, our career-centred lives add a lot of extra stress to the burden of raising kids, so those who get stressed easily may choose not to have kids. In comes the chilled gene.
Another one I’ve heard is that genetic suicidal tendencies will eventually disappear from the gene pool - for obvious reasons.
But here’s a more general scope: The theory of natural selection can be expressed as follows:
- Limited resources + expanding population = struggle for survival.
- Struggle for survival + inherited genetic variations = natural selection.
In developed societies where we can all scrounge off the state, we no longer have a struggle for survival, so does natural selection become meaningless?
Ever read a novel entitled The Mote in God’s Eye?