Contraception, Abortion and Evolution: Population growth round two

Men who have lots of sex and indeed lots of different partners tend to have more offspring. For all of history and pre-history that has been the case. There have always been some second order effects such as, those with lots of different partners would have greater risk of contracting a venereal disease which can prevent further offspring being produced due to infertility or even death. On top of that, those who sleep around probably make more enemies. It is conceivable that they have a higher murder rate than their monogamous counterparts. Though I don't have anything other than anecdotal evidence to support this particular assertion.
Another issue is that the promiscuous males could loose their regular partners, who prefer to find a more faithful man.
However, in spite of all of that, more sex generally produces more offspring.

But in the last few decades the use of reliable contraception has become wide-spread, also in many countries abortion is readily available. In the past people generally had the choice to have sex or not. That led to pregnancies. Now there are two different choices, whether or not to have sex and it is a separate issue to choose to have kids. So the people who are having the most children are the ones who want to have them the most and not the ones who want sex the most. This is an enormous change as a driver of evolution. Also lesbians, or indeed any woman who can't find or doesn't want a male sex partner, can just go along the a sperm bank. So sex is not even a prerequisite to having kids.

New positive drivers that will lead to more children:
1: Following a religious organisation that discourages contraception and abortion. Perhaps the success of science in developing contraceptives will lead to a less scientific and more religious species.

2: Strong desire to have children. In the past, from an evolutionary point of view, it was very important to be able to attract a mate, have a desire to have sex and then the desire to look after the child when he arrived. Now there is a new issue, there needs to be a desire to have children, which clearly related to the desire to look after them once they have arrived, but they are distinct.

New negative drivers that will lead to fewer children:
1: Ambition in women to succeed in the world at the cost of having fewer children. A woman who doesn't want a career but just wants to start having lots of babies will clearly be more successful from an evolutionary point of view. In the past when there was more of a risk of starvation, the more worldly mothers could help provide better for her kids. Now with very high survival rates, having the kids in the first place is the key issue.

2: The alpha male types who never want to settle down, at least partially motivated by the fact that they have a constant supply of available females. In the past such men would have many offspring, even if they didn't stick round long enough to look after many of them. However, now with reliable contraception, the man who wants to settle down young have have lots of kids has an evolutionary advantage.

All of this is not just going to affect humanity in the future. To a certain extent, the effects have been seen already. For example in Northern Ireland, we saw a growth of the catholic population relative to the protestants at least in part due to the catholic prohibition on contraception.

Whether religiousness is down to nurture or nature, we can indeed witness that people who observe a rule that forbids the use of contraception have an evolutionary advantage.

We may well see population growth taking off once again as over the next few generations there will be a growth in the desire of people to have children because those who want to have children have a new evolutionary advantage.

On the other hand, the desire to look after children once they arrive is possibly now less important than it was previously, since in wealthy countries at least, social services often step in to look after children that have been neglected by their parents.