So if our origins were idyllic, what went wrong?

There was a problem. While predators were less prevalent they were not nonexistent. The group was vulnerable to animals such as leopards which might find us easy pickings.

The women had to concentrate on rearing the young, so the job of protecting the group from leopards fell to the men.

We are learning machines and thus we adapt to our environment and the nature of the tasks we undertake. Within the tribal home openness and love and spontaneity were the order of the day. But once we went out to kill the leopards which threatened us we had to adapt to a different kind of environment – a hostile one – and a different kind of task – one which required discipline and hostile behaviour from ourselves. If we were to effectively protect the tribe from leopards we had to become like leopards.

Now if this behaviour had been limited to the hunt, everything might have been fine. But it is hard to entirely successfully divide oneself into two separate mindsets, one for home and one for work. The men would have been bound to bring some of the aggressiveness and competitiveness they learned on the hunt back into the previously harmonious tribal home.

All of us were new to this. Our understanding was limited, and what mattered was maintaining the stability of the group. The women were worried that this aggressive behaviour would compromise the harmony of the tribal home and thus have a detrimental influence on the infants. And so they criticised the behaviour of the men. In this harmonious society, criticism of one individual by another had rarely been necessary.

At first this would not have been a big problem, we were still very healthy and thus very flexible. What made it a big problem is that there was no solution. Gradually, over time, it would increase. The more the men felt criticised at home the more time they would want to spend on the hunt. And they went from hunting only predators, to hunting animals for food. Previously we had been vegetarians.

There was one powerful approach to this problem, but it was not, in itself, a solution, and that was sex.

Sex is clearly necessary for reproduction. It fulfils that function in all mammals. But, in more social mammals, it fulfils a second function, that of social bonding. We can see this particularly in the behaviour of very social mammals such as the bonobos and dolphins.

One way to bond with another individual or ease the tension of any form of emotional conflict, is through the mutual exchange of pleasurable sensation. While reproduction requires sexual contact between the male and the female, the use of erotic pleasure for social ends need not be restricted to male/female activity. And thus we find that, among bonobos, dolphins and other species, sexual activity occurs also between members of the same sex.

The bonobos, our nearest genetic relatives, spend a lot of time rubbing genitals. Adult males generally won’t rub genitals with their mothers, but otherwise these genital exchanges are not restricted by age or gender or kinship. Bonobos do not form permanent relationships. And bonobo society is matriarchal. Male bonobos are bigger and stronger, but the females are more closely bonded with each other and thus the centre of power.

This gives us some clue as to what the life of the earliest humans might have been like – matriarchal, no pair bonding to compromise the communal whole and sexual behaviour bisexual and largely indiscriminate, acting as a kind of social glue through shared pleasure.

It is important to point out here that this was pre-neurosis, pre-armouring, and therefore sexuality would not have taken any of the armoured forms that it did later. Armoured sex can be a conduit for anger and, in the extreme, can morph into rape.