Purely as a matter of opinion, the way to think about this is not as an advantage for an individual, but for as a gene pool.
Mostly a human gene pool's survival and prosperity is best served by community co-operation, mutual support and self sacrifice for the good of loved ones and other community members. Sometimes though, the group as a whole has had it and the route to the survival of any of the gene pool is for one or a few to sacrifice the rest and make an all-out bid for personal survival. E.g. a terrible winter in which there is insufficient food and everyone is starving to death.
Another situation where psychopathy could be useful is warfare. Sometimes having a cold blooded killer with no remorse on your side isn't such a bad thing.
Ultimately, it's a matter of variety. You never know what challenges your community is going to face, and what range of behaviors are going to be optimal. Having a full range of behavior types available in your community gives it flexibility in it's response, especially to to existential challenges.
You're looking at it the wrong way I think. Human culture (yes, even including warfare) only works with instincts towards cooperation. But once that culture exists, individual actors can succeed by essentially hacking those instincts to their own benefit. Evolution doesn't work to the collective benefit of entire gene pools--it works to the benefit of an individual's own genes. Within a population, divergent strategies can both be successful.
I'm not going to rule out that psychopathy can have been a good thing in some society roles, but they do look more like shirking parasites? (An evolved strategy that is turned on sometimes, depending on environment.)
[Edit: Afaik, psychopathy is not turned on after someone reaches adulthood. An evolved strategy for catastrophes would be turned on at e.g. hunger or stress.]
I especially wonder if warfare is a good example? Most of the time when humans evolved we were in a clan society. Clan warriors aren't generally known for live and let live-attitudes to people from outside their clan anyway; a psychopath would probably not stand out much in blood thirst. (And if you are in a war party, you really really need to trust the members in the party. Manipulative people would not last long when they were caught at it.)
Historically, soldiers have generally been reluctant to use their weapons. During WWII, around 20% of soldiers actually fired their weapons in combat. Even fewer shot to kill often aiming over the heads of the enemy. This is a form of posturing both to the enemy and their comrades. Through extensive use of conditioning, that rate and lethality of fire was raised during Vietnam and subsequent wars.
Even among tribal societies, warfare is highly ritualized in a manner that does not optimize for maximum lethality. Richard Gabriel, in studies on tribal societies in New Guinea have noted that hunts occurred with accurate feathered. Tellingly, tribal warfare employed featherless arrows. Similarly "counting coup" among American Indians involves touching rather than killing the enemy.
Cold blooded killers have their uses for society, especially in warfare. An excellent book on this subject is On Killing.
Cold blooded killers aren't synonymous with psychopaths. It turns out that many of the Nazis weren't psychopaths, but rather psychologically unremarkable people whose institutions and culture allowed them to collectively perform acts of evil over and above what any of them could have done individually. This is called the "banality of evil", and it became widely understood after the Milgram experiment and the Eichmann trial.
Groups of people have always been more ruthless than individuals. Psychopaths are remarkable not in their ruthlessness but in their ability to achieve it all by themselves.
It's different than the normal HN fare, but worth a read. We may be a society of killer apes, but we're not as eager to kill in warfare as you might think. Especially when the other guy was compelled at gunpoint by his government to join the military (that is, drafted) just like you were.
The point was, with the attitude to strangers in clan warfare (not modern post-clan societies), psychopaths have nothing to add regarding ruthlessness. See old Scandinavia.
For stylized cattle raids (e.g. historical Ireland, before the vikings) among old neighbors, there will of course be agreed levels below extermination (or the neighbours will be gone long before western contact).
Well, communities have subgroups. Even if someone is a net drag on the larger community, they could contribute to a subgroup.
For example, a leader might be good for their country at the expense of the international community. Or a senator might be good for their state but bad for their country. Or an activist might be good for his community but bad for society at large.
Such a person probably wouldn't be popularly seen as a shirking parasite. The subgroup that benefits would probably say they were doing a super job.
I was discussing the period when we humans evolved. Not so large groups then. Evolutionary pressure creating psychopaths from a group evolutionary basis seems unlikely (these generally need quite specific circumstances to work).
(Your argument also miss that psychopaths manipulate and damage the direct environment around them most.)
Perhaps psychopathy is like being bald - no real advantages, perhaps a small disadvantage, but it doesn't disadvantage you enough to stop you having a few kids so the genes get passed on anyway.
Indeed, if psychopathy is a combination of traits ('feels no empathy' and 'good at faking empathy') perhaps the survivors had a combination of traits that helped them to survive, while those with one or the other failed to survive.
There are large effects on behavior of psychopathy, people that are affected by a psychopath will mostly -- at a minimum -- make a point of warning everyone else they know. That is very detrimental for the psychopath. (Note that how we communicate really applies evolutionary pressure. Just check the number of muscles in a human face compared to most anything else. This is not a small effect.)
Also, psychopathy seems to be partly environmental and partly from genetics. And exist in most populations.
All this suggests an evolved behavioral strategy.
Researchers need to check for your hypothesis (the large different effects almost cancels each others out in many types of historic societies(!), so it is just a random genetic drift) since afaik it is a standard hypothesis, but it does seem very unlikely.
When you have a lot of sheep around, evolution is bound to come up with a sheep that feeds on other sheep. For such mutants, having 'social camouflage' is a critical trait, because otherwise they would be losing to normal sheep due to their tit-for-tatting.
As for the advantage, it seems pretty clear to me: higher chances at being the alpha-male(female?), plus the resource advantage due to not having the ability for reciprocal altruism (and the ability to get away with that).
All few human psychopaths I have personally met were natural-born leaders. One is now occupying a high-level position within a successful company that produces manupulative F2P games. Another was a woman who, despite her being deaf-mute, was able to organize a successful remote web studio (before it fell apart due to her politicking and other members, including me, bailing out).
Also, quoting Wikipedia: "In Mongolia alone as many as 200,000 of the country's 2 million people could be [Genghis] Khan descendants".
Edit: if I remember correctly, Richard Dawkins' The Selfish Gene discussed cheaters (that is, individuals who didn't reciprocate) as being a viable evolutionary strategy, as long as they are in a minority.
Keep in mind that natural selection does not select for traits, it selects against them. The first question you need to ask is not, "is there some advantage?" but rather, "what are the disadvantages?" Not all traits exist because they are advantageous; many may persist because they are not particularly disadvantageous.
The second thing to keep in mind is that many traits form a spectrum (particularly psychological traits). While the endpoints of the spectrum will likely be very problematic, there may one or more areas in the middle of the spectrum which are advantageous. Furthermore, it may be advantageous to have a variety of the trait in a population.
We have evolved to be born with lots of things balanced in slightly different way, one stronger, one smarter, one sweeter, one more decisive.
Every now and then someone is born with one of their balances in an extreme position. The genes that express the balance either missing or just heavily surpressed.
It is not necessary for every kind of gene expression to be beneficial to mankind in general, as long as the average range of gene expressions are beneficial to our survival.
tl;dr: A certain amount of variation in genes is beneficial to survival of our species, extreme variation (like psychopathy) is less relevant (unless a psychopath wipes out all of us, which is a commonly known weakness of evolution in general)
Ability to easily identify weaknesses is huge advantage at all times. Inability to feel guilt and remorse is huge advantage in hostile environment. This came into disadvantage just recently, when world started to live mostly in peace.
robert sapolsky has some very interesting things to say, regarding the societal benefits of conditions like schizophrenia and ocd.
this video of one of his lectures is quite fascinating:
Don't necessarily think in term of advantage, but rather in term of probability it will stay in the gene pool.
If psychopathy is genetically linked to say, a better resistance to cold or hunger, then it might stay even with the disadvantage of psychopathy, just because people with it will survive better.
Think of it this way: You use your favorite social site, interact with friends, colleagues, acquaintances, or family members through it, and to a large extent it determines what interactions happen between you. Somebody saw how people previously interacted and how (or where) they wanted them to interact, came up with this system, and promoted it until it became popular. Things we've taken for granted at various points in history--moral systems, religions, monarchy, democracy, the nuclear family--were invented in the same way, by people who saw the system as an object to be manipulated, rather than reality itself.
There is a lot of variety in humans at all times, and not all of the traits that comprise this variety have been at a large enough advantage to become the norm. Since psychopaths are not the norm (as far as we know) it probably means there has not been a point in our evolution in which this trait was an advantage enough to propagate.
Based on this account, I imagine that being a psychopath confers some advantage for just about our entire history as creatures that can form and execute plans.
Being a sincere participant in social groups has probably provided an advantage for just as long, if not longer.
Behaving in ones best interest to the detriments of society could be quite rewarding for the individual in a number of circumstances- consider competition for food, resources, and mates.
At one point in our evolution was there some advantage that being a psychopath conferred?
Yes, and there still is. Evolutionary survival is not about living long; it's about passing on genes.
Psychopaths are great at reading people and exploiting emotional weaknesses. Humans are not naturally monogamous, and psychopaths are perfectly equipped for high-frequency sexuality. They've had Game for millions of years.
Absolutely. Not only this, but in many of our power structures (ones where human potential is not a metric) there are obvious benefits to being a psychopath, thereby maximizing exposure and potential gene transmission.
