> Do you have evidence for this that's not a reality TV show?

Yes. Let's start with the fact that there are no recorded instances of an isolated human couple successfully reproducing in the wild ever. Merely having a baby doesn't count. To be a viable evolutionary strategy you have to raise that baby to maturity and then that baby has to reproduce themselves.

In fact, this is not unique to humans. It's true of all simians. In fact, it's true for the vast majority of mammals. The only exceptions I can think of are some species of cats: leopards, cheetahs, tigers, mountain lions.

We can also reason from first principles: you need a minimum viable population in order to maintain genetic diversity. So even if it were possible for isolated human couples to reproduce, you'd need more than one instance of this, and these families would somehow have to find each other in order to procure mates. How are they going to do that?

Comparing minimum viable populations to sterile ants seems to confuse the issue. Applying concept of eusociality in ants to humans seems to be somewhat of a fringe idea https://www.prospectmagazine.co.uk/magazine/edward-wilson-so...

Don't mistake modern density for a requirement. It's hard to find instances of anyone living alone for long periods, but that likely changes as you go back and there where fewer people and those people where more able to survive in the wild.

I remember going into back country with some friends as a teen, miles into 'the middle of nowhere'. Second day camping I see someone run by in yoga pants pushing a stroller as it turns out we where about 300 feet from a ski trail and people would run down the mountain in the summer for fun.

Don't mistake a small loose end in a complex argument condensed to fit in an HN comment for proof that the argument is wrong.

Well the holes in your arguments are deeper than that. A viable strategy need not be the only or even the optimal strategy.

If couple has kids and those kids find someone in a local tribe then both tribes and lone families would have worked. In effect you are trying to redefine his argument not just in terms of recorded history but also both couples not an individual one.

> If couple has kids and those kids find someone in a local tribe then both tribes and lone families would have worked.

You're attacking a straw man. Of course a couple can reproduce if they are in proximity to a tribe. But that still requires a tribe. It is a couple in isolation that is not viable.

The couple are irrelevant at that point. People can travel ~10,000 miles a year on foot. The fact their kids leave in no way impacts them being in isolation. Heck, someone can know where other people are and still be isolated.

QED they can reproduce in isolation.

I rarely see people on HN miss the point quite this badly. Reddit, yes, but not here.

The point is: for your scenario to play out, a tribe has to exist (and it has to be close enough for the couple's offspring to find it, but that's a detail). No tribe, no viable reproduction. Hence, the tribe is the minimum viable unit, even if it also occasionally supports an isolated couple somewhere in the vicinity.

Your argument is only true in the trivial sense that sexually reproducing organisms are only viable in larger numbers than a single pair; but that's a distinction that doesn't demarcate anything interesting. Humans are like ants, you say, but your argument also leads to the same conclusion about tigers, bears and other solitary animals in that they need more than a breeding pair to be viable. It descends into tautology.

Yes, humans are somewhat like ants in that they are usually social. Humans are adaptable enough to survive in pairs, though lack of specialization means they won't necessarily live the most comfortable life, so it would be an unusual choice. But there's nothing elective about ants' socialism. So in the end I don't think your argument works.

> your argument also leads to the same conclusion about tigers, bears and other solitary animals in that they need more than a breeding pair to be viable

No. Those species have specialized adaptations that allow them to live in isolation, which humans lack. And it's not just humans. All simians lack these adaptations. Indeed, the vast majority (perhaps all -- I can't think of a single counterexample) of non-carnivore mammals lack them.

Isolation does not mean other groups don't exist. It means lack of contact, and the adults don't need contact and as I have said children can move as happens with many territorial animals.

Ever heard of bears? I don't believe any of them have something that could be called a tribe (unless you redefine any form of family to be one). They simply don't have a source of food that could sustain any nontrivial population in small territory. Even living alone most of there lives wouldn't stop them from finding a mate and having an offspring.

No, I have never heard of bears. What is a bear? And what do bears have to do with humans?

The OP isn't making absolute points, this is the point. An ant isn't really an organ, at least using normal word meanings. He means that it is effectively an organ, from a reproductive perspective.

People obviously are viable reproductive organisms in a technical/literal sense. But... the way people (and our nearest cousins) actually reproduce is in couples within a tribe/village/troop. People are evolved to reproduce this way and people evolved by reproducing this way.

For Lisper's overall claim to be valid, you only need the weaker result that an isolated couple's expected number of children living to adulthood is less than 2.

That's the concept of minimal viable population (https://en.wikipedia.org/wiki/Minimum_viable_population). Basically it means how much inbreeding is acceptable to have viable descendants.

I'm aware of this concept but the comparison to Naked and Afraid and literally sterile ants made me think he was referring to some distinct idea.

I understand. In fact, classifying individual social insects as organs doesn't sit well with me also, it feels more like philosophy than biology. I think it also ignores other possibilities that could explain why sexual reproduction is reserved to a subset of a population, but well, I don't teach evolution.

evidence you need to start with more than a single breeding pair to not go extinct

https://www.researchgate.net/publication/224771432_Lynch_M_C...

I don't know what evidence you'd want. The claim seems self-evidently true to me.

You were able to find one wiki article on a curious case of a family who, unlike billions of other people, survived as individuals for less than 50 years in partial isolation. That's impressive, but it doesn't change the basic facts of human survival.

Case in point, in the first paragraph of the link you provided about the Lykovs, the article says only one daughter yet survives (as of 1988, so they are probably all gone now).

Minimum viable populations are partially about day to day survival and team work, but in the long term it's about genetic diversity which is critical for long-term population survival. Evidence: all of biology?

Abakan Range is rather difficult place to live which is why they where left alone and the family was not from a culture of nomads. Yet, Agafia made it to 70 and is still alive.

That suggests it's far more viable than you might think. It's just more attractive places to live currently have people living there. Opportunity's for solitude where far greater when global population was lower, but it's unlikely for such things to enter written history.

> Agafia made it to 70 and is still alive

But left no descendants.

I too would like to see a citation for this at least. It doesn't make sense to me why this would be the case.

Me too. Although I thought what he was going to say is the limited genepool would make grandchildren impossible (well nearly...) and generations after that impossible.

People are asking for citations to actual literature that support your claim that a pair of fertile people can't reproduce. I think what you're actually saying is that you can't bootstrap a viable population from a pair of people (which is definitely true from a population bottleneck point of view), but I think you're massively overstating your case. It would really help if you could point to some modern well-accepted textbook or paper that supports your claim.