Some people believe that altruism has evolved through helping your relatives or through helping others to help you in return. I was thinking about it; on the surface the idea looks good -- if you already have this system in place, it is easy to see how it benefits those involved -- but that doesn't explain how the system could have appeared in the first place. Anyone knows the standard answer?

Imagine that you are literally the first organism who by random mutation achieved a gene for "helping those who help you". How specifically does this gene increase your fitness, if there is no one else to reciprocate?

Or imagine that you are literally the first organism who by random mutation achieved a gene for "helping your siblings". How specifically does this gene increase your fitness, or the fitness of the gene itself, if your siblings do not have a copy of this gene?

In other words, it seems simple to explain how these kinds of altruism can work when they are already an established system, but it is more difficult to explain how it could work when it is new.

And this all is a huge simplification; for example, I doubt that "helping those who help you" could be achieved by a single mutation, since it involves multiple parts like "noticing that someone helped you", "remembering the individual who helped you" and "helping the individual who helped you in the past". Plus the problem of how to start this chain of mutual cooperation.

My guess is that... nygehvfz pbhyq unir ribyirq guebhtu frkhny fryrpgvba. Yrg'f rkcynva vg ol funevat sbbq jvgu bguref. Svefg, vaqvivqhnyf abgvpr jub vf tbbq ng tngurevat sbbq, naq gurl ribyir nggenpgvba gbjneqf tbbq sbbq pbyyrpgbef. Gung znxrf vzzrqvngr frafr orpnhfr vg vapernfrf fheiviny bs gur puvyqera, vs gurl nyfb trg gur trarf tbbq sbe tngurevat sbbq. Nsgre guvf nggenpgvba rkvfgf jvguva gur fcrpvrf, gur arkg fgrc pbhyq or fvtanyyvat: vs lbh unir fbzr rkgen sbbq lbh qba'g npghnyyl arrq, oevat vg naq ivfvoyl qebc vg arne bgure vaqvivqhnyf, fb gung bguref abgvpr lbh unir zber sbbq guna lbh pna rng. Ntnva, guvf znxrf vzzrqvngr frafr, orpnhfr vg znxrf lbh zber nggenpgvir. Abgvpr ubj arvgure "urycvat lbh eryngvirf" abe "urycvat gubfr jub uryc lbh" jnf arprffnel gb ribyir urycvat vaqvfpevzvangryl. Npghnyyl, gubfr pbhyq unir ribyirq yngre, nf shegure vzcebirzragf bs be nqqvgvbaf gb gur vaqvfpevzvangr urycvat.