[xux]

A lot of people are focusing on the mechanics, but it seems like humans don't generate body parts just like cells don't generate organelles. The entity is not _meant_ to exist by itself, but form a cohesive living group.

A cell doesn't need to repair itself, it can simply clone itself and then die. A human being doesn't need to regenerate itself because it can reproduce and be cleared away. Evolution evolved to ensure the survival of the species, not the individual.

The human being is constantly generating itself by multiplying cells. Similarly, the species is constantly generating itself by multiplying individuals.

[richardw]

Those mechanisms are good enough to have brought us to this point, but that has no bearing on what kind of future we choose to create for ourselves.

Metals rust and seep into the ground, but we dig them up and build spacecraft from them. Metals aren't _meant_ to do that, but we have some influence over our environment. We might end up having a similar influence over our cells.

[erelde]

This, to me, brings up the question of "where does myself ends and where does my environment begins?". I could change parts of my brain like I'm changing the environment around me, what would I be changing, the environment around me or myself directly? Both?

Classic greek Boaty McBoatface question I know. (cf Ship of Theseus)

[dualogy]

> This, to me, brings up the question of "where does myself ends and where does my environment begins?".

Good question this! Until you find a conclusive answer, ie. until you clearly define/delineate "myself" & "env", you can ignore your follow-up question as irrelevant sophistry:

> I could change parts of my brain like I'm changing the environment around me, what would I be changing, the environment around me or myself directly

[erelde]

That question is exactly what I'm asking, what is "myself" and what is "the environment as defined around myself".

And I'm pretty sure there's no clear answer, but the question and reasonings ensuing are interesting.

By one definition, my possessions, my experiences, my social network would be part of myself. So changing my brain wouldn't be changing myself per se if those remained the same.

Another definition would be the strictly biological body, and of course changing the body would be changing the self.

But there's a fuzzier definition where something in the brain brings up "consciousness" and a sense of self, if I change something in the brain that isn't that particular part, the sense of self, have I changed the self or not?

(I can see my French high school teaching re-surging here...)

[Retric]

Self has no universal meaning robbing the question of any real value. You could include or exclude gut bacteria from you just as easily as you include or exclude identical clones, but that's just an outgrowth of your definition and says nothing about reality.

[ZeroFries]

All abstractions leak eventually. You can't separate anything in the universe from everything else. To clone yourself perfectly (for all time-slices going forward), you'd have to clone the entire universe.

[devoply]

> Evolution evolved to ensure the survival of the species, not the individual.

At some point in our evolutionary history the cells in our body made this choice. Evolution favors survival and potentially reproduction, because otherwise you are no longer in the game. So there was some evolutionary constraint that caused those genes not to regenerate parts.

It's possible we can change things so that those genes are active again. But we don't really understand these systems well enough to do that and won't anytime soon. But science carries on and I am sure you can make lab mice to test hypotheses of how this might work in mammals. And we probably will very soon, if not here then in China.

Evolution is perfectly fine even if you don't reproduce much, as long as you continue to survive in your environment. There are creatures out there that have changed very little and we know this because we have fossil records, and this is because they have been adapted to their environment and stayed adapted despite the environmental changes. And there are even immortal creature that die not because their bodies age and kill them but because they are eaten by other things, but still they don't change much over time. I guess you could say they are better evolved than other creatures that have to constantly change. They made better evolutionary decisions than other creatures very early on.

[tachyonbeam]

It doesn't have to be all about the evolutionary fitness of regenerating limbs. I think it might just be that losing a limb (and having the opportunity/time to regrow it) may have been a fairly unlikely event. Possibly, those genes mutated and were broken, right around the same time that some other genetic advantage evolved that caused a huge gain in evolutionary fitness.

The ability to regenerate limbs could have been lost in mammals simply because some old pre-mammal who happened to have broken regeneration genes was smarter and much better at finding food than the rest, and went on to pass his/her genes to all of us.

Furthermore, the evolutionary advantage of regenerating limbs may not be much in most animals. It's something we really would like to have, But imagine that some ancient primate species was able to regenerate limbs. Under what scenario do primate lose limbs? When some tiger chews them off? If that was ever to happen to a primate, it was basically fucked. Even if the tiger didn't eat it, it didn't fare very well lacking an arm for several months. The primate that is better at spotting tigers and avoiding them has much higher evolutionary fitness.

[piptastic]

You don't have to regenerate parts to live long enough to have offspring. You can do it at like 15 years old. So evolution isn't going to help in that regard much.

[toasterlovin]

Living for a long time after you have children is incredibly useful from the standpoint of genetic fitness. After all, grandparents play an important role in pretty much every human culture. And a grandparent with all their body parts is a whole lot more useful than one without.

[derefr]

The counterpoint being that in resource-scarce evolutionary environments, every grandparent (or even parent) that stays around is consuming resources that could instead go toward creating+maintaining an additional child.

[toasterlovin]

That's assuming that they consume more resources than they extract from the environment. And then there's also that grandparents can use the power and influence they've accumulated to benefit their grandchildren.

[devoply]

Often grandparents will starve to keep grandkids alive. Grandkids eat first.

[vacri]

There are plenty of species where the male dies during mating, and squillions more where the male isn't around after mating.

Evolution only requires that you get to reproduction, however that happens. It doesn't require that you're happy, sad, whatever, just that you reproduce.

[arcticfox]

> Evolution only requires that you get to reproduction, however that happens. It doesn't require that you're happy, sad, whatever, just that you reproduce.

It requires that your offspring actually survive as well. Humans are, at least historically, exceptionally well-equipped to influence the survival of their offspring.

[vacri]

Humans also take figuratively forever to be self-sufficient. Herd animals are born with the ability to walk, for example. Humans take about 10 years before they can be taught to be even somewhat self-sufficient, which is a ridiculously long time in comparison to others.

So, given that humans are sexually mature before they're fully self-sufficient, that enhanced ability to support their offspring is not all advantage - it's actually required for the propagation of the species. If older folks weren't taking care of the younger ones, none of them would reach reproductive age.

[coldtea]

>Living for a long time after you have children is incredibly useful from the standpoint of genetic fitness. After all, grandparents play an important role in pretty much every human culture.

In the time scale that matters to evolution, grandparents played absolutely no role for the Homo Sapiens, and neither did culture.

[simonh]

I don't think that's at all likely. We've had fire and had the physiological adaptations enabling speech for well over a million years. We've been manufacturing complex tools such as spears with stone tips for about half a million years, to Homo heidelbergensis. Even Ergaster had lifespans allowing survival to an age where grandchildren could reach adulthood, allowing for skills transfer.

[toasterlovin]

Do you have children? Raising children is hard. And it's a lot less hard when you have other adults to help. Historically, those would be grandparents and aunts/uncles. But aunts/uncles would probably have children of their own.

[coldtea]

"Historically" is the keyword here. Evolutionary timespans are much much larger than recorded history and human culture as we know it.

[aquadrop]

In many historic cultures, 'elders' were the ones who controlled the tribe.

[hyko]

I agree with you but don't forget the role of genetic drift.

[haywirez]

> Evolution evolved to ensure the survival of the species, not the individual.

Depending on which view you take, evolution can be seen optimized for the survival of individual genes, not species[0]. In Dawkins' book, bodies are portrayed as mere useful survival vehicles for various genes.

(I'm ignorant on this, would love to read counterarguments from someone better versed!)

[0] https://en.wikipedia.org/wiki/Gene-centered_view_of_evolutio...

[ogrisel]

Indeed virii are part of the evolutionary process and can insert genes into hosts from various species. Such genes can be successful from an evolutionary standpoint even if some of the host species disappear.

[skriticos2]

Not contradicting your core argument (though I'm sceptical about the significance in impact of this process), but you are certainly apt at mutating grammar: the plural of virus is viruses - not virii.

http://english.stackexchange.com/questions/3838/viruses-or-v...

ps: this is like kerning, you can't unsee it..

http://xkcd.com/1015/

[ogrisel]

Thanks :)

[nostoc]

The specie as the unit of selection is an idea that is very unpopular in the biological community. A lot of people believe instead that evolution works first and foremost at the gene level, and that gene selection is the driving factor for evolution.

https://en.m.wikipedia.org/wiki/Unit_of_selection

[csomar]

I think the difference in the 21 century is increased awareness of consciousness. Unconscious animals don't care about survival of their own self. They just reproduce.

Humans, since getting a bit of self-awareness have been fantasizing with the idea. Religion, and self-rebirth after death is an example.

Now they are getting more real and more practical. If you think about it, it makes more sense to increase your lifetime than make another person to carry-on your dreams.

Your emotions tell you otherwise, because you were made to reproduce. The brain is working something else. It's evolving and thinks that it can solve this problem and instead re-make the body.

[aquadrop]

This idea can be applied to any species, and yet, there are animals who regrow body parts - octopus can regrow tentacles, crayfish and lobsters can regrow claws, salamander can regrow tail and limbs, etc.