Hacker News Reader

> 1. Humans have existed as a distinct species for about 200,000 years.

No, that's wrong. Humans, genus Homo, have existed for about 2.5 million years; the subspecies H. sapiens sapiens for about 200,000. The species H. sapiens is a little less clear, there's debate over whether it starts around 200,000 years ago (and includes just a few subspecies, notably H. sapiens sapiens and H. sapiens idaltu) or whether it starts around 500,000 years ago and includes several others.

> 2. Given the process of natural selection, in another 200,000 years we will have been replaced by something different than us -- not necessarily bigger or smaller, smarter or dumber, just different.

Unlikely; while speciation requires time, time alone is not generally enough, and even if it were, there is no reason to expect the time from the last speciation event to now (whether 500,000 years or 200,000) to be the time from now to the next speciation event.

(Colonization of Mars -- if Earth-Mars interaction is limited once the colony is established -- might actually accelerate that, since the one thing that does contribute to speciation is geographical separation which prevents significant interbreeding between segments of the wider population.)

> 3. In a million years, there will be nothing remotely resembling human beings -- it will be as though we had never existed.

Human beings, genus Homo, have been around for two and half million years already, and H. sapiens (whether you take the narrower or broader view of the species) would be a flash-in-the-pan as species of its size, lifespan, and geographic range are concerned if it wasn't around for several million more (H. erectus -- with competing members of the genus Homo around on Earth for pretty much its whole time of existence -- lasted about 1.75 million years), and things "remotely resembling human beings" have been around significantly longer -- and can be expected to be around significantly longer than humans in the strict sense, unless humans are wiped out completely in a cataclysm rather than subjected to the kind of pressures that produce speciation.

> The sun will become a red giant and envelop the earth in somewhere north of five billion years, which is five thousand times longer than we can possibly exist as an identifiably distinct species, using the optimistic forecast of item (4) above.

The million year forecast isn't "optimistic"; while it may be unlikely that human beings would be around for 5 billion years, your particular argument for that point is, well, based on one controversial claim and a couple of unjustified claims that don't follow from that controversial claim.

> The million year forecast isn't "optimistic"; while it may be unlikely that human beings would be around for 5 billion years, your particular argument for that point is, well, based on one controversial claim and a couple of unjustified claims that don't follow from that controversial claim.

Where's the refutation of my point that we will have entirely disappeared in a million years, replaced by some other species? This isn't a philosophy debate, where words like "controversial" and "unjustified" carry weight among people trained in critical thought.

> Where's the refutation of my point that we will have entirely disappeared in a million years

Where's the support for the claim?

> This isn't a philosophy debate, where words like "controversial" and "unjustified" carry weight among people trained in critical thought.

"Unjustified" always carries weight among people trained in critical thought, at least, when its true -- i.e., no adequate support has been provided for the conclusion presented. You've simply asserted that humans have been around for only 200,000 years as a species (which is one of two common viewpoints about H. sapiens, though "humans" in this context usually means the genus Homo and not the species H. sapiens -- 500,000 is the other, because where exactly at what point H. sapiens becomes a distinct species is debated), and jumped from there to the conclusion that H. sapiens will be replaced in another 200,000 years and that nothing similar will be around in a million years. Neither of those conclusions follow from the premise, which itself is less-than-certainly correct.

> 2. Given the process of natural selection, in another 200,000 years we will have been replaced by something different than us -- not necessarily bigger or smaller, smarter or dumber, just different.

In the very, very long run, who knows.

But int the timescale of tens or even hundreds of thousands of years I don't think there will be any natural selection process that will apply to the current status of humanity as a species, unless for some reason civilization will fall and humans are scattered throughout the globe.

We've pretty much stopped evolving as a species through natural selection events. There's not much of that happening in the homogenized urban setting where the majority of people live, and will live for the foreseeable future.

Actually, having the current civilization as a substrate for the species does change the playing field considerably from what it was a few thousand years ago.

As for biodiversity creating some sort of 'better adapted species' to take over our position - the sad truth is that biodiversity is in rapid decline, and I don't know when it will stop. We are not killing the planet per se, only... homogenizing it and making it fit for humans.

In a million years, sure, who knows what will happen. But in the current mass extinction event - if we can feed the the human species it's very difficult for me to imagine anything will replace us when the timescale is only the current estimated age of the species.

Prepare to be rickrolled for the next 100k years. Or maybe we will move into some dense compute substrate made of exotic materials.

> We've pretty much stopped evolving as a species through natural selection events.

This is quite false. All that has happened is that we've (to some extent) replaced genes with memes, and memes evolve just like genes do.

Evolution is still underway, actively and blindly selecting individuals and ideas with equal efficiency.

> There's not much of that happening in the homogenized urban setting where the majority of people live, and will live for the foreseeable future.

I'll just give one example that falsifies the thesis -- what is called Asperger Syndrome (AS). A thousand years ago, someone having the behaviors associated with AS might be at a significant evolutionary disadvantage compared to someone who could pick more olives up off the ground. But today, the AS behaviors represent a distinct advantage because the environment has changed in ways that favor that mental wiring, such that a number of AS "sufferers" (to use the psychological terminology) are famous -- Bill Gates, Albert Einstein, Thomas Jefferson and many others identified as having AS.

AS is so obviously an advantage in modern times that another psychological school of thought called "Grit" goes so far as to describe the same behavior pattern as an advantage:

http://en.wikipedia.org/wiki/Grit_(personality_trait)

Of course, the Grit people don't call it AS or even mention AS, they just say how advantageous it is to have the intense focus and obsession with only a few activities (or even one) this behavior produces in many modern success stories.

It's evolution at work. I'm sure many more examples could be found, less dramatic than this one.

Evolution is the central theory of biology, and it didn't just stop for human beings when we built the first TV set or began dwelling in arenas of pure thought -- quite the contrary.

Success in the way you describe it has nothing to do with evolution. To choose someone at random - Sarah Palin is almost twice as successful as Gates or Einstein (she's had 5 children - those two only 3 each).

Unless people with AS / Grit have more children than those without, there's no selective pressure to increase the prevalence of the trait in the population. You could consider health of the children - so maybe you should count great-grandchildren rather than direct children.

BUT - I agree that evolution probably hasn't stopped - it just is selecting for different traits than it did 15,000 years ago. What exactly is being selected for in US in 2014, I can't say.

I think I was parroting Michio Kaku there about the end of natural selection for humans as a species.

You can hear his arguments and draw your own conclusions: https://www.youtube.com/watch?v=UkuCtIko798

Actually, we have _not_ stopped evolving because of natural selection. A significant proportion of people choose not to have kids nowadays, or are just having one child. In a generation or five all this "I don't want kids because there are too many of us in this planet already" crap will be over, and we'll only have people left (in developed countries) that get drunk and don't use condoms and decide to have the kids anyway, people prone to religious belief systems that forbid contraception, and just people that plain have very strong ingrained urge to have a family/kids, despite career pressures and all the information/stimulus overload from internets and 24h connectivity and all.

I'm actually using a very inclusive sense of 'us' here, meaning any sort of life. I'd prefer intelligent life that I can emphasize with, but I'll take what I can get.

Humanity isn't that special and I'm sure intelligent life would arise again without us, but now that Earth has developed fungi that can digest cellulose Earth is never going to have this much fossil fuel sitting around again. Maybe that doesn't matter and humanity or some other species will colonize space anyways... but maybe it does.

> I'm actually using a very inclusive sense of 'us' here, meaning any sort of life.

Okay, fair enough, that's reasonable -- so once we detect any sort of extraterrestrial life, then we can forget about leaving the planet. After all, there's life everywhere, so our leaving Earth loses its significance.

I think we'll colonize Mars for the adventure, or to satisfy our curiosity, not as a first step in colonizing the universe. The latter might be what we'll say, but it won't be the real reason.

However, humanity lives in an increasingly global environment, and natural selection works slowly - so no two generations will be able to draw a line saying "they're a different species," so they'll still likely call themselves human. And they'd still be our descendants, so I don't know why we wouldn't still think of them as "us" in some way. I don't see a split in what is considered "human" unless we do become an interplanetary civilization, because then it's conceivable that groups of humans could be removed from contact with the rest of humans, and end up evolving in a different direction. Though I wonder how much convergence there would be anyway, given that we save people from a lot of things that could keep them from passing on their genes. I think there will be a wide range in what is considered "human."

> However, humanity lives in an increasingly global environment, and natural selection works slowly - so no two generations will be able to draw a line saying "they're a different species,"

True, but what makes a species a species remains the same. Eventually our descendants wouldn't be able to mate with us (or would want to), and that perspective will mark the end of the human species.

> I think there will be a wide range in what is considered "human."

See above.

What a load of begging questions. I wonder what you have to be, to be special according to the flavor of meaning you just happen to prefer?

> What a load of begging questions.

The expression "begging the question" doesn't mean what you think it does.

> I wonder what you have to be, to be special according to the flavor of meaning you just happen to prefer?

The answer is obvious -- no particular form of life is special or supernatural. It's all part of natural selection, changing species adapting to a changing environment. And this isn't just some hypothesis, it's the central idea in evolution, a very well-supported scientific theory.

And our "flavor of meaning" has no part to play, only objective evidence, the evidence that overwhelmingly supports the theory of evolution.