The analogy breaks down in that rate of infection of a disease is historical but very much informs ongoing public health measures that should be taken.
It’s just a fact it really changed my perspective. American as a people have a learned helplessness mostly because of wealth, when asked to do something they gripe about the boss making excuses and acting juvenile. Asians just do the thing.
You think the study of archeology, anthropology, genetics, and ecology across the entire Western academic system is being subverted to support DEI using a theory that existed long before the time "DEI" was a known acronym? And you can't provide evidence?
Out of Africa was fought by the majority of Western scientists during the early 20th century because of their pro-European biases. The reason its accepted is because the preponderance of evidence supports it.
there were also a lot of sociocultural changes coming out of the 60s/70s that changed the scientific conclusions we drew.
it used to be that we saw changes in ancient pottery and language and assumed that previous people had been replaced by new people with different techniques. then, in the 60s/70s it became popular that these changes didn’t mark population replacement but were more cultural spread and shift.
then genetics came around in the 90s and obliterated the cultural hypothesis and showed that in most of these cases it was largely population replacement.
there are lots of theories from the mid-20th that haven’t yet had their ‘genetics in the 90s’ moment.
> then genetics came around in the 90s and obliterated the cultural hypothesis and showed that in most of these cases it was largely population replacement.
I think the current consensus is a fusion of the two stances, particularly as some of the changes have appeared to be too rapid to reflect population displacement, and genetics clearly indicate genetic admixture with varying distinguishing characteristics relevant to the region and timeperiod as opposed to straight displacement.
Unsatisfying, I know, but basically any firm position on either side has equally firm arguments against it.
I had a recent discussion about this, will try to pull up the sources, but my understanding is displacement is the majoritarian current and cultural shift with same population very much a secondary that only applies in a minority of the cases
a lot of these admixture events show near total displacement of the y chromosome also
I'm not disbelieving your source entirely, but it seems a little ridiculous to assume population displacement across all pre-history (or undocumented history if you'd prefer that term). Particularly when modern populations are so genetically diverse.
For one example, the idea a single "sea people" were responsible for the shift from bronze age to iron age in the eastern mediterranean is nearly universally rejected at this point. The populations of the mediterranean seem to descend at least in part from the bronze-age populations of the area. However the economic and cultural impact of the same period undeniably transfused rapidly through the region as heavily demonstrated with the archaeological record.
Even in the case of neanderthals we didn't fully displace so much as mostly displace but also admixed. Same with denisovans, cro magnons, etc. Genetic testing of cro-magnons shows modern-day descendants, and not just in the matrilineal or patrilineal line (i.e. presumably indicating either descendants of rape or partial infertility, as is presumed in the case of neanderthals).
With the spread of agriculture (seed cultivation, husbandry, plow, etc) we also see a mixture of genetic and cultural transfusion. Ditto with the horse, except much more rapidly, and horse-based technology much slower. This is partially why there's a gradient of genetic similarity across europe rather than a "european" set of genes—and with the horse technology, we have the benefit of an archeological and in certain cases textual evidence of trade between northern europe and the rest of the world.
Now, some of this is a matter of quibbling over semantics—is it displacement or is it admixture? Understandable. But the cultural diffusion in the material record is undeniable regardless of which term you pick. I'm not so sure it's worth picking a primary cause rather than accepting the inherent messiness of the archeological and genetic record where, as in the case of neanderthals, there isn't very solid evidence of infertility demonstrating firmly that the migration was mostly, if not entirely, displacement, as presumably non-hss-mixed neanderthals are extinct.
>when modern populations are so genetically diverse.
Are they? Are there any studies that confirm that hypothesis?
My understanding[0][1][2][3][4][5][6] (there are plenty more references, but I assume you get the point) is that modern human populations are incredibly similar, and not very diverse at all. In fact, all humans are more genetically similar to each other than many other species are, including chimpanzees and wheat.
> Are they? Are there any studies that confirm that hypothesis?
??? what is there to confirm? Why are you trying to spin an internal comparison as external? Indigenous populations tend to be more related to physically close indigenous populations than physically far apart indigenous populations. This is what I was referring to with the "genetic gradient". Comparing us to chimpanzees makes zero sense, let alone wheat, as we aren't trying to have sex with either, let alone "displace" them. I mean, hopefully not.
It's true that our diversity has lessened over time but this is "I don't see color" levels of delusion.
when modern populations are so genetically diverse.
They are not. Humans as a species (in case you're not understanding what I mean by "species," I mean all the bipedal primates generally referred to as "Homo Sapiens") are not very genetically diverse.
And I provided documentation to support that assertion.
I didn't even get into the genetic evidence that variation within human population groups is greater than the variation between such groups.
That you made some sort of assumption as to the reason for my assertion, is on you and not me.
I merely pointed out that your assertion is not supported by the genetic evidence. Full stop.
I don't understand why you're using diversity in this comparative manner when I was clearly not. I was just pointing out there's a lot of genetically distinct humans and this genetic distinction follows geographic trends. It's your choice to interpret it as a comparison to other species and frankly I'm bewildered why you decided to take the conversation there.
>I don't understand why you're using diversity in this comparative manner when I was clearly not.
Clear to whom? You? I'm sure it was. To anyone else? Not so much.
I read your words "I'm not disbelieving your source entirely, but it seems a little ridiculous to assume population displacement across all pre-history (or undocumented history if you'd prefer that term). Particularly when modern populations are so genetically diverse."
And you made the claim that "modern populations are so genetically diverse." Did someone commandeer your account or force you to write that at gunpoint?
If not, it was you who referenced genetic diversity.
Or does "modern populations are so genetically diverse" mean something other than "modern populations are so genetically diverse?"
As for my response, my apologies. Clearly I did not communicate my thoughts effectively. I will attempt to do so again.
>I was just pointing out there's a lot of genetically distinct humans and this genetic distinction follows geographic trends.
And your assertion is flat wrong. In fact, modern humans have very little genetic diversity, measured any way you'd like.
What's more, the human populations with the most genetic diversity are those native to Southern and Eastern Africa.
Populations everywhere else in the world are incredibly genetically similar to each other.
So much so that the differences within geographical population groups are greater than those between such groups.
As to my references to chimpanzees and wheat, that was just to point up that humans -- regardless of geographical population -- are not genetically diverse at all.
And that's it. Humans, regardless of geographic population, are remarkably similar in genetic make up. Humans are not, as you asserted, "so genetically diverse." Exactly the opposite.
Do you understand now? If not, I obviously need to learn to write more clearly.
Diversity does not imply comparison to other species. I'm still struggling to figure out how that entered the conversation. We are either diverse or not, and we are not clones, so we are diverse.
This is one of the most unpleasant conversations in recent memory. Haven't you ever heard of good faith conversation? Jesus. Absolutely rank vibes.
Humans, regardless of geographic population, are remarkably similar in genetic make up. Humans are not, as you asserted, "so genetically diverse." Exactly the opposite.
No doubt those biased Europeans felt their theory had the preponderance of evidence behind it. Funny how often the settled science is like that until the incumbent scientists die off rather than because better evidence was considered and adopted by science.
I don't think a group of people living somewhere for thousands of years would be "getting it wrong." You're embedding an assumption that evolution has been working toward an end goal of getting humans to spread globally, which isn't how evolution works.
It doesn't seem all that improbable that humans or close ancestors had colonized other parts of the world for thousands of years only to die off due to climate change/disease/other factors about 40,000 years ago when they had to start all over again. Or maybe the ancestors colonized it and the extinction event was Homo Sapiens out of Africa, although in this case you would expect more DNA mixing. It seems more likely that the ancestors died out for whatever reason and the humans moved into their habitats to refill that ecological niche.
I don't see how you could say that's more likely without evidence, lack significant gaps in archaelogical finds between eras of human presence in a region.
Oh, and fun fact: an Apollo moon mission racked up nearly 3 million passenger miles per flight and did not suffer a single fatality. Even if the astronauts on Apollo 13 had not survived, and the whole program cancelled right then and there, by fatalities-per-passenger-mile a Saturn V to the moon would still be far "safer" than driving, which averages one death every quarter of a million miles.
I think this demonstrates two important flaws with the "passenger miles" concept: 1, miles are not always fungible between modes of transport. 2, intuitively we care more about the risk per trip, rather than the risk per mile.
"Pressure" as a concept doesn't apply to black holes. They are the size they are because of their mass. The bigger the mass, the larger area where their gravity is so great light can't escape. Scientists model black holes as only have a mass and a spin on the inside because that's all the external universe cares about. Information being inscribed on the exterior is an artifact of tike dilating as an object approaches a black hole, iirc.
The Schrödinger wave-function is expressed in a unit which is the square root of an inverse cubic meter. This fact alone makes clear that the wave-function is an abstraction, forever hidden from our view. Nobody will ever measure directly the square root of an inverse cubic meter.
Freeman Dyson, Why is Maxwell’s Theory so hard to understand?
Sorry, my mistake, I was distracted when I wrote that reply. Yes, I did write that, but it's not actually essential to the point I was trying to make, which was: what could the result of measuring anything to an infinite precision possibly look like?
> what could the result of measuring anything to an infinite precision possibly look like?
Depends on what you're measuring. To illustrate why that isn't a facetious response, consider the difference between 'measuring' pi, 'measuring' a meter and 'measuring' the mass of a proton. (Or, for that matter, the relative mass of three of something to one of it.)
By repeatedly throwing a needle on a striped pattern: [1]. Obviously, you will need an infinite number of throws for an infinitely precise measurement of pi.
That would affect only a few borderline trials and would average out with subsequent throws. It would be much more worrisome that the length of a needle or the width of a stripe is not infinitely precise, that would consistently affect all the trials.
Considering that we don't know the value of pi (not that we could write it out nor read it), I'm not sure your definition of "measure" is the same as mine or most people's.
Hmm, I should say "the numerical value of pi in base 10" (or really any rational base), even if we were to weaken that with the qualifier "a to arbitrary degree of precision".
We know pi in the sense of "a unique real number satisfying many useful properties".
Isn't "3.14" pi to an arbitrary degree of precision? Or am I misreading that.
> We know pi in the sense of "a unique real number satisfying many useful properties".
We know it a lot better than that. We have efficient programs that output the numerical value of pi for as many digits as you want.
There's a bunch of real numbers we can identify that are far harder to make use of or approximate, and don't have easy exact description of their value.
You can calculate or 'measure' an arbitrary approximation of that ratio by various methods, but calculating all of it takes infinite time, which I don't have and thus can't do it.
Because the basic understanding of physics is that all particles move at constant speed c in spacetime; the proportion of their speed that is happening in the three spatial dimensions is determined by their mass. So, any particle's speed through space is a fraction of the "speed of light" c; the higher its mass, the lower the fraction.
The other items I mentioned are then caused by the speed of these particles. The speed of sound in a medium is determined by how fast particles collide into other particles in the medium. The speed of the earth around its axis (the length of a day) is determined by the speed of the particles making it up in the warped spacetime of the earth's gravitational field. The speed of chemical reactions is also limited by how fast atoms and electrons move and can interact with each other.
The length of a day, at least, is unrelated. There was a big splash in the news not long ago because it was determined that the length of Earth's day was changing and we might need to change it by a second.
Venus has a much, much slower rotation on its axis, but Mars is almost the same.
I doubt it was a big splash of news given that leap seconds have been a fairly routine thing for quite a while. Lately there’s been talk about a possible negative leap second, as Earth’s rotation speed has been increasing for a few years now. Many things can have a measurable on Earth’s rotation, including dynamics of the molten outer core, earthquakes, ocean currents, and melting of polar ice caused by the climate change.
Even before we invented precise enough clocks that there was any need for leap seconds, we knew that Earth’s rotation is slowing down due to tidal drag – the moon is literally robbing angular momentum from Earth, and getting farther from Earth in the process. Back in the Cambrian, day length was around 21 hours. Shortly after the formation of the moon, 4.5Ga ago, it would have been only around five hours, assuming the giant impact hypothesis is correct.
Leap seconds are just an imperfection in how we measure days. The recent splash was largely because it was being blamed on changes due to global warming.
In any case, it all goes to my point- the Earth's mass has no bearing on its rotational speed.
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