RonO wrote:
The early genomic interpretation of the first large batch of human
genomes (The data set was short on African genomes) came up with the inference that there was a population bottleneck around 100,000 years
ago, but later estimates claimed that the bottleneck was much further
back in time than that.
Toba was like, what? Maybe 74,000 years ago? It had to be a bottleneck.
The last time Yellowstone detonated it was like 50 Krakatoa eruptions
happening all at once. The Toba eruption was roughly 2.8x Yellowstones.
It was a bottleneck.
I've argued for many years how molecular dating, when it isn't just
plain wrong, exaggerates age.
They claim that they
can place the population bottleneck that may have nearly been our
extinction back to 900,000 years ago.
There was a very large asteroid strike about 800k years ago, many
sources claim multiple hits in the 800,000ish period.
Asteroids can be worse than volcanoes as all their energy is released
at once, while volcanoes erupt over hours, days, weeks and could be
months.
I know, I know, you don't get a steady, even eruption over a period of
weeks. Krakatoa erupted for like 5 months, Wiki claiming it peaked
in month-3.
If there's a large impact it's pretty much over with as soon as
whatever got kicked up lands. The fires may still be burning but all
the energy it's going to release has already been released...
I also recall some claims that some genetics that may have been
useful for cannibalism plots to this time. Not my area of interest,
and the searching the Google archive is a joke at this point (Google
ruins everything, it seems) but do with it as you may...
What they do not consider is a speciation event. A speciation event
would look like a population crash if only a small portion of the
existing population participated in the speciation event.
Actually, it would look like the Retrovirus evidence.
I've argued that it doesn't mean that our ancestral species wasn't in
Africa. It just means that the African POPULATION either died out
or was genetically swamped -- absorbed by either the Pan side of
the family tree or the Eurasian population.
The problem here is that the test can't actually tell you what they
are pretending it says.
They're not sampling 900,000 year old DNA, so there is no
comparison what so ever. It literally is speculation.
They are looking at TODAYS genetics and pretending that tells
us what the DNA looked like 900,000 years ago.. an assumption
that has been falsified time and time again.
Like the Chromosome 11 insert. It's pretty common even in
Europe, but nobody has identified the population that it stems
from. And nobody would have any clue that this population
ever existed if it weren't for this insert...
Fact is, you can't even go back to the early Holocene and find
a matching population in Europe today. It looks like a
replacement happened about 4.5k years ago...
https://www.nationalgeographic.com/history/article/130423-european-genetic-history-dna-archaeology-science
But most seem to believe that it was more like what happened
with Neanderthals earlier: The new arrivals out bred and
genetically swamped the old guard.
Coastal -- Aquatic -- populations could support a higher
population density than inland hunter-gatherers, while an
agricultural society could support a higher population
density than could the coastal groups...
DNA is an either/or game. A baby gets its DNA from THIS
man or THAT man, but never both.
What is
amazing is that the latest estimate for when the chromosome 2 fusion
event occurred (around 900,000 years ago) coincides with when the
bottleneck started
As the term "Latest estimates" implies, that figure is (very) subject
to change.
and the fusion was present in the population of Homo
that existed when the Neanderthals and Denisovans left Africa and took
the chromosome 2 fusion with them around 800,000 years ago.
The asteroid impact of around 800k years ago was probably similar to
Toba in that it favored Africa.
The impact was exactly in the wrong place for "Out of Asia," and of
course the northern hemisphere would've suffered the prolonged
consequences... likely something similar to a Younger Dryas cooling
event.
The fact is, the current claim is that a VEI8 volcano erupts on an
average of about once every 50k years. There's literally no shortage
of potential bottlenecks. It's really about how big we're talking about,
and what we can align them with.
Also: Such events favored coastal groups, aquatic ape. The ocean
moderates temperature and the sea is a fairly dependable source
for food... compared to hunter gathering during a global volcanic
winter.
Outside of NOAA, a government agency, nobody buys into the
"Ice Dam" claim for touching off the Younger Dryas cooling. What
evidence there is seems to falsify it, and the premise is just plain
stupid as the end of every glacial period should have resulted in
the same type of event. Even the end of the Younger Dryas should
have touched off another one!
No, do the Google on "Bolide Forcing" and "Younger Dryas." Next
on the list, though not as popular, is a large volcano...
-- --
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