Not a bad book.
Posted on 07/28/2019 9:41:55 PM PDT by SunkenCiv
In new research published in Proceedings of the National Academy of Sciences, we detail how during this remarkable journey the ancestors of modern humans met and genetically mixed with a number of archaic human groups, including Neandertals and Denisovans, and several others for which we currently have no name. The traces of these interactions are still preserved in our genomes.
For example, all modern non-African populations contain about 2 percent Neandertal ancestry. This strong universal signal shows that the original Neandertal mixing event must have happened just after the small founding population left Africa.
We can even use the Neandertal genetic signal to date when they left Africa. The large size of Neandertal DNA fragments in the genome of an ancient skeleton from southern Russia, which is 45,000 years old, shows that at most 230-430 generations could have passed since the initial mixing event (dating it around 50-55,000 years ago).
By analyzing where the archaic genetic traces are found today (from previous genetic studies) and using paleovegetation maps that identify favorable savannah-like habitat along the route 55,000 years ago, we have reconstructed the likely geographic locations and number of the archaic hominin mixing events.
(Excerpt) Read more at phys.org ...
For most of the past 2 million years, the ocean levels have been much lower than today, meaning most of the time our ancestors (in any part of the world) were down on what is now the continental shelf. That's where the liquid freshwater was, that's where the food supply was plentiful, and that's where the seagoing transportation was feasible. Even today, after how much time? and with remarkable modern technology, most of the human race lives within 500 or so feet of sealevel.
A problem with DNA research, that isn’t backed up by physical evidence, is that there are the rare beneficial mutations that can change genes in a species without contact with other groups. And there isn’t likely to be physical evidence remaining of crude humanoids from so long ago.
I guess when there is enough knowledge that will be addressed. Seems, for now, everyone just assume the changes come from contact with ‘new’ groups.
Would have been a wonderful place for humans to live during the whole Ice Age.
This just proves that Neanderthal chicks were easy.
The problem with using DNA is to try to determine ultimate geographical origin based on where this or that DNA bit survives today. The technology has been improving remarkably, such that DNA sequences can be extracted from very, very old remains, much moreso than might have been suspected even ten years ago.
They probably didn't take 'no' for an answer, so much for 'anatomically modern'...
Sore, at this point in our knowledge it’s very reasonable to work on the assumption that new races contributed the new genes.
But we may discover they’re just beneficial changes by radiation.
Intriguing that the Laschamp Event (75% weakening of the magnetosphere) happened 41,400 (±2,000) years ago: roughly approximating the time of the ‘new’ races in SE Asia.
just something to bear in mind!
What I really want found is evidence of the “giants” mentioned in practically all myths- not ‘Hobbits’!
The Laschamp Event evidence shows that the magnetic field of the Earth can change quickly, and just as quickly change back. Other magnetic field evidence shows large increases and polarity changes. Either the magnetic field of the Earth has an unknown mechanism as its cause (not unlikely, since it remains unexplained), or the Earth is sometimes in the presence of an outside magnetic field (perhaps from some kind of massive solar event). Either way, magnetic field fluctuations are just a uniformitarian alibi for events — such as global glaciation — that are caused by brief, unusual events. The Earth’s magnetic field means squat to the Earth’s climate.
[snip] What is remarkable is the speed of the reversal: “The field geometry of reversed polarity, with field lines pointing into the opposite direction when compared to today’s configuration, lasted for only about 440 years, and it was associated with a field strength that was only one quarter of today’s field,” explains Norbert Nowaczyk. “The actual polarity changes lasted only 250 years...” [/snip]
https://www.sciencedaily.com/releases/2012/10/121016084936.htm
Very good points - and the dates may go back further than 1.8 million years.
A lot of people in the Anthropology business seem to believe that Homo Erectus evolved outside the African continent.
I get the impression that theory might be very dangerous for job security in the academic world, and it's rare that I see detailed commentary on that idea.
How does Toba bear on all of this?
” magnetic field fluctuations are just a uniformitarian alibi for events”
Not “just”.
I’m sure they can be! And that there are examples of the backward doing so. But radiation-caused mutation is an established fact. And a huge weakening of the magnetospere would increase mutation.
A strict limit though would be “beneficial” mutations. Very rare. That’s the catch.
I don’t mean to denigrate the study of mating-influenced genetic change, and the myriad factors involved such as climate.
But it’s a fact that radiation can cause it too.
( Though beneficial mutation is a rare result in all but the simplest organisms- it happens.)
Looks good, but dated. Published 2001. There’s been a lot of new data, fossils, DNA sequencing and many other discoveries since.
The Denisovans weren’t discovered until 2010, and their DNA sequenced in 2012.
If we wrote a book on everything we know right now, who knows how relevant it will be in 2037?
It all comes dow nto classification.
There’s been a tendency from the late 1980s onward to reclassify many separate homo species back into Homo Erectus.
Homo Egaster was considered the oldest, and from Africa, but now it appears to be part of the Homo Erectus species along with Java Man, except for Homo Heidelbergis, which was given its own distinct species.
The new list of Homo Erectus:
Homo erectus bilzingslebenensis (0.37 Ma)
Homo erectus erectus (Java Man, 1.6–0.5 Ma)
Homo erectus ergaster (1.9–1.4 Ma)
Homo erectus georgicus (1.8–1.6 Ma)
Homo erectus heidelbergensis (0.7–0.3 Ma), now mostly treated as a derived species, H. heidelbergensis.
Homo erectus lantianensis (Lantian Man, 1.6 Ma)
Homo erectus nankinensis (Nanjing Man, 0.6 Ma)
Homo erectus palaeojavanicus (Meganthropus, 1.4–0.9 Ma)
Homo erectus pekinensis (Peking Man, 0.7 Ma)
Homo erectus soloensis (Solo Man, 0.25–0.075 Ma)
Homo erectus tautavelensis (Tautavel Man, 0.45 Ma)
Homo erectus yuanmouensis (Yuanmou Man)
Ancient Tree With Record Of Earth's Magnetic Field Reversal In Its Rings Discovered
Doesn't. The claims of a genetic bottleneck hasn't panned out, and obviously, with a crowded SE Asia, it wouldn't do very well, would it? ;^) The eruption of Toba is now known to have had basically no impact on India, for example, where humans already lived, and continued to thrive.
In the history of early Britain below, the earliest settlers were the H. heidelbergensis. (The presenter pronounced the en in heidelbergensis, which is missing in other responses above).
The account maintains that those earliest inhabitants were supplanted by the arrival of H. neanderthalis, who weren't as artful at toolmaking as H. heidelbergensis:
https://www.youtube.com/watch?v=kk5-ynRPfss
:^)
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