Fossils from Morocco complicate the story of modern humans
nature.com
nature.com
* In the last few years the Out Of Africa theory (modern humans originated solely in Africa) has received stiff competition from the Multi Regional theory. Namely that waves of human species have left Africa since we diverged from chimpanzees 4 million years ago and that our ancestors are from all the homo-inhabited regions of the world to a greater or lesser extent.
* Neanderthals and Denisovans are 2 known species that certainly inhabited much of the world (apart from the Americas) from around 2/300,000 to 50,000 years ago.
* We certainly bred with Neanderthals and Denisovans, some of us contain up to 4% of their DNA.
* Mammals generally take about 5 million years before they evolve far enough to be reproductively isolated. Of course before then there can still be breeding problems, for which there is evidence of in our breeding with the aforementioned.
* DNA from human skeletons several hunreds of thousands of years old can still be analysed.
* Mitochondrial DNA is passed by mothers only and so undergoes very little mutation. So it provides a stable and valuable signature for detecting ancient affinities between species/sub-species.
* By analysing the variation within genes certain characteristics can be interpreted like population size (eg; there were very few Denisovans) and that there are as yet unidentified species that humans have inherited from.
* Neanderthals possessed the FOXP2 gene known to be central in human speech.
* One of the oldest known oral traditions has evidence to verify a story from around 30,000 years ago: that Australian aboriginees brought the palm tree seeds with them from the north. See: http://www.abc.net.au/news/2015-04-03/aboriginal-legend-palm...
Forgive any errors in this amateur homework report.
Most interesting fact I learned: At one point there were as many as 6 human species (Homo sapiens, homo errectus, etc) on earth at the same time!
> * Mitochondrial DNA is passed by mothers only and so undergoes very little mutation
[1] From: https://en.wikipedia.org/wiki/Mutation_rate#Variation_in_mut...
> Human mitochondrial DNA has been estimated to have mutation rates of ~3× or ~2.7×10−5 per base per 20 year generation (depending on the method of estimation); these rates are considered to be significantly higher than rates of human genomic mutation at ~2.5×10−8 per base per generation. Using data available from whole genome sequencing, the human genome mutation rate is similarly estimated to be ~1.1×10−8 per site per generation.
Also quite amusing in the context of contemporary Australia's philosophy where alien plants and animals are concerned! :)
> “It suggests that Aboriginal oral traditions may have endured for up to 30,000 years, and lends further weight to the idea that some Aboriginal myths pertaining to gigantic animals may be authentic records of extinct megafauna”
Wow ^ 2
Hundreds of Aboriginal tribes had hundreds of contradictory myths on hundreds of subjects. Most of them are verifiably false (e.g. those rocks over there are not, in fact, the remains of three young women who got turned into stone for disobeying their father). Some of them are probably correct by complete accident.
As for gigantic animals... well, they're a pretty common motif in myths and stories all around the world. Maybe it's some distant memory our cultures all have of the larger animals that used to live around here... or maybe it's just because giant animals are cool. In Aboriginal myths, giant animals are often really really giant, because they're used as explanations for geographic features -- e.g. rivers are caused by the meanderings of a giant snake.
We can look at story drift even in non primitive societies where they have writing and it's huge within generations.
Most of middle east cultures draw the myth from Mesopotamian cultures, whose flood myth most likely refers to the flooding of the Persian gulf (which Eufrat and Tigris drain to currently, but used to be a fertile lowland with multiple rivers) cca 8kya.
https://www.livescience.com/10340-lost-civilization-existed-...
Considering the map in this article, with abundance of rivers across the whole Persian gulf plain, I would suggest that the myth of exile from Eden is also related to it - after the flooding and subsequent move of people upriver between the Eufrat and Tigris there was a need to create irrigation channels to keep the agricultural production up at necessary levels. Creating and maintaining these channels is hard, back-breaking work, and it might have inspired the famous 'By the sweat of your brow you will eat your food' line.
I thought the GP was actually referring to this event. Do we have a time frame for that which negates that possibility, because otherwise I'm not sure how your evidence refutes rather than corroborates.
The article I linked clearly states that it was a fertile land basin until 8kya. I decided to ignore kbenson's lack of reading comprehension hiding behind an attempt to insert himself as an arbiter through nitpicking about a thing he obviously knows nothing about, but I see he's not the only one refusing to read the article, so I'll restate my point:
My point of contention is the 15kya date. By 15kya the receding of ice age ice caps has barely started, so 15kya the ocean levels were not affected in any major way. The major geography-changing ocean level rise came a few thousand years later.
The linked article clearly states the following: "Then, about 8,000 years ago, the land would have been swallowed up by the Indian Ocean, the review scientist said." and "The Gulf Oasis would have been a shallow inland basin exposed from about 75,000 years ago until 8,000 years ago, forming the southern tip of the Fertile Crescent, according to historical sea-level records."
While I see how it's possible you could interpret me as trying to insert myself as and arbiter instead of expressing my own lack of knowledge and asking for clarification, it was fully your own choice to not only decide that was the interpretation you believed as fact, but to then broadcast that negative interpretation as fact to others. A little assumption of good faith goes a long way, and I don't think it's too much to ask for.
But like I said, that's ok.
You are right that this topic is politically sensitive - so sensitive that the data is basically ignored outside of science.
Another way of looking at it is that we are the Neanderthals and Denisovans.
The Neanderthals population is estimated at 70,000 at their peak. At 2% of 7 billion, we Neanderthals are now two thousand times more plentiful!
The other is that human population is filled with new genes that are under positive selection which have only partially spread through the population. Humans are probably the worst species to study genetically as all the normal assumptions you need to make don't hold.
One minor nitpick, your evidence of the oldest oral tradition is not very strong as there are only four major points on the compass. The likelihood of chance and cherry-picking is high.
I think the point is that the palms are introduced (not native) more than their cardinal direction (i dont believe they were using a western compass at the time so as to have four directions)
From the Wiki:
"A DNA study of fully sequenced genomes, published in September 2016, showed that the ancestors of today's San hunter-gatherers began to diverge from other human populations in Africa about 200,000 years ago and were fully isolated by 100,000 years ago, well before the first archaeological evidence of modern behaviour in humans."
P.S. the 'oldest art is 30 thousand years old' bit is in the context of 'behavioral modernity' theory at the time it was posited, based on European cave art; in the meantime, we've found even older art in a cave in Indonesia (40 thousand years old).
After some time the changes in the ADN make the two population incompatible for reproduction, so they become different species. [An easy case is when the number of chromosomes changes in one of the part but it doesn't change in the others. But more subtle changes are more frequent.]
The time scales being discussed here are orders of magnitude too short to even consider speciation, evidenced by what we know about our human/Neanderthal hybrid ancestors, and the fact that a Pygmy or Khoi-San person can have viable offspring with any person of the opposite gender in the human diaspora today.
There is a difference between the discovery & subsequent scientific reports and the story drawn from them. The story is less accurate, tends to be more romantic and gets the widest exposure. Even the scientists subscribe to one version or another because they are human. The likely change in the common story is the source of the surprise and excitement.
This process guarantees that there will always be a surprise, and roughly speaking it will be directly proportional to how long the story has been in place and inversely proportional to the number of such competing stories.
Can someone explain to me why there's so much difference?
IIRC The half life of carbon 14 is too short to distinguish samples that have been decaying for 50k years from background noise. You have to use other kinds of radiometric dating instead.
Edit: it looks like both are affected by differences in brain development. https://www.mpg.de/623578/pressRelease201011021