
Rethinking our human origins in Africa - XzetaU8
http://www.nhm.ac.uk/discover/news/2018/july/the-way-we-think-about-the-first-modern-humans-in-africa.html
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netcan
_" Ancient H. sapiens appear to have been even more physically diverse than
the world's populations are today, which doesn’t fit with the idea that they
all started from one small group._"

I believe that the theory they're supposed to be debunking is not that the old
(>300,000 yrs) sapiens population descended from a single regional population.
The theory is that by 300k ybp there was a divverse sapiens population in and
near Africa. They had a wider range of physical appearance than modern humans.
Our ancestors descended from a sub-population of archaic sapiens (before
mixing with other homo species).

The theory explains why we're so much more homogeneous than very old sapiens
who still sometimes exhibited "primitive" (isn't this a truism?) skull shapes
and such. We went through a bottleneck at some point.

IE, many flavours of sapiens existed. We descend from one of them. The Morocco
& Levant sapiens have no descendants.

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singularity2001
> A new paper challenges the traditional idea that our species evolved from a
> single population in one region of Africa.

every article or paper on this topic in the last 10 years talked about a
complicated network of genetic branches instead of a simple linear tree

~~~
bilbo0s
In fairness...

> _a complicated network of genetic branches..._

kind of implies a tree.

I haven't read the other papers, but, at it's root, the paper that is the
subject of this posting seems to imply that the root species came much, much
earlier than we typically believe. I'd need more access to the genetic data
they are basing that conclusion on to know if they are right? But it _sounds_
right. Why could sapiens _not_ have risen in Africa millions of years earlier?
(At the same time, we have to be careful. _Sounding_ right is not how we
should be evaluating scientific theories.)

~~~
dspillett
_> In fairness...

> >a complicated network of genetic branches...

> kind of implies a tree._

Not quite. The implication is that some separate branches that developed
distinct (but not incompatible) differences over time due to geographical or
social separation later merged into other branches, meaning that there isn't a
simple linear sequence from every point in the tree back to the one root.

~~~
julienchastang
Exactly. I have heard the expression "braided stream" be used for this
description.

~~~
singularity2001
Yes! Neanderthals being the most prominent recent example.

Now let's convince linguists that Semitic and PIE languages are related and we
have won!

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simonh
This makes a lot more sense to me. Whenever I see a description of a long
period of history as being mainly static, such as humans evolving as a
separate group within Africa for a hundred thousand years or more, it sets off
alarm bells. It just sounds like historians and archaeologists only have a few
reference points to work from so they extrapolate between them in a straight
line or a nice smooth curve. Real human history is messy, complicated and
often violent.

I'm not getting at the science or it's practitioners, they can't just make up
complex changes without evidence, but let's be honest that any such seemingly
static periods of history due to limited evidence are probably just
placeholder theories for whatever was actually happening.

~~~
Radim
This reminds me of the so-called "dark ages". Bronze age collapse, Middle
ages…

Early historians used to call them _dark_ because of just such "limited
evidence". Little surviving records, compared to the periods before/after.

But these "periods of silence" may have given us something less tangible but
even more lasting than literature and architecture. The fabric of societies
was rewoven, new modes of thinking and organization emerged from the chaos.
People may not have been into books and stone, but they were certainly not
idle!

The inhales and exhales at the scale of humanity are sometimes hard to
appreciate, or even tell apart, from our individual level.

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fastaguy88
The observation that humans (originally human females) descended from a woman
who lived about 240,000 years ago in Africa was first demonstrated by Allan C.
Wilson, who looked at the evolution of mitochondrial DNA sequences, in 1987.

This was a very controversial result, in part because the length of human
history was so young (much less than the 1 million years that some fossils
suggested), and because the origin was placed in Africa. Shortly after this, I
heard Wilson discuss the controversy, and he remarked that he was surprised
that there was so much disagreement about the idea that a set of genes in a
population could be attributed to a single individual. He pointed out that
this was well understood by population biologists in the early 20th century;
basically, for any population of individuals at some time in the past, after a
long enough time, the descendants of that population will have genes that can
be traced back to one individual -- that one individual whose children had
children who had children ... Though well established in 1987 (and decades
earlier), but it was still argued about (and apparently still is).

Mitochondrial DNA can be traced back to an individual Africa (mitochondrial
eve), less than 300,000 years ago.

~~~
karmakaze
> controversial result, in part because the length

This part doesn't make sense. The controversy must have been a
misunderstanding. 'mt-MRCA' is a moving target. It is the most recent common
ancestor (MRCA) of the currently living population. The mt-MRCA for the
population earlier in time would be older than the current mt-MRCA. Similarly
for Y-MRCA.

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at-fates-hands
Interesting.

In the early aughts, my TA in University was writing a similar paper for his
doctoral degree. All of the professors in the department said it was good
enough to be a PhD paper.

His premise was there were several divergent populations not only in Africa,
but in Nordic regions and Eastern Europe from where we evolved from.

It's cool to see this shift in the dominant paradigm is finally starting to
shift, some 20 years after my TA (and presumably many others) proposed it.

~~~
escherplex
Nice to see academic researchers are now trying to utilize a more
phenomenological approach in their theorizing. Ideally, _What does the
available data strongly suggest?_ should be in the forefront rather than group
conformity to some conditioned or ingrained ethnic or anti-ethnic grounded
chauvinistic penchants. Time to grow up :)

~~~
posterboy
Nah! The problem in the first place is to wonder where to find any data at all
and in the last twenty years new data has become available. It's a back and
forth, really.

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rjsw
The summary doesn't seem to mention the idea that there may have been one or
more population bottlenecks between the emergence of H. sapiens and now.

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wallace_f
A neanderthal skull juxtaposed with one from a human shows the more-primitive
elongated shape mentioned in the article or primitive human species:

public.media.smithsonianmag.com/legacy_blog/skulls.jpg

To me it is fascinating to imagine what this species was like with their
larger brains, but smaller frontal lobes, which are believed to have been
more-focused on their senses and athleticism.

~~~
jameskegel
Just curious, why is this being grey’d?

~~~
yathern
Probably because this talk of skull-shape and less intelligence sounds a lot
like phrenology - an old psuedoscience used to determine the latent abilities
of a person, based on their skull shape. Which ultimately was related to their
race - and used to look down upon different people groups.

Once you believe there is a strong causation between skull shape and
intelligence, the racist conclusions write themselves.

I assume good faith on the part of the GP, though.

~~~
wallace_f
I've read a bit about them and most sources say this, 'they were more
encephalized and even in absolute terms had larger brains, but probably were
not more intelligent.'

I didn't have any idea anyone would interpret this as racist, wtf?

The discussion on skull evolution I reference here is also mentioned in the
OP. How can I be accused of racism and not the OP? That isn't consistent.

~~~
drharby
Ha! Pump your breaks tiger; no one is accusing you of racism, people are
makimg the observation that some could make that interpretation, amd such
interpretations have a marked history in America.

Don't get hostile or defensive over a misunderstanding, please.

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citizen_e
I know some people who would use this research to try and argue that humans of
different races are in fact more separate genetically than is popularly
believed. Does this research suggest anything of the sort?

~~~
craftyguy
No.

~~~
just_myles
No. However, I am certain that there will be others that will try. You can
count on it.

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zone411
If you're interested in the ancient DNA, I highly recommend "Who We Are and
How We Got Here: Ancient DNA and the New Science of the Human Past" by David
Reich.

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patrickg_zill
It's been obvious for a while now, that the out of Africa theory was far too
simplistic.

Denisovan DNA for instance, of which there is no sign in any African and very
few European people...

~~~
jshowa1
Except the article still says its out of Africa, just not from a single region
in Africa.

