| Two species of Humans?
Posted: 4/29/2008 3:10:45 PM | Ancient humans started down the path of evolving into two separate species before merging back into a single population, a genetic study suggests. The genetic split in Africa resulted in distinct populations that lived in isolation for as much as 100,000 years, the scientists say.
This could have been caused by arid conditions driving a wedge between humans in eastern and southern Africa. Details have been published in the American Journal of Human Genetics. It would be the longest period for which modern human populations have been isolated from one another.
But other scientists said it was still too early to reconstruct a meaningful picture of humankind's early history in Africa. They argue that other scenarios could also account for the data. At the time of the split - some 150,000 years ago - our species, Homo sapiens, was still confined to the African continent.
The results have come from the Genographic Project, a major effort to track human migrations through DNA. The latest conclusions are based on analysis of mitochondrial DNA in present-day African populations. This type of DNA is the genetic material stored in mitochondria - the "powerhouses" of cells. It is passed down from a mother to her offspring, providing a unique record of maternal inheritance.
"We don't know how long it takes for hominids to fission off into separate species, but clearly they were separated for a very long time," said Dr Spencer Wells, director of the Genographic Project. "They came back together again during the Late Stone Age - driven by population expansion."
Although present-day people carry a signature of the ancient split in their DNA, today's Africans are part of a single population. The researchers compiled a "family tree" of different mitochondrial DNA groupings found in Africa. A major split occurred near the root of the tree as early as 150,000 years ago. On one side of this divide are the mitochondrial lineages now found predominantly in East and West Africa, and all maternal lineages found outside Africa.
On the other side of the divide are lineages predominantly found in the Khoi and San (Khoisan) hunter-gatherer people of southern Africa. Many African populations today harbour a mixture of both. The scientists say the most likely scenario is that two populations went their separate ways early in our evolutionary history.
This gave rise to separate human communities localised to eastern and southern Africa that evolved in isolation for between 50,000 and 100,000 years. This divergence could have been related to climate change: recent studies of ancient climate data suggest that eastern Africa went through a series of massive droughts between 135,000-90,000 years ago.
Lead author Doron Behar, from the Rambam Medical Center in Israel commented: "It is possible the harsh environment and changing climate made populations migrate to other places in order to have a better chance of survival. "Some of them found places where they could and - perhaps - some didn't. More than that we cannot say."
Dr Wells told BBC News: "Once this population reached southern Africa, it was cut off from the eastern African population by these drought events which were on the route between them." Modern humans are often presumed to have originated in East Africa and then spread out to populate other areas. But the data could equally support an origin in southern Africa followed by a migration to East and West Africa. The genetic data show that populations came back together as a single, pan-African population about 40,000 years ago.
This renewed contact appears to coincide with the development of more advanced stone tool technology and may have been helped by more favourable environmental conditions. "[The mixing] was two-way to a certain extent, but the majority of mitochondrial lineages seem to have come from north-eastern Africa down to the south," said Spencer Wells.
But other scientists said different scenarios could explain the data. Dr Sarah Tishkoff, an expert on African population genetics from the University of Pennsylvania, said the Khoisan might once have carried many more of the presumed "East African" lineages but that these could have been lost over time.
"Although there is very deep divergence in the mitochondrial lineages, that can be different from inferring when the populations diverged from one another and there can be many demographic scenarios to account for it," she told BBC News. She added: "As a general rule of thumb, when mitochondrial genetic lineages split, it will usually precede the population split. It can often be difficult to infer from one to the other."
The University of Pennsylvania researcher stressed it was not possible to pinpoint where in Africa the populations had once lived - complicating the process of reconstructing scenarios from genetic data. The Genographic Project's findings are also consistent with the idea - held for some years now - that modern humans had a close brush with extinction in the evolutionary past. The number of early humans may have shrunk as low as 2,000 before numbers began to expand again in the Late Stone Age. | |
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| Two species of Humans?
Posted: 4/30/2008 1:50:24 AM | why africa ?
why not upper cumbuckter west ?
did all the birds come from one bird in africa ?
hmmmmmmm
this needs some thnking | |
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| Two species of Humans?
Posted: 4/30/2008 5:14:02 AM | | I can't remember the specifics, but i remember tribes battling each other and separated by the shape of their nose. If their nose was thin and narrow, they belonged to a certain tribe, and if it was toow wide they were rejected. Was this nose shape a result of the separation or mixing with europeans? | |
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| Two species of Humans?
Posted: 4/30/2008 9:13:48 PM | .
I thought they traced all the markers back to one tribe in south central africa for all of mankind? Has that changed now?
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| Two species of Humans?
Posted: 5/1/2008 1:25:37 AM | No. At some point, all markers will always trace back to "one" individual. It's a question of the time frame and the amount of differences.
Essentially, genetic markers are used like long strings of little clocks. We start with one set, which is passed on to all the children. The clocks start ticking off randomly. With each generation, the clocks get a little more different, but they will always be most similar between siblings [as they inherited the same random version].
Fast forward from 100000 years ago to now...we can safely assume that people who have a common ancestor only a couple generations ago will have basically identical clocks, as the clocks change very slowly. We can omit most relatives, and just compare tribes, cultures, ethnic groups. Comparing the results, we reverse the clocks. The greater the number of differences, the farther back we have to go to find the shared ancestor.
What this study has done, is shown that at one point in time 40000-100000 years ago, there is a big gap. Instead of all clocks gradually matching up, in that time frame, all clocks match up ONLY with Khoisan peoples, or other humans. It's not until 100000 years ago that the two sets match again. If you keep counting back, 10000000 years ago, the clocks would also match up with gorillas and chimps. 1000000000 years ago, they'd match up with a sponge.
Off the top of my head, I think someone mentioned Europeans. Europeans are not a group with a separate origin, but basically one small and recent offshoot of African populations. The same is true of Asians, although they more recently diverged from Europeans. There is some question on this, since it is possible that some non-African humans also have some ancestry among other hominids like Homo erectus. Their ancestry is still largely Homo sapiens, but it's possible they branched off much earlier and have re-mixed since then.
It's a lot easier to explain this with branching diagrams. Picture a big, bushy tree, all of it modern man. At the ground is modern man 100000 years ago. Five feet up, one major branch comes off. The main trunk doesn't branch again for many feet. Near the top, all kinds of smaller branches appear on both the trunk and the first branch. They're all overlapping and mixed with one another, but there's a big chunk of history where they went their separate ways. | |
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| Two species of Humans?
Posted: 5/1/2008 1:51:41 AM |
No. At some point, all markers will always trace back to "one" individual.
Yes, it going to be Adam. | |
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| Two species of Humans?
Posted: 5/1/2008 2:39:15 AM |
Yes, it going to be Adam.
I don't think you understand the underlying science here. | |
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| Two species of Humans?
Posted: 5/2/2008 10:39:34 AM | Actually in evolutionary genetics we refer to the mitocondria eve and the chromosonal adam.
According to the text books and the exam im sitting next week! | |
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| Two species of Humans?
Posted: 5/2/2008 1:23:48 PM | Adam and Eve were amoebas swimming around in a primordial soup.
When that truth is finally proven beyond a shadow of a doubt, the theists are going to react harder than they did when Darwin announced we came from apes.
Priceless !
I've been keeping a keen interest on National Geographic's Genographic Project too. It's fascinating stuff and I hope they eventually find some unquestionable answers. | |
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| Two species of Humans?
Posted: 5/13/2008 11:51:06 AM | i love you ancient muse... lol hit on the dot, as far as religion is concerned..
take a look at different races.. blacks whites and aztech as the easiest to explain... africa has been the "black" area their pigment represents the ability to be directly exposed to sunlight thousands of years... from that the whites came to be into colder climates and pigment was not needed and there for geneticaly turned off... then the asians then on to the native americans then on to the southern americas.... where the ability to live in high altitudes developed... all of wich prety much stayed in the same gographical locations...now we have artifitial means of living in different environments... and now the melting pot begins on to a new species of humanity... we are so abundant that the entirety of earth is our geographical location... ultimatly tho if we do evolve along side technology... what happens when technology is not present? as well as genetics may prove to artificially advance our race..
but that is a different discussion all together... | |
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| Two species of Humans?
Posted: 5/13/2008 1:49:28 PM |
Yes, it going to be Adam. Actually, it would point to eve.
I heard something a few weeks ago in passing, that male genome is gradually disappearing, while the female is passed on. Or something like that.
"black" area their pigment represents the ability to be directly exposed to sunlight thousands of years Actually, pigment has to do with folic acid. Hence, reproduction is the (main?) reason. It has nothing to do with protecting us from cancer causing rays. Eskimos have a diet high in folic acid, so have darker skin. | |
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| Two species of Humans?
Posted: 5/13/2008 5:07:07 PM |
Yes, it going to be Adam.
Actually, it'll be more along the lines of "Atom"
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| Two species of Humans?
Posted: 5/13/2008 6:18:07 PM | ancientmuse:
When that truth is finally proven beyond a shadow of a doubt, the theists are going to react harder than they did when Darwin announced we came from apes.
and IF it turns out that darwin was wrong beyond a shadow of a doubt how is everybody else going to react?
this thread seems to have very similar attitudes to the christian fanatics threads, you are more a like than you care to admit.
Sorry, nothing to do with the OP, but back on thread (ish). something has always puzzled me about human evolution. Modern man (homo sapien sapien) with the same physical make up as we have today and more importantly the same size brain as we have to day has been around for about 100-150,000 years. So why has civilisation and the technological explosion only been around for approx 10,000 years.
Why is it we were happy being hunter gathers for over 90,000 years then suddenly change. If you respond to this please note DON'T use the ice age as an explanation it doesn't fit, but thanks for responding. | |
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| Two species of Humans?
Posted: 5/13/2008 8:58:34 PM | I gots a feeling that when Adam and Eve are proven to be little micro-organisms that religions are simply going to adapt to that discovery. Adam and Eve could be energy and dark energy for all I know, and I'm not religious or claiming how religions came to know certain patterns in behavioural relationships.
Hey is this about the little people fossils found? I remember reading about tiny little people bones found that were said to be very old. | |
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| Two species of Humans?
Posted: 5/13/2008 11:11:52 PM | Well.....the problem with 'proof' is that it doesn't work real well when opponents are judging by different criteria. I can't imagine this issue ever being absolutely 'proven' to the satisfaction of all. Science doesn't deal in absolute proof, anyway, just increasing degrees of confidence, or decreasing credence for whatever 'dis-proofs' have been offered as alternatives.
Our diverse perspectives are both our blessing and our curse. They bog us down when we need to be moving on, yet also offer us endless alternatives whenever our current path looks less than promising. Aren't we a wonderful species?
Dave | |
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| Two species of Humans?
Posted: 5/16/2008 8:40:54 AM | The human form could be improved upon...so why wasn't it? Two or more forms vying for dominance would have increased the chances of a better species, more adaptable. Having the brain so high (although encased in armour) isn't a bad idea...but a fall can damage it. What if it were lower...in the rib cage area? Place the heart in the head...a pump at the "head" of a well, so to speak. Makes as good of sense as anything...and may well have evolved into a stronger circulatory system, less prone to weakness in the arteries and veins and a stronger heart that would not work so hard when we are reclined.
Anyhow's...interesting little thread. | |
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| Two species of Humans?
Posted: 5/16/2008 10:55:52 AM | Why is it we were happy being hunter gathers for over 90,000 years then suddenly change. If you respond to this please note DON'T use the ice age as an explanation it doesn't fit, but thanks for responding.
lots of reasons really, you could take us way back in time if we didnt have any wars. wars force new technoagly to be made and people to work together. so as one clan got bigger maybe needed more space to hunt and gather they would become a threat to another. well only natural that you would defend you land, so you would have smaller clans of humans grouping up and making bigger. with that comes sharing of information, and new tools.
really is like anything, it always starts off slow then snowballs. look computers, now strech thetime line out and it would look the exact same as mankinds civillisation and the rest of out tecnolagy exploisons. we can do things faster now due to when we work on something we have more people working on it.
also have to work out that well we will achive more goals in a lifetime due to living longer, and having better schools. you dont think the iron age, bronze age and such were massive jumps in technoalgy? lets see you figure that out without any books or knowalge on it.
without some really great minds throughout the corse of history we could be short alot of things. every idea works off the last.
well the ice age wouldnt be a soul reason it surly would delay the progress of mankind alot. thats a whole new lifestyle they had to learn 2 times, once for the start and once when it was stopping.
alot to due with your question isnt a simple one worded answer but a matter of look at everything. how could you have a civilization when most of your people have to hunt and gather? wouldnt be till farming was invented and worked that you could even think about staying in one place for extended amout of time. also need to learn abotu food preservation for the winter in some places.
its alot easier to keep 50 people feed, cloathed and happy then it is 1000. | |
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| Two species of Humans?
Posted: 5/16/2008 7:34:35 PM | Mankind did not start out as a "hunter-gatherer". Mostly ate a vegtarian diet...perhaps some small game if it could be caught. Protein was needed in bulk...thus, hunting developed. Larger animals would drive men away from their kills, so better weapons were needed, and built. Following the herds as a nomadic tribe was fine...for small numbers. Larger numbers needed to camp for longer periods, sending out hunting parties. Agriculture started as soon as someone noticed that if they stayed near the berry patch, there was more for them because the animals avoided the area. Spilling some grain that was to be eaten and having it grow there gave them the idea of spreading more around. It became a matter of claiming open ground and seeding it. Better shelters were needed...the village was soon growing. Potters, artists, weaponsmakers...mankind started to specialize in certain areas, trading their skills and goods for food.
Not all cultures practiced animal husbandry. Most North American did not raise any animals...except for a small group in the southern USA that may have raised turkeys. The idea of having a "larder on the hoof" meant needing feed for them too. Storage areas for feed and animals was usually in the same building as the family lived in. A prosperous farmer became a leader...and soon lived in a separate home.
The advent of "hay" allowed herd farming in the northern reaches of Europe.
The issue of Neanderthals living at the same time as regular humans has been a tough one to crack. What happened? They were bigger boned, larger muscled, bigger brain pan...they seemed better suited for dominance. Perhaps, as is often the case, how the brain was used proved to be the turning point for mankind...and the demise of the neanderthals. | |
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| Two species of Humans?
Posted: 6/2/2008 9:05:28 PM | | You cant believe everything the govt tells people to put out...we were all put here on earth as a test...different races....and its not working...govt still keeps it all messed up with their documents of proof....they real proof is looking at the DNA of Hh people only two exsist and where they are now? Boy and a Girl brother and sister heard of that one? h h weird blood line..where in the world did it come from?.....a test.. | |
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| Two species of Humans?
Posted: 6/2/2008 9:07:58 PM | | H h bloodline? This is the rarest I have ever known a boy and a girl brother and sister but where are they now? Look it up....we all were placed here with different DNA the govt put out documents and tells people what to say heaven forbid they put the truth out.. | |
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| Two species of Humans?
Posted: 6/2/2008 9:09:14 PM | | Dont know how old this thread is hope you past your test ever heard of Hh blood line? Ask about this to some and let me know what you find out....curious... | |
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| Two species of Humans?
Posted: 6/2/2008 9:12:13 PM | | If you ever get a chance I dont know how old this thread is but Hh bloodline do you know where it came from? It makes me wonder about all the bloodlines and why some end...a computer can figure these out? | |
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| Two species of Humans?
Posted: 6/4/2008 8:14:46 PM | Evolution isn't a slow process, its quantum leaps, with long rest periods. once a galactic cycle. The problem is we have a choice to become better with free will, but how many actually do? what use is a physical change without an inner change? does it matter if our bodies change slightly? we dont even use a quarter of our brain. Why arint people using both sides in balence? why do people only use one side over the other? why are people waiting for something to change them, and not changing themselves ? :) this might be a philosophical question :P
Its funny when you think of it, a scientist is all logic, one side of the brain, and a spiritualist is the other side, so is it fair to say neither knows what they are talking about completly? :) | |
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| Two species of Humans?
Posted: 6/7/2008 12:36:39 PM | Somewhere I read or saw that when early mans diet changed to include more fish it affected his brain which led to art and culture. They do call it brain food after all.
Also, how does the bottleneck of about 72k years ago fit in to the research. I believe the total human population was no more than a few thousand after a huge volcanic eruption.
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| Two species of Humans?
Posted: 6/8/2008 10:24:37 AM | Vancer notes:
I gots a feeling that when Adam and Eve are proven to be little micro-organisms that religions are simply going to adapt to that discovery.
From what I understand, the Catholic Church is already allowing for the possibility that Adam and Eve were not Homo sapiens. Not that they advertise it much, even to their own. | |
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