Friday, April 16, 2010

The Evolution of Homo Sapiens

The Fjordman Report

The noted blogger Fjordman is filing this report via Gates of Vienna.
For a complete Fjordman blogography, see The Fjordman Files. There is also a multi-index listing here.



Australopithecus afarensisHomo sapiens, our own species, is distinct from other mammals: great apes such as chimpanzees, gorillas and orangutans and from early hominids. At some point between 8 and 4 million years ago gorillas and then chimpanzees split off from the evolutionary line that would lead to humans. As Michael H. Hart explains in his fine book Understanding Human History, Australopithecus afarensis, our likely hominid forefather, lived in East Africa about 3.5 million years ago. The Australian anthropologist Raymond Dart (1893-1988) discovered the first fossil of an Australopithecus africanus, a slightly more evolved version of A. afarensis, in 1924 in southern Africa. It was neither ape nor human and caused a stir at the time. Prior to this find, most Western scholars had believed that humans evolved in Eurasia.

Louis Leakey (1903-1972), the son of British missionaries, was an archaeologist and naturalist working in British-ruled East Africa. He went to school at Cambridge University in England, majoring in anthropology and graduating in 1926. From the very start Louis felt that our species arose in Africa, a concept which is now widely held but was controversial at that time. Through their tireless exploration and research, Louis and his English wife, the archaeologist and anthropologist Mary Leakey (1913-1996), made the Olduvai Gorge in the Serengeti region in northern Tanzania, famous for its wildlife, their domain. They made a series of spectacular paleoanthropological and archaeological discoveries in East Africa and founded a Leakey family dynasty of leading scientists that is currently in its third generation.

Lucy, the skeleton of an Australopithecus afarensis that lived 3.2 million years ago, was discovered in Ethiopia in 1974 by the American paleoanthropologist Donald Johanson (born 1943) along with the French anthropologist Yves Coppens (born 1934). The genus Homo diverged from Australopithecines more than two million years ago with Homo habilis, which made very crude stone tools called Oldowan after the Olduvai Gorge. About 1.8 million years ago a new species, Homo erectus, arose in East Africa, the first hominid to spread out of Africa. The earliest fossil of Homo erectus (“human that stands upright”), the Java Man, was discovered by Dutch physician and paleoanthropologist Eugène Dubois (1858-1940) in 1891 on the island of Java, then under Dutch colonial rule. H. erectus existed not just in Africa but in parts of Eurasia as far as Java in Southeast Asia, but apparently never settled in Australia or the Americas; this was achieved by early modern Homo sapiens during the past 40,000 years.

The exact evolutionary sequence leading to our own Homo sapiens is disputed, but a commonly held view is that we derive from Homo erectus, which again derived from Homo habilis, which in turn derived from Australopithecus afarensis. The prevailing view among anthropologists is that Homo sapiens originated in Africa about 350,000 years ago. They are often referred to as “archaic Homo sapiens.” About 100,000 years ago Homo sapiens sapiens, which includes all modern humans, arose in sub-Saharan Africa and eventually spread throughout the entire world, displacing all other variants of the hominid family.

There were undoubtedly other, less evolved, Homo species which are now extinct. It is not impossible that there was some multiregional evolution or admixture with existing Homo populations when anatomically modern men moved into Eurasia; this remains a hotly disputed area of paleoanthropology. For example, Homo floresiensis (“Flores Man”) is a possible species discovered in 2003 on Flores in Indonesia. It apparently survived until after 10,000 BC, which would make it the final branch of archaic humans to go extinct. Yet there is not yet a consensus on the matter, with some scholar viewing it as a version of Pygmies.
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A very widespread view among scientists is the “Out of Africa” theory of the recent African origin of anatomically modern humans. According to this theory, Homo sapiens originated in Africa, moved into Eurasia and beyond 50-60,000 years ago and replaced other, more archaic human species. The British anthropologist Chris Stringer (born 1947) is one of the leading proponents of the recent “Out of Africa” theory.

A strikingly large proportion of leading evolutionary biologists, starting with Alfred Russel Wallace and Charles Darwin, come from the English-speaking countries. The American physical anthropologist Jeffrey H. Schwartz (born 1948) researches the origins of primates, including humans. Henry McHenry (born 1944) Professor of Anthropology at the University of California, Davis, studies evolutionary history of hominid bipedalism, locomotion (e.g. walking, jogging, running) on two legs. It is not uncommon to see animals standing briefly on two legs, but only a few of them do this consistently. Most other animals, including chimpanzees, gorillas and even cats, may stand on two legs on a temporary basis in order to perform a particular function. Today, only humans and birds demonstrate habitual bipedalism.

The human family tree grows more complex all the time, but I personally believe that the out-of-Africa theory is largely correct. The pathologist Robin Warren (born 1937) in 1979 discovered the bacterium Helicobacter pylori at the University of Western Australia together with physician Barry J. Marshall (born 1951). In 2005 they shared the Nobel Prize in Medicine for their discovery of H. pylori and its role in gastritis and peptic ulcer disease. Thanks to them, peptic ulcer is no longer a chronic, frequently disabling condition, but a disease that can be cured. Infection of the stomach by H. pylori is ubiquitous among humans, but genetic diversity in it decreases with geographic distance from Africa. Like its hosts, simulations indicate that the bacterium spread from East Africa almost 60,000 years ago.

Two prehistoric migrations peopled the Pacific. One reached New Guinea and Australia, and a second, more recent, one extended through Melanesia on to the Polynesian islands. These migrations were accompanied by two distinct populations of Helicobacter pylori. The first split from Asian populations 31,000 to 37,000 years ago and, in concordance with archaeological history, remained largely isolated thereafter in Australia until the European colonial period. The second human expansion 5000 years ago dispersed one branch of the large Austronesian language family into Melanesia and Polynesia. These languages have their greatest diversity in Taiwan outside of mainland China, where the Austronesian expansion probably began just before 3000 BC, at roughly the same time as the Indo-European expansion began in Europe. Austronesian-speaking peoples gradually spread throughout the islands of Southeast Asia and from there on to the Pacific islands in several waves as they invented improved outrigger canoes capable of undertaking such long sea voyages.

17 comments:

darrinh said...

One of the favourite lines supporting the "Out of Africa" theory is the one that because Africans today are so genetically 'diverse', that we must have come from there. But this does not make sense, as one would expect a 'parent' population to be much more homogeneous than proceeding generations. Africans are diverse because the flow of genetic material went inwards, not outwards.

Also interesting to note that Australian Aborigines and Africans are among one of the most unrelated genetic groups on the planet, how does that work if they came from Africa?

All theories and simulations always assume Africa as the epicentre, but the reverse angle looks much more correct.

Fjordman said...

Darrinh: That's an absurd statement. It's essentially the same principle as with linguistic evolution. If you dropped a person who knew absolutely nothing about history down on planet Earth in 2010 he would assume that English originated in North America, since most of those who speak English as their first language live there. But if he checked more closely he would see that there was a greater diversity among Germanic languages related to English in northwest Europe, which would indicate its true origins. Ditto for Spanish and Portuguese, where most of those who speak these languages now live in Latin America, but where the greatest diversity of Romance and Indo-European languages is found in Europe, their original source.

I have seen studies indicating the lowest amount of genetic diversity among Native Americans and the highest among Africans. This is exactly what you should expect if mankind originated in Africa and the Americas were the last major landmass to be settled by humans. For that matter, the greatest diversity of great apes is also in Africa. I'm pretty sure the out-of-Africa theory is correct.

Those who are clever would claim that this contradicts the "cold climate" theory for the evolution of high IQ which I have supported previously, but this is not true. Homo sapiens probably evolved from apes in Africa and spread throughout the world from there. The cold climate theory does not say that evolution is impossible in Africa, only that evolutionary pressures for high intelligence worked faster in the cooler regions of Eurasia because humans encountered a natural environment there with cold winters that they had never had to endure in Africa.

aku said...

However, it seems that evolutions of humans is currently stalled. If it is true that there is no evolution of species as such, but if instead evolution works trough speciation, with our success our evolution has frozen, or at least it is extremely slowed. Every change is quickly dissolved in the population that is really massive and global.

If you think about it, if any future evolution will be culturally driven (I think this is self evident), this is strong argument against globalization. Or any other kind of uniformity enforcement.

Another interesting question - is this uniformity enforcement drive actually encoded in human genome? This is really some weird new perspective, at least for me.

The Sentinel said...

I favor the MR theory, it has a lot of evidence emerging to support it and detract away from the OOA theory; these two are the latest important pieces:

“The conventional view of human evolution and how early man colonised the world has been thrown into doubt by a series of stunning palaeontological discoveries suggesting that Africa was not the sole cradle of humankind.

Scientists have found a handful of ancient human skulls at an archaeological site two hours from the Georgian capital, Tbilisi, that suggest a Eurasian chapter in the long evolutionary story of man…”

Source


“The discovery of an early human fossil in southern China may challenge the commonly held idea that modern humans originated out of Africa…”

Source

(In the OOA theory the premise is that Homo erectus marched out of Africa around a million years ago but that Georgian skull is 1.8 million years old.)

rebelliousvanilla said...

darrinh, when a population moves, it becomes less diverse gentically since only a portion of the people left and hence only a portion of the genes. Still, genetic diversity isn't that important considering(obviously, to an extent, since massive inbreeding leads to a whole lot of problems) how hybrid vigor and outbreeding depression work in humans.

If genetic diversity was so great, then Africans should be the greatest human group with the greatest achievements and greatest health and they aren't.

xlbrl said...

It is obvious that the next evolution within man will be scientific, and that this may be good or it may be horrific, but will likely be both.

Engineer-Poet said...

What I've seen says that human evolution is anything BUT at a standstill; it has been accelerating over the last several thousand years.

The only thing which could accelerate evolution is selection pressures (natural, sexual, social).  Goodness, what could create such pressures?  Natural selection from new environments, new foods, and new vices (e.g. alcohol)... gee, ya think?  Sexual selection pressures in cultures where women have mate-choice (e.g. European) and where they don't (e.g. most Islamic)... no surprises there.  And social evolution pressures:  strict orthodoxy in Islam, moderate orthodoxy in China, and often large rewards for successful revolutionary ideas and methods in the West.

Goodness, could we possibly have different varieties of Man based on where and what they came from?  Is it heretical to even suggest it today?  (Of course it is; to mention it gets you grouped with the KKK.)

darrinh said...

"I have seen studies indicating the lowest amount of genetic diversity among Native Americans and the highest among Africans. This is exactly what you should expect if mankind originated in Africa and the Americas were the last major landmass to be settled by humans. For that matter, the greatest diversity of great apes is also in Africa. I'm pretty sure the out-of-Africa theory is correct."

Fjordman, this runs counter to how the evolutionary process is supposed to work and neither does it make sense. Changes generally occur due to mutations, therefore as time moves forward one would expect mutations to accumulate and thus increase the genetic diversity of children populations.

darrinh said...
This comment has been removed by the author.
Gary Rumain said...

E=P,

What do you mean by moderate orthodoxy in China?

could we possibly have different varieties of Man based on where and what they came from?

The answer to that is no. The reason is that all humans are able to interbreed with each other. If you ever read some of the biology books by Lyal Watson, you discover in one of them a comment about the common seagull. Gulls from one part of the world are unable to breed with gulls from another part (opposite ends of the Pacific, I think he said) even though they all appear to be outwardly identical. That implies that all humans are generically extremely close and have not had enough time to diversify genetically, unlike gulls.

Engineer-Poet said...

Quoth Gary Rumain:

"What do you mean by moderate orthodoxy in China?"

The pressure for social conformity, aka "harmony".  But China doesn't long for the 7th century either.

"The answer to that is no. The reason is that all humans are able to interbreed with each other."

That's the definition of speciation, not variety.  A cherry tomato can pollinate a Big Boy, but you can't tell me that the two varieties don't have very different characteristics.  It's those characteristics, which breed true, that we're talking about.

I recall reading that the San (Kalahari Bushmen) are not as reliably inter-fertile with other races as each is with members of its own.  This indicates speciation is/was in progress.

"That implies that all humans are generically extremely close and have not had enough time to diversify genetically, unlike gulls."

No, not "all", and some are closer than others.

Quoth darrinh:

"Fjordman, this runs counter to how the evolutionary process is supposed to work and neither does it make sense. Changes generally occur due to mutations, therefore as time moves forward one would expect mutations to accumulate and thus increase the genetic diversity of children populations."

You must have read the chapter on mutations, but not read the book on population genetics.  A group which splits off from a larger group will have less genetic diversity, and any characteristics carried by the original members will be over-represented in the population they start ("founder effect").  Because any alleles not carried by the split-off group get "left behind", the genetic diversity of the original population remains greater.  The same mutations can be re-created over time, but so will new ones.

One_of_the_last_few_Patriots_left said...

Thanks, Fjordman, for another interesting post here at Gates of Vienna. I confess that the matter of human evolution has always fascinated me.

A few comments, in no particular order:

Note that dogs are deliberately bred by humans to exhibit "diversity." That is, we breed them to enhance or diminish specific physical and even BEHAVIORAL characteristics. Unnerving as this idea may be when applied to humans, it does suggest that the notion that different races of humans will exhibit different overall behavioural patterns, no matter how politically taboo, is nevertheless valid.

A couple of years back, I read an interesting science article about Iceland, which was settled by the Vikings about a thousand years ago.
(Some of your relatives, Fjordman?)
With a very harsh environment, a small population of about 200,000, and very good geneological records, this has proven to be an excellent population for genetic research with a goal of determining which genes control which functions, including disease states, of the human body.

Not that I am any sort of expert, bit I also tend to favor the Out-of-Africa hypothesis due to a bit of seat-of-the-pants logic: extremely primitive humans with virtually zero technology could not survive in a colder climate. I am in southern New Hampshire, and as I sit here writing this my outdoor thermometer says that it is only 46*F. Never mind the computer, try this without CLOTHING! Anywhere far north or south of the equator, you need some kind of clothing (i.e. technology) even if only greasy animal skins.

Because of the high cost of doing genetic sequencing, gene studies have for the most part concentrated on the much shorter mitochondrial DNA sequences, or on PARTIAL nuclear DNA sequences.
The technology is rapidly advancing to the point where it will become possible to sequence a person's ENTIRE genome for less than $1,000.
At this point we will be able to compare the entire genome of a person from one race with the entire genome of someone from another race. We ain't seen nothin' yet!

EileenOCnnr said...

The idea that humans originated in Africa is a theory that is more believed in nowadays than firmly established.

Indeed, once-upon-a-time anthropologists worked under the hypothesis that humans originated in Asia (or somewhere on the Eurasian continent). Then, as you (FM) pointed out, the research shifted from Asia to East Africa starting with the Leakeys. The main reason for this shift was not based in science, however, but rather politics. After the communists took over, China was closed to Western researchers looking into human origins. Thus the shifting geographical interest.

It may, indeed, be that humans originated in Africa -- I don't know. But the Out of Africa theory is by no means proven, and a lot of the evidence from Africa is fraught with problems.

For instance, many of the fossils of species considered to be our earliest ancestors exhibit what is known in paleoanthropological circles as "chimp-like conditions" (I'm quoting from memory, but look into articles by Tim White to see what I mean.) Meanwhile, oddly enough, there's almost no evidence for Pan (chimps and gorillas) in the fossil record. The most parsimonious explanation is that the human ancestor fossils exhibiting "chimp-like conditions" are, in fact, fossils of chimp ancestors. See Walter Ferguson, primatologist, for more on this ("'Australopithecus afarensis': A composite species", also here). But those palentologists who have garnered fame and glory by discovering the "missing link" in Africa are reluctant, of course, to admit that there might be something amiss about their fossil record.

In the last half a century, too little fossil research has been done in Eurasia as compared to the time and money that has been devoted to East Africa. Nevertheless, finds like those at Dmanisi, Georgia, and Homo floresiensis in Indonesia suggest that there might, indeed, be more to the story than simply Out-of-Africa. See "Did Early Humans First Arise in Asia, Not Africa?" for instance.

(cont....)

EileenOCnnr said...

(cont....)

As far as the genetics go, a lot of the calibrations of the "molecular clocks" for humans have been set to match the fossil record! There you get into circular arguments that are very problematic to say the least.

The Helicobacter pylori is all very neat, but since we're talking about modelling here, such evidence is circumstantial. And when I see statements such as this by the researchers -- "For H. pylori, only 47% of the variance was accounted for by geographic distance (Fig. 2b, p ≤ 0.001), but this estimate rose to 72% when a standard conversion of genetic diversity was plotted against the logarithm of the geographic distance for the 442 haplotypes from geographic locations with at least ten isolates (Fig. S4)." -- little red flags get raised in my brain. I don't know exactly what this sentence means, but I do see that the data has been massaged ("but this estimate rose to 72% when a standard conversion of genetic diversity was plotted..."). Frankly, someone's going to have to explain that to me before I can evaluate whether or not the researchers' conclusion that H. pylori went along for a ride with us from Africa is likely correct.

Too many contemporary paleoanthropologists are stuck in a paradigm. The reaction to the possible new human species in Siberia recently was very telling. All of the questions centered around, if this really is a new species, when did it leave Africa? I saw not one scientist or science journalist or even blogger ask if it left Africa at all or if it might have evolved there in Siberia or somewhere else in Eurasia. I mean, why not? Why this fixation with Out of Africa?

The OoA theory might be right; but if it is not, it is going to be a very, very hard paradigm to break because it fits so well with political correct ideas -- I mean, how nice that we're ALL Africans!

Engineer-Poet said...

I'm sorry, but this is just wrong.

"Indeed, once-upon-a-time anthropologists worked under the hypothesis that humans originated in Asia (or somewhere on the Eurasian continent). Then, as you (FM) pointed out, the research shifted from Asia to East Africa starting with the Leakeys. The main reason for this shift was not based in science, however, but rather politics. After the communists took over, China was closed to Western researchers looking into human origins. Thus the shifting geographical interest."

The only way you could believe this is if you've never looked at the evidence, even third-hand through the popular science press.  For one thing, your objection is wrong-headed.  Researching the genetics of modern populations in an area can be done by taking samples from immigrants from those regions, even if scientists can't go there at the moment.  Second, China has been open to such research for quite a while.  If the Africa hypothesis was going to be disproven by better evidence from China, it would have happened by now.

For another thing, the science of genetics allows the origins of many different things to be traced back to their point of origin by looking at the same "founder effects".  Dogs, cats, rats, plants, and even the HIV virus have been tracked down to where they began, which is where the genetic diversity is greatest.  Doing the same with humans points to Africa, not Asia.

"The most parsimonious explanation is that the human ancestor fossils exhibiting "chimp-like conditions" are, in fact, fossils of chimp ancestors."

The origins of human chromosome 2 (formed by the fusion of 2 ape chromosomes), plus a number of endogenous retroviruses shared between apes and humans, prove otherwise.

I'm sorry if that bugs you, but facts are facts.  They do not go away just because you don't like them.  People who want to be believed when they say that Islam is dangerous and list the facts which prove it cannot afford to be hypocritical about human origins.

"The OoA theory... is going to be a very, very hard paradigm to break because it fits so well with political correct ideas -- I mean, how nice that we're ALL Africans!"

Non sequitur.  We were once all proto-apes, too.  Most of the world is not African in any reasonable sense of the word; it's not that you can't go home any more, but grandma's house isn't your house.

EileenOCnnr said...

Engineer-Poet said: "Researching the genetics of modern populations in an area can be done by taking samples from immigrants from those regions, even if scientists can't go there at the moment."

Sorry, I should've been more clear. I was referring to the fossil evidence, not the genetic evidence. The shift in looking for fossils in East Africa rather than Asia happened just after the war and primarily because China became a no-go area for Western researchers.

Engineer-Poet said: "Second, China has been open to such research for quite a while. If the Africa hypothesis was going to be disproven by better evidence from China, it would have happened by now."

Well, it may be open to Western researchers now, but they're not going there -- not in the numbers that they flock to East Africa. Which was my point. Many, many more research hours and dollars have been spent in East Africa than in Asia so it's not surprising that most of the fossil evidence for our earliest ancestors comes from Africa.

Check out, for example, "The Palaeolithic Settlement of Asia" for some historical background on what I'm talking about.

Engineer-Poet said: "The origins of human chromosome 2 (formed by the fusion of 2 ape chromosomes), plus a number of endogenous retroviruses shared between apes and humans, prove otherwise.

"I'm sorry if that bugs you, but facts are facts."


It doesn't bug me at all. I wasn't trying to deny that we are descended from apes -- hell, we ARE apes!

I was just trying to explain that there are some problems with the fossil evidence of our (so-called?) earliest human ancestors that have been found in East Africa. Again, I refer you to Walter Ferguson's "'Australopithecus afarensis': A composite species". The gist of that paper is that amongst some of the A. afarensis fossils are the remains of Pan -- so that's why A. afarensis exhibits "chimp-like conditions" -- because some of the bones are actually chimp (or maybe gorilla) ancestors.

Engineer-Poet said: "Most of the world is not African in any reasonable sense of the word; it's not that you can't go home any more, but grandma's house isn't your house."

I didn't mean that. What you've said "does not follow" from what I said. I just meant that in the world of politically correct thinking, anything "ethnic" -- especially Africa -- is considered wonderful. So, since we're all supposedly "Out-of-Africa," (and maybe we are, I'm not denying the possibility!), it has become very difficult for many researchers to even consider any other possibility, the appeal of being OoA is so great. Thus, as I pointed out, when the remains of a possible new human species were recently found in Siberia, NO ONE suggested anywhere that I saw that it may have evolved IN Siberia (or elsewhere in Asia). EVERYone has presupposed it MUST have come OoA, and the question was just when. Very bizarre thinking, if you ask me -- and not at all scientific.

Engineer-Poet said...

There's no logic in the world of PC, so no point in talking about science in relation to it either.  As for "out of Africa" vs. "out of Asia", chimpanzees and bonobos are both African and the ancestral primate population was spread east of what is now Africa when it rifted from what is now S. America.  I agree that the "out of Africa" conclusion gives certain nutcases fodder for their political views, it just has no logical relationship to them and does not give any reason to conclude "out of Asia"... except for political reasons.