Elaine Meinel Supkis
The debate over the history of humanity rages onwards. Scientists shed increasing light on the subject thanks to genetic research coupled with archeological research. The "hobbit" bones found in Indonesia still baffles everyone. Meanwhile, the human/chimpanzee split shows interesting intersections.
By MATT CRENSON, AP National Writer 1 hour, 45 minutes ago
NEW YORK - Humans and chimps diverged from a single ancestral population through a complex process that took 4 million years, according to a new study comparing DNA from the two species.By analyzing about 800 times more DNA than previous studies of the human-chimp split, researchers from the Broad Institute of MIT and Harvard were able to learn not just when, but a little bit about how the sister species arose.
"For the first time we're able to see the details written out in the DNA," said Eric Lander, founding director of the Broad Institute. "What they tell us at the least is that the human-chimp speciation was very unusual."
The researchers hypothesize that an ancestral ape species split into two isolated populations about 10 million years ago, then got back together after a few thousand millennia. At that time the two groups, though somewhat genetically different, would have mated to form a third, hybrid population. That population could have interbred with one or both of its parent populations. Then, at some point after 6.3 million years ago, two distinct lines arose.
The only way to understand all this is to look at the whole environment 10 million years ago. Starting with the concept of the Garden of Eden, namely, where all the Great Apes originated, and why they spread and why some came back into Eden which is equatorial Africa, this all hinges on two forces at work: the war over territory waged by various groups and rapid geological changes that led to the latest series of iceages.
Archonta is a term used to group primates, bats (Order Chiroptera), tree shrews (Order Scandentia) and flying lemurs (Order Dermoptera) together, as well as many extinct mammal groups such as primate-like microsypoids, and rodent-like plesiadapids and carpolestids. Bats are accomplished flyers, and have a fossil record extending back to the Eocene, about 45 million years ago. The origin of bats, has not been resolved, because earlier fossils from the Paleocene 60 million years ago are only known from teeth, which do not tell us if they were flying mammals. Modern bats are divided into two groups microchiopterans and megachiropterans. Megachiropterans are larger and do not have much of a fossil record. The relationship between the two groups is subject to some debate.Primates are the most well studied group of all mammals. Fossil evidence for primates is also very extensive, going back to the early Eocene 55 million years ago. Primates are identified by the structure of the ear bones, in particular the shape of the petrosal bone. The rodent-like plesiadapids and carpolestids are often grouped together with true primates, because no fossil ear bones have yet to be discovered, showing if they are truly primates or not. These groups, do not have a post-orbital bar (cheek bone), which all modern primates have. Plesiadapids were very diverse after the extinction of the dinosaurs, but went extinct just as the rodents were diversifying in the late Eocene 40 million years ago. The first true primates are the adapids and omomyids. The adapids looked remarkably like modern lemurs, which some people suggest that they are ancestral to. Omomyids, were small and had large eyes. They looked a lot like modern Tarsiers. Most scientists believe that humans and most modern primates evolved from the omomyids, rather than the adapids. Antropoid primates include South American monkeys (Platyrrhini) and old world monkeys (Catarrhini) as well as Apes and humans (Hominodidea). Fossil apes have a well studied fossil record, going back 22 million years ago in Africa.
It is rather amusing that bats come from the same family. Maybe this is why right wingers who act like aliens from outerspace call us "moonbats."
We know, despite having virtually no fossils from the earliest years of our evolution due to the fact that we were very small and easily eaten, the roots of the ape species lie back during the reign of the last dinosaurs simply because there are many monkey species in the New World as well as Africa. Rapidly, South America shot away from Africa starting from just before the meteor hit the Yucatan.
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Already, at 50 Ma (million years ago), Africa was cut off from South America and not yet touching Eurasia. During this time, tailess apes rapidly evolved into many species. They overwhelmingly preferred jungles and trees with plenty of water.
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During this period, as the various monkeys and ape species flourished, there was great variations within the ape family, namely, the tailess tree swingers. Unlike monkeys who use their hands while using the tail to hang around, these apes lost their tails when they were ground dwellers and when they took back to the trees, used their hands instead. They evolved long arms for swinging as well as short legs for when they ran on the ground. They lived happily in the jungle Garden of Eden in central Africa. Evidently, they were so successful, they kept extending their territory.
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When Africa crashed into the Arabian Subcontinent, this caused rapid geological changes in the African Rift Valley as well as opening up a whole new world for the tree swingers. These swingers swung their way out of Africa during this warm Eocene and spread throughout Eurasia including colonizing the volcano chains all the way down through Sumatra. This was not a one way street. Once all the niches were filled, successful apes then traveled back into Africa. Once there, they found their nearest relatives and evidently, not being homicidical like humans, managed to mate with them according to this latest data concerning our genes.
A whole horde of monkeys also made these same trips. It seems that monkeys and apes are very prone to spreading out. I would surmize, this is due to our joint interest in eating each other. Horses, for example, don't eat each other or near relatives. From humans on down to virtually all monkeys, this desire to dine upon one's relatives is a very strong force.
For example, here is a story about a stoneage tribe who suddenly fled their jungles.
By JUAN FORERO
Published: May 11, 2006
SAN JOSÉ DEL GUAVIARE, Colombia — Since time immemorial the Nukak-Makú have lived a Stone Age life, roaming across hundreds of miles of isolated and pristine Amazon jungle, killing monkeys with blowguns and scouring the forest floor for berries.But recently, and rather mysteriously, a group of nearly 80 wandered out of the wilderness, half-naked, a gaggle of children and pet monkeys in tow, and declared themselves ready to join the modern world.
"We do not want to go back," explained one man, who uses the sole name Ma-be, and who arrived with the others at this outpost in southern Colombia in March. "We want to stay near town. We can plant our own food. In the meantime the town can help us."
While it is not known for sure why they left the jungle, what is abundantly clear is that the Nukak's experience as nomads and hunter-gatherers has left them wholly unprepared for the world they have just entered.
The main point of interest of this article is not only how readily the tribes moved outwards fleeing stresses but they also had pet monkeys with them that were baby monkeys they adopted and which they eat when the monkeys become troublesome adults. This reveals a clever human twist on eating relatives. Namely, one reason why humanoid brains evolved very rapidly and why humans became weaker physically is because we come from a branch of the ape family that figured out how to use guile to cultivate trust so we can eat.
The jungle stone age dwellers assured the reporter that their very favorite food is monkey meat and the very tastiest part is the brains. In Asia, they even sell monkey brains in a can. The near universal prohibition on cannibalism is to stop the Blue Beard effect, namely, men eating their mates or children.
When the early chimp/human strolled back into Africa after wandering all over Asia, the gap between the stay at homes and the returnees evidently was smaller than that between horses and mules, for example. Namely, they could mate and bear children. When the climate suddenly worsened 5 million years ago as we began to enter the present round of ice ages, the larger proto-humans which evolved into chimpanzees, took over the Garden of Eden territory and never left it, content to fight with each other ferociously for resources. So their teeth grew sharp and their arms strong as they ceased the total upright walking which the explorer apes that traveled thousands of miles perfected and using their knuckles, strolled along on all fours again.
The chimp/humanoids that were shoved out of the pleasant jungles had to fend for themselves on the increasingly hot, hostile ground. So the engine of evolution slowed down to a crawl for the chimpanzee population and went into high gear with the human population. Each subspieces of human would suddenly expand outwards and kill off all other near relatives for as the brain grew in size, the ability to tell each other apart grew, too. Often, it lay in the ability to communicate. Sharing sounds led to the ability to discern intentions or dissuade attacks not to mention seduction.
This is why the discovery of the Hobbit bones in Indonesia has so many people excited. If they are really the bones of another species of humanoid and lived a mere 20,000 years ago, this is quite amazing considering how much humans love to eat relatives!
John Roach
for National Geographic News
May 18, 2006
The "hobbit" humans that lived on the Indonesian island of Flores some 18,000 years ago were actually a population of modern humans stricken with a genetic disease that causes small brains, a new study says.The argument is being made by a group of scientists who have analyzed all the scientific evidence presented so far about the evolution of the proposed species Homo floresiensis.
Preliminary analysis of the remains pegged them as belonging to a totally new species (see hobbit fossil photos).
But gaps in the understanding of how these people existed alongside modern humans and came to wield sophisticated stone tools are coming under greater scrutiny.
In a comment appearing in tomorrow's issue of the journal Science, researchers challenge the evidence used to rule out the notion that hobbits were modern humans with a disease known as microcephaly.
This genetic disorder causes smaller brain size in modern humans and can also lead to short stature.
If they were really small humans who lived as a tribe, this is still interesting when one considers how much diversity we have despite very little genetic drift. All humans of any stature, color, hair qualities, whatever, can mate and bear fruitful young.
This is the real riddle! In birds, for example, tiny differences equals inability to mate. Virtually undetectable differences bar fertility! This is true in nearly all the animal world. Horses and donkeys can mate but not bear fruitful young. Lions and tigers are slightly closer to each other but it remains a strong rule, usually, animals with just one or two differences can't mate.
Not only are humans extremely diverse looking, when we "tame" any plant or animal, we "unlock" their genetic underpinning and speed up evolution to light warp speed and achieve the same effect! Namely, because we force them to express many changes rapidly, they still can mate! So all chickens no matter how they look can mate with all other chickens with ease. Take a rooster with stripes and show him some red hens and off he goes to mate and the red hens don't mind. In nature, that nearly never happens because the red hens would run away and the male wouldn't be interested in them anyway.
Since the qualities the animals express are desired by humans, the males and females can't use appearances or size as mating guides so they simply mate with no discrimination. This loss of discrimination makes them fare poorly in nature. Or it causes them to revert to an earlier model, for example, horses in the wild tend, over time, to turn brown and mottled so they blend into the landscape. This is due to the natural pressure of the predator community that eats colorful horses that stand out.
Horses living in nature in cold climates will evolve white fur in winter and brown in summer, for example.
So one can assume that all the variations in human appearance is artificially produced by humans choosing to breed in various ways that distingish themselves from other human tribal groupings. And that this is a fairly recent thing most likely developed by homosapiens itself. For this group of Great Apes was created in the Rift Valley cauldron and when they walked out of Africa, they were heavily armed with fire, stone and deadly spears and most likely already taming various animals. They killed whatever was in their paths especially other humanoids.
They left Africa 75,000 years ago right after a tremendous volcanic eruption in Indonesia which killed off or weakened many humanoids and changed the climate briefly but very disasterously for a few dozen years, thus propelling up and out of Africa, waves of humans. In less than 10,000 years, the outermost edge reached Australia. By 12,000 years, the last Neanderthal was eliminated.
Since then we ruled the planet. Coincidentally, 12,000 years is when the last "Hobbit" was alive, too.
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