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The most bitterly debated question in the discipline of human evolution is likely over where modern humans evolved. The out-of-Africa hypothesis maintains that modern humans evolved relatively recently in Africa and then spread around the world, replacing existing populations of archaic humans. The multiregional hypothesis contends that modern humans evolved over a broad area from archaic humans, with populations in different regions mating with their neighbors to share traits, resulting in the evolution of modern humans. The out-of-Africa hypothesis currently holds the lead, but proponents of the multiregional hypothesis remain strong in their views.
Scientists are uncovering more and more ancient hominids all the time -- here meaning bipeds including humans, our direct ancestors and closest relatives. They strive to find the earliest one, to help answer that most fundamental question in human evolution -- what adaptations made us human, and in what order did they happen?
Did we interbreed? Does our species possess any genes leftover from our extinct cousins? Scientists have suggested that perhaps the Neanderthals did not die out, but instead were absorbed were absorbed into modern humanity.
Roughly 50,000 years ago, modern humans expanded out of Africa, spreading rapidly across most of the world's lands to colonize all continents except Antarctica, reaching even the most remote Pacific islands. A number of scientists conjecture this migration was linked with a mutation that transformed our brains, leading to our modern, complex use of language and enabling more sophisticated tools, art and societies. The more popular view suggests hints of such modern behavior existed long before this exodus, and that humanity instead had crossed a threshold in terms of population size in Africa that made such a revolution possible.
Is the 'hobbit' -- the nickname given to diminutive skeletons found on the Indonesian isle of Flores in 2003 -- in fact an extinct human species, enough to be called Homo floresiensis? Are these skeletons just examples of deformed Homo sapiens? Are they a different species than us, but perhaps not an extinct human species and instead as separate as chimpanzees are? Solving this mystery could help shed light on the radical paths human evolution may have taken.
Recent evidence suggests that humanity is not only still evolving, but that human evolution is actually accelerating, speeding up to 100 times historical levels after agriculture spread. A number of scientists challenge the strength of this evidence, saying that it remains difficult to ascertain whether or not certain genes really have recently grown in prominence because they offer some adaptive benefit. Still, if human evolution is accelerating, the question becomes why? Diet and diseases may be some of the pressures that caused humans to change.
Roughly 24,000 years ago, our species, Homo sapiens, was not alone in the world -- our closest relatives, the Neanderthals, (Homo neanderthalensis) were still alive. The so-called 'hobbit' found in Indonesia might also have been a member of the genus Homo, and it apparently survived until as recently as 12,000 years ago. So why did they die and we survive? Did infections or radical shifts in their environments kill them off? Or did our species do away with them? Some evidence exists for both scenarios, but no conclusion is agreed upon.
Humans are unique for looking naked compared to our hairier ape cousins. So why did this nakedness evolve? One suggestion is that our ancestors shed hairiness to keep cool when venturing across the hot savannahs of Africa. Another is that losing our fur coats helped free us parasite infestations and the diseases they can spread. One unorthodox idea even suggests human nakedness developed after our ancestors briefly adapted for a streamlined life in the water, although most aquatic mammals of roughly human size actually possess dense fur.
Our ancestors evolved an upright posture well before our large brains or stone tools even appeared. The question, then: Why stand and walk on two legs when our ape cousins get by on four limbs? Walking as bipeds might actually use less energy than movement on all fours does. Freeing up the arms might also have enabled our ancestors to carry more food. Standing upright might even have helped them control their temperature better by reducing the amount of skin directly exposed to the sun.
There is no question that our large brains have provided humans an extraordinary advantage in the world. Still, the human brain is an incredibly expensive organ, taking up only about 2 percent of the body's mass yet using more than a fifth of the body's energy, and until about 2 million years ago none of our ancestors had a brain larger than an ape's when compared to body size. So what kicked off the push for a larger brain? One possibility is that increased smarts helped our ancestors make better tools. Another is that larger brains helped us interact better with each other. Perhaps radical changes in the environment also demanded that our ancestors deal with a shifting world.
Evolution in humans is commonly thought to have essentially stopped in recent times. But there are plenty of examples that the human race is still evolving, including our brains, and there are even signs that our evolution may be accelerating.
Comprehensive scans of the human genome reveal that hundreds of our genes show evidence of changes during the past 10,000 years of human evolution.
"We know the brain has been evolving in human populations quite recently," said paleoanthropologist John Hawks at the University of Wisconsin at Madison.
Surprisingly, based on skull measurements, the human brain appears to have been shrinking over the last 5,000 or so years.
Originally posted by OhZone
I don't believe that any skeletons of humanoids have ever been found on the Savannah.
Only in forested areas, or areas that were forests at the time the found creature lived.
And still they misuse the word "mutation" showing that they have no idea of what they are talking about. Or it is that they think you/we don't know what it means and they are doing a snow job to make themselves look good.
Somehow they find it impossible to just say, "We don't know".
Man you are so right, there has never been any proof that any species turned into another species.
Somehow they find it impossible to just say, "We don't know".
Are you kidding? Do you know what science is? Science is about taking a topic that you don't know, forming a hypothesis, testing the hypothesis, and forming a conclusion. Questioning is the very foundation of the entire field! Why do you think there are so very few scientific laws?
The scientists just do not know, and they try to find someone who is good at guessing, and go with them, thats all they do.
Today mankind has the science to make evolution jumps, but that would not be natural evolution would it. There are probably endless ways the human race can go from here, and its upto who ever runs this world.
Originally posted by xEphon
So, not only are we evolving and getting smarter, but our brains are getting smaller. Good deal.