Homo Sapiens (Modern Humans) evolved
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From skeletons to teeth, early human fossils have been found of more than 6,000 individuals. With the rapid pace of new discoveries every year, this impressive sample means that even though some early human species are only represented by one or a few fossils, others are represented by thousands of fossils. From them, we can understand things like:
"how well adapted an early human species was for walking upright
"how well adapted an early human species was for living in hot, tropical habitats or cold, temperate environments
"the difference between male and female body size, which correlates to aspects of social behavior
"how quickly or slowly children of early human species grew up.
While people used to think that there was a single line of human species, with one evolving after the other in an inevitable march towards modern humans, we now know this is not the case. Like most other mammals, we are part of a large and diverse family tree. Fossil discoveries show that the human family tree has many more branches and deeper roots than we knew about even a couple of decades ago. In fact, the number of branches our evolutionary tree, and also the length of time, has nearly doubled since the famed "Lucy" fossil skeleton was discovered in 1974!
Due to billions of years of evolution, humans share genes with all living organisms. The percentage of genes or DNA that organisms share records their similarities. We share more genes with organisms that are more closely related to us.
Humans belong to the biological group known as Primates, and are classified with the great apes, one of the major groups of the primate evolutionary tree. Besides similarities in anatomy and behavior, our close biological kinship with other primate species is indicated by DNA evidence. It confirms that our closest living biological relatives are chimpanzees and bonobos, with whom we share many traits. But we did not evolve directly from any primates living today. DNA also shows that our species and chimpanzees diverged from a common ancestor species that lived between 8 and 6 million years ago. The last common ancestor of monkeys and apes lived about 25 million years ago.
Dating is worked out by methods such as
"Potassium-argon dating, Argon-argon dating, Carbon-14 (or Radiocarbon), and Uranium series. All of these methods measure the amount of radioactive decay of chemical elements; the decay occurs in a consistent manner, like a clock, over long periods of time.
"Thermo-luminescence, Optically stimulated luminescence, and Electron spin resonance. All of these methods measure the amount of electrons that get absorbed and trapped inside a rock or tooth over time.
"Paleomagnetism. This method compares the direction of the magnetic particles in layers of sediment to the known worldwide shifts in Earth"s magnetic field, which have well-established dates using other dating methods.
"Biochronology. Since animal species change over time, the fauna can be arranged from younger to older. At some sites, animal fossils can be dated precisely by one of these other methods. For sites that cannot be readily dated, the animal species found there can be compared to well-dated species from other sites. In this way, sites that do not have radioactive or other materials for dating can be given a reliable age estimate.
"Molecular clock. This method compares the amount of genetic difference between living organisms and computes an age based on well-tested rates of genetic mutation over time. Since genetic material (like DNA) decays rapidly, the molecular clock method can"t date very old fossils. It"s mainly useful for figuring out how long ago living species or populations shared a common ancestor, based on their DNA.
Most of you are probably questioning "If we evolved back than why aren't we evolving now as modern humans?"
If there's one thing that's certain, it's that humans, like other living things, will continue to evolve. But that doesn't mean that humans are marching on a path toward becoming giant-brained, telepathic creatures out of Star Trek. All it means is that the human genome will continue to change from generation to generation.
A background mutation rate guarantees this process. Each baby's DNA carries about 130 new mutations. Most of them have no effect on our well-being.
this isn't quite evolution yet. Evolution is the change in allele frequency in a population over time, not changes between a single parent and a single offspring. Evolution wouldn't technically occur unless and until some of these variations spread through the population, changing from an isolated mutation or difference to a widespread trait. What we have here is the foundation for evolution -- a potential for evolution, if the environmental circumstances allow.
The idea of humans continuing to evolve is obviously unacceptable for conservative Christians who have adopted a creationist ideology, but it also creates some problems for more liberal believers who accept science. Even if they have reconciled themselves with the ideas that humans evolved alongside and just like all other life on this planet -- and not all do -- they tend to assume that this evolution occurred to bring us to the point where we are now.
Evolution is treated as a process which had a goal, at least where homo sapiens is concerned, and that goal must be us. If that's the case, though, then it's hard to accept that we would change. The goal's been reached, we're here, and that's the end for human evolution -- right? If we continue to evolve, though, then either there is no goal or we aren't that goal.
most paragraphs from http://humanorigins.si.edu...
Though I do understand what you're trying to say,modern humans are most certainly evolving even though most of them have kids anyway excluding natural selection. As a person posted ,-
'Sigh... copy paste... including plagiarism of at least one source. Also, the resolution is vague. Very easy to get an auto win with semantics.'
Humans are evolving whether you like it or not. We will always evolve. If you look, now the average Indian lives longer, sicker and more resistant to heat (in terms of food). I don't want long arguments so..
Humans are still evolving, albeit slower than ever.
1 votes has been placed for this debate.
Vote Placed by Ragnar 3 years ago
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Reasons for voting decision: Concession... Overlooking any other issues.
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