Fossils of possible new human species found in China - Page 10

I will reiterate -- that evolution occurs (changes in the gene frequencies and heritable traits within a population over time) has been proven. How, exactly, the lines connect fossil forms to living forms is something that can't (at present) be proven, but is inferred by balancing evidence from multiple areas to weigh the most supported answer. Darwin wasn't the first to come up with the idea that populations change -- this was known by people who selectively-bred animals. His theory was that this same process, performed as a result of selection "by the hand of nature" and over a long enough time, could account for differences in species today that derived from a common ancestor. The observation of genetic change over time is the fact part. The proposal that this process can account for all species today because of common ancestry and changes through time is the theory part.

Fossilization is a rare event, considering the number of individuals of a given species that ever existed. Any individual which was consumed and digested in entirety will leave no fossil remains. Fossils are more likely to form in some environments than others. Species living at high densities are more likely to be represented in fossil layers than are species living at low densities -- though the La Brea Tar Pits provides an example in the opposite direction, being as trapped prey attracted a disproportionate number of predators which then got trapped themselves. Put all these together, and we can begin to understand why human and pre-human fossils are rare and individually significant.

Dating may use strata for initial dating, but only when that strata has been accurately dated by other methods that allow for a sort of "triangulation" or corroboration of dates. For example, radio-isotope dating might give a window of 5,000 years in which an object was formed or deposited, sedimentation and mineral composition may give another range, etc. I'd have to go back into my texts to go over all the methods that are used, but there are quite a few -- not all are applicable for a given time-frame, environment, or material, but most items uncovered are dated using multiple methods. When there is a range of overlap between several methods, that is taken to be strong evidence of the actual date of an item. The actual papers describing these dating tests are not typically published in the popular media, but they are available if you look for them. Typically, popular media and textbooks try to sum up a lot of data received and analyzed from multiple sources and present it as simpler sentences that can be understood by an audience of either students or people with just an interest in the subject. They are a "digest" of sorts, but they do not represent the actual full library of evidence -- simply because to justify every statement in a "digest" article would turn it into an encyclopedia. But the information is out there if you wish to investigate it further yourself.

I don't think there are any "fossil humanoids" that are 20 million years old -- that's over 3 times older than the proposed split between the chimpanzee ancestors and human ancestors. Most of the "pre-human" fossils differ from "pre-chimpanzee" fossils primarily in the anatomical changes related to walking bipedally -- there wasn't much of a difference in brain size until much later.

The earliest fossils of "anatomically modern" humans are only about 200,000 years old. The oldest evidence of "art" is about 75,000 years old (pierced shells -- cave paintings go back I think to about 40,000 years ago). The oldest evidence thus far of agriculture is only about 10,000 years old. What this implies is that while according to fossils, humans "looked" like us 200,000 years ago, further changes must have been continuing to occur in how they were able to think. Behavior and cognition do not get preserved in the fossil record -- they must be must be inferred and interpreted by archaeological remains of things the individuals made, did, or left behind.

We do not know they had the same intelligence -- we know only that their brain volume was similar. Intelligence does tend to increase along with brain volume, but it's not the only factor. Cognition relies on the interconnectedness of neurons, which can differ even when brain volume remains the same, and cannot be inferred from fossils. The earliest dates of archaeological evidence of these "cognitive breakthroughs" being younger than "modern brain capacity being reached" suggests that much more was going on with regards to changes in the brain than simply "getting bigger." Thus it is incorrect to say that humans from 200,000 years ago had the same intelligence of humans today -- it's possible they might have, but available evidence doesn't support the assumption.

 

As far as making something "interesting" (I read that as something not necessary for survival, but something more artistic or aesthetic), we must recognize that to do so, in addition to possessing cognitive ability for symbolic thought (which may not have been present to the degree it is today in humans 200,000 years ago), there must be a surplus of time that did not need to be devoted to procuring food and other necessary resources -- in essence, leisure. It is likely that increasing cognitive ability allowed for more efficient food procurement, which resulted in an increase in leisure time, and "art" resulted as a by-product. Some hypothesize that production of art developed along a sexual-selection pathway -- art serving to attract females was beneficial because in order to create art, males would have to be cognitively developed enough to solve food-procurement problems successfully enough to leave leisure time for art production. Art thus worked like the peacock's tail -- an attractant that served to advertise the artist's fitness. This is all just interpretive, however.

 

It is theory that we evolved from apes -- to "prove" it would require a time machine and the ability to tag all offspring from all individuals of all proposed ancestral species and track them through a few million years to the present day, determining how offspring vary through all generations. While that is not feasible, we can find evidence that would be left behind should the theorized pathway have occurred -- fossils of individuals intermediate in form and dating, and DNA investigation of shared and divergent heritage, for example. This is utilization of "if...then..." statements to test a theory, and results in an accumulation of evidence favoring one scenario over another. It's akin to trying to determine the origin of a fire by analyzing remains left behind -- we can't "prove" exactly how something happened without documenting its course from start to finish, but we can trace a most likely sequence of events based on interpretation of evidence and an understanding of the properties of the original parts.

 

Advances in technology and understanding follow a logarithmic, not linear, graph. Thus the difference between now and 100 years ago would be much more great than the difference between 1100 and 1200 years ago. Additionally, during the period you cite (2000 years ago to 1000 years ago) there was a suppression of accumulated knowledge -- much of the ancient Greek, Roman and Middle Eastern advances in science and philosophy were given a cultural stamp of being heretical, altering the progression that would have been predicted had the logarithmic graph continued uninterrupted. Things generally picked up where they left off in Western Europe after the Middle Ages.

This is because cultural transmission of knowledge is greatly facilitated by the ability of individuals to read and write -- something else that increased in prevalence over time. The more people there were to read and interpret the discoveries of others before them, the more minds were available to discover novel solutions to old problems, or make improvements or advancements where others had left off. Being literate allows for a greater potential amount of knowledge to be learned than being illiterate.