Don't tell me there's no proof for evolution

rosborne979 wrote:

neologist wrote:

Thanks. That is a very understandable explanation. Does it also account for the degree of spoliation where the descendants (if that is the correct word) no longer bear a physical resemblance?

Sorry, I don't understand the question.

The idea that the forces driving evolution (variation and selection) will eventually lead to organisms of widely differing forms, is supported by the fossil record as well as genetics. Is that what you're asking?

Yes. Is that also a process of speciation?

Populations almost always change. They flow away from their original form over time erasing their ancestral trail as they go. Extinction events wipe out particular branch populations and leave dramatic gaps in the fossil record. But more often an ancestor form is simply superceded by its more specialized decendents and they simply dwindle away slowly and quietly. It's relatively rare to find an existing animal that has an existing ancestor still in its original form.

Could you summarize the significance of your paper in layman's terms?

Yes. Orrorin tugenensis is a 6 million year old bipedal hominid with several ape-like features of the front teeth, jaw, humerus and finger bone, but with more human-like features of the back teeth, mandibular symphysis, and leg bones. As such Orrorin is by far the earliest known member of the family of man (Hominidae) and is already quite distinct morphologically from the African Great Apes (Gorillidae). This indicates a divergence between Hominidae and Gorillidae that dates back to a substantial period prior to 6 Ma, and we estimate about 8-7 Ma for this event. If so, then the discovery of Orrorin refutes all hypotheses in which humans diverged from apes later than 7 Ma, including most of the recent estimates by molecular biologists who tend to think of the divergence as having taken place later than 5 Ma, and even as recently as 2.5 Ma. In other words, the much vaunted "molecular lock" seems to be telling us the wrong time.

The fact that Orrorin is found with other fauna that indicates a wooded to forested environment, tends to refute the "savannah" hypothesis of human origins. It seems more likely now that bipedalism originated from an arboreal ancestor, rather than via a knuckle-walking ground dweller similar to chimpanzees. Thus, previous palaeoecological and palaeoenvironmental scenarios of human origins will need to be reconsidered in light of the new data.

Furthermore, in some features of the dentition and femora, Orrorin is more human-like than any of the australopithecines (Lucy and her kin) which raises the possibility that australopithecines are a side branch of hominid evolution that went extinct without issue about 1.5 Ma. If so, then there would have been a more direct line of descent between Orrorin and Homo, via a Pliocene form (possibly Praeanthropus).

Finally, the period 8-7 Ma was one of major faunal change world-wide. In Africa there was a massive change from archaic lineages prior to 8 Ma to more modern lineages after 7 Ma. The characteristic African fauna that we observe today (hippos, rhinos, modern subfamilies of antelopes, monkeys, giraffes, hyaenas, elephants, leopards, porcupines, hares, ostrich, etc) appeared during this transition, whereas many archaic lineages became rare or disappeared altogether. Hominids were part of this change, and thus hominid origins can be better understood as being part of an overall change in African mammal faunas that took place between 8 and 7 Ma. Previous hypotheses of human origins led to the rather unlikely scenario that human evolution was delinked from that of other African mammals. If we are correct, then the origin of the human lineage was part of a generalised faunal shuffle, and as such the forces driving it are more understandable.

The cause of the major faunal change between 8 and 7 Ma was probably the growth of the Artic Ice Sheet to a size where it started to impinge on global climatic patterns, in particular squeezing the northern climatic zones (arctic, taiga, boreal, subtropical) equatorwards. This event led to the borealisation of much of mid-latitude Eurasia with many mammal lineages going extinct in Eurasia, and to the onset of desertic conditions in Africa (Sahara in particular) with an attendant diminution in areas covered in forests. The vegetational changes forced by this climatic change included the installation of large areas of grasslands and woodlands, which in turn led to a large scale change in food resources for African mammals, with many lineages (elephants, pigs, antelopes, rhinos, equids, etc.) developing high crowned cheek teeth and cementum on the teeth. Early hominids initially remained faithful to their largely frugivorous diet (i.e. their teeth did not change much), but they developed a new way of getting between food resources - bipedalism, whereas most mammal lineages merely changed their diet as the vegetation changed around them (and barely altered their locomotor repertoires). This is why the study of locomotion is so important for understanding hominid origins.

Martin-Pickford
Museum Natl Hist Nat,
Lab Paleontol,
GDR 983,
F-75005
Paris, France.

Evolution is a religion or this thread is in the wrong place.

you decide.

Bartikus wrote:

Evolution is a religion or this thread is in the wrong place.

you decide.

Issues which affect religion are discussed on the religion forum. Scientific theories which challenge religious belief are therefore appropriate for discussion on a religion forum.

How does it affect religion when evolution is based on observable evidence (i'm told) and religion based on faith

How does the theory of evolution affect a person's faith?

barticus

Quote:

How does it affect religion when evolution is based on observable evidence (i'm told) and religion based on faith

. You have to ask that of the deeply fundamental religionists. They MUST try to show that all this scientific evidence is in error and that the Bible is inerrant.

Bartikus wrote:

How does the theory of evolution affect a person's faith?

Science places its faith in the ability of physical reality to tell the story. It is adaptable, flexible, just like life itself, an aspect of nature, not something outside of nature.

rosborne979 wrote:

Bartikus wrote:

How does the theory of evolution affect a person's faith?

Science places its faith in the ability of physical reality to tell the story. It is adaptable, flexible, just like life itself, an aspect of nature, not something outside of nature.

So science operates by faith as well?