Religion: Why writing things down matters
One of the causes of "just-so" storytelling about human evolution is the fact that, until comparatively recently, people did not write things down or manufacture a lot of objects.
People like Pascal Boyer can write books like Religion Explained, secure in the knowledge that no documents or extensive artifacts are likely to turn up from 50 000 years ago that challenge his claims.
To see what difference this makes, consider the case of King Tut's tomb. Archaeologists have unearthed an extensive story of the short-lived effort of one Pharaoh to convert Egypt to monotheism. We actually know a fair bit about what happened there, due to deciphering writings and examining extensive artifacts.
Now and then a brief light is shone on a far earlier era, and here is one: An Australian cave painting depicts a marsupial lion ("Cave Painting Depicts Extinct Marsupial Lion " by Stéphan Reebs, Natural History Magazine 09 May 2009):
Several well-preserved skeletons of the leopard-size beast have been found. Now, a newly discovered cave painting offers a glimpse of the animal's external appearance.Similarly, an article in Science, 323 (30 January 2009) pushes back the art timeline:
In June 2008, Tim Willing, a naturalist and tour guide, photographed an ancient painting on a rockshelter wall near the shore of northwestern Australia. Kim Akerman, an independent anthropologist based in Tasmania, says the painting unmistakably depicts a marsupial lion.
It shows the requisite catlike muzzle, large forelimbs, and heavily clawed front paws. And it portrays the animal with a striped back, a tufted tail, and pointed ears.
Those last three features aren't preserved in skeletons, but Aborigines would have known them well. Australia's first people landed on the continent at least 40,000 years ago and were contemporaries of the big predator.
In 2002, a discovery at Blombos Cave in South Africa began to change how researchers view the evolution of modern human behavior. Archaeologists reported finding two pieces of red ochre engraved with crosshatched patterns, dated to 77,000 years ago. Many experts interpreted the etchings as evidence of symbolic expression and possibly even art, 40,000 years earlier than many researchers had thought (Science, 11 January 2002, p. 247). Now the Blombos team reports on an additional 13 engraved ochre pieces, many dated to 100,000 years ago. The researchers suggest that some of the engravings may represent an artistic or symbolic tradition. If so, the timeline for the earliest known symbolic behavior must once again be redrawn.Go here for more (paywall).
When timelines are getting redrawn this often, my advice is - for now - forget them. At some point, our ancestors differentiated themselves from knuckle-dragging apes, and that was an event with great consequences (if that is now it really happened), about which we have almost no information.
Note: Here is a contest question at Uncommon Descent: Question 3: In 400 words, to be judged in two weeks, and printed as a post: What do we really know about human evolution that could not simply be overturned by a new find? The winner will receive a free copy of Expelled. The contest will be judged in two weeks, May 27.