The title tells what the story is about. What has science found recently, outside new sets of bones and the geology in which they are buried, that provides us now information about the evolution of Homo Sapiens out of the the last creature that we know from DNA that we share as an ancestor with Chimpanzees.
Whatever that creature was, the DNA of both Homo Sapiens and of Chimpanzees have been changing for approximately 5 to 6 million years since then. Humans have learned to walk upright freeing our hands for other tasks, to talk, and for some reason, we have lost our fur. This last is particularly interesting, and the timing, if not the reason, is indicated in the DNA of lice.
It seems that there are two different types of lice which afflict humans. One is the head louse, an affliction we share with our cousin the Chimpanzee, since the environment the head lice live in is the fur or hair on our bodies. Humans, however, are also afflicted by a second type of louse. [No, not my ex-wife or her boyfriends.]The second type is the misnamed body louse.
The environment the so-called body louse lives in is human clothing. DNA shows that only 114,000 years ago the head lice and body lice shared a common ancestor. The body lice appeared when a new environment opened up for them to live in, and that new environment was human clothing (or exo-fur, as I explain to my impatient dogs when I have to put on my clothes and shoes - my exo-fur and paw-covers - before I can take them outside. Need to translate these things into words they might understand, you know.) But that is how louse DNA can point to the time that people began wearing clothes.
Apparently also, there were two waves of human and human-related migrations out of Africa. The first was of Homo Erectus, who left Africa and spread across Eurasia sometime between 1 and 2 million years ago. The second was the wave of Homo Sapiens who left Africa and spread to Eurasia about 66,000 years ago. DNA strongly suggests that Homo Erectus died out and was not an ancestor to Homo Sapiens. See the article for the details.
I'm going to skip writing about the much more complicated human ancestral tree that DNA is suggesting, and skip directly to what fascinates me most.
A curious thing about early Homo species is that they looked quite human early on. "By 600,000 years ago everyone had a big brain, and by 200,000 years ago people in Africa looked like modern humans," says archeologist Richard Klein of Stanford. "But there was no representational art, no figurines, no jewelry until 50,000 years ago. Some kind of cognitive advance was required, probably in language or working memory. But since size hardly changed, the brain change that produced behaviorally modern humans must have been in structure."As I recall (and don't ask my source) the first ornaments found in a human grave were placed there about 36,000 years ago. Ornaments such as small items of jewelry have no practical purpose. They have to be symbolic. Note the relationship to brain-size above.
The source of such structural changes must come, like every aspect of our physiology, from genes. Combing the genome for genes that emerged just when language, art, culture and other products of higher intelligence did, researchers have found three with the right timing.
The first, called FOXP2, plays a role in human speech and language, but it must do something else in other species, because the decidedly nonverbal mouse has a version of it. Using the standard molecular-clock tactic, Svante Paabo and colleagues at the Max Planck Institute estimate that the human version of FOXP2 appeared less than 200,000 years ago—about when anatomically modern humans stepped onto the world stage—and maybe as recently as 50,000. If so, then it is only humans as modern as those in the last diaspora out of Africa who developed advanced, spoken language. Another gene with interesting timing is microcephalin, which affects brain size. It carries a time stamp of 37,000 years ago, again when symbolic thinking was taking hold in our most recent ancestors. The third, called ASPM and also involved in brain size, clocks in at 5,800 years. That was just before people established the first cities in the Near East and is well after Homo sapiens attained their modern form. It therefore suggests that we are still evolving.
Then let's look at what the human race was doing 6,000 years ago. This was the period of the Sumarian civilization in the Tigris-Euphrates valley where the Sumarians built their cities of Ur, Erich and Kish, created the first writing (Cuneiform script) built the Ziggarats and developed the first law and impressive literature and myths. Karen Armstrong also points out that the major religions all began to develop at this time.
One last thing. If humans learned to speak only after Homo Erectus spread out into Eurasia but before the Homo Sapiens moved out of Africa about 66,000 years ago, then the Humans had a massive advantage over Homo Erectus. They also ate much the same food, so they needed the same lands. It is very likely that they battled over that land, and the social, speaking hominid found it relatively easy to defeat the non-speaking hominid. That would certainly explaian the disappearance of the Homo Erectus. It would be like a modern army with radio communications going up against one without radios.
You will notice that I persist in using the terms "suggests" and "Points to" rather than saying "tells us this was the cause and result." That's because this science is simply associating what the bones tell us, then what the bones associated with the geology tells us, together with what the DNA studies are saying. These associations from different fields of science could each be purely coincidence. But All of them? Are these all just accidental associations that have no common causes? I strongly doubt that.
But I can't prove it on the evidence given - so far.
Sure is fascinating, though, isn't it? What do we get next year? We'll just have to wait and see, won't we.
