Home > Uncategorized > Not human anymore?

Not human anymore?

Now we are 3% Neanderthal, up to 5% Denisovan and a whole lot of other earlier ancestors.

According to Jill Neimark in Discover, May 2011:

It used to be: Humans as the crown of creation. Where evolution turned a crouching ape into a tall, erect human male over the ages. But that ascent-of-man picture is now looking as dated as the flat Earth hypothesis. In the new view the path to Homo Sapiens was very indirect. Along the way our planet witnessed many variations of the human form, multiple migrations out of Africa. According to paleoanthropologist William Jungers: “Human evolution used to seem simple and linear. Now you look at almost any time slice and you see diversity. We may be special and we may be lucky. But we are far from the only human experiment.”

Using DNA sequencing, scientists have learned that anatomically modern humans interbred with Homo neanderthalensis (Neanderthals) probably around 60.000 years ago in the Middle East, before they fanned out to populate Europe and Asia. Today 1 to 4 percent of the genome for people living outside Africa is Neanderthal.

Similar genetic analysis has also revealed an entirely new human group, called the Denisovans. The findings based on a 50.000 year old pinkie finger found in a cave in Denisova, Siberia. A small find, sure, but enough to establish that humans living in New Guinea today carry nearly 5 percent Denisovan DNA.

Perhaps it all started with Ardipithecus ramidus, a creature nicknamed Ardi, that lived 4.4 million years ago in Ethiopias Afar Rift. Ardi climbed trees with her apelike hands and powerful built, grasping big toe, yet also walked the on the ground in her woodland habitat.

Especially surprising was Ardis teeth. The males of the species lack the long canines that are the hallmark of aggression in apes. Ardis teeth were short and blunt, a signature human trait. One that caried over to Lucy (Australopithecus afarensis) much later. Apparently long teeth were no longer necessary to scare off competing males and ensure female sexual favours. Instead the males travelled long distances to seek out food for their chosen female, then walked back on their hind legs, carrying provisions in their hands. Where the extra food gave sexual loyalty, and the steady supply of food led reproductive success.

Flo the hobbit.

If the Ardi discovery was surprising. Then the discovery of Homo floresiensis on the island of flores in Indonesia was even more surprising. These small people might show us that small is just as adept as big Homo lines.

The ancestors of hobbits probably left the Rift area of Africa for South East Asia some 2 million years ago. More amazingly, hobbits seems to have survived into modern times alongside modern humans. They fashioned stone tools, hunted cooperatively, and even cooked with fire. All with a brainsize one-third the size of a Homo sapiens adult. 

According to australian archaeologist Michael Morwood: We know for certain that Flo’s ancestor were on Flores at least a million years ago, because we have found stone tools on the island that are that old. 

But how is that possible with such a small brain?  Anthropologist Dean Falk have looked at the hobbit skulls using three dimensional CAT scans:

“It was beautiful. The scans show that the hobbit brain was uniquely folded and unusual complex. The temporal lobes were really wide, which is an advanced feature. At the very front were two enormous convolutions in an area associated with executive functions like planning ahead, again a complex feature.”

Flos brain was globally reorganized in comparison to the brains of apes. That means that brain architecture and function are not always tightly contrained by size.

Interbreeding.

Back to our own line. There has been at least two periods of interbreeding after we left Africa. First about 60.000 years ago in the eastern Mediterranean, and then about some 45.000 years ago in eastern Asia. Offspring of the first interbreeding went to Europe, Asia and North America – Offspring of the second interbreeding went to New Guinea and possibly Australia.

Our species didn’t branch out from all the others as sharply and irrevocably as we like to think…..

Simon

 

 

 

Advertisements
Categories: Uncategorized
  1. No comments yet.
  1. No trackbacks yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: