The other humans--and how they relate to you #1: the Neanderthals

Okay, so in my last post we established that modern humans, emerging from Africa 50-60000 years ago, interbred with archaic "fossil" forms of humans living in other parts of the world. This interbreeding, if drawn in graph form, looks something like this:

So, as we see here, Han Chinese, Melanesians (a big group of people living on islands in the western Pacific, which includes Papuans and Solomon Islanders), and Frenchmen all have a certain degree of Neanderthal ancestry. Melanesians, however, also have ancestry attributed to the mysterious Denisovans.

When the first modern humans exited Africa, they encountered several other species of living humans. These "fossil" humans can no longer be considered mere extinct side branches of the human family tree; if you are not sub-Saharan African, then they are your ancestors.

We know based on the dating of remains that there were three non-African human species alive at the time of the great migration from Africa. Up first is:

1. The Neanderthals

The best-known of the archaic humans, Neanderthal man inhabited Europe, the Middle East, and Central Asia (perhaps as far east as the Altai Mountains in southern Siberia) between 350,000 and 30,000 years ago. The Neanderthals, or at least their traits, co-existed with modern humans for at least 25,000 years. The oldest accepted Neanderthal site is found in Croatia (dated between 32-30,000 years ago) with a more controversial site located in Lagar Velho, southern Portugal (estimated at 24,500 years old).

Neanderthal man was the classic "caveman," with a somewhat flattened, elongated skull, beetling brow, and chinless jaw. These early humans were quite short, with the males maxing out at a height of around five feet, six inches. According to the most recent scientific findings I just made up, Neanderthals were highly insecure about their height, making them very hard to put up with. This created a social distance that allowed the Neanderthals to co-exist with modern humans for 25,000 years. What they lacked in height they made up in might, for Neanderthals were much stronger than modern humans, especially in their arms and hands.

Neanderthals hunted with spears, could make fire, could speak as well or nearly as well as moderns, buried their dead, and wore clothing. They apparently lacked a couple of inventions we moderns take for granted: missile weapons and needles. Without missile weapons, such as bows, Neanderthals were forced to kill the animals they hunted at close range, the danger of which is obvious; and without needles, the types of clothing they could make was limited to skins held together with small bone awls. While in many ways Neanderthals were very much like modern-day primitive peoples, there is evidence that their mental processes may have been very different from our own: there is no evidence that Neanderthals created representational art, or in fact art of any kind--a trait they actually shared with early modern Homo sapiens. This implications of this are not clear: were Neanderthals (and early modern humans) capable of less abstract thought than we are? Could they grasp metaphors? Did they possess a sense of beauty, of the numinous? In any case, the earliest known representational art is about 35,000 years old, and in all known cases linked to modern human populations. Is the ability to create and appreciate art the result of a genes or genes that arose after Neanderthal-human admixture?

It's also not known if Neanderthals could appreciate or create music, although there is the famous find of the Divje Babe flute from Slovenia. A hollowed-out bear femur from a Neanderthal site, the object has been variously interpreted as either a musical instrument and the result of another bear chewing on the dead bear's remains. In his book The Singing Neanderthals (2006) Steven Mithen hypothesized that Neanderthal communication was not purely linguistic, but a sort of hybrid language-music, with the separation of the two not occurring until later in human development. It may be that, like art, an appreciation and comprehension of music is an almost exclusive development of later humans--almost exclusive, that is, because at least one group of animals has also been shown to understand music: the Psittaciformes Order of birds (better known as parrots).

Okay, sapiens--time to meet the rest of the family

In my previous post on Solomon Island blonds, I brought up the unexpected relationship between New Guineans/Solomon Islanders and a fossil group of humans, the Denisovans. The evidence of Denisovans in the family tree of Oceania was the second such proof of modern human-fossil human mixing during prehistoric times, with the first study showing admixture between Neanderthals and pretty much everybody who isn't sub-Saharan African. Since Oceanians are definitely not sub-Saharan Africans, that means they've got both Denisovan AND Neanderthal ancestors, with the bulk of their genes being from a group that left Africa 50-60,000 years or so ago.

So, you might be asking, this is all well and good, but what the hell does it mean, exactly? First off...what's the difference between a fossil and a modern human?

Whew...ye gods, how do I brew this down into a few sentences? "Modern humans"--meaning people who look more or less like the sort of people you see wandering around now--originated in Eastern Africa 200,000 years or so ago. At the time of these earliest "modern humans" there were older populations of humans who'd left Africa a million or so years ago to inhabit Europe, the Middle East, and Asia. Since there was no little or no mixing between Africans and the people in Europe, Asia, etc. over the intervening 800,000+ years, the people on these continents had developed greater physical differences than Africans, Europeans, Asians, etc. possess now. These physical differences were sufficient enough that these regional human variations are usually considered to be not just different races, but different species altogether. Just as there are different species of parrots or dogs (domestic dogs, coyotes, wolves, etc.), two hundred thousand years ago there were several different species of humans.

Between the mid-1980s and last year, the majority of scientists considered these various human species unlikely to have successfully interbred. The modern humans who lived in East Africa finally decided to get off their caveman arses around 50-60,000 years ago and go check out the rest of the planet, and when they did they were so superior to the older human forms that they simply wiped them completely out.

This hypothesis, called "Out of Africa" received a bit of a serious blow in early 2010, however, when it was shown by scientists at the Max Planck Institute in Leipzig, Germany and UC Santa Cruz that modern human DNA could be shown to have Neanderthal ancestry. The older idea of us moderns tromping out of Africa and hunting down the hapless, stupid, and hairy Neanderthals was out. Our ancestors had made love, not war, and the evidence could still be shown in Europeans, Chinese, and Papuans.

The picture of human prehistory got even messier in December 2010, when researchers sequenced the DNA from a fossil finger bone and a tooth. They were able to show that the owners of the finger and tooth were not Neanderthals, as they expected, but a second group of humans that had been isolated from the Neanderthals for 500,000 years or more. Since the relics came from a came in southern Siberia known as Denisova Cave, these people have come to be known as the Denisova Hominids--and their DNA was still apparent among the living people of Oceania.

So, got all that?

Next up, we'll get to actually meet the fossil humans whose neighbourhoods our thoughtless, boorish ancestors blundered into all those years ago.