Early days

It is truly amazing that we know so much now about our early days. For example, Africans do not have DNA which is specifically derived from Neanderthals, whereas people in the rest of the world do carry a small amount. This confirms the picture of human history derived from studying fossils. Neanderthal bones have not been found in Africa, so it isn’t surprising that their DNA is not there either. The fact that non-Africans have some of the DNA found in Neanderthal bones confirms that which geneticists knew from other studies: we have two distinct groups of human ancestors—those who left Africa in ancient times and those who stayed.

Quoted from an essay on Biologos

The primate family tree

Its not so long ago that nature's genealogies were constructed by the painstaking cataloging and comparing of anatomical features. Whilst this technique has to a certain extent been successful it is too blunt an instrument for dissecting out the fine detail.

The genetic revolution has changed all that. In this recent paper scientists have taken a close look at the entire primate family:

We conduct a phylogenetic analysis to determine the origin, evolution, patterns of speciation, and unique features in genome divergence among primate lineages. The resultant phylogenetic tree is remarkably robust and unambiguously resolves many long-standing issues in primate taxonomy. Our data provide a strong foundation for illuminating those genomic differences that are uniquely human and provide new insights on the breadth and richness of gene evolution across all primate lineages

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The story unfolds over a period of about 90 million years and covers many different creatures. Some, like the orangutang, are seriously endangered now. One of the stand out features of the primate group is their brains. Being remarkably cerebral they have a large brain:body size ratio, and of course of all the primates in all the world there is one whose brain is bigger than them all!

The Neanderthals

Here is an interesting overview on what we know about the Neanderthals. Its 45 minutes long and features Simon Conway Morris as a contributor.

Marking on Eggshells

Overlooking the Verlorenvlei River in the Western Cape area of South Africa stands the Diepkloof Rock Shelter – a large sandstone feature. Earlier this year scientists reported that as a result of excavations they had uncovered 270 Fragments of Ostrich Shells 2-3 cm in diameter extracted out from the rocks. What was remarkable about these pieces is that they had been engraved.

This unique collection demonstrates not merely the engraving of a single geometric pattern but the development of a graphic tradition and the complex use of symbols to mediate social interactions. The large number of marked pieces shows that there were rules for composing designs

Texier et al Proceedings of the National Academy of Sciences April 2010

Using three independent methods the researchers established that the rocks layers they were found in are around 60,000 years old. So sixty millennia ago someone was employing themselves in the art of decorating eggshells.

Humans before Adam?

The evolution of religion

A recent essay in the journal Science discusses the evolution of religion.

There are two strands to these kinds of studies. The first is to look for archaeological evidence for symbolic thought (like these carvings), or burial practices that indicate a belief in an afterlife. The second is more psychological, and considers what kind of thought processes are required for religious belief to exist and ask how they could have evolved (i.e. what benefits would there have been for survival and reproduction).

The article admits that the data available is really sketchy but one thing I found interesting was the reference to a study of children showing that they tend towards teleological explanations i.e. we seem built to look for an ultimate purpose.

The children were asked whether rocks are pointy because a) they are made of small bits of material or b) to prevent animals from sitting on them. The youngsters preferred the second option.

More questions than answers (what’s new!) but whether by natural selection or otherwise we’re built to seek a higher meaning to life.

Gene trees

It is well known that the genomes of humans and chimpanzees are very similar – over 95% similar in fact. The differences are in some ways more interesting than the similarities because they give clues as to how and when the ancestral line split apart. Then if you add into the mix the gorilla genome we can go even further back and predict when the human-chimp-gorilla line split.

The problem is that it’s not an exact science. There are a number of variables to factor in like different natural selection pressures, ancestral populations sizes, recombination, and gradual speciation etc, but a recent paper describes a new method of working it all out. They found that the divergence time of the human-chimpanzee line comes out consistently at around 4 million years ago and the human-chimp-gorilla split was around 6 million years ago.

The picture above shows just how complicated the flow of genetic information can get in what seems like a straight forward family tree.

The paper is here

Who were Adam and Eve? Part 1

In uniting the twin progeny of God’s Word (the Bible and Creation) the most serious question raised is, ‘How do Adam and Eve fit in?’

There are at least two possible scenarios that I’d like to suggest.

The first is the simplest and most literal option. Adam was miraculously moulded from the dust of the ground and Eve just as miraculously was moulded from Adam’s flesh: in other words exactly as a straight reading of Genesis 2 describes.

The Bible does indicate that there were other humans around at the time but Adam and Eve were special. In the Garden of Eden they were separated off from the world beyond its boundaries, free to live and walk with God, and the first creatures to have a knowledge of and relationship with Him.

This was the beginning of God’s direct revelation. With such revelation comes responsibility. Knowing what God wants brings the opportunity to accept or reject it. As Genesis 3 documents they chose the latter and so sin (choosing to go against God) entered the world.

Following their eviction Adam and Eve’s family went on to build their lives in the dog-eat-dog world outside. And the rest? Well that's history.

See here for an alternative scenario.

Something for the mantlepiece

A new 100 000 year old find from South Africa may provide an insight into the culture of early humans. This one is a piece of engraved ochre and can be added to various other examples of pierced shells and geometric carvings that have been dated as being over 75 000 years old. The only explanation for objects like these seems to be human culture of some kind.

Looking at the photographs of these artefacts with my untrained eye I can't help thinking that some of them look fairly innocuous, but then others have clearly deliberate markations - like the one above.

The big question is: What are they for? Are they symbols intended to mean something?

The authors of this paper (Henshilwood et al) are sure that the marks are not notations (record keeping). Instead they believe them to be symbolic and part of a tradition of symbology.

Cain's Enemies

I used to think that the story of the human family is precisely the same as the story of Adam and Eve's. That may be true spiritualy but Genesis 4 gives three reasons to suspect that outside of Eden they were not alone.

Firstly there's the classic question of Cain's wife. Its amazing that the incestuous explanation of this has persisted for so long... like incest is only wrong for genetic reasons? There is no reason in the text insisting that Cain married his sister - its based purely on the assumption that there were no other humans around (and that the first family were geneticaly dramaticaly different from the rest of us). Cain started his family outside of Eden, which is where I would suggest he found his wife as well.

Secondly there is the question of Cain's enemies. When God told him he was to be evicted from Eden how did he respond?

'Behold, you have driven me today away from the ground, and from your face I shall be hidden. I shall be a fugitive and a wanderer on the earth, and whoever finds me will kill me.' v 14

Whoever finds me will kill me? It seems that Cain knew full well that outside of Eden's protection he would be in a world of violence and danger. Perhaps he was talking about wild animals? Well the text simply doesn't read that way. See how God reassures him, it seems to be pointedly aimed at the only animal we know that could understand such a curse... humans:

'Then the Lord said to him, “Not so! If anyone kills Cain, vengeance shall be taken on him sevenfold.” And the Lord put a mark on Cain, lest any who found him should attack him.' v 15

If there still lingers any doubt verses 23, 24 seem to clear the matter up.

And thirdly there's the details of Cain's building projects.

'When he built a city, he called the name of the city after the name of his son, Enoch. ' v 17

Now we'd be wrong to thing of this as a spralling metropolis like London, New York or Sydney but equally its something more than pitching a tent. The Hebrew indicates that this was a guarded settlement and so its another indication that there were other human beings around at the time - to live with and to try and live without.

Roll back the clock

One way of working out how far back the human line goes is to use the 'Mitochondrial Clock'.

Mitochondria are like the engine of the cell - they supply the energy to help the cell do what it needs to do. But what's handy is that these little boiler houses have their very own package of DNA (separate from that found within the nucleus of the cell).  Rather being a mix of both parent's DNA - like in the nuclear version - the package found in Mitochondria comes entirely from the mother.  That keeps things nice and simple.

As time goes on that DNA mutates a little and on average it mutates at a predictable rate.  So if you take a group of modern day people and see how different their mitochondrial DNA is, then it's possible to trace how far back it would have been that those people had the same DNA pattern - what's dubbed as Mitochondrial Eve.

Well a new piece of work has looked at the accuracy of this method and calibrated it. The researchers worked out that humans dispersed from a small population around 55-70 000 years ago (Soares et al, American journal of Human Genetics 2009).  As part of their study they ran checks against known points in recent history where human populations have resettled, and these used these to verify their findings. What this means is that the group being tested shared an ancestor in a small group of human beings all that time ago.

This is way before Adam and Eve walked the Garden of Eden and together with other evidence illustrates that the human lineage extends a long, long way. I discuss the Biblical for this here