Common origin of life

I have heard Christian philosopher William Lane Craig suggest that the idea that all life came from one source was being questioned in the scientific community. I realize that no explanation for the beginning of life has been accepted. But was not sure how much dispute there was in science about all life beginning with a first cell. As a layman I would be interested in how you think the data stands on this issue at present. I appreciate your, Dr. Collins as well as Dr. Craig's defense of the Christian faith with the book of reason, nature as well as Revelation.

Response: The apparent ubiquity of the genetic code is pretty convincing evidence for a common origin of all life.  My collaborator Martin Nowak has made some progress with “pre-life” ideas about how (at a physical/mathematical level) evolutionary processes might have got started, and there is a pretty respectable hypothesis called RNA World.  However as you say there is no generally accepted theory of how this all happened and many surprises in store.

The idea that life in some form might have originated outside earth and arrived by way of meteorites, which was once seen as almost completely bonkers, is now considered less implausible than before since there is more evidence for complex molecules in space and we realise that some forms of  life can survive in massively extreme environments.  We also realise that there are almost certainly many billions of planets in our galaxy alone.

On the other hand it’s also becoming clear that the characteristics of Earth that allow it to sustain complex intelligent life are very special. Not only do we need to be about the right distance in a stable orbit from the right kind of star, in a stable solar system that has enough big planets to prevent too many meteorites, but we also need a large moon to reduce meteorite impacts still further, a strong enough magnetic field to keep solar radiation at bay, enough surface water that is not boiled off into space etc.. It seems almost certain that these characteristics arose when the earth in its present form was formed by the collision of two planets. Getting such a collision “right” so that the result is a stable earth and moon rather than two more wandering and unstable planets is obviously not straightforward.  There is also the way in which the atmosphere was prepared for intelligent life by microorganisms making atmospheric oxygen – something that seems far from inevitable.

Hope this helps somewhat.  All of this illuminates the “how” of God creating life and humanity on Earth. It of course does nothing at all to undermine the fact of God’s Creation.

Time available for evolution?

I am a retired physicist and was fortunate to find a copy of “Faith of a Physicist” while searching the shelves of a bookstore some years ago. It was my introduction to Dr. Polkinghorne’s work – I have since read several more – and I find his use of a “bottom up” approach attractive; it helps me in the struggle to rationalize my Christian faith. I have a rather simplistic question of a practical nature. In common with most scientists I believe the evidence for evolution is overwhelming.

My problem is with the time available for the development of the world, as we see it today, from the initial single celled organism that was created. An important link in human evolution appears to be “Lucy”, alive about 3 million years ago. She is thought to have been a close relative of homo sapiens, exhibiting bi-pedalism, and yet it took 3 million years for the relatively small changes necessary for her evolution into what we know today as humans. If we take those 3 million years and divide it into the full life of the earth of 4.5 billion years we arrive at the number 1500. So there has only been time, even in the full life of the earth, for 1500 evolutionary “Lucy” steps to have taken place to get us from a single celled organism to the complexity we see now. The number of steps is surely too few to achieve this; even if evolution were 10 or 100 times more rapid, the steps available would still be insufficient. How are we to resolve this dilemma? Does this mean that God has had a more active role in evolutionary development than we think?

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This is an interesting point.

The timescales in evolutionary development are complex and ill-understood: my friend and collaborator Martin Nowak is a pioneer of the field of Evolutionary Dynamics, but it’s a rapidly evolving field. However the natural unit of evolutionary time is generations rather than years: there may be roughly only 15,000 human generations since “Lucy” but millions of ant-generations and billions of bacteria-generations.

Nevertheless it appears that it took about 1.8bn of the 3.5bn years since the origin of life on earth for even multi-cellular organisms to form, and another c1.2bn years for vertebrates. Much remains to be understood!