Four Questions – Part 2 – How Old is the Earth and Why? Did Man and apes come from a common ancestor?
This is the second part of a series of articles addressing the questions of a Bible college student. The student asked the following four questions and a series of follow-up questions of a facebook page Theistic Evolution and a facebook group named Celebrating Creation through Natural Selection. I compiled the answers given by many members of the facebook group into these answers.
The Four Questions
-How long are the days in Genesis 1?
-How old is the earth and life and why?
-Did man and apes come from a common ancestor?
-Were Adam and Eve real people?”
The Follow Up Questions
-How does holding an allegorical view of Genesis affect theology?
-How does an evoultionary process of death and survival of the fittest harmonize with what the Bible seems to teach about death entering the world through sin?
-Are the views possible to reconcile?
-As I am sure you all know, one of the biggest things that Biblical creationists believe is that an evolutionary world view will lead to a secular world-view (rejecting God) an the devaluing of Human life, leading to genocide, eugenics, abortion, etc. What would be your response to this? Do you feel that the evolution based curriculum taught in public schools carries bias that would lead to this?
Question 2 – “How old is the earth and life and why?”
When answering the first of these four questions, we covered some of the biblical evidence indicating that the Bible was not written with the intention of providing an historical timeline of life on earth. If anything, the Bible is clear that the earth is much older than its ancient readers could imagine.
Some of the verses in the Bible, that indicate that the earth is “ancient”, “everlasting” and “old” and that indicate that one should not attempt to use the Bible as a calendar, were covered in another article, “Does the Bible suggest an age for the earth?” I suspect that an earnest Bible scholar could compile a much longer list of verses that do not fit well with a young earth supposition. We can safely assume that it is extremely difficult, if not impossible, to make claims about the age of the earth based on the Bible and that the Bible tells us so.
So, as the Bible does not appear to be interested in giving us an age for the earth or life and has to be forced to contradict itself to create an age for the earth, we are left to let creation speak for itself. Creation is after all a direct witness to Gods actions, especially in those areas where the Bible is mute or can be misinterpreted. The Bible clearly indicates that our natural world provides evidence about God and that we should learn from it. We covered some of the verses that suggest that nature can speak of God in the article “Should we look to nature to help interpret scripture?“
Given, then, that the Bible is silent about how long the earth has existed and how long there has been life on earth our best source of information is science, the study of the natural evidence.
The evidence from many sources indicates that the earth is at least 4 and 1/2 billion years old. The number of ways that this can be confirmed as a minimum age scientifically is astounding. We have geologic, astronomic, chemical and biological data. The consensus of geologists fits nicely with the evidence from paleontology, cosmology, genetics and physics.
We might surmise that God wanted us to be very clear, at this point, that the earth is very ancient and that God is, indeed, the “Ancient of Days” who has been planning his sons and daughters a very long time.
The exact age of the earth is difficult to ascertain. Four and a half billion years is a minimum estimate based on physics and geology, it may grow longer if we find older rocks and better/more accurate dating methods. Because of tectonic drift, we don’t have access to the original surface of the Earth so we cannot date it. the oldest rocks we have found on Earth have been dated, by various methods, to about 4.28 billion years old. So that tells us that the Earth is at least that old. Studying the rest of the Solar System, we find the oldest material to be around 4.6 billion years old. So we currently have evidence for the Earth being somewhere around 4.3 to 4.6 billion years old. Like all planets, Earth would be slightly younger than its parent star. Our Sun formed around 4.57 billion BC, so that dates Earth to about 4.5 billion BC.
Earth started out as a ball of magma, and even after the crust formed it went through a period of being rather like Venus is today. Clearly, it was a barren planet back then. The materials that were in earth’s relative region of space had to come together, to accrete and this took time. After this a nuclear furnace was lit in earth’s core and it was uninhabitable for about 2 billion years.
Life is at least two to three billion years old on our planet, as fossils seem to suggest, though potentially older. The first life was likely oxygen separating bacteria, they were essentially alone for a very long time. As an atmosphere formed and the geological processes necessary to cause rock to be pushed from a water covered planet took place life on land became possible. It took the decomposition of rock and the decompostion of living things to make the first soil, this was a lengthy process which finally allowed plant life to take off and make their own environment.
It is the environment that plants make that allow animal life to survive on land, prior to that animal life was stuck to the saltwater seas and the decomposition and fossilization of that made the layers of limestone world-wide. While the timetables are unspecific, the process is linear and definite.
Here’s a list of some of the dating techniques which establish a minimum age of the earth.
- None of these techniques can give a maximum age for the earth. Each of these techniques can give a minimum age, that is each declares the earth to be “at least this old. All of these are longer than the young-earth estimates. Some young-earth folks have suggested that the radiometric dating techniques are a self-fulfilling prophecy of sorts. One of the members of the Celebrating Creation by Natural Selectiongroup, Alasdair Crawford, a physicist has contributed the math as to why this is not true-Dendrochronology (tree ring chronologies, 8,000 years by California Bristle Cone Pines, 12,000 by German Pines)
-Human Y-chromosomal ancestry – greater than 10,000 years
-Oxidizable Carbon Ratio dating – greater than 10,000 years (20,000 +/- 200)
-Lunar rocks (-3.6 billion)
-Rock varnish – greater than 10,000 years
-Thermoluminescence dating – greater than 10,000 years
-Coral (400,000 years)
-Fission track dating – Greater than 100,000 years
-Ice layering (Minimums from 40,000 -Chinese Dundee ice core to 900,000 – EPICA ice core antartica)
-Lack of DNA in fossils – 100,000 years
-Permafrost – 225,000 years from Prudhoe Bay
-Weathering rinds – 300,000 years
-Amino acid racemization – 1 million years
-Baptistina asteroid family – 160 million yearss
-Continental drift – 200 million year
-Cosmogenic nuclide dating – minimum a few million
-Erosion – ex: the Grand Canyon, a few million
-Geomagnetic reversals – Several million years
-Impact craters – a few million
-Iron-manganese nodules – several million
-Length of the prehistoric day – 370 million
-Naica megacrystals – 1 million
-Nitrogen in diamonds – 200 million
-Petrified wood – millions of years for complete permineralization
-Relativistic jets – at least one million
-Sedimentary varves (36,000 by Japanese diatoms)
-Stalactites – stalactites over a meter long should take at least 10,000 years. Caves are full of many that are tens and hundres of meters.
-Space weathering – millions
-Distant starlight – ten billion years minimum for the universe
-Helioseismology – 4 and a half billion
-Radiometric decay. Here are some varieties of radiometric dating.
- Carbon -14
- Uranium 238
- Uranium 235
- Throrium 232
- Rubidnium 287
Here’s Alasdairs explanation as to why the initial assumptions will not lower the value given by radiometric dating. It’s actually pretty clever how radioactive dating really works.
The common explanation of it is that there’s a radioisotope sample in the rock and by the amount left we know how old it is. Anti-evolutionaries often wonder about the “assumption” of the initial sample’s amount of radioactive material. As with most scientific concepts, the real picture is more complex. Turns out there is no assumption at all about initial parent-daughter ratios.
Basically, when the rock is molten, the parent and daughter isotopes are all mixed up, very homogenous (that’s just the 2nd law of thermo). As the rock solidifies, it solidifies into different minerals within the rock – that all have different amounts of parent isotope, but the same parent-daughter ratio.
This is where the maths starts coming in – different amounts of radioisotope decay at different rates. It decays at a rate proportional to big an amount there is. Basically compound interest in reverse. Because of this, the parent daughter ratios in different minerals within the rock become more different from each other over time. The bigger the difference between them, the older the rock. There’s only one possible age for each set of parent-daughter ratios. They’re plotted like so:
The slope gives you the information about the date, and the y intercept information about the initial parent daughter ratio. Zero assumption.
This also has the effect that only an exponential decay can result in these linear isochrons. Can radioisotopes leech out of the rock? Absolutely. Does this show up in the data? absolutely. Because leeching isn’t an exponential process, it destroys the linear isochron. We can see if stuff has leeched out. This also has an interesting effect. Folks who don’t accept an ancient earth are often concerned about changing decay rates? When you remember how radioactive dating actually works, you’ll notice that it dates the rock to the time it was last molten. If decay rates were millions of times faster like young-earth proponents claim? Well E=mc^2 would like a word with them – it would produce so much energy, the rock would melt and produce a YOUNGER age, not an older one.
This graphic from www.biologos.com illustrates some of the dating methods that evidence a very old earth.
Question 3 – “Did man and apes come from a common ancestor?”
This is another question that the Bible does not address. Thus, it is wisest to trust the evidence that God has provided in nature and that a multitude of scientists have studied. The Bible doesn’t address aeronautics, thus we find it wisest to assume that an airplane mechanic with years of experience and the accumulated knowledge of airplane engineers going back to the Wright brothers is better able to judge if the plane can fly then we are as amateur aeronautic philosophers.
Humans are apes. We are a part of the ape family. According to the evidence, we do share common ancestors with the other apes. This evidence also points to a universal common ancestor with all life on Earth. We share very distant common ancestors with fish, reptiles and so far as we can tell amoeba.
As well as the extensive paleontological record that God has left us, we are lucky to be living in a time when we have the ability to sequence and analyze complete genomes of organisms. As we are now able to analyze the full DNA complement of living primates and evens some extinct primates, we can reconstruct the family tree of hominids going back millions of years. We call this “molecular evidence”. The molecular evidence coincides amazingly well with the paleontological evidence. Darwin could not have forseen this evidence. Only God could have provided it.
Molecular evidence suggests that between 8 and 4 million years ago, first the gorillas, and then the chimpanzees (genus Pan) split off from the line leading to the humans. Our common ancestor with our fellow ape would have been in the genus Sahelanthropus. Whether it was the well-known Sahelanthropus tchadensis or another, even older member of the genus is not entirely certain.
If you familiarize yourself with the evidence of molecular genetics, take a look at the information available to us in chromosome II and psuedogenes. You’ll find it very convincing. If you are up for a bit of molecular genetics, we have an academic article written by a pair of Christians that you may find enlightening. Molecular Genetics and Primate Evolution By David Layzell and Graeme Finlay This video from Dr. Kenneth Miller a biologist and a Catholic Christian covers some of the genomic evidence that humans and other apes share a common ancestor. http://youtu.be/5saKcgnswA4
Indeed, the genetic and archeological evidence has grown ever more compelling. Despite what you may have been told, a common designer cannot begin to account for the genetic homology (sameness).
We assume that God anticipated that we humans would develop the capacity to read the evidence that he has left for us.