This page at a glance
The theory of evolution has had an enormous impact on human thought and our understanding of ourselves and our place in the world. And it has caused consternation and division among christians who believe God created the world in 7 days as described in Genesis.
The vast majority of scientists accept evolution without question, including most scientists who are christians. But why should christians think evolution is true?
This page discusses the following topics:
- A brief outline of what evolution is.
- The evidence for evolution
- Arguments against evolution
- The consequences of evolution for christian faith
- Who were the first humans?
What evolution is
The theory of evolution doesn’t explain the origin of the first life which appeared on earth almost 4 billion years ago, but explains the development and diversification of all life from then. Evolution is built on several key concepts.
Evolutionary science has concluded that all life has come from the first single cell life-forms, in a process known as “common descent”. Thus a “family tree” can be drawn showing this process.
The growth of an organism and its different features (e.g. hair colour, blood group or intelligence in humans) is controlled by genes in the organism’s DNA. (For a brief outline of DNA and genes, see DNA, genes and human history.) When species reproduce, they pass on their DNA to their offspring, but small modifications in the DNA can occur. Over many generations these modifications can result in significant differences from the ancestral population.
When these differences are beneficial for survival, these genes are passed on to larger numbers of offspring and these characteristics can work their way through a whole population of organisms. If the changes become large enough, a new species is formed.
These processes take enormous lengths of time, so we cannot observe major transitions, but smaller transitions have been observed.
The evidence for evolution
The age of the earth
Many different evidences point to the earth being a lot older than a few thousand years:
- Sediments are deposited in lakes at rates that can be measured, often with different layers in summer and winter. These layers can be counted, and some lakes shown to be hundreds of thousands of years old. Some ancient lakes on longer exist, but the patterns can still be seen in the geology.
- Coral reefs also have annual layers, and some reefs can be seen to be 200,000 years old. Likewise polar ice can be measured to be more than 100,000 years old.
- Radiometric dating (potassium-argon and uranium-lead) of volcanic rock can measure rock strata more than 70 million years old.
If life had been created in 7 days, we’d expect the fossil remains of dead creatures to by quite mixed up through the rock strata as a result of Noah’s flood. However, in fact, fossils are distributed through the rock strata in a quite orderly manner, and the radiometric dating of these fossils and the progression of these fossils from older and simpler forms at the bottom to newer and more complex forms at the top are consistent with each other. A consistent geological column can be constructed, showing the gradual evolution from simple to complex.
The continents of Africa/Europe and America are moving apart, with molten rock rising up to fill the gap at a location known as the Mid Atlantic Ridge. The solidified rock can be radiometrically dated and magnetic polarity measured. It turns out that the earth’s magnetic field has reversed polarity several times, and these changes and the dating indicate the Mid Atlantic Ridge is almost 200 million years old. Moreover, working backwards shows that the continents fit together, physically and geologically, indicating an even older age when those land masses were joined (more than 200 million years).
The fossil record shows the gradual evolution of more complex life from single celled organisms about a billion years ago, through fish, amphibians and then reptiles around 400-300 million years ago, and mammals and then birds around 230-150 million years ago, to finally hominids and humans.
But the fossil record also contains more detailed evidence – fossils show evidence of some of the transitions between the major types of creatures, for example:
- fossils of a creature that was part of the transition from fish to land animals, with a fin with the beginning of fingers;
- fossils of cynodonts, reptiles that show a transition between reptiles and mammals in their teeth and in the bone structures in their jaw and ear;
- the fossil record shows many stages of the transition from land animals to whales (a surprising direction for evolution to take!);
- fossil remains plus bone structure of modern animals show the transition from dinosaurs to birds.
DNA may be the best evidence for evolution and common descent.
DNA is a complex molecule which contains the biological instructions that determine everything about us. These instructions are passed from adult organisms to their offspring during reproduction (for more on DNA, see DNA, genes and human history). The information is in the form of 4 complex organic chemicals found in pairs in the DNA molecule. Human DNA contains about 3 billion items of these “base pairs”, and the majority of this information is the same in a wide variety of creatures.
Genes are made up of thousands or millions of base pairs and determine our biological characteristics such as hair colour, blood type, etc. Genes are grouped together into chromosomes, each of which is a string of DNA. Offspring receive genetic code from each parent in a somewhat random way, and DNA isn’t passed on perfectly (some of these base pairs are changed during reproduction), so all humans have slightly different DNA from each other.
In humans, ancestry and paternity can be determined by comparing DNA and noting where the variations occur – if key sequences are common, the two people being compared are related, with the closeness of the relationship determined by the amount of DNA in common. With large DNA databases now available showing the extent of change from one generation to the next, these determinations can now be quite accurate.
The same principles can be used to examine the evolutionary process. It turns out that humans have only about 0.1% variation in their DNA, whereas our DNA varies by anywhere from 1% to about 7% with that of various monkeys and apes. The variation when compared to other animals is greater.
(These numbers caused me some confusion at first, for I have read that humans are genetically very similar to some unexpected animals such as rats and pigs. But it appears that here the comparison is of genes, which can be composed of a different sequence of base pairs and still perform the same genetic function.)
On the same principles as used in human genealogy, the closeness of the DNA of humans and apes gives an indication of closeness in evolutionary descent. Further, once a variation has occurred, it almost never changes back again, so tracing where in the family tree the variation occurs and doesn’t occur, can give an indication of when the evolutionary trees diverged. For example, the DNA evidence suggests that the common ancestor of humans and chimpanzees was about 6 million years ago.
Use of DNA in this way gives consistent results in terms of relationships and timespans, and thus reinforces the conclusions from the fossil evidence that humans and other animals today have gradually evolved from earlier organisms and creatures.
- Comparing the anatomy of living creatures today shows that there are many similarities in bone structure, suggesting common descent.
- Biogeography shows that the distribution of animals across the globe, especially comparing locations which are isolated from each other, shows consistency with the evolutionary tree.
I think sometimes scientists overstate the degree of certainty that evolution is true – after all, we cannot actively observe it nor conduct direct experiments. Nevertheless, the evidence is certainly suggestive that evolution and common descent have occurred. Either this is how God created, or else he has made it look as if it is how he created.
Fossil of vertebrate between in transition from water to land-based (from BioLogos).
Arguments against evolution
Gaps in the fossil record
The fossil record is incomplete, and some of the transitions are particularly sparse. Critics say that these gaps show species cannot evolve into new species, but scientists explain that some species or locations are not conducive to fossil formation, and we’d expect there to be some gaps. In any case, gaps are slowly being reduced.
The Cambrian explosion
The fossil record for the Cambrian Period, more than 500 million years ago, shows the relatively sudden appearance (over a period of perhaps 5-30 million years), without previous ancestors or transitional forms, of most of the plant and animal groups known today. Critics say this is impossible. Current evolutionary science has several possible explanations, but there is not yet a consensus (as far as I know). But there are other periods of rapid change, so there is no reason to suppose this “explosion” in species wasn’t possible naturally.
The evolution of life requires numerous small changes to cumulatively lead to new and more “advanced” species, and for every step in the process to confer a survival advantage so that the organism survives to allow the next step in the process. Critics say this is very difficult to demonstrate, and some claim some organisms are “irreducibly complex” so that they cannot evolve in this way.
Evolutionary scientists have explained some of these transitions, and believe it is only a matter of time until all can be explained. Again, I think they may claim too much certainty (demonstrating feasibility is not the same as showing a process actually occurred), but it seems likely they will be able to demonstrate enough to confirm that evolution is probable.
The origin of life
The most difficult challenge is the origin of life itself (abiogenesis) where amino acids had to form, then link together to form proteins, then many proteins combine to form genetic code and a living cell. This is an enormously complex achievement and presently there is no known process to achieve this, though many have been suggested.
Critics of evolution say it couldn’t happen naturally, and they may be right. But we cannot be certain of this, and it is probably wisest to be cautious – because of the great strides made in understanding evolution, it may be that scientists will crack this problem too.
The book of Genesis
Finally, many christians simply say that evolution is contrary to the book of Genesis, which they believe tells the literal historical truth about origins. While this view is understandable, it assumes the Old Testament should be understood as being historically accurate when the evidence suggests it is more likely to include legendary material (see What the scholars tell us about the Old Testament).
Doubts about the details
The details of the theory of evolution have not all been worked out yet. There are many transition processes that are uncertain. There are even secular scientists who reject major planks in the theory – for example distinguished French biologist Pierre-Paul Grasse accepted that evolution has occurred but argued that it couldn’t have occurred via mutation and natural selection.
Despite some areas of uncertainty that are not always admitted by evolutionary scientists, the critics have generally not proven their case. It may be that some details of the present understanding of evolution may be found to be wrong, but it seems unlikely that it will be significantly altered.
Evolution as a problem for christian faith
Evolutionary scientists, especially atheists, often stress that the evolutionary process is unguided, which appears to indicate God couldn’t be working within it. But this appears to be based on a confusion.
It certainly seems true to say that evolution can generally be explained in terms of natural causes alone (with a few doubts about some processes, especially abiogenesis). But it is difficult to see how evolutionary scientists could devise an experiment to show that non-natural causes (e.g. God) could have no part in the process. And it certainly remains quite reasonable to think that God could have designed the whole process and set it up so that human life would evolve.
It therefore seems best that both christians and atheists should do science without invoking God in the science. But it also seems true that science cannot be used to banish God either.
Evolution and suffering
Life on earth includes suffering by both people and animals. A literal view of Genesis allows belief that God created the earth without suffering and death, and human sin led to suffering and death. But the evolutionary process included and even required animal suffering before any humans existed. Was God the author of this suffering?
I think there is little we can say against this argument. It does seem that God has set up a rather bloody process to bring about human life on earth, and we can only guess at why. But there are good reasons to believe that the God of Jesus exists and is the true God, stronger reasons than we have to doubt, and so we can only trust him despite not having answers to this problem.
Adam and Eve, the fall, and original sin
The DNA evidence indicates there was no single primeval ancestral couple, and hence no progenitors to pass on original sin, and evolution suggests there was apparently no “fall”, because death entered the world before humans appeared.
I find it easy to believe that Genesis 1-3 is more like a folk tale than literal history – it certainly reads more like a folk tale or a myth. I am therefore quite happy to accept that any doctrine of “original sin” has to be slightly redefined (I can’t accept the traditional formulation of the doctrine anyway).
But the New Testament references to Adam and Eve and Genesis create difficulties for some christians.
- Some theologians say we shouldn’t be concerned, it is not uncommon for Jesus and the New Testament writers to interpret their scriptures (our Old Testament) in fanciful ways, and even occasionally use Jewish non-scriptural legends as a basis for their teachings. (For more on this, see How to interpret the Bible.)
- Others simply say that Jesus and Paul were people of their time and wrote using the understandings of his day when it came to the science of origins. Some christians feel this undermines the inspiration and accuracy of the Bible, but others suggest that it is better to understand the Bible as a book with fallible human authors inspired by God but not necessarily speaking scientific truth.
This approach isn’t without its problems. If Jesus and Paul, for whatever reason, said things that are not literally, historically, scientifically true according to today’s understandings, what else should we question? I think questions like this can be resolved, by considering the evidence in each case, and relying on the Holy Spirit’s guidance, but it does mean that we don’t have the certainty some christians think we need to have.
In the end, the evidence points to Jesus truly being the son of God and evolution being true, so I believe we have to hold onto both truths even though we cannot fully explain things.
Alternative christian views
Many christians (e.g. Answers in Genesis) believe the Bible cannot be interpreted in the way I have described, and so hold to a literal, historical view of Genesis 1-3 – the world was created in 6 literal days something like 6,000 to 10,000 years ago, and Adam and Eve, the tree and the snake were all literally true. Some accept an older date, interpreting the days figuratively, but hold to the rest. This view requires them reject virtually all of the science of evolution
It seems to me that this is building too much on a slender foundation. The early chapters of the Old Testament look like they are legendary and the evidence that they should be interpreted literally is quite weak. Creationism seems like it is being faithful to the scriptures, but it requires us to ignore strong scientific evidence to uphold a belief that isn’t at all certain.
Intelligent Design (ID) is the view that “certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection.” This view is inferred from “the informational properties of natural objects”, leading to the conclusion that “form of information which we observe is produced by intelligent action, and thus reliably indicates design”. Thus intelligent design is compatible with evolution and an old age of the earth, it simply argues that natural selection cannot explain all the design in nature.
ID claims to be science rather than religion as creationism is. However ID seems to me to falter at three points:
- ID builds its case for design on reasonable inference, but in science that is just the way a hypothesis is formed. To be truly science, a hypothesis needs to make a prediction that is falsifiable, which is then tested by observation. So far, it seems ID hasn’t been able to do this. Even if it was true that God intervened supernaturally at several points in the evolutionary process, I can’t see any way this could be proven – naturalist scientists could always argue that there is indeed a natural explanation even if it isn’t known.
- It is hard to see why would God use a hybrid process like evolution with occasional supernatural interventions, which has the appearance of God designing a process that he didn’t quite get right, and had to correct it along the way. It seems more likely that, if God wanted to use an evolutionary process, he would set it up at the beginning (i.e. at the big bang) so that stars, planets (at least one of which was habitable) and human life would form naturally.
- ID claims to be science, but evolutionary scientists sometimes accuse ID of being creationism and religion in disguise. It certainly seems like ID proponents could have mixed motives. However it is fair to say that some naturalist scientists are prone to draw unscientific conclusions against religious belief which also cannot be called scientific, so both “sides” may be guilty of using science to further their religious or anti-religious purposes.
This view (promoted, for example by BioLogos) accepts the science of evolution as being the way God chose to create the universe and life, and seeks to use science to better understand God’s creation. It faces the problems I have outlined squarely and seeks to develop answers that are scientifically and theological sensible.
It seems to me that this is the only view we can reasonably adopt.
Evolution as a positive for christian faith
Many christians believe we can know God through “the book of God’s words” (the Bible) and “the book of God’s works” (the natural world, discovered by science).
So Scientists like zoologist Jeff Hardin, professor Denis Lamoureux and the BioLogos team all believe God can use the discoveries of science to correct our wrong interpretations of scripture, and christians should all be open to this.
Keeping the faith
Many university students who were brought up christian give up their christian belief in the face of the challenge from evolution – primarily because they were taught that the two were incompatible.
Far from compromising christian faith, acceptance of evolution can save christian faith for many people.
So who were the first humans?
The evolution of hominids and humans
The ancestors of humans first walked on two legs about 6 million years ago. About 2 million years ago, the hominins (the direct ancestors of humans) began to evolve as species separate to the rest of the hominids (the “Great Apes”, including chimpanzees, gorillas and orang-utans).
Further evolution led to many species, all with the Latin name homo, meaning human. These other species spread from Africa to other parts of the globe, but subsequently died out, as shown on this diagram. (This diagram follows the favoured Out of Africa model of human origins. A less favoured Multiregional Continuity Model model suggests greater connections between the various species.)
It is generally believed that the groups shown in the diagram were indeed different species. Even though neanderthals and modern humans coexisted for a while, it is doubtful if they could interbreed. Humans have significant amounts of DNA in common with Neanderthals, but it is generally believed that these came from a close common ancestor of both species.
The first biological humans
So we can see from this that, biologically, the first of our species of homo sapiens lived about 200,000 years ago, while the first of the homo genus lived about 2 million years ago.
But christians believe that human-ness is about more than biology.
Are humans different to animals?
Naturalism is the view that the natural world is all there is. Most atheists and many scientists would be naturalists.
If naturalism is true, humans are merely physical, and physical processes control everything, including in our brains. Consciousness is a mystery, something that occurs in our brain, but there is no “us” apart from our brain and its processes. This makes it difficult to see how we can have free will and make genuine choices, including moral choices, because there is nothing to change the physical processes going on in our brains – no “us” to intervene and make any different choice than the one our brains will inevitably make.
This is a common view among neuroscientists, but is contradicted by our common human experience, where it seems that we are real conscious beings, able to make ethical and other choices and be held responsible for them. In fact, psychologists tell us that it would be next to impossible for us to live as humans if we didn’t believe our self is real and we are capable of making moral choices.
So we have two opposing options. Either accept the scientific conclusion that we are no more than smart animals, or accept our common human experience that we are more than that, and believe that the scientific view is limited by its inability to measure or observe the non-physical.
Christians generally, along with most people, believe humans are more than smart animals, and our laws (e.g the UN Declaration of Human Rights) reflect this.
But this then leads to the question, how are humans different?
What is human?
While christians believe that humans are more than simply intelligent animals, and most believe a key is that humans are created in “the image of God”, this is understood in several different ways.
Perhaps the image of God can be found in our consciousness and our abilities to love, reason, make moral judgments, laugh and make music and art? However some of the “higher” animals also show signs of some of these attributes, making the distinction less clear. Further, some people (e.g. new born babies, elderly people suffering dementia, those with mental disabilities) may not have some or most of these attributes, but that doesn’t make them less human.
This argument is seen by some as conclusive, but I’m inclined to think that it just shows that we cannot easily and fully define our humanity, and we do indeed share some aspects of God’s image with some of the higher animals. This view would generally be called dualism.
Spiritual capacity and relationship with God?
Perhaps the image of God is seen in our spiritual capacities, especially our ability to have a relationship with God? Many of our spiritual capacities may be similar to our abilities (moral sense, goodness, ability to love, etc), and relating to God probably requires that we have self awareness or consciousness. But most of us would think that there is more than this.
Some would say humans, but not animals, have a soul or a spirit, which is how we relate to God, experience the Holy Spirit, and experience spiritual regeneration. While I don’t believe we have a “immortal soul” which lives on after we die (I think rather we live in the next world because we are resurrected, not because we are immortal – see Do we have an immortal soul), I am certainly a dualist – i.e. I believe humans are more than physical.
But then the question arises – how do we get this non-physical nature and capability? Denis Lamoureux outlines three approaches that christians have adopted:
- At one point in the evolutionary process, God intervened to select a couple from among the “human” (or sub-human) population and created his image, including moral accountability and the ability to know him, within that couple. They went on to be ancestors of all “true” (i.e. spiritual) humans, for a time living and being able to mate with the “non-spiritual” hominins/humans. Trouble is, genetics tells us that there is no primeval couple that were the ancestors of us all. Further, if they did indeed interbreed, what would be the spiritual status of their offspring?
- A second viewpoint is similar, except that God intervened to implant spiritual capacities in a large group of “humans”, perhaps even the entire human (home sapiens) population. This overcomes the genetic objection by positing a large number of ancestors.
- Lamoureux suggests that we should consider the parallels with the process of human embryological development in the womb. No-one knows for sure when and how non-physical characteristics, such as consciousness, ethical awareness and the ability to form a spiritual relationship with God, are created in us, but he suggests the process is likely gradual, just as our body and brain grow gradually. So, he argues, the same might be true of the evolutionary process – the image of God in us grows gradually.
While these ideas seem to have merit, it seems to me that none of them are fully satisfactory. We may never understand spiritual development, because it cannot be measured physically (although some suggest it may explicable in purely naturalistic terms), but the problems with this approach to the image of God suggest we may need to look elsewhere.
In the Old Testament, the word translated “image” in the phrase image of God is used in many other places in relation to idol worship For the people at the time, an idol “was believed to be the true manifestation of the god in the midst of the people.” God forbade the worship of idols because they were not in any way true images of him, but also because he had something else in mind.
The phrase “made in the image of God” can apparently be equally well translated “made as the image of God”. God’s intention was nothing less than calling us to show his image to the world. “The image is not a built-in ability or capacity of human beings, but a role we are called to live.” (BioLogos)
I feel drawn to the third view, but I can see truth in all of them. It would be difficult to be called by God to be his image-bearers in the world, and to have a relationship with him, if we didn’t have the abilities which, generally at least, separate us from animals.
But I am happy to accept there is truth in all three views.
So who were the first humans?
The matters we have considered here lead to some clear, and perhaps disturbing, conclusions.
- We don’t know who the first fully human beings were, but they probably lived 50,000 to 100,000 years ago. There is no clear answer to this question because the growth into humanity was likely gradual.
- We cannot say how our spiritual capacity came about, any more than we can say how our consciousness, our ability to make choices, and think rationally and ethically, came about.
- Granted this, we cannot easily see how God decided when to start holding individual homo sapiens morally responsible, any more than we can say when unborn or newborn babies become morally responsible.
This is disappointing, perhaps even distressing. We don’t have answers, nor a likely pathway to arrive at answers. Scientific naturalists will be scornful of our views.
And yet we have no choice. Humanity, law and culture are on our side, and despite the confidence of scientists, science struggles to address these things because they are apparently non-physical. Most people think humans are different, and “higher”, than animals, and as much as they understand what naturalistic scientists think about humanity, would generally be critical of the view. Christians have even stronger reasons to believe in the value and “sanctity” of human life.
It may be tempting to go back to a literal reading of Genesis and creation de novo, but the evidence suggests we cannot (see Why the fuss about evolution?).
We can instead learn to be humble and not expect to understand everything, while doing our best to understand what we can.
It seems to me that evolution has really occurred, and while it causes some difficulties for christian belief, these difficulties are not as strong as the difficulties of explaining the world and human experience without God. I see little point in opposing evolution. It is probably true, it doesn’t change our belief in Jesus, and our energies can be better spent building the kingdom.
- Biologos on the fossil record, genetic evidence and other evidence for evolution, and the fossil evidence for the evolution of humans.
- Dennis Lamoureux: I love Jesus and I accept evolution. An evolutionary biologist and theologian on evolution.
- Genetics and evolution by the Smithsonian Institute and a Professor of Pediatrics.
- Evolution and christian faith by Zoologist Jeff Hardin, Geneticist Francisco Ayala and BioLogos.
- DNA, genes and human history, Evolution and its critics and Evolution and God on my other website, Is there a God?.
- Old Testament scholar, Peter Enns, on evolution.
- Human evolution in Wikipedia.
- Adam and Eve and theories on the first humans, by BioLogos and Peter Enns.
- BioLogos on the image of God, and a longer series by Peter Enns.
Photo Credits: Top graphic by The PIX-JOCKEY (photo manipulation) via Compfight cc, 30,000-year-old cave painting of a hyena, found in the Chauvet Cave, France, and Chart of human evolution, both in Wikipedia.