Though the title might seem funny — "Am I a Monkey? Six Big Questions about Evolution" ( Johns Hopkins University Press, 2010) — the book is serious. Among other things, Ayala tackles the tension between religion and science, taking a softer position than some other scientists, notably British evolutionary biologist Richard Dawkins.
Ayala, an evolutionary biologist at UC Irvine, recently talked with The Times.
What are your thoughts on Richard Dawkins? How is your take different from his?
I admire Richard Dawkins. He's been a good personal friend for three decades. Considering the matter of religion, it surprises me that he is so antagonistic toward people of faith. He often says he is 95% certain that God does not exist. There is no way from science to reach such a conclusion. Science and religion are like two windows through which we look at the world. Though the windows are different, they need not be in contradiction.
Can you talk more about how science and religion can live in tandem?
Science deals with the origin of organisms, the origin of human beings, and biodiversity of living things. Religion deals with the meaning of life and the purpose of life, and the moral values that should govern our lives. So these are different matters. Science has no way of exploring values.
You write: "Science is a wondrously successful way of knowing the world, but it isn't the only way. Knowledge also derives from other sources, such as common-sense experience, imaginative literature, music and artistic experience."
All of them teach us something, but in a different way. The great French writer Albert Camus once said, and I'm paraphrasing: One learns more about the universe by contemplating a starry night than reading all the books of physics and astronomy. So what he was saying is that common experience can teach us something. Creative literature, music and art can also teach us.
So, let's answer the title of your book: Am I a monkey? How closely are we humans related?
We are very closely related to the chimpanzees; less so to other apes and monkeys. It depends on how you choose to measure the relationship. In time, our closest ancestor with the chimps lived 7 or 8 million years ago, which is tiny compared to how long life has existed on Earth, which is 3.7 billion years.
We are genetically and evolutionarily very close. But we are extremely different when it comes to intelligence. Consider cultural evolution, how humans live — our technology, our literature and art, our morality and religion; our politics and government institutions. It not only creates a new world for us, it affects the way we adapt to the environment.
We adapt not by waiting for our genes to change, but rather we've reversed the process — we adapt by changing the environment according to the needs of our genes. We live in cold regions by using clothing and housing. We fly and navigate not because we have evolved wings or gills, but by using airplanes and boats.
The rate of biological adaption versus the rate of culture evolution — it is not comparable. Biological evolution happens very slowly. Cultural evolution can happen over years or even months. In cultural evolution, we invent the things we want. In biological evolution, we wait for gene mutations.
You write that evolution is a theory but that it is also a fact. Explain.
First, it is a theory. But the word "theory" in science means something different than in general usage, where it commonly means "a hunch." That's not the way we use the word in science. A theory in science is a body of knowledge and the evidence that supports that knowledge.
Evolution is also a fact — the evidence is so strong. All the experts accept it. We have more evidence for evolution than we have for the existence of atoms and molecules. And you don't see people going around doubting atoms and molecules.
You discuss "What is life?" Can you talk about this?
We have hypotheses of how life began, but we definitely don't have the final answer.
The two essential components of life are DNA (heredity) and metabolism (life processes). They are like the software and the hardware of a computer; we need both. The difficulty is that DNA (the software) has the information about metabolism, about how to make the computer. But that information cannot be read without the computer.
Scientists have now discovered ribozymes, RNA molecules that function also as enzymes. They can function both as software and as hardware.
This interview was edited for clarity and brevity from a longer discussion.