Photo by Vern Evans

Jared Diamond is the author of five best-selling books about human societies and human evolution, which have been translated into thirty-eight languages.

1991’s The Third Chimpanzee is his first book, followed by the 1997 Pulitzer Prize winner Guns, Germs, and Steel—considered a masterpiece on how human societies evolved. His other books are Why is Sex Fun?, Collapse, and The World Until Yesterday.

Diamond was originally trained in physiology and membrane biophysics and he received his Ph.D. from Trinity College at the University of Cambridge. He is known for his breadth of interests that draw from a variety of fields, including the biology of New Guinea birds, digestive physiology, and conservation biology. Diamond is currently a professor of geography at the University of California Los Angeles. As a biological explorer, his most widely publicized finding was his rediscovery, at the top of New Guinea’s remote Foja Mountains, of the long-lost Golden-fronted Bowerbird, previously known only from four specimens found in a Paris feather shop in 1895.

Diamond’s prizes and honors include the US National Medal of Science, the Tyler Prize for Environmental Science, and election to the US National Academy of Sciences. He is a director of World Wildlife Fund/US and of Conservation International. Jared Diamond is the 2016 Humanist of the Year. The following is adapted from his speech in acceptance of the award, presented on May 27, 2016, at the American Humanist Association’s 75th Annual Conference in Chicago, Illinois.

IT’S A GREAT PLEASURE to receive this award, and to have the opportunity to talk with you. I’ve realized that I’m with a kindred group here, where it’s possible for me to say things and to speak from a point of view that I wouldn’t dare share in another context, particularly in the United States.

So I’ll use this opportunity to discuss the relationship between science and religion, a question that interests me as a scientist and that interests many for the controversy it brings.

Basic to religion is a presumed distinction between humans and so-called animals, and a presumed uniqueness of humans in the universe. But science is just our body of knowledge about the reality of the world as best we can understand it. So, what does science have to say about the foundations of religion in reality? Two areas of science are most relevant: one is evolutionary biology, which has been well understood for 157 years since Darwin’s publication of On the Origin of Species; the other is astronomy.

Let’s begin with evolutionary biology. Evolution is often mislabeled as a theory, but evolution of course is a well-established fact just as the earth’s revolution around the sun is not a theory but a well-established fact. We’ve had compelling evidence for more than a century that our modern human species gradually evolved from now-extinct species that anyone would agree were animals. So we can’t make a sharp distinction between humans and animals.

The human evolutionary line separated from the line leading to modern gorillas about seven million years ago, and then separated from the line leading to modern chimpanzees about six million years ago. Gradually, over the course of the last six or seven million years, various species of the human evolutionary line evolved to be more similar to us modern humans, and less dismissible as animals. But there was never a sharp break in time between humans and animals.

For most of this last six million years, there have been multiple co-existing human species, some more like us modern humans, and some more like so-called animals. It’s only in the last 32,000 years since the extinction of the Neanderthals that the human evolutionary line has consisted of only one species, namely us. There has also always been geographic variation within various human species, just as there is geographic variation within most animal species. Hence, at any given time during the emergence of modern Homo sapiens over the last 200,000 years, there were populations more like us moderns, and other populations less like us moderns and more like animals.

Also, we know that our species hybridized recently with at least two other human species now extinct, namely, with the Neanderthals and with Denisovans. Most of us today carry about 3 percent of Neanderthal genes in our genome, but when our hybridization with Neanderthals was still taking place 32,000 years ago, there were first-generation hybrids who were 50 percent Neanderthal in their genes, a second generation crossed with Neanderthals who were 75 percent Neanderthal, and another second generation that crossed with Homo sapiens who were 25 percent Neanderthal.

So, what do all these facts mean about religion’s supposed distinction between humans and animals? It means that there isn’t a clear distinction. There is variation in time. There is variation in space. But religions haven’t incorporated that fact. If there was a god that created humans in his or her or its image as distinct from animals, when and where did that god draw that arbitrary distinction between human and animals? Was it when we became just 25 percent Neanderthal in our genes, or when we got down to 12 percent, or 6 percent, or now 3 percent?

If we modern humans get judged and sent to heaven or hell, when and where in our evolutionary history did we start to get judged? Do chimpanzees get judged? Did Homo erectus get judged? Did 50 percent and 25 percent Neanderthals not get judged while 12 percent Neanderthals did? Was it possible to have some kind of 50 percent heaven reserved for 50 percent Neanderthals? If a male chimpanzee today dies in the course of killing chimpanzees belonging to another chimpanzee clan, does that chimpanzee get rewarded by going to a heaven where he will be greeted by seventy virgin female chimpanzees?

I mention all these things as examples of the problems that the fact of biological evolution causes for a worldview based on a presumed sharp distinction between humans and animals. I’m not claiming that these basic problems are insuperable. But they are problems that need to be taken seriously for a religion, and as far as I know, they haven’t yet been taken seriously. That, then, is one of the two areas of science that I think has implications for religion.

The other area of science with consequences for religion is astronomy, specifically the subfield of astronomy concerned with so-called extrasolar planets, which are planets orbiting stars other than our sun. That issue of extrasolar planets is relevant to the supposed uniqueness of humans in the universe. Chimpanzees and primitive humans could already see with their naked eyes that there are thousands of stars up in the sky. Since Galileo invented the telescope, and as telescopes have been improved, we’ve learned that there are not thousands but trillions of trillions of stars.

But until recently, we couldn’t detect any planets orbiting those stars comparable to the nine or now eight planets that we know orbit our own star. We just didn’t have the methods. Because we’ve never been visited by flying saucers, it has seemed possible, although very improbable, to assume that the only intelligent life in the universe is we humans here on Earth (because, until recently, it’s always been the case that none of the other thirty million species on Earth rival us in intelligence).

In the past few decades, however, astronomers have developed a series of methods for detecting planets outside the solar system. As of May 10, 2016, astronomers had identified 3,264 planets outside our solar system, out of which 100 are the size of our planet Earth. Some nine of those planets lie in what is called the habitable zone of their stars, meaning that they lie at a distance from their star where it’s neither too cold, nor too hot, so life could evolve. Nine habitable planets. Out of the extrasolar planets we know of, 0.3 percent may be habitable by life as we know it.

Most stars that we’ve searched have proved to have planets, so we have to assume that planets are the overwhelming rule, not the exception. If there are at least one trillion stars in the universe, and if most of them have planets, of which 0.3 percent could support life as we know it, that means that there are about three billion planets capable of supporting life.

Experiments in laboratories suggest that it’s easy for a planet in the habitable zone to evolve life. The famous Miller Urey experiments of the 1950s showed that if you expose a container holding water, methane, ammonia, and hydrogen to either electricity or to ultraviolet light or to heat, then they will spontaneously form the building blocks of earth biology including amino acids, sugars, nucleotide bases, and porphyrins. So, it’s likely that the universe contains not just a billion planets capable of supporting life; it’s likely that the universe contains a billion planets actually supporting life.

Probably some of those planets have only living creatures less intelligent than us humans, and probably some of those planets have living creatures more intelligent than us humans. That makes it extremely unlikely that if there is a God, he, she, or it is more interested in us than in all the other more intelligent life forms that surely exist on other planets. This is another fact that needs to be taken seriously if one wants to reconcile religion with science.

Again, I’m not claiming that the facts of the real universe are incompatible with religion. It’s just to say that those facts of the real universe raise problems that have not yet been resolved. You may object to my conclusion that there are probably a billion planets out there supporting life. Why is it, you may ask, that we’ve not yet been visited by flying saucers and six-legged green creatures who demand to be taken to our leader? Doesn’t this suggest that there really are not inhabited planets with life out there? No. The reason we haven’t been visited by flying saucers is pretty clear, if we consider the space-distance problem, the target problem, and the civilization lifetime problem.

As for the space-distance problem, the speed of light (186,000 miles per second) is the maximum speed you can achieve in the universe. But even if a flying saucer could achieve the speed of light, the closest stars to Earth are several light-years away, which means that a flying saucer going at top speed is still going to take several years to reach the earth. But it’s extremely unlikely that a flying saucer is going to approach the speed of light. It’s going to take a prohibitively long time to reach us. That makes it implausible that we are going to see flying saucers.

The second reason we haven’t encountered flying saucers is the target problem. Given that there are billions of stars out there, it means that from any planet capable of launching a flying saucer, there are also large numbers of potential targets, many far closer than Earth. Earth is really just one of an enormous number of targets for any civilization capable of sending out flying saucers. That’s another reason that we’ve not yet been visited.

The third reason concerns the likely duration of a civilization capable of sending out flying saucers. Just consider the history of life on Earth. After four-and-a-half billion years, we finally get an intelligent species, by our standards, and in 1957, we finally launch Sputnik, which doesn’t escape from the solar system but at least it’s up there in space. And a few decades later we launch an object that is headed off into space. But given the rate at which we’re destroying the basis of our own foundations, sometime be-fore the year 2050 human civilization will have destroyed its capacity for sending objects into outer space, which means that of the four-and-a-half billion years of life on Earth, there will have been only a couple of decades available for sending objects out into the galaxy. We have to assume, based on our experience and common sense, that any civilization capable of sending out flying saucers will also have developed the capacity to destroy itself. These are, I’m sure, the three reasons why we have not yet been visited by a flying saucer, nor will we be.

Excerpts from the Q&A

Q: With all the new information from the sequencing of domestic animals and plants, and from archeology, do you have plans to update Guns, Germs, and Steel?

A: It just so happens that 2017 is the twentieth anniversary of the publication of Guns, Germs, and Steel, so my publisher, Norton, and I have agreed that we will release a new edition next March for which I have written a new afterword reflecting on what we’ve learned since 1997.

Q: What are your thoughts on the cooking hypothesis to explain human evolution and why we’re so different from, say, the chimpanzees?

A: We humans have this large brain (though sometimes there’s reason to doubt it), but metabolically, it’s a very expensive piece of machinery. So the question is, how have humans been able to support the metabolic cost of this big brain?

The cooking hypothesis says that a contribution to our ability to extract lots of energy from the environment is our mastery of fire. Mastery of fire enables us to cook, and one might say that cooking has provided a wonderful outlet for Jared Diamond’s happiness because his wife Marie is a great cook, and it has provided a job for one of Jared Diamond’s two sons who is a professional chef. But what does a cooking hypothesis have to do with human evolution?

The hypothesis, formulated by Richard Wrangham and others, says that the process of cooking breaks down the structure of food and breaks down chemical bonds, so you yourself with your enzymes don’t have to do as much work to digest those chemical bonds as if you were eating raw food, and therefore, you can get more calories out of a pound of chicken.

One of my postdoctoral fellows in physiology fifteen or twenty years ago is a wonderful biologist named Stephen Secor. He and I did a project together in my physiology laboratory at UCLA on pythons in which Stephen fed pythons various meals and measured their digestive efficiency. That is to say, he measured how many calories a python could extract out of a rat or a chicken. Wrangham then collaborated with him to determine the energetic benefit of cooking food.

So Stephen fed his pythons a chicken. It was either raw, what the pythons would normally eat, or he fed his pythons a cooked chicken, because Stephen’s pythons are cooperative. And then Stephen measured the calories that went into the python’s mouth, and the calories that came out the other end, and it turns out that a python that has been fed a cooked chicken extracts 10 to 20 percent more calories out of the cooked chicken than out of the uncooked chicken, because the python itself hasn’t had to do all the enzymatic work of digesting the food.

This, then, is experimental support for the cooking hypothesis, and it implies that we humans could also get 10 to 20 percent more energy out of all food once we learned how to cook it, compared to chimpanzees that hunt, prey, and eat raw meat. Ten to twenty percent may not strike you as very much, but in the animal world, an advantage of even just 2 or 3 percent over another animal, 2 or 3 percent per generation, is an enormous advantage. It would make a big contribution to the evolutionary success of the human species. So, yes, I like the cooking hypothesis.

Q: Thank you for a wonderfully informative talk. I’m disappointed with one thing you said, and that’s that you only give such talks to audiences like ours who basically agree with you. I think a respected scientist who is an excellent expositor can make great inroads talking to people more religiously oriented, who need to hear what you have to say.

A: First of all, I’m ecstatically happy that you found only one thing to complain about. Secondly, I have given talks about religion in other contexts. I recently gave a talk about religion at my university, UCLA, and I did not get fired as a result. If I’m talking about religion to the general public, then I’ll lead them in more gently than I led you in this evening. I ask people to consider what would be the opinion expressed by a visitor from outer space from the Andromeda nebula if the visitor came to Earth and saw a human religion. What would the visitor then say about human religion, I ask.

One does have to be careful, though. Because I write and talk about controversial matters, there have been occasions where my host had to hire bodyguards in order to protect me. I have received death threats, and so, as the father of children and as a husband, yes, I’m cautious in what I say to whom.

Q: I’ve read various projections about the effects of climate change by 2050, 2100, and so on. It sounds like you’re a little more pessimistic than some of those projections.

A: When people ask me, are you a pessimist or an optimist? my answer is I’m a cautious optimist. By that I mean I rate the chances of a happy ending at 51 percent. The risk our civilization faces now is not the unstoppable threat of an asteroid hurtling towards us, something that we can do nothing about. In fact, all the things people talk about as threats to our civilization over the next decade—threats such as climate change, deforestation, water problems, overharvesting of seafood—these are all problems that we know perfectly well how to solve. The only thing missing is the political will, and therefore, when I say that I think the chances are 51 percent that we will solve our problems by the year 2050, I’m really making a prediction about whether we’ll muster the political will or not. Naturally, I hope that we will, and one of my goals is to encourage people to develop the political will.

Q: Regarding your points about the little green men visiting us, as far as the target portion of your discussion, aren’t we making ourselves a target by the megawatts of broadcast energy we’re now pouring into space? I realized we’ve only been doing it for sixty years, and there’s not enough time for them to travel, but doesn’t that make it easier for whoever’s out there to target us?

A: Yes. It’s a significant issue, the signs of our presence that we’re radiating unintentionally into space. But I’m more concerned, and I would say more angry, about the signs of our presence that some of us are directing intentionally into space. There are well-intentioned astronomers who have sent objects into space. There’s an object that was sent into space that gives, in human writing, the coordinates of our galaxy, and there are astronomers who want to beam signals into outer space in order to get a response. So what do they think the response is going to be? They are tacitly assuming that if there are creatures out there who detect us, and come to visit, they will sit down with us and have pleasant conversations.

We have lots of models on Earth for what happens when intelligent creatures (we) encounter other, somewhat less intelligent creatures like chimpanzees and gorillas, and other humans. We’ve chopped the hands off of gorillas and used them for trophies. We’ve killed chimpanzees and used them as bush meat, we’ve shut them up in cages, injected them with drugs, and performed medical experiments on them.

When we humans have encountered other humans over the last millennia, it has always been a matter of might makes right, doing to them what we came to do. So, my view is that those astronomers who intentionally beam signals into outer space in the naïve belief that the result is going to be a nice conversation are some of the most dangerous people on Earth—except for the fact that I don’t think what they’re sending into outer space is ever going to arrive, thank heavens.