Dr. Nathan H. Lents is a university professor in molecular biology and an American scientist. He is the author of two books: Not So Different: Finding Human Nature in Animals (2016) and Human Errors: A Panorama of Our Glitches, from Pointless Bones to Broken Genes. Professor Lents writes the Blog: The Human Evolution Blog, Psychology Today and he is the host of the podcast: This World of Humans.
In Semana magazine and in some newspapers in Colombia, his most recent book Human Errors has already been discussed. In this book, Lents explains, with many examples, the poorly designed human anatomical details. If they were the product of an intelligent designer we could not think that He is very intelligent. Instead, if we think that they are products of random mutation we can infer aspects of our evolutionary saga of four billion years. Lents reviews the design of the human eye, the nasal cavities, the shape of the larynx, the bones of the body, the hands, the spine, the difficulties we have in reproduction, and not just only under the sentence: «you will give birth in pain» . In addition, he gives a list of organs that have no use but had in the past: muscles, lymph nodes, nerves that take strange paths, etc.
Ana Vélez: These examples of imperfections in human design are precisely the ones that reveal very interesting and specific issues of our evolutionary past, how do you explain that being as defective as we are there are people who believe that we are the perfect design of a God who made us at His image and likeness?
Nathan Lents: I don’t think that religious belief has to interfere with the understanding and acceptance of the scientific reality about the world, as well as our bodies and minds. Some people disagree. They find that biology, geology, and astronomy threaten their faith about how the universe, the world, and human beings came to be. I can’t speak for them, but there is only a conflict between science and religion when people choose to interpret ancient religious texts in a strictly literal way. Of course, people are free to do that, but there is an overwhelming abundance of evidence that the exact words of scripture cannot possibly be literally true. People should know that choosing to interpret the Bible literally requires a complete rejection of basic scientific truths. The same knowledge base of evolution informs all of biology, including medicine. The same knowledge base about astronomy and physics operates in satellite communications and GPS technology. If we are wrong about how to measure the age of the universe, then it’s a mystery how our satellites work, even though we built them. That doesn’t make sense, obviously, so I think we’re pretty safe in believing in science.
Ana Vélez: I wonder what you think about the bad design of the human mind, like human morality, the fact that we are selfish, advantageous, corrupt and vengeful. Do you dedicate sections of your book to these topics? To coexist in peace we have to create laws that force us to behave in a certain way, and invent punishments for those who do not obey, precisely because we were not created «morally good».
Nathan Lents: I don’t cover morality, per se, in this book, although I do in my first book, “Not So Different.” I do, however, discuss the balance between competition and cooperation. You mention some very anti-social behaviors, but we are also capable of very pro-social and even selfless behaviors. The trick is to create social structures that promote cooperative behaviors and discourage the anti-social ones. Cooperation is great, but it also allows free-loaders. Competition keeps us performing well, but can lead to needless pain and suffering. It’s a balance and it changes over time. Furthermore, the laws and systems that you mention are not unique to humans at all. Other social animals have codes of conduct that must be learned while animals are young. Animals from wolves to elephants to apes have rules, punishments, apologies, and reconciliation. These are not human inventions. So shaping behavior to be more cooperative and beneficial to the common good is something that all social mammals do.
Ana Vélez: In your book, you say that being omnivores is a defect, however, some people believe that it is an advantage because if you eat everything, the world will always offer you some option not to starve. If you eat only of one thing, as it happens to pandas or koalas that feed almost exclusively on bamboo in the first case and eucalyptus in the second, there is a risk of dying of starvation if a plague were to exterminate those plants. That’s why Mexican tacos are good because if you do not like rice, you fill the tortilla with beans, if you do not eat avocado, you put tomatoes; and in the end, you are full and satisfied.
Nathan Lents: On a personal level, I absolutely agree that variety is the spice of life! But on a more serious note, you are correct that adapting to only one specific food can leave a species very vulnerable if something happens to that single food source. If there is a blight that kills most of the bamboo in a large region, the pandas will starve. This is one of the great ironies of evolution and we see time and time again… specialization can be a path toward great success, allowing a species to completely dominate a certain ecological niche. However, when things change, specialists are in big trouble. Humans did the opposite, we have evolved to become the ultimate generalists and can thrive with a variety of diets. However, the point I make in the book is that being a generalist has a cost also. Because once a species gets accustomed to a varied diet, after many generations, they become dependent on the variety. This is because all kinds of micronutrients are provided in the food and so our bodies lose their ability to make those micronutrients for ourselves. Our dietary need for the vitamins C, D, and B12, and the mineral calcium are really odd and only make sense if you consider that we were living and evolving in a giant salad bowl, a cornucopia of nutritious food, for millions of years. Our bodies got lazy.
Ana Vélez: We have many bones in our hands, is it not because of having many bones that the hands are agiler but also are fragile, is it? Think of a handmade with three or four bones, perhaps it is less likely to fracture but with it, we could not make music or art or lead to the development of intelligence. So there are aspects where the advantage beats the disadvantage, what can you comment about it?
Nathan Lents: Evolution has done a great job of optimizing the design of our hands and feet, but if you look at the ankle and the wrist, they are really clunky designs and all the pointless bones create points of weakness and also limit movement and rotation. The ankle especially is poorly designed for the work that it does.
Ana Vélez: An intelligent god or designer would not have done sexual dimorphism with such a disadvantage for women: to be less strong and have to bear the energetic cost of reproduction, in addition to menstruation. What is your opinion about it?
Nathan Lents: Sexual dimorphism has advantages and disadvantages. While it seems that women bear a greater burden because of pregnancy and childbirth, men have their own problems and this is made evident by their shorter life expectancy. Young males are prone to risky and foolish behavior and this has cost many of them their lives. Older men are more prone to heart disease and stroke. Even when it comes to reproduction and family life, many cultures have engaged in polygamy with one man having lots of wives. If anyone is tempted to think this is great for men, remember that it means that the competition among men is much greater in that scenario. While a few men win big, most men will be excluded from marriage and reproduction altogether.
Ana Vélez: Ken Ham is a renowned creationist who opposes the ideas of your book. He says, for example, that «in their attempt to show common descent, evolutionists often emphasize the small similarities between humans and animals and ignore the massive differences that separate us from animals.» You, who just wrote a book about the similarities between animal and human feelings, what answer do you have for him?
Nathan Lents: I responded to his criticisms with a blog post of my own, but he has not answered me. First of all, he is absolutely wrong to say that biologists ignore the massive difference between humans and other animals. The question of consciousness, symbolic thought, and advanced reasoning is one of the biggest areas of research consuming many scientists. The question of how humans became so different is the biggest question in anthropology. That being said, outside of the issue of conscious thought, there are striking similarities in human and animal behavior that creationists seem to ignore. Because of their need to see humans as altogether different, it is they that ignore evidence, such as the common emotional underpinnings of behavior among social animals. We are learning that animals are capable of a lot more “advanced reasoning” that we ever thought possible, and so the gulf between humans and other animals is narrowing. This makes perfect sense given our common ancestry with other animals. Those who deny the common ancestry of all life have to believe a lot of very strange things in order to explain every day observations about life on earth. There is no simply no evidence for “Intelligent Design” and mountains of evidence for common ancestry and evolution. There is a predictable pattern to how their criticism will proceed over the next couple decades. They will deny, deny, deny, and argue, argue, argue, while scientists continue to do their work collecting and interpreting evidence. Then, once the evidence is truly overwhelming, the creationists will say, “so what?” and pretend that they never opposed the idea.
Ana Vélez: Ken Ham believes that your ideas are guided by the hypothesis that evolution is real, that happened, and claims that everything would be different if that assumption were modified, what is your response to that?
Nathan Lents: It is true that science operates on assumptions, but that’s not just science, all forms of logic and intellectual interrogation involve assumptions. However, the assumptions form the basis of future experimentation and are thus repeatedly tested every time we do an experiment. The way he uses the word “assumption” seems to imply that it’s something taken as automatically true and not tested or criticized. That’s the opposite of how assumptions work in science. Because they are the foundation of future hypotheses, when those hypotheses are tested, the underlying assumptions are also. If the assumptions were wrong, the hypotheses would be also and the experiment would reveal that. The theory of evolution and common ancestry is the underlying assumption of thousands of experiments conducted around the world every single day. So far, none of those millions of experiments have refuted this theory and all of them have sustained it. At this point in time, there’s simply too much evidence in support of evolution to consider it anything other than a proven fact. It’s not surprising that people like Ken Ham use words like “theory” and “assumption” incorrectly because they’re not scientists. I hate to be unkind, but when it comes to biology, Ken Ham has no idea what he’s talking about.
Ana Vélez: In your book Not So Different, you explain similarities between the feelings we call more human and feelings that have been measured and studied in animals, why do not you tell us about the most interesting and unexpected ones?
Nathan Lents: Many people are surprised to learn that animals form loving, committed relationships, both friendships and mating relationships, and then feel profound grief when those relationships are lost. Most people are also surprised to learn that animals understand fairness and equity and insist on it in their social transactions. The behavioral culture of animals involves rules, etiquette, punishments, reconciliation, and so on. They have a rich social environment and their behaviors are not purely instinct. Animals learn how to behave in their respective societies, just like we do. Scientists are only now beginning to appreciate how rich the social cultures of other animals are. We can expect to see many more exciting discoveries in the future.
Are your books translated into Spanish? Are they available on Amazon?
Nathan Lents: Both of my books are on Amazon. I don’t believe that either is translated into Spanish yet, but I hope they are soon. I speak Spanish myself, though not perfectly, and I would enjoy taking these conversations anywhere in the world!
Thank you, professor Lents, for answering my questions.