María Martinón-Torres says that her book Homo imperfectus reflects the “chaotic” way that her mind works. The volume explores what makes humans imperfect by weaving scientific details with literary references. The 48-year-old paleoanthropologist, originally from Ourense in northwestern Spain, heads the National Center for Research on Human Evolution in Burgos. Her background in medicine allows her to see the diseases we suffer as chapters in a story that explains what Homo sapiens is like today.
Question. The book is like a culinary deconstruction of the human being, a journey through the ingredients of our evolution to the dish we are now.
Answer. I try to identify what ingredients we’re made of and how they are mixed. It is very difficult to separate the ingredients. In some places, we find a taste, like an evolutionary advantage, but in other places, we find other textures, like other stages of life or a disease. I like to describe it from the point of view of imperfection, which has always been reviled. We want to be perfect creatures, but the reality is that we are full of imperfections, and that gives our species its richness.
Q. Our diversity made us indestructible.
A. Exactly. The law of nature does not prioritize the individual, but the collective. Individually, we have to deal with many problems and vulnerabilities, but that personal suffering does not interfere with our success. And therein lies the key. Natural selection is not concerned with happiness, health or well-being. Those are human issues. Natural selection is concerned with survival, and humans are concerned with living well. The history of our species is collective and social, and therefore we end up dealing with individual suffering.
Q. Will the pursuit of happiness ever be an evolutionary advantage?
A. Natural selection is an unstoppable filter. When there is a crisis or an important change in the environment, the varieties that are better adapted will prosper or have more children, period. Where does it make the cut? In the traits that can harm our reproductive success. Everything that happens after reproduction is our business. Cancer, which usually appears in old age, is a real issue, but it has no impact on reproduction. Happiness and wellness are the same. If we are capable of generating environments of greater happiness, that contributes to prosocial behavior, and that matters to us. Although happiness is not really a characteristic that is going to be favored by natural selection, it is reached when we put into action the prosocial characteristics that have been positively selected throughout evolution. Our strength is not individual. It is always as a group. This allows us to welcome and compensate and protect individual weaknesses or frailties. The weakest individual is not the one who is physically frail or sick, but the one who is alone. Natural selection favors many characteristics that allow for connection, including longevity: we live longer not to have children, but to take care of others. Natural selection favors us being a long-lived species to take care of highly dependent individuals, who need others from very early and until very late. Rather than being a disadvantage or a weakness, dependence is the reason why we live so many years.
Q. Are we programmed to protect the vulnerable?
A. This is our hallmark as a hypersocial species, the consequence of one of our most useful weapons, which is empathy. Our brain allows us the incredible experience of living our life and imagining that of others, which gives us great advantages in our survival, because we can recognize friends and anticipate enemies. This is reflected, for example, in the care for the vulnerable. Most of our characteristics, even the negative ones, lead us to seek acceptance by the group. We feel most protected and fulfilled when we’re part of a family, a group, a club or a tribe. I believe that the portrait of the human being as ruthless, opportunistic and selfish is not really our true nature. Natural selection favors altruistic and prosocial behaviors for our success. We have to get rid of the cliché that human beings are bad and selfish. There is very little margin for individualism in this species.
Q. Did other extinct species, like Neanderthals or Denisovans, fail due to lack of empathy?
A. In the case of the Neanderthals, I don’t think it was that, because they were a compassionate social group. They buried their dead, they had symbolic thought, they also had a sophisticated behavioral capacity, they controlled hunting, they knew their environment. In the case of the Neanderthals, it has been a demographic issue. There were very few of them and ice-age Europe was a harsh and arid environment. They had great abilities, they were well adapted, but they were very isolated and their population was decreasing. We, on the other hand, were at a peak moment, fully developing our capabilities, and we entered Europe when they were already disappearing, because of something that is fundamental to the human species: diversity. Neanderthals, being an isolated group, were probably also a very homogeneous group genetically. They had less to work with when new threats such as infections appeared. Sapiens, however, were more diverse. The diversity and flexibility of behavior is the key to the strength of a species, because you have a greater repertoire with which to face a greater number of dangers.
Q. In the book you mention that 90% of the people who have lived have had a hunter-gatherer lifestyle. Is that a determinant?
A. When we look back at the evolutionary history of Homo sapiens, since it appeared on Earth 200,000, almost 300,000 years ago, we see that we have been living as a hunter-gatherer species much longer than in cities and towns. This is new. Our biology has been shaped over hundreds of thousands of years to adapt to a lifestyle that suddenly, in this last tweak of the last 10,000 years, has changed radically. But biology has other rates of change, and a mismatch occurs, because our adaptation is much slower than the speed at which we are capable of transforming the world. We have created a completely new world, of routines, of diet, of interactions, of sexual relationships, of exposure to new toxins that have nothing to do with what has happened in 90% of our history as a species.
Q. Is our understanding of our past biased?
A. There has always been a lot of bias. For example, I always say that we do not give the Neanderthal version of events. When we study the brain of Sapiens and Neanderthals, we immediately think about what we can do that Neanderthals did not. These poor Neanderthals went extinct because they had less working memory than Homo sapiens, we say. And I say, if they had the same brain size, there will be something that they did have more developed than us and we don’t know what it is. Maybe they were much sharper visually, maybe they were more empathetic, more expressive. Perhaps they communicated with greater nuance and with greater expression. We have a hard time imagining what they could have that we didn’t have. One of the great biases is to see ourselves as a prototype of the perfect species that has things that others do not have. We always tell our story in terms of success.
Natural selection favors altruistic and prosocial behaviors for our success
Q. We read evolution as if our destiny is to become the kings of creation.
A. Natural selection is humbling: the same rules of evolution apply to us, to cauliflower, to pine trees and to viruses. I don’t think we are better adapted than tulips in Holland or an eagle flying in the sky. They are different types of adaptations to different worlds. We’re not doing badly, but there are still many adjustments to be done. Illnesses are a reflection that there are still many nuts to tighten throughout evolution.
Q. Have we learned many new things about sapiens?
A. In recent years, the image we had of ourselves as a uniform category, a perfect lineage that triumphantly advanced and colonized the world, has changed. Now we see that the key to the success of our species is to have room for exceptions, for crooked lines, for asterisks. This has allowed us to adapt to such different environments. We have not come forward as a uniform species, quite the contrary. And that includes our mixing with other species.
Q. So going back to the sapiens recipe, we are more like croquettes that have been made with food from different places.
A. Well, yes, and that’s very good on an evolutionary level, discovering that we are a mixture and that this mixture has given us advantages. Most of the genes that have been positively selected from our mix with Neanderthals have to do with the immune system. We are a croquette with a lot of ancestors, but also with a lot of flavor and a lot of history.