We are programmed to survive or die in the attempt, there are no other options than those. Our most primitive purpose is to perpetuate existence and for this it is necessary to find a partner and adapt to everything that surrounds us, but there are also many other aspects of nature and the beings that inhabit it that we do not know. Evelyn Segura, biologist and scientific communicator, is responsible for disseminating them, both in the program What animal! From La 2 de Televisión Española, as a collaborator in the current affairs section of the animal world in Arusitys, a program of La Sexta and now thanks to his new book, Adapt or die (Ed. Paidós, 2019) in which he reels some unknown details of the animal world and belies some myths of popular culture. Surely you have ever wondered why we do not remember when we are babies, why we are one of the few animals that are born totally dependent or if the pets that accompany us at home have feelings for us. All these and many more curiosities Evelyn Segura has revealed to us, if you also want to know the answers to these questions you just have to keep reading.
We all have an innate survival strategy, but do you think humans are capable of adapting or have we forgotten to survive?
We have not forgotten to survive, what happens is that we have not adapted well to the environment, but we modify that environment according to our needs or our whims. We change everything around us to have a more comfortable survival. I believe that we have reached a point of comfort more than animal survival.
But there is still some of that animal survival in us, which is nothing more than perpetuating the existence of the species through the children. And for this we need to have a couple that we look for based on their DNA, as you explain in the book, how can we do it without hardly realizing it?
This is a topic of interest for the scientific world and there are several studies on it. There is research that says we are able to recognize people who have a DNA more compatible with ours through smell. It is assumed that depending on our genetic code we release a certain smell and that it can be attractive for those people with whom we are more complementary. We have defenses and a genetic code that what you end up doing is configuring a specific immune system, some defense tools of the organism that what it does is detect everything that is alien to our body. What the human being does is to select the person who is rather its opposite pole, in this way, a greater breadth or variety of defense tools is offered to the offspring, which translates into better health.
In the physical field, what interests us the most is the facial symmetry, because that shows that your body is healthy
In the physical theme, although we have a bit of modesty to recognize that the physical is important, in fact it is. We are visual animals, we see the environment through the information that comes to us by the sense of sight and by selecting a couple, in addition to the smell, obviously also influences the physical. An example of this is that we look at the facial proportions, the face plays a very important role, although some are fixed more than others. It seems that what interests us most of the other person is the facial symmetry, because that shows that their body is healthy, so they are a potential couple worthy of being selected.
But some hormones, such as phenylethylamine, also intervene ...
Yes, we could say that it is the "natural drug of love". Phenylethylamine is a chemical compound of the amphetamine family that floods our brain when we fall in love and that causes an uncontrollable and obsessive desire for the loved one. But we can also find this substance in foods such as bananas, lentils or chocolate, a sweet that is usually associated with pleasure but whose consumption causes negligible effects on our brain.
The infatuation does not last more than four years
It has struck me that you say that we can not be in love for more than four years. Why? Is it the same in animals?
When we fall in love our body suffers a huge energetic waste, besides suffering an effect similar to that of drugs. Some experts say that this strenuous state can not be sustained for more than four years, but not all of us are equal nor relationships. In any case, it is a stage that is concentrated at the beginning of a relationship and that once it is over, a new phase of the relationship must be accommodated with much less euphoria and excitement.
The animals also have hormonal alterations during the mating season, which we could consider equivalent to our falling in love, and that their function also focuses on establishing the necessary ties to procreate.
Each animal has different gestation times. How long is the shortest and longest pregnancy of all species?
The shortest pregnancy is that of the opossum with a duration of only about 12 or 13 days, but there is a trick. Opossums are marsupial mammals, so the offspring are born very underdeveloped and must remain safely in the pouch for 60 to 90 days more. As for the longest gestation among mammals is that of the elephants, which can last until almost two years. However, there is an even longer pregnancy and corresponds to the eel shark. This deep-water inhabitant is around three and a half years pregnant.
When we fall in love our body suffers a huge energetic wear, besides having an effect similar to that of drugs
The factors that intervene in an animal having a gestation time and not another are multifactorial. The anatomy, the physiology and the availability of food can be some determining factors of the gestation time. The evolution has determined the time and the type of gestation more adapted for each species.
You say that humans start to gestate as females and then we differentiate between men and women. When does this differentiation begin?
During the first weeks of gestation, the fetus does not really have defined sex, but the nipples are already there. It follows a pattern of female development until about sixty days after fertilization sex chromosomes come into action. At that time, if there is Y chromosome, we proceed to male differentiation, but their nipples do not disappear. Since it does not suppose either costly or unfeasible for the health of the male organism, evolution has not bothered to eliminate them. They are a small reminder of our origin.
Speaking of memory, why does not anyone remember his own birth or the next three years? Why is this amnesia?
We are born helpless and dependent on parental care to survive. Our brain is very underdeveloped and needs a lot of time to acquire the complexity that characterizes us. At birth, we are not yet ready to save memories, but that does not pose a risk to our survival. Of course, one thing is to remember and the other to recognize. A baby perfectly recognizes the voice of its mother.
Komodo dragons may choose to reproduce alone in the absence of males
But then, why are we born at 9 months of pregnancy if we are not yet ready to be worth it for ourselves?
There are two theories that explain it and that, in my opinion, are not exclusive. On the one hand, we are animals with a big head. If we were born with the same level of development as other nearby species, our head would be too big to be able to advance through a birth canal that we had to close to stand up. The standing complicated us the arrival to the world.
On the other hand, a pregnancy is highly expensive and whoever has gone through one will know that the last weeks are exhausting and that we come to think that we can not do any more. Well, it's true. Babies are born when mothers literally can not anymore. The moment of delivery occurs when the child's needs can no longer be met by the mother.
The females of most animals are responsible for bringing the descendants to the world, but the role of the male in some cases is even more remarkable. Among all the animals, which one could receive the title of best father?
Good parents there are more than we imagine in the animal world, as well as the equitable distribution of parental care. However, if I have to choose one, maybe I'll keep the Emperor Penguin. Two months after arriving at the breeding colony, the female lays an egg that quickly passes through the male with extreme care. While she returns to the sea to feed herself, the good father is in charge of incubating her only egg, on her legs and covered by a feathered fold. It can take two months until the mother returns and it is not easy to endure four months without eating and enduring temperatures of sixty degrees below zero and gusts of wind of 200km / h. If the chicken is born before the arrival of the female, the male is still able to regurgitate a substance to feed his little one. A breeze not easy.
There are many stories without scientific foundation rooted in popular knowledge such as the influence of the moon at the time of giving birth to a baby
You say that chromosomally we are not so different from other living beings. What animals are we most similar to?
Genetically humans are very similar to chimpanzees, because we share nothing more and nothing less than 98%. Although surely this does not catch your attention, but what really may surprise us more is that with a col the chromosome similarity is 40%. Of course, reading that DNA is another story.
How animals live death and some myths of the animal world
What is parthenogenesis? How is it possible? Can it be given in other animals?
The strict definition of parthenogenesis is the generation of a new individual from an unfertilized female sexual cell, something like a self-womb. In spite of how strange it may seem, in nature there are some examples. The drones, for example, originate from unfertilized eggs of the queen bee. The tail lizards do not need males to have offspring, they alone are enough. The Molly Amazon fish are also a unisexual species, but in this case, they have not completely renounced sex. To trigger the development process of the ovule, they mate with males of species with which they are closely related and manage to avoid genomic degeneration by stealing part of the male's DNA. Komodo dragons can also choose to reproduce alone in the absence of males, in this case it is a good strategy when they can not find a mate. In this case, from the unfertilized eggs will be born males that, once adults, will be able to reproduce.
I remember seeing an image of an elephant with its dead baby caressing it for hours or dogs that do not separate from their deceased owners. Can animals also feel sad?
Yes. It is difficult and controversial to assign animals the same feelings as humans, since we can not be sure if they feel exactly the same as us. In any case, some animals do establish strong relationships with other individuals and feel their loss. When you invest a lot of time and energy in raising the offspring or establishing social relationships with other individuals in a group, it is an important loss that you regret.
And suicide is only a human thing?
The answer is complex, but yes. Suicide implies self-awareness and explicit will to end one's life. From what we know today about animals, we can only attribute suicide to humans. In reality, suicide is going against nature. What instinct dictates is to want to live and survive. When an animal shows a behavior that may seem the opposite, like a dog that stops feeding when it loses its owner, it is a reaction to the loss, because it does not want to be fed by another hand, not a willingness to want to die.
You dedicate a section to deny some of the existing myths about scientific knowledge. Can you tell us any of them?
We have a restless and extremely curious mind. In the past, knowledge was much more limited and when you could not explain what you observed, stories were invented that tried to respond to these concerns. Legends and myths were born of the need to understand the world and were accepted for lack of a better explanation. However, thanks to scientific advances we have been able to understand how the world really works and unveil many of its secrets.
Climate changes have happened throughout the history of the planet, but never at the speed that is happening today, nor that its main cause is a species
But there are still many stories without scientific foundation rooted in popular knowledge such as the influence of the moon at the time of giving birth to a baby, that bats do not see or that we take advantage of only 10% of our brain. It is hard for me to understand why it is easier for us to believe in myths than in the proven results of a scientific study.
The great impact of humans on the planet
Although humans only represent 0.01% of the planet's biomass, we are the ones that cause the most damage. Have we lost the ability to assess the consequences of our actions?
I do not know if we have never been consistent ... what happens is that we are many, we are in almost every corner of the planet and our impact is growing. Despite having complex brains, it is hard for us to think as a species and we do not value our global impact. What happens on the other side of the planet we do not feel as our own and it is difficult for us to identify with it. We have become accustomed to living well off and with unnecessary luxuries that we are not willing to give up easily. I want to believe that, although too little by little, we are improving and adopting a more sustainable lifestyle.
One of the theories of bipedalism is that it emerged as an adaptation to climate change at that time. How do you think the climate change that we are experiencing today could affect us?
In many ways. In fact, it is already affecting us and the most vulnerable ecosystems, such as tropical forests, are already suffering their effects. The world as we know it today is changing and there is no other option than to modify our way of living in it. The climatic changes have happened throughout the history of the planet, but never at the speed that is happening today, nor that its main cause is a species. If we want to live for a long time we must stop our impact and seriously rethink our way of life.