Natural selection will take care of low fertility, says expert

PAP: According to Statistics Poland data, in 2021 the fertility rate in Poland was 1.33. It is assumed that the rate above 2.1 guarantees the replacement of generations. Is low fertility only a problem of Europe and Poland?

Professor Bogusław Pawłowski, head of Department of Human Biology at the University of Wrocław: Not only Poland, but the entire Western world, and even China and other Asian countries struggle with low fertility. This is a complex bio-cultural issue. In different regions of the world, the reasons for this may vary slightly, and one of the common factors highlighted by human behavioural ecologists may be that the costs of raising a child are getting higher.

From the point of view of evolutionary psychology, it can also be assumed that evolution has not sufficiently equipped us with a psychological mechanism that would directly target the necessity of having children. Evolution has equipped us with the self-preservation instinct, with a strong motivation to fulfil the sex drive, to secure resources that are necessary to live, but also, especially in the case of men, to find a partner. These are very important biological considerations, but they are means to an end rather than an evolutionary goal.

PAP: What does it mean?

B.P.: “It means that we really want to live, have a partner and get great pleasure from sex, and have an appropriate socio-economic status. We strive for all this, not always feeling or understanding that these are only 'motivational means' to be able to pass on our genes more effectively, to have offspring. Of course, these are not the only means, because when a child is born, the intensification (or emergence) of maternal behaviour is also such means.

“In almost the entire history of mankind (and that's already hundreds of thousands of years), this mechanism was enough to simply reproduce. People were not aware of the biology of reproduction, and therefore what actually would lead to the conception and birth of a child and that it was a direct consequence of intercourse. Even if they were linked, research by ethnologists indicates that there are such societies, for example in the Amazon, where people were or are convinced that in order to get pregnant a woman must have sexual contacts with many men and that only from this diverse sperm can a new human emerge.

“A strong sex drive is, of course, also sufficient for procreation in other animals. When we understood the biology of reproduction well, we invented a reliable hormonal contraception, which also enabled us to very effectively separate the main motivation that used to lead to reproduction (the pursuit of sexual pleasure) from its goal, i.e. procreation. Previously, various forms of contraception had been used, but they were less effective.”

PAP: How to achieve a higher fertility rate in Poland?

B.P.: “People make decisions based on what they expect from life and what the ecological or socio-economic conditions are. Whatever happens, if the 500 plus programme suddenly changes to 700 plus, in my opinion it will not change the current trend. We know that similar mechanisms in Germany or France probably do not work as the governments would like. However, in terms of reproductive rates, Poland is worse than in many other European countries. Perhaps part of this difference results from the fear of some young women of certain regulations, including the almost absolute abortion ban, even in the case of a serious genetic defect of the foetus. It is also difficult to say what percentage of women in Poland is prevented from giving birth by fear of complications and childbirth.”

PAP: So, are we in Western countries in danger of depopulation?

B.P.: “I don't think so, if anything, it will be a reduction in the size of the population - not taking migration processes into account. I think that natural selection will take care of the current phenomenon of low fertility. The gene pool may change slightly and there will be less genetic diversity (for example, 30 percent of people will be childless). In addition to this negative genetic consequence, there will be - or actually there is - of course, a problem with the pension system, etc. Even if a small proportion of women decide to have children, it will mean that there will be genes in the gene pool that will somehow foster a strong need to have children and the ability to care for them. As a consequence, in time there may be a change in the trend and an increase in fertility. However, we should not expect the current demographic trend to change anytime soon.”

PAP: Is it a yo-yo effect?

B.P.: “Hmm... I wouldn't call it that. Remember that there has never been such a dramatic decline in fertility before. In principle, many children were always born, although much fewer of them survived than today - even in 19th century Europe, almost 40 percent of children died. The very fact of a large decrease in child mortality in the 20th century caused a decrease in the number of children born, for example in Europe.

“Since many natural phenomena have changing, e.g. sinusoidal trends, the current fertility trends may reverse. Personally, I would not predict a demographic disaster, and given the global overpopulation, reducing the number of offspring may have ecological advantages. More and more young people understand the threat to the planet posed by the climate crisis. Each new born baby is one of the biggest contributors to carbon dioxide production. I don't mean the fact that it breathes, but the resources it has to use throughout its life, and the huge energy it takes to obtain them. Psychotherapists notice that there are more and more patients - probably young women - with ecological phobias, who also often declare that they do not want to have children for ecological reasons.

“It is possible that the number of life options - travelling, various entertainments or forms of spending time - has increased so much that with a long period of youth resulting from extended education, it sometimes also affects the reluctance to have a child and to change lifestyle. Another potential factor could be that more and more couples choose to have only one child. Meanwhile, in families with many children, children also learn to care for or be responsible for their siblings and experience the associated joy. In this case, they may be more inclined to have children later on. Meanwhile, only children often receive a lot from the environment, but less is required of them, and they have no childhood experience of caring for siblings. According to research on the family pattern in this regard, this family factor may therefore also, to some extent, influence the subsequent decision to have children and how many.”

PAP: On a global scale, there is no question of a decrease in fertility rate.

B.P.: “Remember that a significant population increase basically only concerns Sub-Saharan Africa (over 4 children on average), because even Asia has slowed down in this respect, even though it still has a positive birth rate. From the point of view of climate stability, a decrease in fertility rate would be a blessing. The increases in billions of people are happening faster and faster. At the beginning of the 19th century, there were about 1 billion of us, after more than 120 years, around 1930, it was 2 billion, and now we have probably exceeded 8 billion.”

PAP: How does overcrowding, for example in cities, affect decisions regarding pregnancy?

B.P.: “In small communities, women make decisions about having children faster. This may be related to stronger social pressure to have children, among other things. In such stable communities, in the absence of migration, people live surrounded by relatives. It turns out that in such conditions, on average, women have higher fertility rates. Humans as a species basically have a cooperative way of caring for children. We know this from observations of traditional hunter-gatherer societies, and it is the best model for the social structures we have lived in for most of our evolution. When a woman has many relatives nearby (mother, sisters, aunts, etc.), it is easier to count on their help when caring for and raising a child. Today, with quite a strong mobility, women often do not have any relatives around them. This, according to some human behavioural ecologists, more often causes them to decide not to have children, or to have fewer children.

“Even though the decline in fertility is observed all over the world, even in Africa, the factors responsible for this trend are of a complex bio-cultural nature. Most researchers of this phenomenon generally agree that prolonged education of women, effective contraception, pressure to gain a higher social status, increased economic competition and ecological factors seem to be at least partly responsible for the decline in fertility worldwide. It is difficult to say when and if this trend will reverse. However, humanity seems to be facing more serious problems, and if those are solved, I do not think that even a further decline in the fertility rate - not to zero, of course - will threaten the existence of our species.”

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Professor Bogusław Pawłowski is the head of Department of Human Biology at the University of Wrocław. He specialises in human evolution, with an emphasis on the biological determinants of human behaviour and evolutionary psychology.

Interview by Szymon Zdziebłowski (PAP)

PAP - Science in Poland, Szymon Zdziebłowski

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