Lewontin’s Paradox: What It Is And What It Says About The Concept Of Human Races
Evolution is the process by which organisms change over time. Spontaneous heritable mutations produce variability in populations of living beings, which allows natural selection to “favor” and select those individuals that best adapt to the environment.
Together with genetic drift and gene flow, natural selection largely explains the evolutionary process: the strongest remain, while the weak do not reproduce and their genes are lost throughout history.
Thus, we can affirm that evolution bases its operation on genetic inheritance. If a character is not heritable, its variability in the population matters little, since it will not condition the phenotype of subsequent generations. All of these foundations seem obvious today, but different thinkers have challenged them over the years, in order to get to the point where we are today.
Today we introduce you to the world of population genetics and unresolved issues, at least from a genetic and social point of view. Don’t miss the fascinating Lewontin paradox and how it applies to human existence.
Before introducing Lewontin’s paradox, it is necessary to lay certain foundations. Human beings have 23 pairs of chromosomes in each of our cells, that is, a total of 46 These contain genes, which in turn differentiate into alleles, which are defined as each of the alternative ways in which the same gene can be expressed. Thus, any gene will be made up of 2 alleles, A1 and A2, for example.
Of the 46 chromosomes found in the nucleus of our cells, one comes from the mother and one from the father. Thus, if a mother has the alleles (aa) for a gene and a father has the alleles (AA), the only possible frequency in the offspring would be the following: Aa, one allele from the father (A) and another from the mother (a ). Dominant alleles (A) are those that only need one copy in the gene to manifest themselves, while recessive alleles (a) have to present two copies in the genome to become valid (aa). The fixed position of this gene or any other gene on a chromosome is known as Locus.
When the two alleles are the same for the same trait, whether dominant (AA) or recessive (aa), the individual is said to be homozygous for a gene. When this is not the case, the individual is called heterozygous (Aa), even though only the dominant allele (A) over the recessive one (a) is manifested externally.
With this express class, we understand a little about the mechanisms of evolution: from a theoretical point of view, The more individuals present genomes with heterozygous characters, the more likely it is that the population will remain over time, since natural selection will act negatively on some characters, but it will be able to select others positively.
In general, The loss of genetic information results in homozygosity, which leads a species to long-term extinction Processes such as genetic drift or inbreeding favor this situation, but they are beyond our powers at this time. With these foundations laid, we can delve into Lewontin’s paradox.
What is Lewontin’s paradox?
Richard Lewontin is an evolutionary biologist, geneticist and philosopher who was born in New York, United States, in March 1921. He is still alive, at an impressive age of 91 years. This fascinating researcher was one of the pioneers in applying molecular biology techniques, such as gel electrophoresis, which continue to be essential in the field of science today. He specialized in population genetics, as we will see in the following lines.
Lewontin was a defender of the hierarchical theory of evolution Although it is difficult to find information about this current of thought, it can be summarized in the following lines: in it, natural selection does not act solely on the basis of genes (as we have seen so far), but cells are also considered evolutionary units, organisms, species and clades, among other organizations.
Transporting this postulation into the world of animal populations, Lewontin’s paradox would tell us that Theoretical predictions about the relationship between population size and genetic diversity are not corroborated in the real world As anecdotal as this may seem, you will see how it is transported to the human collective.
Lewontin’s paradox (or “Lewontin’s fallacy”, for its English translation) has led to a great debate in the scientific community, since based on it it is argued that the conception of the human race does not make any sense. In an article published in 1972, Richard Lewontin postulated that 85% of the genetic variation in humans occurs between individuals from the same population and that, failing that, only the remaining 15% is due to differences between ethnic groups
This means that, broadly speaking, an individual is different from another due to their individual condition and not due to their ethnic origin or supposed racial heritage. Thus, the theories that circulate around race would be dismantled, and the supposed behavioral differences between individuals could only be explained by cultural constructs, not by genetic bases. If the race does not explain variations at the genotypic (genes) or phenotypic (external characteristics) level, its usefulness in the field of taxonomy is null
Some of the concepts that we have previously explained to you come into play here. Certain researchers (such as Anthony William Fairbank Edwards) have tried to dismantle Lewontin’s paradox, since they do not consider the researcher’s approach correct. Although it is true that the frequency of different alleles (AA or aa, for example) at an individual locus does not report a significant difference between ethnic groups, it does when several areas of the genome are taken into account at the same time. We explain ourselves.
If the allele frequencies at several loci (plural of locus) are factored at the same time , this statistical researcher argues that individuals can be classified into an ethnic group with almost 100% reliability. That is, the frequency of the alleles tends to “cluster” in the different ethnic groups, so, if only the alleles are taken into account separately, clearly the population reality of the human being is not being fully represented.
Some renowned biologists, such as Richard Dawkins, agree with Lewontin that individual variability is much more important than ethnic variability when explaining genotypic and phenotypic differences in humans. Despite this, he does not think that the concept of race or ethnicity has no taxonomic interest: “no matter how small it may be, if a racial characteristic is linked to another racial characteristic, it is already informative and, therefore, of taxonomic importance.”
The question that remains in the air, despite the ruminations, is the following: is a person of one race “more” genetically different compared to that of another race, or two different individuals of the same race?
Summary and considerations
According to different biologists around the world, and based on articles published relatively recently, “the use of the biological concept of race in human genetic research, so disputed and confusing, is problematic at best and harmful at worst.” Without a doubt, Lewontin’s paradox and its consequent debates are of great biological interest, but We must not forget that we are talking about human beings with diverse feelings and identities not statistics and gene expressions.
Today, the concept of the human race is considered problematic and offensive and, therefore, there does not need to be a scientific basis to support its replacement with other, more correct words, such as ethnicity. Science is a fruit of society, and not vice versa, so it must adjust to the new social codes in the most inclusive and permissive way possible. No matter how much something is “scientifically correct,” if it hurts collective sensitivity and closes bridges of dialogue, it does little to encourage the search for knowledge.
