Satoshi Kanazawa

The Scientific Fundamentalist

Social sciences are branches of biology I

Hydrogenology, anyone?

Posted Sep 21, 2009

Biology is the study of all living organisms, their behavior and social systems. Humans are living organisms. Thus, social sciences (the study of human behavior and their social systems) are within the purview of biology. Social sciences are branches of biology, and all social scientific theories about human behavior must be consistent with established principles and laws of biology.

Yet most social scientists would object to such subsumption of social sciences under biology, and claim that the uniqueness of the human species would require a separate science. Some would even claim that such uniqueness makes humans independent of and immune to laws and principles of biology; biology is not important for human behavior. According to a 1996 study, 168 sociologists surveyed on average attribute only 4.7% of sex differences in occupational interests, and 15.3% of sex differences in aggressive criminality, to biological (genetic, prenatal, and postnatal nonsocial) factors. A typical sociologist therefore believes that nearly 85% of the variance in sex differences in violence and aggression is explained by purely social and cultural factors like gender socialization. Many years ago, I was once such a sociologist.

There is no question that humans are unique. As the great sociobiologist Pierre van den Berghe points out, however, humans are not unique in being unique. For every species is unique. If it is not, it would not be a separate species. If uniqueness of a species requires a separate scientific discipline, then there would have to be as many scientific disciplines as there are species (dog science, cat science, giraffe science, etc.). In reality, biology covers all species in nature, except for humans, or so goes the conventional wisdom in social sciences.

To claim that social sciences are not part of biology and to establish a separate and incompatible science just for humans is as peculiar and unnecessary as the establishment of hydrogenology, the study of hydrogen apart from, and incompatible with, physics. Yet the idea of hydrogenology separate from physics makes as much sense as the idea of social sciences separate from biology. Hydrogen is a very unique element: It is by far the most abundant element in the universe; it is the lightest and simplest element; it is the only element whose nucleus does not contain a neutron; it has the fewest number of isotopes in nature; it has extremely low boiling and melting points; the hydrogen molecule is the simplest molecule; it has a velocity higher than any other gas at any given temperature and it therefore diffuses faster than any other gas.... The list goes on.

Yet it is completely unnecessary to establish hydrogenology devoted only to the study of hydrogen because physics constructs general laws and principles applicable to all elements, including hydrogen. Boyle's Law and Avogadro's Law hold for hydrogen as they do for all other gases despite its uniqueness. Physics as a science has advanced as it has because it does not make exceptions; it formulates general laws and principles that apply to all elements, not specific ones for each element.

Of course, physicists, like other scientists, specialize in certain types of matter; some are elementary particle physicists, others are condensed matter physicists. So there is nothing wrong with some scientists specializing in human behavior. In chemistry, some specialize in the study of carbon compounds, but nothing in "carbonology" (organic chemistry) is inconsistent with the general principles of chemistry. I am not calling for the elimination of social sciences, only its subsumption as "human biology." In his 1998 book Consilience, the Harvard entomologist Edward O. Wilson most comprehensively and emphatically calls for the unity, or consilience, of all sciences and humanities (such as arts, literature, music, and ethics), guided by the principles of evolutionary biology. Consilience is what we need in order to subsume social sciences under biology.

Most social scientists do not see how the same laws of biology hold for humans as they do for all other species. For instance, most social scientists claim that, even though all other species in nature have innate, species-typical nature, which determines how members of the species behave, humans are an exception to this rule and have no innate nature. They claim that humans are born blank slates and all of their behavior is determined by socialization and other environmental factors. Most social scientists do not see how such human exceptionalism - their tendency to formulate theories specific only to humans - has hindered the development of social sciences. It would take tremendous faith in the Biblical creation to believe that humans are somehow the only species that is exempt from the laws of biology that permeate the rest of nature.

Hydrogenology apart from physics is not necessary, because hydrogen, while unique, is only quantitatively, not qualitatively, different from other elements. Hydrogen is a distinct element from helium, but helium is nothing but hydrogen with an extra pair of proton and electron. Lithium, while distinct from hydrogen and helium, is nothing but helium with an extra pair of proton and electron. All elements are the same, except in the number of protons and electrons they contain; all unique properties of different elements derive from it. That is why the same laws and principles of physics apply to all elements, regardless of their unique natures.

The same is true of biological organisms. Humans are a distinct species from chimpanzees, but chimpanzees are nothing but humans with a few percentage points of their genome altered, and gorillas are a few more percentage points away. All animal species are the same, except for the genes contained in their genomes. All laws and principles of biology apply to humans as they do to all other animal species. Biology's reductionism (classifying all biological organisms in terms of their genetic makeups, and explaining their behavior and social systems by the same set of principles of evolutionary biology) and generality (not making exceptions for any species) allow it to be applicable to all species. Reductionism and generality are two important principles of science.

In my next post, I will explain why, contrary to what most social scientists believe, all good science is reductionist, and all human behavior must be explained at the level of the genes (and molecules, and atoms, and particles).