Human nature

:For the film, see Human Nature (film).

Psychology and biology

A long standing question in philosophy and science is whether there exists an invariant human nature. For those who believe there is a human nature, further questions include:

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• What determines/constrains human nature?
• To what extent is human nature malleable?
• How does it vary between people and populations?

Since human behavior is diverse, it can be difficult to find absolutely invariant human behaviors that are of interest to philosophers. A lesser (but still scientifically valid) standard for evidence pertaining to "human nature" is used by scientists who study behavior. Biologists look for evidence of genetic predisposition to behavioral patterns. Genetic predispositions can be influenced by the environment, so penetrance of genetically predisposed behavioral traits is not expected to reach 100 percent. A type of human behavior for which there is a strong genetic predisposition can be considered to be part of human nature. In other words, human nature is not seen as something that forces individuals to behave in a certain way, but as something that makes individuals more inclined to act in a certain way than in another.

Related Topics:
Scientists who study behavior - Predisposition - Penetrance

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Tabula rasa

John Locke's philosophy of empiricism saw human nature as a tabula rasa. In this view, the mind is at birth a "blank slate" without rules, and data is added and rules for processing it are formed solely by our sensory experiences.

Related Topics:
John Locke's - Empiricism - Tabula rasa

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An alternative view is seen in E. O. Wilson's sociobiology and the closely related theory of evolutionary psychology.

Related Topics:
E. O. Wilson's - Sociobiology - Evolutionary psychology

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Behavioral genetics

The nature vs nurture debate.

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Behavioral genetics

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Human diversity

Population genetics

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Arguments for invariance

All individuals and all societies have a similar facial grammar. Everyone smiles the same, and the way we use our eyes to convey cognition or flirtatiousness is the same. Evaluations of facial attractiveness are consistent across races and cultures with a preference for symmetry and proportion which are explained by scientists as markers of health during physical development attributable to good genes or a good environment. Human females find male faces that are rated more masculine and less caring, more attractive during the part of their menstrual cycle when they are most fertile. In utero exposure to testosterone (normal for the male fetus) alters brain development toward greater spatial and mathematical potential, greater physical roughhousing during childhood play, and to find females attractive once puberty is attained. Female brain development with its emphasis on verbal fluency is the default, absent exposure to testosterone.

Related Topics:
Facial grammar - Menstrual cycle

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No success has ever been scientifically demonstrated in re-assigning an individual's handedness. Although individuals may change their external behavior (picking up scissors with their right hand instead of the left, for instance), their internal inclination never changes. Even people who lose a limb, who physically do not possess the ability to pick up scissors with their left hand, will try to do so if they are 'left handed.' The percentage of left-handers in all cultures at all times remains constant (because left-handedness is a recessive trait).

Related Topics:
Handedness - Scissor - Limb - Recessive trait

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Newborn babies, far too young to have been acculturated to do so, have measurable behaviors such as being more attracted to human faces than other shapes and having a preference for their mother's voice over any other voice.

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Arguments for social malleability

The Duke of Wellington is said to have become indignant upon hearing someone refer to habit as "second nature." He replied, "It is ten times nature!"

Related Topics:
Duke of Wellington - Habit

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William James likewise referred to habit as the fly-wheel of society. Habits, though, are by definition acquired, and different habits will be both the effect and the cause of very different societies.

Related Topics:
William James - Fly-wheel - Society

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Different human societies have held very different moral codes. Thus, regardless of whether objective morality exists or not, humans are clearly capable of imposing a wide variety of different moral codes on themselves.

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Some have argued that the role for nurture comes not from the absence of innate impulses in human nature, but from the plethora of such impulses -- so many, and so contradictory, that nurture must sort them out and put them into a hierarchy.

Related Topics:
Innate - Impulse - Hierarchy

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Identical twins have identical genes, and therefore identical innate behavior. If all behavior were innate, one would expect identical twins to behave in perfectly identical ways all the time. However, this is clearly not the case. In particular, twins who grew up separated (and in different environments) show the greatest differences in behavior.

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There is no single universal law of behavior that holds true for all human beings. There are many such laws that apply to the majority of individuals (for example, the majority of individuals try to avoid dying), but there are always exceptions (some individuals commit suicide). Most animals, including humans, have an innate self-preservation instinct (fear of injury and death). The fact that humans may override this basic instinct is seen as evidence that human nature is subordinate to the human mind, and/or various outside factors.

Related Topics:
Suicide - Self-preservation instinct

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Finally, it has been noted that recent advancements in biology have opened the door to genetic manipulation. This means that we will soon have the possibility of altering our genes and therefore changing the instincts that are coded in those genes.

Related Topics:
Biology - Genetic manipulation

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