From Frontiers in Psychology via the U.S.National Center for Biotechnology Information:
Abstract
The
age-old philosophical, biological, and social debate over the basic
nature of humans as being “universally selfish” or “universally good”
continues today highlighting sharply divergent views of natural social
order. Here we analyze advances in biology, genetics and neuroscience
increasing our understanding of the evolution, features and
neurocircuitry of the human brain underlying behavior in the
selfish–selfless spectrum. First, we examine evolutionary pressures for
selection of altruistic traits in species with protracted periods of
dependence on parents and communities for subsistence and acquisition of
learned behaviors. Evidence supporting the concept that altruistic
potential is a common feature in human populations is developed. To go
into greater depth in assessing critical features of the social brain,
the two extremes of selfish–selfless behavior, callous unemotional
psychopaths and zealous altruists who take extreme measures to help
others, are compared on behavioral traits, structural/functional neural
features, and the relative contributions of genetic inheritance versus
acquired cognitive learning to their mindsets. Evidence from population
groups ranging from newborns, adopted children, incarcerated juveniles,
twins and mindfulness meditators point to the important role of
neuroplasticity and the dopaminergic reward systems in forming and
reforming neural circuitry in response to personal experience and
cultural influences in determining behavior in the selfish–selfless
spectrum. The underlying neural circuitry differs between psychopaths
and altruists with emotional processing being profoundly muted in
psychopaths and significantly enhanced in altruists. But both groups are
characterized by the reward system of the brain shaping behavior.
Instead of rigid assignment of human nature as being “universally
selfish” or “universally good,” both characterizations are partial
truths based on the segments of the selfish–selfless spectrum being
examined. In addition, individuals and populations can shift in the
behavioral spectrum in response to cognitive therapy and social and
cultural experience, and approaches such as mindfulness training for
introspection and reward-activating compassion are entering the
mainstream of clinical care for managing pain, depression, and stress.
Keywords: heredity, social, cultural, genetic, neural circuitry, emotions, empathy, compassion
Introduction
In the mid-1800s, the French Philosopher Auguste Comte constructed the word altruism from the Latin
alteri
(“others”) to name his vision of a moral call to place the needs of
others over one’s self-interests. Altruism has since been defined in
many senses, including an extreme selflessness in undertaking actions
benefiting others without evident self-benefit and incurring personal
risk. The conundrum created by Comte’s concept continues to reverberate
through social debate, philosophy, theology, and biology, highlighting
complex issues in the spectrum of behavior ranging from extreme
selfishness to extreme selflessness (
Ricard, 2015). The very concept of altruism raises important issues underlying two sharply divergent views of natural social order.
Philosophical,
political and biological arguments on whether humans are naturally
selfish or unselfish have flared for centuries and continue today.
Thomas Hobbes contending in his work
Leviathan printed in 1651
supporting strong Monarchist governments and running through current
culture in Ayn Rand’s popular works assert there is a natural “universal
selfishness” manifest in humans, with all behaviors characterized as
altruistic being in reality actions that in some measure were in the
actor’s best interest. Rand’s continuing influence on political
discourse can be seen in the powerful American Speaker of the House and
former Vice Presidential candidate Paul Ryan’s attribution of Rand’s
Atlas Shrugged as formative in developing his political principles (
Weiner, 2012).
In Biology, the Oxford University Lecturer and popular science author
Richard Dawkins has proclaimed, “We are survival machines – robot
vehicles blindly programmed to preserve the selfish molecules known as
genes” (
Dawkins, 1976).
Sharply
alternate opinions more supportive of Comte’s vision have also
resonated for centuries and continue unabated. Two highly influential
18th century philosophers David Hume and Jean Jacques Rousseau argued
that by nature humankind is unselfish. A contention strongly supported
today by the prolific neuroscientist and popular science author Richard
Davidson (
Davidson, 2015). A middle position emphasizing a dual nature for humankind was presented in the 15th century essay by Pico della Mirandola
Oration on the Dignity of Man,
asserting that we can shape our own destiny by freely choosing whether
to descend into brutish behavior or rise to the superior orders of the
divine. This is a vision expanded upon by the Dalai Lama who wrote that
“the most important thing in this existence of ours is to do something
that can be of benefit to others. What we need more than anything is to
develop an attitude of altruism – that is really what gives meaning to
life” (
Dalai Lama, 2007).
The
second debate invariably accompanying any discourse on altruistic
behavior is what is due to nature versus nurture. To better understand
the scientific basis for addressing such profound social and
philosophical issues, here we examine the biology and neurological basis
of human altruism. We analyze the neural systems and the role of
heredity, both genetic and neuron-based (cultural and social), in the
development of behavior in the selfish–selfless spectrum, with the goal
of discovering how and why portions of the population experience
dramatically differing levels of empathy and compassion that strongly
influence their worldview and role in society.
Evolution of the Prosocial Brain
The
term “altruism” has meant many different things in different times and
places. Since Comte’s moral call to place the needs of others above
one’s own needs, different disciplines have applied different
definitions, and the semantics are themselves a necessary starting point
(
West et al., 2007). Group selection theory explains behavior such as kin sacrifice in terms of gene survival as opposed to individual survival (
Simon et al., 2013;
Gardner, 2015).
Therefore, according to this evolutionary theory, related individuals
will be more likely to perform altruistic acts and decrease their own
survival if it benefits the survival of a related individual that
carries many of the same genes. This theory is supported by extensive
evidence in the literature of preferential treatment of kin (
Madsen et al., 2007), while others argue that group selection is an emergent property of natural selection by individual fitness (
Zhang et al., 2014;
Kennedy et al., 2018).
One question is how kin-preference is identified and conferred by an
organism. Kin-preference may be a function of the extensive time spent
with and proximity to the relative as opposed to an ability to identify
genetic relatedness, as argued by cases of cronyism and altruistic
preference for close friendships (
Stewart-Williams, 2008). From an evolutionary biology perspective, “altruism” or empathic acts could be selected for culturally as a sign of fitness (
Taborsky et al., 2016), as attested to by examples of prosocial behavior for non-relatives across the animal kingdom (
Field and Leadbeater, 2016;
Wilkinson et al., 2016).
A more semantically “true” form of altruism may have its roots in the
parental instinct to care for offspring, and may explain why empathic
behavior is more commonly observed in species with protracted periods of
pre-adult growth (
Preston, 2013)
requiring extended rearing and the resultant passing of learned
behaviors, called acquired cognitive learning, as well as “neuron-based
heredity,” including social and cultural factors that may have genetic
and cognitive elements (
Gash and Deane, 2015),
to come into play. Thus, the importance of passing to kin the learned
behaviors promoting culturally selected traits of compassion may
counterbalance the selective value of genes promoting extreme selfish
behavior (
Bell et al., 2009).
The
concept of altruism as an enhanced parental instinct relies on the
evolution of several factors in both the altruist and the recipient:
signaling of kinship status and need for compassion, recognition by kin
of the signals, and donation-behavior by the kin (
Sinervo et al., 2006).
While this behavioral signaling mechanism may underlie parental
instinct and compassion which is probabilistically directed toward kin,
it is possible that simple parental behaviors – such as offspring
retrieval, sustenance and shelter sharing, and emotional comforting –
are behavior patterns of signaling-recognition-action that have been
enhanced by evolutionary mechanisms (
Preston, 2013)
resulting in broader altruistic behavior from prosocial brains with
greater capacity for receiving and passing on experience and acquired
information. And as recent studies have shown, parenting-associated
prosocial helping behaviors not only enhance the survival of the
offspring, but also promotes better health, slower decline in
functioning levels and lower risk of mortality for care-givers (
Brown and Brown, 2015).
Collectively, the evidence indicating prosocial altruistic capability
provides for complex interactions that have come to form the foundation
of our civil, societal interactions (
Matusall, 2013).
Social interactions often extend not only to members of our families,
but to other members of our own social species, and often to members of
other domesticated species on which we depend for our survival and
social well-being.
The Selfish–Selfless Spectrum
Human
evolution, especially since the separation from the last common
ancestor shared with the great apes, is posited to have been driven by
bipartite hereditary processes involving genetic and neuron-based
systems (social and cultural heredity) (
Gash and Deane, 2015).
The development of large interactive social groups that share resources
and work cooperatively toward accomplishing common goals distinguishes
humans from the other great apes. The survival and success of large
cooperative societies requires most of their members to mute their
innate selfish drives and strengthen their selfless behavior. Converging
evidence that will be reviewed here strongly supports that complex
combinations of genetic and neuronal factors, including parenting,
underlie the spectrum of selfish–selfless behaviors. Given the gaps in
knowledge in this multidisciplinary area of research, we propose the
spectrum be initially plotted as an inverted U-shaped curve with the
x-axis representing the range from extreme selfishness to extreme selflessness and the
y-axis representing the percent population at each point (
Figure ).
We also propose that the extreme selfishness end of the spectrum is
exemplified by callous-uncaring psychopaths and the extreme selflessness
end by zealous altruists that take extreme measures to help others. We
hypothesize that the landscape and peak of the curve shifts for given
populations based on social and cultural factors (neuronal-based
heredity) and genetic makeup....
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