Emile Durkheim described human beings as “Homo duplex,” or “two-level
man.” The lower level is the level of the profane—the level of
ordinary consciousness and self-interested pursuits.  The higher level
is the level of the sacred at which we lose our petty selves and
become simply a part of a larger whole.  Charles Darwin believed that
morality evolved by multi-level selection, and that some of our
virtues evolved because they conferred an advantage upon our groups.
In this talk I’ll put Durkheim and Darwin together. I’ll suggest that
we are Homo duplex precisely because we evolved by multi-level
selection. I’ll then describe the “hive switch,” which is an
off-switch for the self. I’ll describe some applications of “hive
psychology” in daily life, including sports and business.

Maternal behavior has an important influence on the development of the young. From insects to mammals it has been shown to influence sexual behavior of offspring. In humans, the quality of the mother-daughter relationship is a predictor of the onset of puberty and sexual behavior. We will discuss the importance of individual differences in reproductive strategy in rats and we will examine the mechanisms that may control the maternal influence on daughter’s sexuality.

Might the genes and traits that underlie our weaknesses also underlie our greatest strengths?  Over the past 15 years or so, researchers in psychiatry and behavioral genetics have repeatedly identified a handful of neurotransmitter gene variants as “risk genes” for mood and behavioral problems: When combined with bad experiences, this risk-gene model asserts, these variants open the d   oor to troubles ranging from melancholy and restlessness to depression and antisocial behavior.

But what if we turn this notion inside out? Rising from work in child development, primatology, genetics, and endocrinology, an alternate view, the “sensitivity-gene” hypothesis, holds that “risk” alleles produce not just psychic vulnerability but psychic and social sensitivity — a heightened response to experience both bad or good, with bidirectional outcomes to match. To cite a Swedish vernacular distinction (and another frame for this idea), our genes tend to place us along a temperamental spectrum running from “dandelions,” who perform roughly the same in almost any environment, to “orchids,” who fail in poor environments, do decently in benign ones, and thrive with extra support.

This hypothesis challenges our current view of mental dysfunction in seeing sensitivity not simply as weakness but as a malleable source of strength and happiness. It also has startling evolutionary implications: In humans most of these sensitivity genes  have emerged within the last 50,000 to 80,000 years, as we spread across the globe and became modern humans; orchid genes, it follows, may have helped provide a mix of steadiness, flexibility, and responsiveness to change helpful for exploiting new surroundings. As writer David Dobbs explains in his talk, the sensitivity-gene hypothesis — the subject of an Atlantic feature that Dobbs is currently expanding into a book — also has some fascinating gene-culture implications.

Eating together in groups – commensality – was part of a bundle of
activities during most of human evolution.  In contemporary
organizations and environments, it remains the case that people make a
practice of eating with others even though modern inventions such as
refrigerators, restaurants, and railroads have unbundled food
consumption from food procurement and preparation.  In this talk,
three new studies will be presented.  First, a field project will be
discussed that explores the value of communal food preparation and
consumption inside firehouses in a large urban department.  Second, an
experimental economics study will be reviewed that tests the degree to
which people are cooperative as a function of eating.  And, third, I
will report on a pair of studies that obliquely address the degree to
which people believe that eating together involves something “more
than food.”

Gaze-following, or the ability to adjust visual attention to that of others (also known as joint visual attention), may be a fundamental behavior of terrestrial vertebrates. Psychologists have typically employed laboratory experiments to study gaze-following in humans, using eye-tracking software to record changes in attention shifts or saccades when presented with either faces with averted eye direction or dynamic social scenes. However, the lack of appropriate tools has limited the objective evaluation of gaze-following between individuals in natural (non-laboratory) environments. In this talk I will describe the results of four studies in which we use semi-automated analysis to track the motion and head direction of over 6,000 pedestrians in natural crowds, revealing the extent, influence, directional flow and context-dependence of socially transmitted visual attention. The applications of this research will be discussed.

Listen to the podcast (40 MB, 42:28 minutes)

Whole-genome sequences provide a rich source of information about human evolution. Here we describe an effort to estimate key evolutionary parameters based on the whole-genome sequences of six individuals from diverse human populations. We use a Bayesian, coalescent-based approach to obtain information about ancestral population sizes, divergence times, and migration rates from inferred genealogies at many neutrally evolving loci across the genome. We introduce new methods for accommodating gene flow between populations and integrating over possible phasings of diploid genotypes. We also describe a custom pipeline for genotype inference to mitigate biases from heterogeneous sequencing technologies and coverage levels. Our analysis indicates that the San of Southern Africa diverged from other human populations 108–157 thousand years ago (kya), that Eurasians diverged from an ancestral African population 38–64 kya, and that the effective population size of the ancestors of all modern humans was ~9,000.

Throughout the evolution of our species, the human food chain has had a major impact on our health outcomes. Examples of such impacts among isolated and modernizing human populations are many. Without intervention, the long-term consequences of these changes has had or can have a devastating impact on a population. Research will be presented from our early and current field and laboratory work on food chain disorders and health transitions, all of which involve evolutionary processes and consequences at a population level.