Watch: How Does a Dead Fish Swim Upstream?

Take a quick look at this trout swimming upstream. Notice anything unusual?

You’ve probably seen something similar countless times; the fish wriggles against the currents that push it backwards, slowly making headway until it turns and ducks out of the influence of the stream. Nothing special in that.

The only thing is, this particular fish is dead.

Dads Pass On More Than Genetics in Their Sperm

Eat poorly, and your body will remember—and possibly pass the consequences onto your kids. In the past several years, mounting evidence has shown that sperm can take note of a father’s lifestyle decisions, and transfer this baggage to offspring. Today, in two complementary studies, scientists tell us how.

A Symbiotic View of Life: We Have Never Been Individuals

The notion of the “biological individual” is crucial to studies of genetics, immunology, evolution,development, anatomy, and physiology. Each of these biological subdisciplines has a specific conception of individuality, which has historically provided conceptual contexts for integrating newly acquired data. During the past decade, nucleic acid analysis, especially genomic sequencing and high-throughput RNA techniques, has challenged each of these disciplinary definitions by finding significant interactions of animals and plants with symbiotic microorganisms that disrupt the boundaries that heretofore had characterized the biological individual. Animals cannot be considered individuals by anatomical or physiological criteria because a diversity of symbionts are both present and functional in completing metabolic pathways and serving other physiological functions. Similarly, these new studies have shown that animal development is incomplete without symbionts. Symbionts also constitute a second mode of genetic inheritance, providing selectable genetic variation for natural selection. The immune system also develops, in part, in dialogue with symbionts and thereby functions as a mechanism for integrating microbes into the animal-cell community. Recognizing the “holobiont”—the multicellular eukaryote plus its colonies of persistent symbionts—as a critically important unit of anatomy, development, physiology, immunology, and evolution opens up new investigative avenues and conceptually challenges the ways in which the biological subdisciplines have heretofore characterized living entities.

Consilience: The Unity of Knowledge

One of our greatest living scientists–and the winner of two Pulitzer Prizes for On Human Nature and The Ants–gives us a work of visionary importance that may be the crowning achievement of his career. In Consilience (a word that originally meant “jumping together”), Edward O. Wilson renews the Enlightenment’s search for a unified theory of knowledge in disciplines that range from physics to biology, the social sciences and the humanities.

Using the natural sciences as his model, Wilson forges dramatic links between fields. He explores the chemistry of the mind and the genetic bases of culture. He postulates the biological principles underlying works of art from cave-drawings to Lolita. Presenting the latest findings in prose of wonderful clarity and oratorical eloquence, and synthesizing it into a dazzling whole, Consilience is science in the path-clearing traditions of Newton, Einstein, and Richard Feynman.

Prof. Robert Sapolsky – The Neuroscience Behind Behavior

Robert Sapolsky is an American neuroendocrinologist and author. He is currently a professor of biology, and professor of neurology and neurological sciences and, by courtesy, neurosurgery, at Stanford University.

Recorded: May 2017

Army ants dynamically adjust living bridges in response to a cost–benefit trade-off

The ability of individual animals to create functional structures by joining together is rare and confined to the social insects. Army ants (Eciton) form collective assemblages out of their own bodies to perform a variety of functions that benefit the entire colony. Here we examine ‟bridges” of linked individuals that are constructed to span gaps in the colony’s foraging trail. How these living structures adjust themselves to varied and changing conditions remains poorly understood. Our field experiments show that the ants continuously modify their bridges, such that these structures lengthen, widen, and change position in response to traffic levels and environmental geometry. Ants initiate bridges where their path deviates from their incoming direction and move the bridges over time to create shortcuts over large gaps. The final position of the structure depended on the intensity of the traffic and the extent of path deviation and was influenced by a cost-benefit trade-off at the colony level, where the benefit of increased foraging trail efficiency was balanced by the cost of removing workers from the foraging pool to form the structure. To examine this trade-off, we quantified the geometric relationship between costs and benefits revealed by our experiments. We then constructed a model to determine the bridge location that maximized foraging rate, which qualitatively matched the observed movement of bridges. Our results highlight how animal self-assemblages can be dynamically modified in response to a group-level cost-benefit trade-off, without any individual unit’s having information on global benefits or costs.

The Master and His Emissary: The Divided Brain and the Making of the Western World

This book argues that the division of the brain into two hemispheres is essential to human existence, making possible incompatible versions of the world, with quite different priorities and values.

Most scientists long ago abandoned the attempt to understand why nature has so carefully segregated the hemispheres, or how to make coherent the large, and expanding, body of evidence about their differences. In fact to talk about the topic is to invite dismissal. Yet no one who knows anything about the area would dispute for an instant that there are significant differences: it’s just that no-one seems to know why. And we now know that every type of function – including reason, emotion, language and imagery – is subserved not by one hemisphere alone, but by both.

This book argues that the differences lie not, as has been supposed, in the ‘what’ – which skills each hemisphere possesses – but in the ‘how’, the way in which each uses them, and to what end. But, like the brain itself, the relationship between the hemispheres is not symmetrical. The left hemisphere, though unaware of its dependence, could be thought of as an ’emissary’ of the right hemisphere, valuable for taking on a role that the right hemisphere – the ‘Master’ – cannot itself afford to undertake. However it turns out that the emissary has his own will, and secretly believes himself to be superior to the Master. And he has the means to betray him. What he doesn’t realize is that in doing so he will also betray himself.

The book begins by looking at the structure and function of the brain, and at the differences between the hemispheres, not only in attention and flexibility, but in attitudes to the implicit, the unique, and the personal, as well as the body, time, depth, music, metaphor, empathy, morality, certainty and the self. It suggests that the drive to language was not principally to do with communication or thought, but manipulation, the main aim of the left hemisphere, which manipulates the right hand. It shows the hemispheres as no mere machines with functions, but underwriting whole, self-consistent, versions of the world. Through an examination of Western philosophy, art and literature, it reveals the uneasy relationship of the hemispheres being played out in the history of ideas, from ancient times until the present. It ends by suggesting that we may be about to witness the final triumph of the left hemisphere – at the expense of us all.

Nonlinear Dynamics and Chaos – Steven Strogatz, Cornell University

This course of 25 lectures, filmed at Cornell University in Spring 2014, is intended for newcomers to nonlinear dynamics and chaos. It closely follows Prof. Strogatz’s book, “Nonlinear Dynamics and Chaos: With Applications to Physics, Biology, Chemistry, and Engineering.”

The mathematical treatment is friendly and informal, but still careful. Analytical methods, concrete examples, and geometric intuition are stressed. The theory is developed systematically, starting with first-order differential equations and their bifurcations, followed by phase plane analysis, limit cycles and their bifurcations, and culminating with the Lorenz equations, chaos, iterated maps, period doubling, renormalization, fractals, and strange attractors.

A unique feature of the course is its emphasis on applications. These include airplane wing vibrations, biological rhythms, insect outbreaks, chemical oscillators, chaotic waterwheels, and even a technique for using chaos to send secret messages. In each case, the scientific background is explained at an elementary level and closely integrated with the mathematical theory. The theoretical work is enlivened by frequent use of computer graphics, simulations, and videotaped demonstrations of nonlinear phenomena.

The essential prerequisite is single-variable calculus, including curve sketching, Taylor series, and separable differential equations. In a few places, multivariable calculus (partial derivatives, Jacobian matrix, divergence theorem) and linear algebra (eigenvalues and eigenvectors) are used. Fourier analysis is not assumed, and is developed where needed. Introductory physics is used throughout. Other scientific prerequisites would depend on the applications considered, but in all cases, a first course should be adequate preparation.

The Trouble With Testosterone: And Other Essays On The Biology Of The Human Predicament

From the man who Oliver Sacks hailed as “one of the best scientist/writers of our time,” a collection of sharply observed, uproariously funny essays on the biology of human culture and behavior.

In the tradition of Stephen Jay Gould and Oliver Sacks, Robert Sapolsky offers a sparkling and erudite collection of essays about science, the world, and our relation to both. “The Trouble with Testosterone” explores the influence of that notorious hormone on male aggression. “Curious George’s Pharmacy” reexamines recent exciting claims that wild primates know how to medicate themselves with forest plants. “Junk Food Monkeys” relates the adventures of a troop of baboons who stumble upon a tourist garbage dump. And “Circling the Blanket for God” examines the neurobiological roots underlying religious belief.

Drawing on his career as an evolutionary biologist and neurobiologist, Robert Sapolsky writes about the natural world vividly and insightfully. With candor, humor, and rich observations, these essays marry cutting-edge science with humanity, illuminating the interconnectedness of the world’s inhabitants with skill and flair.