Posts tagged evolution
Articles and news from the latest research reports.
Roger Alsing coded a program to give a slight mutation to a random string of DNA which was used to render polygons on a canvas.
The Cambridge Declaration on Consciousness
We declare the following: “The absence of a neocortex does not appear to preclude an organism from experiencing affective states. Convergent evidence indicates that non-human animals have the neuroanatomical, neurochemical, and neurophysiological substrates of conscious states along with the capacity to exhibit intentional behaviors. Consequently, the weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness. Nonhuman animals, including all mammals and birds, and many other creatures, including octopuses, also possess these neurological substrates.”
Physics and math shed new light on biology by mapping the landscape of evolution
August 8, 2012
Researchers capture evolutionary dynamics in a new theoretical framework that could help explain some of the mysteries of how and why species change over time.
Although the qualitative description of evolution – its observed behavior and characteristics – is well-established, a comprehensive quantitative theory that captures general evolution dynamics is still lacking. There are also many lingering mysteries surrounding the story of life on Earth, including the question of why sex is such a prevalent reproductive strategy. A team of scientists from the Chinese Academy of Sciences; Jilin University in Jilin, China; and the State University of New York at Stony Brook, led by Prof. Jin Wang, has examined some of these puzzles from a physical science prospective. They propose a new theory of evolution with two ingredients: the underlying emergent “fitness” landscape and an associated evolutionary force called “curl flux,” which causes species to move through the emergent fitness landscape in a spiraling manner.
The researchers captured evolutionary relationships in a system of equations. They then created quantitative pictures that visualized evolutionary pathways as journeys through a mountainous terrain of peaks and valleys of biological fitness. The key breakthrough beyond the conventional quantitative theory of evolution is the emergent curl flux, which is generated by interactions between individuals within or across species. The underlying emergent landscape gradient and the curl flux act together as a “Yin and Yang” duality pair to determine the dynamics of general evolution, says Wang. An example of similar behavior is the particle and wave duality that determines the dynamics of the quantum world, he notes. The researchers also note that this combined effect is analogous to the way electric and magnetic forces both act on electrons.
The new theory provides a physical foundation for general evolution dynamics. The researchers found that interactions between individuals of different species can give rise to the curl flux. This can sustain an endless evolution that does not lead to areas of higher relative fitness, even if the physical environment is unchanged.
This finding offers a theoretical framework to explain the Red Queen Hypothesis, which states that species continually evolve in order to fend off parasites that are themselves continually evolving. The hypothesis, first proposed by evolutionary biologist Leigh Van Valen in 1973, gets its name from the character of the Red Queen in Lewis Carroll’s book Through the Looking-Glass, who observed that in her world it was necessary to keep running just to stay in one place. The idea of endless co-evolution through the maintenance of the genetic variation due to the curl flux could help explain the benefits of sexual reproduction, since the mixing and matching of genes preserves a greater diversity of traits. When a species’ arms race with a co-evolving parasite takes an unexpected twist, a previously unnecessary trait could suddenly turn into the key to surviving. In the co-evolving world, there is no guarantee for “survival of the fittest” and it is often necessary to keep running for survival.
Source: PHYS.ORG
Scientists peek at the early evolution of sex chromosomes
Two new studies offer insight into sex chromosome evolution by focusing on papaya, a multimillion dollar crop plant with a sexual problem (as far as growers are concerned) and a complicated past.
The research reveals that the papaya sex chromosomes have undergone dramatic changes in their short evolutionary histories (they are about 7 million years old; by comparison, human sex chromosomes began their evolution more than 167 million years ago). One of the two studies compares the papaya X chromosome with that of a closely related non-sex chromosome (called an autosome) in a sister species. The other looks at differences between the X and Y chromosomes.
Predatory beetles can detect the unique alarm signal released by ants that are under attack by parasitic flies, and the beetles use those overheard conversations to guide their search for safe egg-laying sites on coffee bushes.
Full article: Predatory beetles eavesdrop on ants’ chemical conversations to find best egg-laying sites
Deep-sea squid removes its own arms to distract baffled predators
A species of deep sea squid can jettison its own bioluminescent arms to distract predators and attackers. Later, when the squid has safely escaped, it re-grows its lost limbs.
Moths know how to melt into the background
Many species of moth are experts in camouflage, with the ability to make themselves practically invisible to predators by matching the pattern on their wings with that of their background. But surprisingly little is known about the behaviour surrounding this conjuring trick.
Most creatures need a good sense of balance — especially tree-dwellers that swing among high branches. In mammals, the ability largely comes from three loop-shaped structures in the inner ear called semicircular canals; in most species, the size, shape, and arrangement of those loops (inset) is extremely consistent from one individual to another. But in three-toed sloths (such as Bradypus variegatus, the brown-throated three-toed sloth, pictured), many proportions of the semicircular canals are surprisingly variable from one sloth to another.
The overall variability is at least twice that seen in other species of mammals the team analyzed, researchers report online today in the Proceedings of the Royal Society B. That high degree of variation stems from the sloths’ languid lifestyle, the researchers suggest.
Sloths, which move extremely slowly when they move at all, don’t require the sense of balance that a swift, agile creature such as a primate needs. The finding supports one of Charles Darwin’s notions about evolution: If an organ isn’t crucial, variations in its structure or performance aren’t lost over time, keeping the potpourri in the population.
Artificial Beginnings: Understanding the Origin of Life by Recreating It
The Origin of Life on Earth was certainly, in retrospect, and from the human vantage point, the most fateful event in the history of the Universe. On a young, tepid Earth chemistry sprung into biology and set course on a four billion year journey that would eventually lead to us. However, all traces of the first, primitive organisms have vanished. They were outcompeted and devoured by their evolutionary descendents, leaving nothing to form fossils. Though we will never be able to set eyes on the first Earthlings, the first pioneers, we can understand what they must have been like through more subtle, indirect approaches. Comparative biochemistry across the whole of life takes us back quite a ways, though not to the first cells. The most recent common ancestor shared by all living organisms—bacteria, plants, animals, fungi, archaea, and unicellular eukaryotes like amoebae—was born long after the first cell ceased to exist. The only way we can truly understand what life must have been like in its earliest days is to create it ourselves.
Measuring the Evolution of Contemporary Western Popular Music
Popular music is a key cultural expression that has captured listeners’ attention for ages. Many of the structural regularities underlying musical discourse are yet to be discovered and, accordingly, their historical evolution remains formally unknown. Here we unveil a number of patterns and metrics characterizing the generic usage of primary musical facets such as pitch, timbre, and loudness in contemporary western popular music. Many of these patterns and metrics have been consistently stable for a period of more than fifty years. However, we prove important changes or trends related to the restriction of pitch transitions, the homogenization of the timbral palette, and the growing loudness levels. This suggests that our perception of the new would be rooted on these changing characteristics. Hence, an old tune could perfectly sound novel and fashionable, provided that it consisted of common harmonic progressions, changed the instrumentation, and increased the average loudness.